In our country rich in hydrocarbons, geothermal energy is a special exotic resource, which in today's state of affairs is unlikely to compete with oil and gas. Nevertheless, this alternative type of energy can be used almost everywhere and quite efficiently.
Geothermal Energy is the warmth of earthly subsoil. It is produced in depths and enters the surface of the Earth in different forms and with different intensity.
The temperature of the upper layers of the soil depends mainly on external (exogenous) factors - solar illumination and air temperature. In the summer and day, the soil is heated to certain depths, and in winter and at night is cooled after the change in air temperature and with some delay growing with depth. The effect of daily air temperature fluctuations ends at depths from units to several tens of centimeters. Seasonal oscillations capture deeper soil layers - up to dozen meters.
At some depth - from tens to hundreds of meters - the temperature of the soil is kept constant, equal to the average annual air temperature at the surface of the Earth. It is easy to make sure that descending into a fairly deep cave.
When the average annual air temperature in this area is below zero, it is manifested as an eternal (more precisely, a long-term) permafrost. In Eastern Siberia, power, that is, the thickness, year-round mourned soil reaches the 200-300 m places.
With some depth (for each point on the map), the effect of the sun and the atmosphere weakens so much that endogenous (internal) factors come out in first place and the terrestrial subsoil occurs from the inside, so the temperature with depth begins to grow.
Heatting the deep layers of the Earth bind mainly with the decay of radioactive elements there, although other heat sources are called, such as physico-chemical, tectonic processes in the deep layers of the earth's crust and mantle. But whatever caused, the temperature of rocks and the associated liquid and gaseous substances with depth is growing. The miners are faced with this phenomenon - in deep mines are always hot. At a depth of 1 km, the thirty-degree heat is a normal phenomenon, and deeper the temperature is even higher.
The thermal stream of earthly subsoil, reaching the surface of the Earth, is small - on average its power is 0.03-0.05 W / m 2, or about 350 W · b / m 2 per year. Against the background of the heat flux from the sun and heated air heated, this is an imperceptible value: the sun gives every square meter of the earth surface about 4,000 kWh every year, that is, 10,000 times more (of course, it is on average, with a huge scatter between polar and equatorial latitudes and depending on other climatic and weather factors).
The insignificance of the heat flux from the bowels to the surface on most of the planet is connected with the low thermal conductivity of rocks and the peculiarities of the geological structure. But there are exceptions - places where the heat flux is great. This is, first of all, the zones of tectonic faults, increased seismic activity and volcanism, where the energy of the earth's depth finds the output. For such zones, thermal abnormalities of the lithosphere are characteristic, here the heat flux, reaching the surface of the Earth, can be at times and even for orders more powerful "ordinary". A huge amount of heat to the surface in these zones is putting eruption of volcanoes and hot water sources.
Such areas are most favorable for the development of geothermal energy. In Russia, it is, above all, Kamchatka, Kuril Islands and the Caucasus.
At the same time, the development of geothermal energy is possible almost everywhere, since the rise in temperature with a depth - the phenomenon is ubiquitous, and the task is to "mining" heat from the bowels, just as mineral raw materials are produced from there.
On average, the temperature with depth grows by 2.5-3 ° C for every 100 m. The ratio of the temperature difference between two points lying at different depths, to the detection difference between them is called a geothermal gradient.
The inverse value is a geothermal stage, or the depth interval, on which the temperature rises by 1 ° C.
The higher the gradient and, accordingly, below the stage, the closer the heat of the depths of the Earth comes to the surface and the more promising this area for the development of geothermal energy.
In different areas, depending on the geological structure and other regional and local conditions, the rate of temperature growth with depth can vary abruptly. On the scale of land, the oscillations of the magnitudes of geothermal gradients and steps reach 25 times. For example, in Oregon (USA), the gradient is 150 ° C per 1 km, and in South Africa - 6 ° C is 1 km away.
The question is, what is the temperature at large depths - 5, 10 km and more? When the tendency is saved, the temperature at a depth of 10 km should be an average of approximately 250-300 ° C. This is more or less confirmed by direct observations in ultra-deep wells, although the picture is significantly more complicated to linear temperature increases.
For example, in the Kola ultra-deep well drilled in the Baltic Crystal Shield, the temperature to a depth of 3 km changes at a speed of 10 ° C / 1 km, and then the geothermal gradient becomes 2-2.5 times more. At a depth of 7 km, the temperature of 120 ° C was recorded, 10 km - 180 ° C, and 12 km - 220 ° C.
Another example is a well laid in Northern Caspiani, where at a depth of 500 m, a temperature of 42 ° C is registered, 1.5 km - 70 ° C, 2 km - 80 ° C, 3 km - 108 ° C.
It is assumed that the geothermal gradient decreases from the depth of 20-30 km: at a depth of 100 km, estimated temperatures about 1300-1500 ° C, at a depth of 400 km - 1600 ° C, in the core of the Earth (depth of more than 6000 km) - 4000-5000 ° C.
At depths up to 10-12 km, the temperature is measured through boreholes; There, where they are not, it is determined by indirect signs as well as at greater depths. Such indirect signs may be the nature of the passage of seismic waves or the temperature of the plowing lava.
However, for the purposes of geothermal energy, data on temperatures at depths of more than 10 km have not yet been practical interest.
At depths of a few kilometers a lot of heat, but how to raise it? Sometimes the nature itself solves this problem with the help of a natural coolant - heated thermal waters overlooking the surface or lowering depth accessible to us. In some cases, water in the depths of warming up to the state of the steam.
There is no strict definition of the concept of "thermal waters". As a rule, under them imply hot underground water in a liquid state or in the form of a steam, including the surface of the earth with a temperature above 20 ° C, that is, as a rule, higher than the air temperature.
The heat of groundwater, steam, steaming mixtures is hydrothermal energy. Accordingly, energy based on its use is called hydrothermal.
It is more difficult to deal with the production of heat directly dry rock - petrotermal energy, especially since sufficiently high temperatures, as a rule, begin with depths of several kilometers.
In Russia, the potential of petrotermal energy is a hundred times higher than that of hydrothermal, respectively, 3500 and 35 trillion tons of conventional fuel. It is quite natural - the heat of the depths of the Earth is everywhere, and the thermal waters are found locally. However, due to the obvious technical difficulties to obtain heat and electricity, the most part of thermal waters are currently used.
Water temperature of 20-30 to 100 ° C is suitable for heating, temperature from 150 ° C and higher - and to generate electricity at geothermal power plants.
In general, geothermal resources in Russia in terms of conventional fuel or any other unit of energy measurement approximately 10 times higher than organic fuel reserves.
Theoretically, only by geothermal energy could be fully satisfying the country's energy needs. Almost at the moment, for the most part of its territory, it is impracticable for technical and economic considerations.
In the world, the use of geothermal energy is most often associated with Iceland - a country located at the northern end of the Mid-Atlantic Range, in an exceptionally active tectonic and volcanic zone. Probably, everyone remembers the powerful eruption of the volcanic Eyyafyatlayokud ( Eyjafjallajökull.) in 2010 year.
It is thanks to such geological specifics, Iceland has huge reserves of geothermal energy, including hot springs emerging on the surface of the Earth and even fountaining in the form of geysers.
In Iceland, currently more than 60% of all energy consumed are taken from the ground. Including due to geothermal sources, 90% of heating and 30% of electricity generation are ensured. We add that the rest of the electricity in the country is made on the hydropower plant, that is, also using a renewable energy source, so Iceland looks like a certain world environmental standard.
"Taming" of geothermal energy in the 20th century was noticeably helped by Iceland in economically. Until the middle of the last century, she was a very poor country, now ranks first in the world at the installed capacity and the production of geothermal energy per capita and is in the top ten in the absolute value of the installed capacity of geothermal power plants. However, its population is only 300 thousand people, which simplifies the task of the transition to environmentally friendly sources of energy: the need for it is generally small.
