Method and device for year-round cooling, freezing of ground at foundation base and for heat supply of structure on permafrost ground in cryolytic zone

FIELD: heating.

SUBSTANCE: invention relates to devices for controlled temperature stabilisation, cooling and freezing of ground at foundation bases as well as for heat supply of structures on permafrost grounds (in cryolytic zone). Method of year-round cooling, freezing of ground at a foundation base and for heat supply of a structure on permafrost ground in cryolytic zone involves drilling of wells, cooling of ground. All year round, cooling and freezing of the ground of a foundation base are controlled and the year-round partial heat supply of the structure is carried out due to the heat of the foundation base ground and adjacent ground layers that are cooled and frozen. The primary circuit of a heat pump with low temperature heat carrier is formed, the boiling temperature of the heat pump working medium is by 10-30°C lower than the minimal temperature of the heat carrier in the primary circuit. The heat pump is installed inside a structure and heat is supplied with the conversion factor above 1-3. The freezing temperature of the heat carrier in the primary circuit of the heat pump is lower than the minimal temperature of the ambient air of the structure's site up to -60°C. The evaporation temperature of the working medium in the secondary circuit is higher than the lower limit of its working range of temperatures up to -75°C. A thermal well is set in the block of a structure base with bearing piles on the periphery or thermal wells being divided into less powerful ones are set at its periphery along with providing for additional bearing function of a pile. The heat carrier of the divided thermal wells is delivered by heat insulated heating conduits to a common heat exchanger of the heat pump primary circuit or to several heat pumps installed in different rooms of the structure.

EFFECT: guaranteed year-round provision for frozen state of structure foundation base along the whole well depth as well as provision for year-round backing up of part (approximately the half) of structure's thermal load by means of a heat pump due to the usage of heat from the permafrost ground being cooled and frozen.

5 cl, 1 dwg, 3 tbl

The invention relates to a device adjustable temperature control, cooling and freezing of the soil Foundation, as well as heating of buildings on permafrost (permafrost conditions).

In industrial and civil construction of buildings in permafrost soils there is a change in the temperature field of the bases of structures under thermal action structures are formed bowl thawing, which leads to the settlement of the building. The main objective of the Foundation construction on permafrost soil - save the frozen state of the soil in which it has a high bearing capacity.

There are many methods and devices for stabilizing and freezing facilities foundations on permafrost, obtained many patents on such methods and devices. However, none of them guarantees year-round freezing of the soil along the entire depth of the borehole and does not contain additional functions of heat supply by the heat of the cooling permafrost soil.

There is a method of increasing resistance of pile foundations in permafrost, including the placement of insulation screen on the surface of the soil Foundation and the calculation of the required parameters (RF patent No. 2159308, publ. November 20, 2000). Insulation screen is placed on the surface and inside of gr is novogo Foundation, its dimensions, geometrical configuration, and thermophysical properties of the material having a spatial anisotropy, determine the terms and conditions of coincidence of the projected temperature field, providing the stability of the structure during the entire period of operation, and the estimated temperature field is obtained by solving the finite difference method the unsteady two-dimensional inhomogeneous heat equation in rectangular coordinates for anisotropic medium with the presence of the mobile phase boundary and represents the engineering-geological cross-section of soil Foundation, enclosing the projected heat insulation screen, and adjacent soil layers.

The disadvantages of this method are the need for a large number of heat-insulating material and the associated large volume of ground work, as well as the probability of a mismatch of the calculated and actual values of temperature fields and prevents subsequent adjustment of the temperature regime of pile foundations.

A device for cooling the soil, proposed to increase the intensity and decrease the duration of the cooling process of the soil, as well as perform cooling of the soil with adjustable process (patent RF № 2110647, publ. may 10, 1998). The device contains a set in g is ondavou the well casing pipe placed in her inner tube, connected by a duct with the suction or discharge pipe of the fan. Inside the casing inserted tube, soamsawali with ambient air or with the duct and with the possibility of longitudinal movement within the casing. The tube is made of a material with low heat conductivity or has a coating of teploneprovodjashchimi material. The inner tube on the end is ejecting nozzle, and on the side surface has a helical rib and hole diameter 0,08-0,12 D. the Latter are located at the bottom of the pipe with a step length of 30-50 D, where D is the internal diameter of the pipe.