In addition to Iceland, the high proportion of geothermal energy in the general balance of electricity generation is provided in New Zealand and Island States of Southeast Asia (Philippines and Indonesia), Central America and East Africa, the territory of which is also characterized by high seismic and volcanic activity. For these countries, with their current level of development and needs, geothermal energy makes a significant contribution to socio-economic development.
The use of geothermal energy has a very long history. One of the first known examples is Italy, the place in the province of Tuscany, now called Larderllo, where else at the beginning of the XIX century local hot thermal waters, poured naturally or mined from non-short wells, were used in energy purposes.
Water from underground sources rich in boron was used here for the preparation of boric acid. Initially, this acid was obtained by evaporation method in iron boilers, and as fuel took ordinary firewood from the nearest forests, but in 1827, Francesco Larderel (Francesco Larderel) created a system worked on the warmth of the waters themselves. At the same time, the energy of the natural water vapor began to be used for the operation of drilling rigs, and at the beginning of the 20th century - and for heating of local houses and greenhouses. In the same place, in Larderllo, in 1904, thermal water vapor became an energy source for receiving electricity.
In the example of Italy at the end of the XIX century, some other countries followed. For example, in 1892, thermal waters were first used for local heating in the United States (Boise, Idaho), in 1919 in Japan, in 1928 in Iceland.
In the US, the first power plant operating on hydrothermal energy appeared in California in the early 1930s, in New Zealand - in 1958, in Mexico - in 1959, in Russia (the first binary geoes binary) - in 1965 .
Old principle on a new source
Electricity generation requires a higher temperature of the hydroist operator than for heating, more than 150 ° C. The principle of operation of the geothermal power plant (GEOES) is similar to the principle of operation of a conventional thermal power plant (TPP). In fact, the geothermal power station is a type of TPP.
The TPP in the role of the primary source of energy is, as a rule, coal, gas or fuel oil, and the working fluid serves water vapor. Fuel, burning, heats water to a steam state that rotates a steam turbine, and it generates electricity.
The difference between the GeoES is that the primary source of energy here is the heat of earthly bowrs and the working fluid in the form of a pair enters the blades of the electric generator turbine in the "finished" form directly from the mining well.
There are three main schemes of work geoes: straight, using dry (geothermal) steam; Indirect, based on hydrothermal water, and mixed, or binary.
The use of one or another scheme depends on the aggregate state and the temperature of the energy carrier.
The most simple and therefore the first of the developed schemes is straight, in which steam coming from the well is skipped directly through the turbine. On the dry pair worked and the first geoes in the world in Larderllo in 1904.
GEOES with indirect work scheme in our time the most common. They use hot underground water, which is injected under high pressure into the evaporator, where part of it is evaporated, and the resulting steam rotates the turbine. In some cases, additional devices and contours are required for cleaning geothermal water and steam from aggressive compounds.
The spent pair enters the discharge well is either used to heating the premises - in this case the principle is the same as the operation of the CHP.
On binary geoes, hot thermal water interacts with another liquid that performs the function of the working fluid with a lower boiling point. Both fluids are passed through the heat exchanger, where thermal water evaporates the working fluid, the pairs of which rotate the turbine.
This system is closed, which solves the problems of emissions into the atmosphere. In addition, working fluids with a relatively low boiling point allow you to use as a primary source of energy and not very hot thermal waters.
In all three schemes, a hydrothermal source is operated, but petrotermal energy can be used to produce electricity.
The schematic diagram in this case is also quite simple. It is necessary to drill two wells connected between their wells - injection and operational. Water pumps water into the discharge well. At the depth, it is heated, then the heat of water or the steam-generated wells formed as a result of strong heating is supplied to the surface. Further, it all depends on how the petrotermal energy is used - for heating or for the production of electricity. A closed cycle is possible with downloading the spent steam and water back to the discharge well or another method of recycling.
The lack of such a system is obvious: to obtain a sufficiently high temperature of the working fluid, the wells must be drilled into a large depth. And these are the serious costs and the risk of significant heat loss when the fluid moves up. Therefore, petrothermal systems are less common compared to hydrothermal, although the potential of petrothermal energy to orders above.
Currently, the leader in the creation of the so-called petrotermal circulation systems (PCS) is Australia. In addition, this direction of geothermal energy is actively developing in the United States, Switzerland, Great Britain, Japan.
Gift Lord Kelvin
The invention in 1852 by the thermal pump by Physico William Thompson (he - Lord Kelvin) provided mankind the real possibility of using low-precious heat of the upper layers of the soil. The heat pump system, or, as Tompson called it, the heat multiplier is based on the physical process of transferring heat from the environment to the refrigerant. In fact, it uses the same principle as in petrothermal systems. The difference is in the heat source, in connection with which there may be a terminological question: how much can the heat pump be considered exactly the geothermal system? The fact is that in the upper layers, to the depths in tens of hundreds of meters, the breeds and the fluids contained in them are heated not by the deep heat of the Earth, but the Sun. Thus, it is the sun in this case - the primary source of heat, although it is closed, as in geothermal systems, from the Earth.
The operation of the heat pump is based on the delay of warm-up and cooling the soil compared to the atmosphere, as a result of which the temperature gradient is formed between the surface and deeper layers, which retain heat even in winter, just as it happens in reservoirs. The main purpose of heat pumps is heating the premises. In essence, this is a refrigerator on the contrary. " And the heat pump, and the refrigerator interact with the three components: the internal medium (in the first case - heated room, in the second - the cooled refrigerator chamber), the external environment - the source of energy and the refrigerant (refrigerant), is the coolant, which provides heat transfer or heat carrier cold.
In the role of refrigerant, there is a substance with a low boiling point, which allows it to select heat from a source, having even a relatively low temperature.
In the refrigerator, the liquid refrigerant through the choke (pressure regulator) enters the evaporator, where due to a sharp decrease in pressure, the fluid evaporates. Evaporation is an endothermic process that requires the absorption of heat from the outside. As a result, heat from the inner walls of the evaporator is closed, which provides a cooling effect in the refrigerator chamber. Next, the refrigerant is suused from the evaporator to the compressor, where it returns to the liquid aggregate state. This is the reverse process leading to the emission of treated heat into the external environment. As a rule, it is thrown into the room, and the rear wall of the refrigerator is relatively warm.
The heat pump is working almost the same way, with the difference that the heat is closed from the outside environment and through the evaporator enters the inner medium - the system of heating the room.
In the real heat pump, water is heated by passing along an external contour laid in the ground or water, further enters the evaporator.
In the evaporator, heat is transferred to the inner circuit filled with a low boiling refrigerant, which, passing through the evaporator, moves from a liquid state into a gaseous, taking heat.
Next, the gaseous refrigerant enters the compressor, where it is compressed to high pressure and temperature, and enters the capacitor, where heat exchange occurs between the hot gas and the heat carrier from the heating system.
Electricity is required for the compressor, the transformation coefficient (the ratio of consumed and generated energy) in modern systems is high enough to ensure their effectiveness.
Currently, heat pumps are quite widely used for premises heating, mainly in economically developed countries.
Ekocorgetic energy
Geothermal energy is considered environmentally friendly, which is generally fair. First of all, it uses a renewable and practically inexhaustible resource. Geothermal energy does not require large areas, unlike large hydropower plants or wind farms, and does not pollute the atmosphere, unlike hydrocarbon energy. On average, geoes occupies 400 m 2 in terms of 1 GW of electricity generated. The same indicator for coal TPP, for example, is 3600 m 2. The environmental benefits of geo supplies also include low water consumption - 20 liters of fresh water per 1 kW, while for TPP and NPPs require about 1000 liters. Note that these are environmental indicators of the "average" geoes.
But negative side effects are still available. Among them, there are most often distinguished by noise, thermal pollution of the atmosphere and chemical - water and soil, as well as the formation of solid waste.
The main source of chemical pollution of the medium is actually thermal water (with high temperature and mineralization), often containing large amounts of toxic compounds, and therefore there is a problem of disposal of waste water and hazardous substances.
The negative effects of geothermal energy can be traced at several stages, starting with drilling wells. Here there are the same dangers as when drilling any well: the destruction of soil and vegetable cover, soil pollution and groundwater.
At the stage of operation, geoes and environmental pollution problems are saved. Thermal fluids - water and steam - usually contain carbon dioxide (CO 2), sulfur sulphide (H 2 S), ammonia (NH 3), methane (CH 4), cook salt (NaCl), Bor (B), arsenic (AS ), mercury (HG). When emissions into the external environment, they become sources of its pollution. In addition, an aggressive chemical environment can cause corrosion destruction of geotes structures.
At the same time, emissions of pollutants on geoes are on average lower than on TPP. For example, carbon dioxide emissions for each kilowatt-hour of generated electricity are up to 380 g per geoes, 1042 g - on coal TPPs, 906 g - on fuel oil and 453 g - on gas TPPs.
The question arises: what to do with spent water? With low mineralization, it may be dropped into surface water after cooling. Another way is to pump it back into the aquifer through the injection well, which is preferable and mostly applied at present.
The mining of thermal water from aquifers (as well as the reappearing of ordinary water) can cause prepaid and movement of the soil, other deformations of geological layers, microdellex. The probability of such phenomena is usually small, although individual cases are fixed (for example, on GeoPES in Paufen-im-Bryceau in Germany).
It should be emphasized that most of the geoes is located on comparatively incompaired territories and in the third world countries, where environmental requirements are less hard than in developed countries. In addition, at the moment the number of geoes and their capacity is relatively small. With a more large-scale development of geothermal energy, environmental risks may increase and multiply.
How much is the energy of the earth?
Investment costs for the construction of geothermal systems vary in a very wide range - from 200 to $ 5,000 per 1 kW of installed capacity, that is, the cheapest options are comparable to the cost of construction of the TPP. They depend, first of all, on the conditions of the location of thermal waters, their composition, system designs. Drilling for greater depth, the creation of a closed system with two wells, the need for water purification can repeatedly increase the cost.
For example, investments in the creation of a petrothermal circulation system (PCS) are estimated at 1.6-4 thousand dollars per 1 kW of installed capacity, which exceeds the costs of building a nuclear power plant and comparable to the cost of building wind and solar power plants.
The obvious economic advantage of GEOTES is a free energy. For comparison, in the cost structure of a working TPP or NPP on fuel accounts for 50-80% or more, depending on the current energy prices. Hence another advantage of the geothermal system: costs during operation are more stable and predictable, since they do not depend on the external consideration of energy prices. In general, the operational costs of GEOTES are estimated at 2-10 cents (60 kop.-3 rubles) per 1 kWh of the power produced.
The second in size after the energy carrier (and very significant) the cost of expenses is, as a rule, the salary of the station staff, which can radically differ in countries and regions.
On average, the cost of 1 kWh of geothermal energy is comparable to that for TPPs (in Russian conditions - about 1 rub. / 1 \u200b\u200bkWh) and ten times higher than the cost of electricity generation on hydroelectric power plants (5-10 kopecks / 1 kWh h ).
Partly the reason for the high cost is that, unlike thermal and hydraulic power plants, GEOTES has a relatively small power. In addition, it is necessary to compare systems that are in one region and under similar conditions. Thus, for example, in Kamchatka, according to experts, 1 kWh of geothermal electricity costs 2-3 times cheaper than electricity produced on local TPPs.
Indicators of the economic efficiency of the geothermal system depends, for example, whether it is necessary to dispose of spent water and which methods this is done whether the combined use of the resource is possible. Thus, chemical elements and compounds extracted from thermal water can give an additional income. Recall the example of Larderllo: the primary there was precisely chemical production, and the use of geothermal energy originally was auxiliary.
Forwards of geothermal energy
Geothermal energy develops somewhat different than wind and sunny. Currently, it is significantly more dependent on the nature of the resource itself, which is sharply different from the regions, and the greatest concentrations are tied to narrow zones of geothermal anomalies associated, as a rule, with areas of development of tectonic faults and volcanism.
In addition, geothermal energy is less technologically capacious than a windmill and especially with solar energy: geothermal stations systems are quite simple.
In the overall structure of world electricity production, the geothermal component accounts for less than 1%, but in some regions and countries, its share reaches 25-30%. Due to the binding to geological conditions, a significant part of the geothermal energy capacity is concentrated in the countries of the third world, where three clusters of the largest development of the industry - Islands of Southeast Asia, Central America and East Africa are distinguished. The first two regions are included in the Pacific "Fire Belt of the Earth", the third is tied to the East African rift. With the greatest probability of geothermal energy and will further develop in these belts. A more distant perspective is the development of petrothermal energy that uses the heat of the land layers lying at a depth of several kilometers. It is almost a commonly common resource, but its extraction requires high costs, so petrothermal energy develops primarily in the most economically and technologically powerful countries.
In general, taking into account the widespread spread of geothermal resources and an acceptable level of environmental safety, there is reason to assume that geothermal energy has good development prospects. Especially when increasing the threat of traditional energy deficits and price increases for them.
From Kamchatka to the Caucasus
In Russia, the development of geothermal energy has a fairly long history, and for a number of positions we are among the world leaders, although in the general energy balance of a huge country, the share of geothermal energy is still insignificantly small.
Two regions - Kamchatka and the North Caucasus were pioneers and centers of development of geothermal energy in Russia, and if in the first case we are talking primarily about the electric power industry, then in the second - on the use of thermal water thermal energy.
In the North Caucasus - in the Krasnodar Territory, Chechnya, Dagestan - the heat of thermal waters for energy purposes was used before the Great Patriotic War. In the 1980s and 1990s, the development of geothermal energy in the region for obvious reasons was stalled and until the status of stagnation came out. Nevertheless, geothermal water supply in the North Caucasus provides a warmth of about 500 thousand people, and, for example, the city of Labinsk in the Krasnodar Territory with a population of 60 thousand people is completely heated due to geothermal waters.
In Kamchatka, the history of geothermal energy is associated primarily with the construction of geoes. The first of them, still working the Pujet and Parantunsk stations, were built back in 1965-1967, while the Paranthan geo ECPP with a capacity of 600 kW became the first station in the world with a binary cycle. It was the development of Soviet scientists S. S. Kutateladze and A. M. Rosenfeld from the Institute of Thermal Physics of the Siberian Branch of the Russian Academy of Sciences, which received the author's certificate of electricity from water from 70 ° C in 1965. This technology subsequently became a prototype for more than 400 binary geoes in the world.
The power of the Pozheti Geo ESP commissioned in 1966 was originally 5 MW and was subsequently increased to 12 MW. Currently, the station is the construction of a binary bloc, which will increase its capacity for another 2.5 MW.
The development of geothermal energy in the USSR and Russia was hampered by the availability of traditional energy resources - oil, gas, coal, but never stopped. The largest objects of geothermal energy - Upper-Mutnovskaya GEAS with the total power of power units of 12 MW, commissioned in 1999, and Mutnovskaya geo-MW Mutovskaya geoce (2002).