A disadvantage of this device is dependent on the temperature of ambient air, from the uncertainty of position of a mobile handset, a low coefficient of heat transfer from the air to the inner surface of the casing.

A device for stabilizing plastic-frozen ground year-round mode of operation for the cold accumulation at the base of the structures, including underground and above-ground parts of the tubular sealed enclosure filled with a coolant, the underground part of which is the evaporator, and overhead - condenser, equipped with a shelf having located on the surface of thermoelectric modules in the form of a battery Peltier elements (application for invention No. 2009114953, publ. Artbra, 2010). This device is equipped with a heat pipe, one end of which having a shelf attached to the hot surface of thermoelectric modules, and the other end, which is the condensation zone, has a ribbed surface, and the axis of the condensation zone is located at an angle φ of inclination to the horizon and, as an option, has a shelf, where the radiators are fitted with fans.

The disadvantage of this device is energy consumption and the possibility of icing ribbed surface of the condenser.

Closest to the technical nature of the proposed device is a thermal pile (RF patent No. 2250302, publ. 20.04.2005). Thermal piles are installed in the permafrost in the winter time by drilling it with a rig wells. Then pile expose and reinforce each other, and then into the gaps wells fill in water, which freezes and rigidly connects the entire structure in the permafrost. Freezing water filled in the gaps wells in permafrost also contributes to the work of the heat pipe when the ambient temperature is below the temperature of permafrost. When it starts cooling of the soil around the evaporator to a temperature almost equal to the ambient temperature. Pile T-shaped metal plate fin the capacitors, performed simultaneously with the elements of the horizontal part of the pile, which allowed not only to provide a sufficiently developed external surface for intensive cooling of the capacitors in the winter, but also to ensure the durability of the heat pipe, connected with thermal pile. If thermal pile of metal, the heat pipe can simply be welded to the steel shaft and the metal fins. In the case of very large loads itself of the heat pipe can serve as both a pile. For more powerful structures, construction of buildings, roads, etc. suitable thermal piles to make concrete, while the heat pipe is a part of the metal reinforcement. The invention was awarded with a Golden medal and diploma at the world exhibition of innovation, research and new technologies in Brussels Eureka-2003".

The disadvantage of thermal piles prototype is a passive thermal control system using heat pipe, the temperature dependence of the environment, do not use the heat of condensation.

Except where noted, a common shortcoming of all analogues and other structures reinforcing the foundations in permafrost conditions is the lack of systems of a heat supply facilities by the heat of the cooled or frozen permafrost soil.

The objective of the proposed izopet the deposits is guaranteed year-round adjustable ensuring the frozen state of the soil Foundation structure throughout the depth of the well, and at the same time ensuring partial, half, cover the heat load of the building with a conversion factor of the heat pump is greater than one due to the heat of cooling and freezing of permafrost and the adjacent layers of Foundation soil.

As a result of use of the present invention will be provided year-round steady state Foundation structures at the expense of permanently frozen grounds, excluding the thawing of permafrost, as well as covering partial, up to half of the calculated value of the heat load due to the heat of cooling and freezing of the soil with increasing temperature in the supply pipe, a heat pump, for example, to +35°C, with subsequent heating-up to the normative.

The above result is achieved by the fact that in the proposed method, year-round cooling, freezing of the soil Foundation and heating structures on permafrost soil in the permafrost zone, which includes the drilling of wells, the cooling of the soil, year-round regulate the cooling and freezing of the soil Foundation and conducted year-round partial heat supply facilities by the heat cooled and frozen soil Foundation and surrounding soil layers, thus forming a primary circuit with low temperature is cooled heat pump in which the working fluid has a boiling temperature lower by 10 to 30°C minimum temperature of the coolant of the primary circuit, the heat pump is fitted inside the building and supply heat conversion efficiency more units 1-3, and the coolant of the primary circuit of a heat pump has a freezing temperature below the minimum temperature of the surrounding air space of the building up to -60°C and evaporation temperature of the working fluid of the secondary circuit above the lower limit of the working temperature range up to 75°C, while termocline set in the centre of the base structure with bearing piles on the periphery or, being divided into less powerful, termocline establish on its periphery, performing advanced carrier function of pile Foundation construction, and the coolant separated thermoskin served on insulated heat pipes to the total heat exchanger of the primary circuit of a heat pump or multiple heat pumps installed in different rooms of the building.