Mutnovskaya and Verkhne-Mutnovskaya geoes - unique objects not only for Russia, but also on a global scale. The stations are located at the foot of the Volcano Mutnovsky, at an altitude of 800 meters above sea level, and work in extreme climatic conditions, where 9-10 months in the year winter. The equipment of the Mutnov geoes, at the moment one of the most modern in the world is fully created at domestic enterprises of energy engineering.
Currently, the share of Mutnov stations in the overall structure of energy consumption of the Central-Kamchatka Energy Node is 40%. In the coming years it is planned to increase power.
Separately, it should be said about Russian petrothermal developments. There are no large PCS yet, but there are advanced drilling technologies for greater depth (about 10 km), which also have no analogues in the world. Their further development will significantly reduce the cost of creating petrotermal systems. Data Developers Technologies and Projects - N. A. Gnatus, M. D. Khutorskaya (Geological Institute of the Russian Academy of Sciences), A. S. Nekrasov (Institute of National Economic Forecasting of the Russian Academy of Sciences) and specialists of the Kaluga Turbine Plant. Now the project of a petrothermal circulation system in Russia is at the experimental stage.
The prospects for geothermal energy in Russia are, although relatively removable: at the moment, the potential is quite high and the positions of traditional energy. At the same time, in a number of remote areas of the country, the use of geothermal energy is economically profitable and in demand now. It is a territory with high geo-energy potential (Chukotka, Kamchatka, Kuriles - the Russian part of the Pacific "Fiery Belt of the Earth", Mountains of Southern Siberia and the Caucasus) and at the same time remote and cut off from centralized energy supply.
In the coming decades, geothermal energy in our country will develop in such regions in our country.
One of the best, rational techniques in the construction of capital greenhouses is an underground thermos greenhouse.
Using this fact of constancy of the temperature of the earth at a depth, in the greenhouse device gives a colossal savings of heating costs during the cold season, facilitates care, makes microclimate more stable.
Such a greenhouse works in the most ending frost, allows vegetables, grow flowers all year round.
Properly equipped bellbed greenhouse makes it possible to grow, including thermal-loving southern crops. There are practically no restrictions. Citrus and even pineapples can feel great in the greenhouse.
But in order to practice everything in practice, it is necessary to observe the tested technologies for which underground greenhouses were built. After all, this idea is not new, while the Tsar in Russia, the greenhouses were given the crops of pineapples, which enterprising merchants were exported to the sale to Europe.
For some reason, the construction of such greenhouses did not find in our country of great distribution, by and large, it is just forgotten, although the design is ideal just for our climate.
Probably the role here played the need to dig a deep pit, filling the foundation. Construction of a plugged greenhouse is quite costly, this is not a greenhouse, covered with polyethylene, but also the return from the greenhouse is much more.
The overall internal illumination is not lost from the gluke to the ground, this may seem strange, but in some cases light saturation is even higher than that of classic greenhouses.
It is impossible not to mention the strength and reliability of the design, it is incomparably stronger than the usual, it is easier to carry the hurricane gusts of the wind, it is well opposed to hail, no interference and snow breakdowns.
1. Kotlovan
Creating a greenhouse begins with digging a pit. To use the heat of the earth to heat the internal volume, the greenhouse must be fairly in-depth. The deeper, the Earth becomes warmer.
The temperature almost does not change during the year at a distance of 2-2.5 meters from the surface. At a depth of 1 m, the temperature of the soil fluctuates more, but also in winter it remains positive, usually in the middle band the temperature is 4-10 seconds, depending on the time of year.
Burning greenhouse is being built in one season. That is, in the winter it will completely be able to function and generate income. The construction is not cheap, but by applying the smelting, compromise materials, it is possible to save literally for an integer order by making a kind of economy, starting from the pit.
For example, do without attracting construction equipment. Although the most time-consuming part of the work is to dig a pit -, of course, it is better to give the excavator. Manually remove such a volume of land hard and long.
The depth of the pit of the pit should be at least two meters. At such a depth, the Earth will begin to share its warmth and work as a kind of thermos. If the depth is less, then a fundamentally idea will work, but noticeably less efficient. Therefore, it is recommended not to regret the forces and funds for the deepening of the future greenhouse.
In the length of underground greenhouses can be any, but the width is better to withstand within 5 meters, if the width is greater, then the qualitative characteristics of heating and lighting deteriorate.
On the side of the horizon, underground greenhouses need to be focused, as ordinary greenhouses and greenhouses, from the east to the west, that is, so that one side of the sides is facing south. In this position of the plant will receive the maximum amount of solar energy.
2. Walls and roof
On the perimeter, the foundation is flooded or blocks blocks. The foundation serves as the basis for walls and framework frames. The walls are better made from materials with good thermal insulation characteristics, an excellent option - thermoblocks.
The roof frame is more likely made by wooden, from impregnated with antiseptic means of bars. Roof design usually straight duplex. The skater bar is fixed in the construction center, for this purpose, central supports are installed on the floor along the entire length of the greenhouse.
The ski bar and walls are connected near the rafal. The frame can be made without high supports. They are replaced with small, which put on transverse beams connecting the opposite side of the greenhouse - this design makes the inner space freely.
It is better to take a cellular polycarbonate as a roof covering - popular modern material. The distance between the construction rafters is customized under the width of polycarbonate sheets. Working with the material is convenient. The coating is obtained with a small amount of joints, since sheets are produced with a length of 12 m.
They are attached to the frame with self-drawing, they are better to choose with a hat in the form of a washer. To avoid cracking, under each self-tapping screw, drill a drill hole of the corresponding diameter. With the help of a screwdriver, or a regular drill with a crossed bat, work on glazing moves very quickly. In order not to be left for the cracks, it is good at the top of the top laying rafters with a soft rubber seal or other suitable material and only then fasten sheets. The peak of the roof along the skate must be paved with a mild insulation and press some kind of corner: plastic, from tin, from another suitable material.
For good thermal insulation, the roof is sometimes made with a double layer of polycarbonate. Although transparency decreases by about 10%, but this is covered with excellent thermal insulation characteristics. It is necessary to consider that the snow does not melt on such a roof. Therefore, the skate must be at a sufficient angle, not less than 30 degrees so that the snow on the roof is accumulated. Additionally, an electric vibrator is installed for shaking, it will save the roof in case the snow will still accumulate.
Double glazing are made in two ways:
Between the two sheets insert a special profile, sheets are attached to the frame from above;
First mount the lower layer of glazing to the frame from the inside, to the underside of the rafted. The second layer of the roof is covered, as usual, on top.
After completion, it is desirable to smoke all the joints of the scotch. The finished roof looks very effectively: without unnecessary junctions, smooth, without outstanding parts.
3. Warming and heating
Wall insulation is carried out as follows. Previously, it is necessary to thoroughly melt all the joints and seams of the wall with a solution, here you can apply the mounting foam. The inner side of the walls are covered with a film of thermal insulation.
In the cold parts of the country, it is good to use a foil tolst film, covering the wall by a double layer.
The temperature in the depth of soil the greenhouse is higher than zero, but colder air temperatures needed for plant growth. The upper layer is heated by the solar rays and the air of the greenhouse, but still the soil takes the heat, so often in underground greenhouses use the technology of "warm floors": the heating element is the electrical cable - protect the metal grid or poured concrete.
In the second case, the soil for the beds pour over concrete or grow greens in pots and vases.
The use of a warm floor can be sufficient for heating the entire greenhouse, if there is enough power. But more efficiently and more comfortable for plants. Use of combined heating: warm floor + heated air. For good growth, they need air temperature of 25-35 degrees at the temperature of the Earth approximately 25 C.
Conclusion
Of course, the construction of a bellged greenhouse will cost more, and efforts will need more than in the construction of a similar greenhouse of a conventional design. But the means embedded in the greenhouse with time are justified.
First, it is energy savings on heating. In no matter how the usual ground greenhouse is heard in winter time, it will always be more expensive and more difficult to a similar method of heating in an underground greenhouse. Secondly, saving on lighting. Foil thermal insulation of walls, reflecting light, increases the illumination by two times. The microclimate in the in-depth greenhouse in winter for plants will be more favorable that it will certainly affect the yield. Saplings will easily come true, gentle plants will feel perfectly. Such a greenhouse guarantees a stable, high crop of any plants all year round.
Instead of pre-sister.
Smart and friendly people indicated that this case should be evaluated only in nonstationary production, due to the huge thermal inertia of the Earth and take into account the annual temperature change mode. The example performed is resolved for the stationary heat field, therefore it has obviously incorrect results, so it should be considered only as a certain idealized model with a huge amount of simplifications showing temperature distribution in stationary mode. So as they say, any coincidence is a pure chance ...
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As usual, I will not give a lot of specifics about the thermal conductivity and thicknesses of the materials, I will limit the description of only some, we assume that other elements are as close as possible to real structures - the thermophysical characteristics are assigned correctly, and the thickness of the materials are adequate to real cases of construction practice. The purpose of the article is to obtain a framework on the distribution of temperatures on the border of the ground building under different conditions.
A little about what you need to say. The calculated schemes in this example contain 3 temperature boundaries, 1st this inner air of the premises of the heated building +20 o C, 2nd is the outer air -10 ° C (-28 o C), and 3rd this temperature in the soil thickness At a certain depth, on which it fluctuates about some constant value. In this example, the value of this depth is 8m and the temperature of +10 O S. Here's here with me someone can argue with respect to the parameters of the 3rd borders, but the dispute about the exact values \u200b\u200bis not a task of this article, as well as the results not Apply for a particular accuracy and possibility of binding to some particular project case. I repeat, the task is to obtain a fundamental, framework for the distribution of temperatures, and check out some of the well-established views on this issue.
Now directly to business. So theses to be checked.
1. The soil under the heated building has a positive temperature.
2. The regulatory depth of the primer of the soil (there is rather the question than the approval). Does the snow cover of the soil takes into account when the data on the freezing in geological reports is given, because as a rule, the territory around the house is cleared of snow, the tracks, sidewalks, soulstek, parking, etc. are cleaned.
Merging the soil is a process in time, therefore, for calculating, we will take an outer temperature equal to the average temperature of the most cold month -10 o C. Soil, we will apply with the above lambda \u003d 1 to the entire depth.
Fig.1. Calculation scheme.
Fig.2. Insulating temperature. Scheme without snow cover.
In general, under the building the temperature of the soil is positive. The maxima closer to the center of the building, to the outer walls of the minimum. Insulating zero temperatures horizontally only applies to the projection of heated room on a horizontal plane.
The freezing of the soil away from the building (i.e., the achievement of negative temperatures) occurs at a depth of ~ 2.4 meters, which is more regulatory value for the selected conditionally region (1.4-1.6m).
Now add 400mm of the middle-density snow with lambda 0.3.
Fig.3. Insulating temperature. Scheme with snow cover 400mm.
The insulance of positive temperatures displaces negative temperatures outward, under the building only positive temperatures.
Dry freezing under snow cover ~ 1.2 meters (-0.4m snow \u003d 0.8m soil freezing). The snow "blanket" significantly reduces the depth of freezing (almost 3 times).
Apparently the presence of snow cover, its height and degree of seal is not constant value, therefore the average drainage depth is in the range of obtained results of 2 schemes, (2.4 + 0.8) * 0.5 \u003d 1.6 meters, which corresponds to the regulatory value.
Now let's see what will happen if strong frosts hit (-28 o c) and preserve enough long enough so that the thermal field is stabilized, while there is no snow cover around the building.
Fig.4. Scheme at -28 about With without snow cover.
Negative temperatures climb under the building, positive pressed to the floor of the heated room. In the foundations area, the soils are frozen. At the removal from the building, the soils are frozen by ~ 4.7 meters.
See previous blog entries.
Description:
In contrast to the "direct" use of high-precanced geothermal heat (hydrothermal resources), the use of soil of surface layers of the Earth as a source of low-precious thermal energy for geothermal heat-pumping heat supply systems (GTST) is almost everywhere. Currently, in the world, this is one of the most dynamically developing areas of use of non-traditional renewable energy sources.
Geothermal heat-pumping systems of heat supply and efficiency of their use in the climatic conditions of Russia
G. P. Vasilyev, supervisor OJSC Insolar-Invest
In contrast to the "direct" use of high-precanced geothermal heat (hydrothermal resources), the use of soil of surface layers of the Earth as a source of low-precious thermal energy for geothermal heat-pumping heat supply systems (GTST) is almost everywhere. Currently, in the world, this is one of the most dynamically developing areas of use of non-traditional renewable energy sources.
The soil of surface layers of the Earth is actually a thermal battery of unlimited power. The heat regime of the soil is formed under the action of two main factors - falling on the surface of solar radiation and the flow of radiogenic heat from the earth's decrees. Seasonal and daily changes in the intensity of solar radiation and the outer air temperature cause fluctuations in the temperature of the upper layers of the soil. The depth of penetration of daily oscillations of the outer air temperature and the intensity of incident solar radiation, depending on the specific soil and climatic conditions, ranges from several tens of centimeters to one and a half meters. The depth of penetration of seasonal oscillations of the temperature of the outer air and the intensity of incident solar radiation does not exceed, as a rule, 15-20 m.
The thermal mode of the soil layers located below this depth ("neutral zone") is formed under the influence of thermal energy coming from the depths of the Earth and is practically independent of seasonal, and even more so daily changes in the parameters of the external climate (Fig. 1). With increasing depth, the soil temperature also increases in accordance with the geothermal gradient (approximately 3 ° C per every 100 m). The magnitude of the flow of radiogenic heat coming from earthly subsoils is varied for different locals. As a rule, this value is 0.05-0.12 W / m 2.
Picture 1. |
During the operation of the GTST, the ground array, which is within the heat influence zone of the pipeline of the soil heat exchanger of the low-precision heat treatment system (heatboring system), due to the seasonal change in the exterior climate parameters, as well as under the influence of operational loads on the heat collection system, as a rule, is subjected to multiple freezing and thawing. At the same time, naturally, a change in the aggregate state of moisture concluded in the pores of the soil and in general, both in liquid and in solid and gaseous phases simultaneously. At the same time, in capillary-porous systems, which is the soil array of the heat supply system, the presence of moisture in the pore space has a noticeable effect on the process of propagation of heat. The correct accounting of this influence today is associated with significant difficulties that are primarily associated with the lack of clear ideas about the nature of the distribution of solid, liquid and gaseous phases of moisture in a particular system structure. In the presence of a soil array of a temperature gradient, the water vapor molecule is moved to places having a reduced temperature potential, but at the same time, the oppositely directed flow of moisture in the liquid phase occurs under the action of gravitational forces. In addition, the temperature of the surfaces of atmospheric precipitation, as well as groundwater, has an influence of the upper layers of the soil.
The characteristic features of the thermal mode of the heat collection systems of the soil as an object of design should also include the so-called "informative uncertainty" of mathematical models describing such processes, or, in other words, the lack of reliable information on the environmental impacts (atmosphere and massif of the soil located Outside the heat influence zone of the soil heat exchanger of the heat supply system) and the emergency complexity of their approximation. Indeed, if approximation of impacts on the external climate system, although difficult, but still at certain costs of "machine time" and the use of existing models (for example, a "typical climate year") can be implemented, then the problem of accounting in the model of influence on the atmospheric system Effects (dew, fog, rain, snow, etc.), as well as approximation of the thermal influence on the ground array of the heat collection system of the underlying and surrounding layers of the soil today is practically not solvable and could be a subject of individual research. For example, a small study of the processes for the formation of filtration streams of groundwater, their high-speed regime, as well as the impossibility of obtaining reliable information about the heat-magnetic mode of the soil layers, which are below the heat influence zone of the soil heat exchanger, significantly complicates the problem of constructing the correct mathematical model of the thermal regime of the low-precision heat collection system. Soil.