In the proposed method as the primary coolant circuit is used FreeziumTM, and as the working fluid of the heat pump uses freon R23.

In the proposed method, the soil Foundation can be any of the permafrost zone, for example insular permafrost, that is IKI.

The technical result is also achieved by the fact that the proposed device for year-round cooling, freezing of the soil Foundation and heating structures on permafrost soil in the permafrost zone, containing mounted without clearance in a dirt hole plugged the bottom of the casing placed in her coaxial tube with an open bottom end, the gap between the pipes on the upper end of the casing pipe is plugged, the upper ends of the pipes include pipes, hollow tubes and pipes filled with coolant, contains a heat pump, low temperature heating circuit, the heating fluid is derived from the soil into the casing pipe, the inner pipe outside insulated pipes through insulated pipelines are connected with suction and delivery pipes of a heat pump, forming a primary circuit, the working fluid of the heat pump has a boiling point lower by 10-30°C minimum temperature of the coolant of the primary circuit, the heat pump is located inside the building and carries out heat conversion efficiency greater than unity, the pipes the pipes are connected with an adjustable liquid pump and the heat exchanger form independent of the primary loop connected to the evaporator of the heat pump.

In the proposed who equip a driving power for the heat pump and the regulated fluid pump is consumed from the mains or from wind power.

Permafrost soil surface (depth up to hundreds of meters) of earth layers as the base of the Foundation of a building as a low-potential source of energy for heating by application of heat pumps, which take away the warmth of cooled and frozen soil and increase the temperature of the coolant supply line.

Pile, she Ermoshina made in the form of a heat exchanger of the type, for example, "pipe", with low temperature (freezing point much lower than 0°C) coolant piping forming a primary circuit of the heat pump; heat pump with a boiling point of the working fluid below the lower freezing temperature of the coolant, auxiliary adjustable pumps of the primary circuit and the feed line, heating appliances structures.

The essence of the invention illustrated by figure 1, 2 and 3.

Figure 1 shows a schematic diagram of a device.

Figure 2 shows the calculated scheme termocline.

Figure 3 shows the changes in the minimum temperature thermoskin 100 and 150 m, the diameter of the frozen soil and the conversion factor of the heat pump during the years of operation of the facility.

The principle of operation of heat pumps offered Tomsona in 1852

Way year-round cooling, freezing is runta Foundation and heating structures on permafrost soil in the permafrost zone is as follows.

The heat taken from the environment, such as soil, is passed into the heat exchanger 1 of the evaporator of the heat pump, closed loop which circulates the working fluid, such as freon. The freon in the evaporator 2 boils and evaporates at a low temperature, absorbing latent heat of evaporation. The pair arrive in the compressor 3, where the pressure and temperature are increased. Compressed vapors of freon do in the condenser 4, where the heat exchanger 5, the refrigerant is cooled, transferring its latent heat of the phase transition of the fluid circulating in the heating system 6. Achladies, the refrigerant becomes a liquid and through the valve or expander 7 is returned to the evaporator 2. The heat pump has its own pump primary circuit or auxiliary 8, if the power of its own is not enough.

Termocline can be located in the centre of the base of the Foundation, and on the periphery of the structure, acting as piles, with the power and depth of piles-thermoskin decreases in proportion to their number, and the heat from the piles of thermoskin connected to a common heat pump placed inside the building, or to the individual heat pumps placed in different areas of the structure.