To overcome the described difficulties arising from the design of the GTST, the method of mathematical modeling of the thermal regime of the heat collection systems and the methodology of accounting in the design of the GTST of the moisture phase transitions in the pore space of the soil massif of heat supply systems in the pore space of the soil array of thermal assembly systems are recommended.
The essence of the method consistent with the constructing of a mathematical model of the difference of two tasks: "base" problem describing the thermal regime of the soil in the natural state (without the influence of the soil heat exchanger of the heat supply system), and the solid problem describing the heat mode of the soil massif with drains (sources) of heat. As a result, the method allows to obtain a solution with respect to some new function, which is the function of the effect of heat drainage on the natural thermal mode of soil and equal difference in the temperature of the soil array in the natural state and the ground massif with drains (heat sources) - with a soil heat scale of the heat collection system. The use of this method when constructing mathematical models of the heat regime of the low-precision heat collection systems made it possible not only to circumvent the difficulties associated with approximation of external influences on the heat supply system, but also use information about the natural heat mode of the soil in the models of experimentally obtained meteorological stations. This allows partially to take into account the entire complex of factors (such as the presence of groundwater, their high-speed and thermal regimes, the structure and location of the soil layers, the "thermal" background of the earth, atmospheric precipitation, the phase transformations of moisture in the pore space and much more), which are essentially affecting The formation of the thermal regime of the heat supply system and joint accounting of which in the strict formulation of the problem is practically not possible.
The methods of accounting in the design of the GTST of the moisture phase transitions in the pore space of the ground massif is based on the new concept of "equivalent" soil thermal conductivity, which is determined by replacing the thermal mode of the thermal heat exchanger of the soil cylinder of the "equivalent" quasi-stationary task with a close temperature field and the same boundary conditions, but with another "equivalent thermal conductivity.
The most important task solved in the design of geothermal heat supply systems of buildings is the detailed assessment of the energy capabilities of the climate of the construction area and on this basis the preparation of the conclusion on the efficiency and appropriateness of the application of a particular scheme decision of the GTST. The calculated values \u200b\u200bof climate parameters given in existing regulatory documents do not give the complete characteristics of the external climate, its variability in months, as well as during certain periods of the year - the heating season, the period of overheating, etc. Therefore, when solving the question of the temperature potential of geothermal heat, an assessment of its capabilities. Combined with other natural sources of low potential heat, assessing their (sources) of the temperature level in the annual cycle, it is necessary to attract more complete climatic data provided, and for example, in the USSR Climate Directory (L.: Hydrometioizudate. Vol. 1-34).
Among such climate information in our case should be allocated, first of all:
- data on the average monthly temperature of the soil at different depths;
- data on the flow of solar radiation on different oriented surfaces.
In tab. 1-5 shows data on average monthly soil temperatures at various depths for some cities of Russia. In tab. 1 shows the average monthly temperature of the soil according to 23 cities of the Russian Federation at a depth of 1.6 m, which seems the most rational, in terms of the temperature potential of the soil and the possibilities of mechanization of work on the embedding of horizontal soil heat exchangers.
| Table 1 Middle soil temperatures for months at a depth of 1.6 m for some cities of Russia |
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| table 2 Soil temperature in Stavropol (soil - Chernozem) |
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| Table 3. Soil temperature in Yakutsk (soil or sandy with an admixture of humus, below - sand) |
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| Table 4. Soil temperature in Pskov (bottom, drinned soil, Substate - Clay) |
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| Table 5. The temperature of the soil in Vladivostok (Buuray's soil is rocky, bulk) |
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The information presented in the tables on the natural progress of the soil temperature at a depth of up to 3.2 m (i.e. in the "worker" of the soil layer for the GTST with the horizontal arrangement of the soil heat exchanger) clearly illustrates the possibilities of using the soil as a low potential heat source. An obvious is a relatively small interval of changes in the territory of Russia temperatures of the layers located at the same depth. For example, the minimum soil temperature at a depth of 3.2 m from the surface in the city of Stavropol is 7.4 ° C, and in Yakutsk - (-4.4 ° C); Accordingly, the interval of changes in the temperature of the soil at this depth is 11.8 degrees. This fact allows us to rely on the creation of a sufficient degree of unified heat-pumping equipment suitable for practically throughout Russia.
As can be seen from the tables presented, the characteristic feature of the natural temperature mode of the soil is the retardation of the minimum soil temperatures relative to the time of receipt of the minimum temperature of the outer air. The minimum outdoor air temperatures are observed in January, the minimum temperatures in the ground at a depth of 1.6 m in Stavropol are observed in March, in Yakutsk - in March, in the city of Sochi - in March, in Vladivostok - in April . Thus, it is obvious that by the time of the onset of minimum temperatures in the soil, the load on the heat-pumping system of heat supply (heat loss) is reduced. This moment opens up quite serious opportunities to reduce the installation capacity of the GTST (capital costs) and must be taken into account when designing.
To assess the effectiveness of the use of geothermal heat-pump systems of heat supply in the climatic conditions of Russia, the area of \u200b\u200bthe territory of the Russian Federation was carried out on the efficiency of using geothermal heat of low potential for heat supply purposes. The zoning was carried out on the basis of the results of numerical experiments on modeling operational regimes of the GTST in climatic conditions of various regions of the territory of the Russian Federation. Numerical experiments were carried out using an example of a hypothetical two-storey cottage with a heated area of \u200b\u200b200 m 2, equipped with a geothermal heat-pumping system of heat supply. The external enclosing structures of the house under consideration have the following diagnosed heat transfer resistances:
- outer walls - 3.2 m 2 h ° C / W;
- windows and doors - 0.6 m 2 h ° C / W;
- Coatings and floors - 4.2 m 2 h ° C / W.
When conducting numerical experiments, it was considered:
- the heat collection system of the soil with low density of geothermal energy consumption;
- horizontal control system of polyethylene pipes with a diameter of 0.05 m and 400 m long;
- the heat collection system of the soil with a high density of geothermal energy consumption;
- vertical system of heat collection from one thermocouple with a diameter of 0.16 m and a length of 40 m.
The conducted studies have shown that the consumption of heat energy from the ground array by the end of the heating season is near the register of pipes of the heat supply system. Lowering the temperature of the soil, which in the soil-climatic conditions most of the territory of the Russian Federation does not have time to compensate for in the summer period of the year, and to the beginning of the next heating season, the soil. Leaves with reduced temperature potential. Consumption of thermal energy during the next heating season causes a further decrease in the temperature of the soil, and by the beginning of the third heating season its temperature potential is even more different from the natural one. And so on ... However, the envelopes of the thermal influence of the long-term operation of the heatboring system on the natural temperature of the soil have a pronounced exponential nature, and by the fifth year of operation, the soil comes out for a new regime close to periodic, i.e., starting from the fifth year Operation, many years of thermal energy consumption from the soil massif of the heat collection system is accompanied by periodic changes in its temperature. Thus, when conducting a zoning of the territory of the Russian Federation, it was necessary to take into account the drop in the temperature of the ground massif, caused by many years of ex-plungement of the heat collection system, and used as the calculated temperature of the soil array of soil temperature, expected to the 5th year of operation of the GTST. Given this circumstance, when conducting a zoning of the territory of the Russian Federation on the effectiveness of the use of GTST as a criterion for the effectiveness of the geothermal heat-pumping heat supply system, the average for the 5th year of operation The coefficient of heat transformation to p tr is chosen, which is the ratio of the generated GTST of the useful thermal energy to the energy spent on Its drive, and determined for the ideal thermodynamic cycle of carno as follows:
K TR \u003d T O / (T O - T and), (1)
where T o is the temperature potential of the heat being discharged into the heating system or heat supply, K;
T and - Temperature potential of the heat source, K.
The coefficient of transformation of the heat pumping system of heat supply to TPs is the ratio of useful heat drawn into the heat supply system of the consumer, to the energy spent on the operation of the GTST, and is numerically equal to the amount of useful heat obtained at temperatures t o and t and per unit of energy spent on the GTST drive . The real transformation coefficient differs from the ideal, described formula (1), by the value of the coefficient H, which takes into account the degree of thermodynamic perfection of the GTST and irreversible energy losses in the implementation of the cycle.
Numerical experiments were carried out using programs created at OJSC Innsolar-Invest, providing the definition of the optimal parameters of the heat supply system, depending on the climatic conditions of the construction area, the heat-shielding qualities of the building, the operational characteristics of heat-pump equipment, circulation pumps, heating devices of the heating system, as well as their modes operation. The program is based on the method of constructing mathematical models of thermal regime of the low-precision heat collection systems, which has allowed us to bypass the difficulties associated with the informative uncertainty of models and approximation of external influences, through the use of experimentally obtained information about the natural heat mode of the soil, which allows partially considering The entire complex of factors (such as the presence of groundwater, their high-speed and thermal regimes, structure and location of the soil layers, the "thermal" background of the earth, atmospheric precipitation, phase transformations of moisture in pore space and much more), which are essentially affecting the formation of the thermal mode of the system Heat collection and joint accounting of which in the strict setting of the problem today is practically not possible. As a solution of the "basic" task, the data of the USSR climate directory was used (L.: Hydrometeoizdat. Vol. 1-34).
The program actually allows you to solve the problem of multiparameter optimization of the configuration of the GTST for a particular building and the construction area. At the same time, the target function of the optimization problem is the minimum of the annual energy costs for the ex-rotation of the GTST, and the optimization criteria are the radius of the soil heat exchanger pipes, its (heat exchanger) length and depth of the embedding.
The results of numerical experiments and the zoning of the territory of Russia on the efficiency of using geothermal heat of low potential for the purpose of heat supply of buildings are represented in graphical form in Fig. 2-9.
In fig. 2 shows the values \u200b\u200band isolating the transformation coefficient of geothermal heat-pump heat supply systems with horizontal systems of heat supply, and in Fig. 3 - for GTST with vertical systems of heat supply. As can be seen from the drawings, the maximum values \u200b\u200bto R Tr 4.24 for horizontal thermal protection systems and 4.14 - for vertical can be expected in the south of the territory of Russia, and the minimum values, respectively, 2.87 and 2.73 in the north, in Welen. For the middle strip of Russia, the values \u200b\u200bto p tr for horizontal heating systems are in the range of 3.4-3.6, and for vertical systems in the range of 3.2-3.4. There are quite high values \u200b\u200bto r tr (3,2-3,5) for the districts of the Far East, areas with traditionally complex fueling conditions. Apparently, the Far East is a region of priority implementation of the GTST.
In fig. 4 shows the values \u200b\u200band isolines of specific annual energy to the drive of the "horizontal" GTST + PD (peak closer), including energy consumption for heating, ventilation and hot water supply, reduced to 1 m 2 heated area, and in Fig. 5 - for GTST with vertical systems of heat supply. As can be seen from the drawings, the annual specific energy consumption for the horizontal GTST drive, shown to 1 m 2 heated area of \u200b\u200bthe building vary from 28.8 kWh / (year M 2) in the south of Russia to 241 kWh / (year m 2) in Yakutsk, and for vertical GTST, respectively, from 28.7 kWh / / (year M 2) in the south and up to 248 kWh / / (year M 2) in Yakutsk. If we multiply the value presented in the drawings for a specific area, the value of the annual specific energy consumption for the GTST drive to the value for this area to p tr, reduced by 1, then we obtain the amount of energy saved GTST with 1 m 2 heated area per year. For example, for Moscow for vertical GTST, this value will be 189.2 kW h from 1 m 2 per year. For comparison, it is possible to give the values \u200b\u200bof specific energy consumption established by the Moscow Regulatory Energy Saving Mower 2.01-99 for low-rise buildings at 130, and for multi-storey buildings 95 kWh / (year m 2). At the same time, 2.01-99 energy consumption consists of 2.01-99 energy costs consist of energy and ventilation costs, in our energy consumption, energy costs for hot water supply are included in the energy consumption. The fact is that the existing approach to evaluating the energy consumption of the building allocates energy costs for heating and ventilation of the building and energy costs on its hot water in separate articles. At the same time, energy consumption for hot water supply is not normalized. This approach does not seem correct, since energy costs for hot water supply are often commensurate with energy costs for heating and ventilation.
In fig. 6 shows the values \u200b\u200band isolating the rational ratio of the thermal power of the peak closer (PD) and the installed electrical power of the horizontal GTST in the fractions of the unit, and in Fig. 7 - for GTST with vertical heat collection systems. The criterion for the rational ratio of the thermal power of the peak closer and the installed electrical power of the GTST (excluding PD) was the minimum of the annual cost of electricity to the GTST + PD drive. As can be seen from the drawings, the rational ratio of the capacities of the thermal PD and the electric GTST (without PD) varies from 0 in the south of Russia, to 2.88 - for horizontal GTST and 2.92 for vertical systems in Yakutsk. In the central strip of the territory of the Russian Federation, the rational ratio of the thermal power of the closer and the installed electrical power of the GTST + PD is both for horizontal and vertical GTST within 1.1-1.3. At this moment you need to stay in more detail. The fact is that when replacing, for example, electrical installation in the central lane, we actually have the opportunity to reduce the power installed in the heated building of electrical equipment installed in the heated building and, accordingly, to reduce the electrical power requested from RAO UES, which today " "About 50 thousand rubles. For 1 kW installed in the house of electrical power. For example, for a cottage with calculated heat lines in the coldest five-day 15 kW, we will save 6 kW installed electrical power and, accordingly, about 300 thousand rubles. or ≈ 11.5 thousand dollars. This figure is almost equal to the cost of the GTST of such thermal power.
Thus, if it is correct to take into account all the costs associated with connecting the building to centralized power supply, it turns out that there are electricity tariffs today and connecting to networks of centralized power supply in the central strip of the territory of the Russian Federation, even on one-time costs of the GTST, it turns out to be more profitable electrical installation, not to mention 60 % energy saving.
In fig. 8 shows the values \u200b\u200band isolines the proportion of thermal energy produced during the year by peak closer (PD) in the total annual energy consumption of the system horizontal GTST + PD as a percentage, and in Fig. 9 - for GTST with vertical heat collection systems. As can be seen from the drawings, the proportion of thermal energy produced during the year by peak closer (PD), in the total annual energy consumption of the system horizontal GTST + PD varies from 0% in the south of Russia to 38-40% in Yakutsk and Turing, And for vertical GTST + PD - respectively, from 0% in the south and up to 48.5% in Yakutsk. In the central lane of Russia, these values \u200b\u200bare both for vertical and horizontal GTST about 5-7%. These are small energy consumption, and in connection with this you need to carefully treat the choice of peak closer. The most rational from the point of view of both specific caps of 1 kW of power and automation are peak electrodes. It deserves attention to the use of pellet boilers.
At the end, I would like to dwell on a very important question: the problem of choosing a rational level of heat-stash buildings. This problem is a very serious task today, to solve a serious numerical analysis, taking into account both the specifics of our climate, and the features of the engineering equipment used, the infrastructure of centralized networks, as well as the environmental situation in cities, worsening literally in their eyes, and much more. Obviously, today it is incorrect to formulate any requirements for the shell of the building without taking into account its (building) of the relationship with the climate and energy supply system, engineering communications, etc. As a result, in the very near future, the solution to the choice of rational levels of heat shields will be possible only Based on the consideration of the complex building + power supply system + climate + environment as a single ecoenergetic system, and with this approach, the competitive advantages of the GTST in the domestic market is difficult to overestimate.
Literature
1. Sanner B. Ground Heat Sources For Heat Pumps (Classification, Characteristics, Advantages). Course on GeoThermal Heat Pumps, 2002.
2. Vasiliev G. P. Economically, the level of thermal protection of buildings // Energy Saving. - 2002. - № 5.
3. Vasilyev G. P. Heat-shop of buildings and structures using low-precipitated thermal energy of surface layers of the Earth: monograph. Publishing house "Border". - M.: Red Star, 2006.
One of the best, rational techniques in the construction of capital greenhouses is an underground thermos greenhouse.
Using this fact of constancy of the temperature of the earth at a depth, in the greenhouse device gives a colossal savings of heating costs during the cold season, facilitates care, makes microclimate more stable.
Such a greenhouse works in the most ending frost, allows vegetables, grow flowers all year round.
Properly equipped bellbed greenhouse makes it possible to grow, including thermal-loving southern crops. There are practically no restrictions. Citrus and even pineapples can feel great in the greenhouse.
But in order to practice everything in practice, it is necessary to observe the tested technologies for which underground greenhouses were built. After all, this idea is not new, while the Tsar in Russia, the greenhouses were given the crops of pineapples, which enterprising merchants were exported to the sale to Europe.
For some reason, the construction of such greenhouses did not find in our country of great distribution, by and large, it is just forgotten, although the design is ideal just for our climate.
Probably the role here played the need to dig a deep pit, filling the foundation. Construction of a plugged greenhouse is quite costly, this is not a greenhouse, covered with polyethylene, but also the return from the greenhouse is much more.
The overall internal illumination is not lost from the gluke to the ground, this may seem strange, but in some cases light saturation is even higher than that of classic greenhouses.
It is impossible not to mention the strength and reliability of the design, it is incomparably stronger than the usual, it is easier to carry the hurricane gusts of the wind, it is well opposed to hail, no interference and snow breakdowns.
1. Kotlovan
Creating a greenhouse begins with digging a pit. To use the heat of the earth to heat the internal volume, the greenhouse must be fairly in-depth. The deeper, the Earth becomes warmer.
The temperature almost does not change during the year at a distance of 2-2.5 meters from the surface. At a depth of 1 m, the temperature of the soil fluctuates more, but also in winter it remains positive, usually in the middle band the temperature is 4-10 seconds, depending on the time of year.
Burning greenhouse is being built in one season. That is, in the winter it will completely be able to function and generate income. The construction is not cheap, but by applying the smelting, compromise materials, it is possible to save literally for an integer order by making a kind of economy, starting from the pit.
For example, do without attracting construction equipment. Although the most time-consuming part of the work is to dig a pit -, of course, it is better to give the excavator. Manually remove such a volume of land hard and long.
The depth of the pit of the pit should be at least two meters. At such a depth, the Earth will begin to share its warmth and work as a kind of thermos. If the depth is less, then a fundamentally idea will work, but noticeably less efficient. Therefore, it is recommended not to regret the forces and funds for the deepening of the future greenhouse.
In the length of underground greenhouses can be any, but the width is better to withstand within 5 meters, if the width is greater, then the qualitative characteristics of heating and lighting deteriorate.
On the side of the horizon, underground greenhouses need to be focused, as ordinary greenhouses and greenhouses, from the east to the west, that is, so that one side of the sides is facing south. In this position of the plant will receive the maximum amount of solar energy.
2. Walls and roof
On the perimeter, the foundation is flooded or blocks blocks. The foundation serves as the basis for walls and framework frames. The walls are better made from materials with good thermal insulation characteristics, an excellent option - thermoblocks.
The roof frame is more likely made by wooden, from impregnated with antiseptic means of bars. Roof design usually straight duplex. The skater bar is fixed in the construction center, for this purpose, central supports are installed on the floor along the entire length of the greenhouse.
The ski bar and walls are connected near the rafal. The frame can be made without high supports. They are replaced with small, which put on transverse beams connecting the opposite side of the greenhouse - this design makes the inner space freely.
It is better to take a cellular polycarbonate as a roof covering - popular modern material. The distance between the construction rafters is customized under the width of polycarbonate sheets. Working with the material is convenient. The coating is obtained with a small amount of joints, since sheets are produced with a length of 12 m.
They are attached to the frame with self-drawing, they are better to choose with a hat in the form of a washer. To avoid cracking, under each self-tapping screw, drill a drill hole of the corresponding diameter. With the help of a screwdriver, or a regular drill with a crossed bat, work on glazing moves very quickly. In order not to be left for the cracks, it is good at the top of the top laying rafters with a soft rubber seal or other suitable material and only then fasten sheets. The peak of the roof along the skate must be paved with a mild insulation and press some kind of corner: plastic, from tin, from another suitable material.
For good thermal insulation, the roof is sometimes made with a double layer of polycarbonate. Although transparency decreases by about 10%, but this is covered with excellent thermal insulation characteristics. It is necessary to consider that the snow does not melt on such a roof. Therefore, the skate must be at a sufficient angle, not less than 30 degrees so that the snow on the roof is accumulated. Additionally, an electric vibrator is installed for shaking, it will save the roof in case the snow will still accumulate.
Double glazing are made in two ways:
Between the two sheets insert a special profile, sheets are attached to the frame from above;
First mount the lower layer of glazing to the frame from the inside, to the underside of the rafted. The second layer of the roof is covered, as usual, on top.
After completion, it is desirable to smoke all the joints of the scotch. The finished roof looks very effectively: without unnecessary junctions, smooth, without outstanding parts.
3. Warming and heating
Wall insulation is carried out as follows. Previously, it is necessary to thoroughly melt all the joints and seams of the wall with a solution, here you can apply the mounting foam. The inner side of the walls are covered with a film of thermal insulation.
In the cold parts of the country, it is good to use a foil tolst film, covering the wall by a double layer.
The temperature in the depth of soil the greenhouse is higher than zero, but colder air temperatures needed for plant growth. The upper layer is heated by the solar rays and the air of the greenhouse, but still the soil takes the heat, so often in underground greenhouses use the technology of "warm floors": the heating element is the electrical cable - protect the metal grid or poured concrete.
In the second case, the soil for the beds pour over concrete or grow greens in pots and vases.
The use of a warm floor can be sufficient for heating the entire greenhouse, if there is enough power. But more efficiently and more comfortable for plants. Use of combined heating: warm floor + heated air. For good growth, they need air temperature of 25-35 degrees at the temperature of the Earth approximately 25 C.
Conclusion
Of course, the construction of a bellged greenhouse will cost more, and efforts will need more than in the construction of a similar greenhouse of a conventional design. But the means embedded in the greenhouse with time are justified.
First, it is energy savings on heating. In no matter how the usual ground greenhouse is heard in winter time, it will always be more expensive and more difficult to a similar method of heating in an underground greenhouse. Secondly, saving on lighting. Foil thermal insulation of walls, reflecting light, increases the illumination by two times. The microclimate in the in-depth greenhouse in winter for plants will be more favorable that it will certainly affect the yield. Saplings will easily come true, gentle plants will feel perfectly. Such a greenhouse guarantees a stable, high crop of any plants all year round.
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