Before using the unit on the site of the future construction is engineering-geologicas the e drilling, to determine the properties and power of the soil, if it was not previously known. Determine the heat load of the structure(s) and conduct heat engineering calculations which determine the parameters of the wells and placed in it without clearance termocline (figure 2)conducting heat from the ground by means of the heat pump (figure 1). Termocline is a heat exchanger, in particular, "pipe", is immersed vertically into the soil at depth. Circulating in the heat exchanger coolant takes heat from the ground and delivers it to the heat exchanger 1, the evaporator 2 of the heat pump (figure 1). Achladies, the fluid inside the pipe is returned to the bottom of the heat exchanger, the loop of the primary circuit is closed. In the secondary circuit circulates the working fluid, such as freon. The freon in the evaporator 2 boils and evaporates at a low temperature, absorbing latent heat of evaporation. The pair arrive in the compressor 3, where the pressure and temperature are increased. Compressed vapors of freon do in the condenser 4, where the heat exchanger 5, the refrigerant is cooled, transferring its latent heat of the phase transition of the fluid circulating in the heating system 6. Achladies, the refrigerant becomes a liquid and through the valve or expander 7 is returned to the evaporator 2.

Heat the ASAS has its own pump primary circuit or auxiliary 8, if power its own is not enough.

Due to the fact that every year the volume of chilled ground around termocline increases, considered the course during this process and its impact on the Foundation of the example coating the heat load of a two-storey house with an area of S=250 square meters, which is home to 10 people, located in the area with similar terms chatanga Krasnoyarsk region.

The SNP-23-01-99 is determined by the duration and the average outdoor temperature of the period with an average temperature not exceeding 8°C, respectively, z_ht=311 days and t_ht=-17,1°C.

The SNP-23-02-2003 determine the degree-day formula:

Dd=(t_int-t_htz_ht,

where t_int=21°C is the calculated average temperature of the inside air of the building; Dd=11849 of degree-days. Normalized specific consumption of thermal energy for heating is determined by the table 8 SNiP-23-02-2003:

$$q_h^{reg}=105KDW/\left(m^2{\cdot }^{\circ }C\cdot \mathrm{with\; a}yt\right)=\mathrm{29,17}$$W·h(m²·°C·day)

and then the heat load of the heating period

Monthly heat load accept, in the absence of data, for example, even within 10 months of the heating season, which is 8640 kW·h, and in June and July only for hot water supply. Take the heat load to be covered by the conversion heat pump heat frozen ground, is equal to, for example, half of the estimated (table 1). The other half of the load is covered with a heat source or degravelles, usually built into the housing of the heat pump.

Limited to the processes of heat transfer from the soil to the heat exchanger termocline. Figure 2 shows the calculated scheme termocline, where d₀the diameter of the outer tube of the heat exchanger, d₁- diameter soil layer after the first month of the cooling cover the monthly load), d-i - after the second month and so on, d₂another diameter.

The calculations are made assuming quasi-stationary mode during each month. The mass of each layer is determined by the formula:

$$m=\frac{Q}{c_p},\left(5\right)$$

where Q is the monthly heat load from table 1, c_p- specific heat capacity of the soil, t_wand t_c- the average temperature of the layer at the boundary with the non-refrigerated and refrigerated layers of the soil. The heat flux from the cooled layer to the heat exchanger defined as

$$q=\frac{t_w-t_0}{R},\left(6\right)$$

where t₀- the average temperature on the outer shell of the heat exchanger, R is thermal resistance from the non-refrigerated layer to a heat exchanger, for example from the d₁₃to d₀:

$$R=\frac{1}{2\pi \lambda h}\ln \frac{d_i}{d_0},\left(7\right)$$

where d_i- diameters of d₁d₂, ..., d_nd_i; h - height of the hollow cylinder (the next layer of soil).

Take, for example, due to lack of data, the following properties of frozen soil:

temperature t w=-4°C [S.I. Alekseev and foundations. The part 12. Quote: "Below the depth of H₀- amplitude zero temperatures and frozen ground will be at a constant negative temperature ≈-4°C. at a depth of ≈15 m"];

thermal coefficients: c_p=2,135 kJ/(kg·°C), γ=917,4 kg/m³, λ=2,09 W/(m·K) [Gavrilov RI. Theoretical estimation of thermal conductivity of segregation ice. Permafrost Institute them. Pielikuma SB RAS, 677010, Yakutsk,mpi@ysn.ruAuthors project O8ODE.RU]; the temperature at the inlet to the evaporator t_inand output of the t_outdefine calculations to provide the specified thermal capacity. The mass is cooled during the year the soil is in this example about 3000 tons.

The calculations carried out since the beginning of the heating season, assuming completely naturally cooled ground (the first year of operation). Calculations and graphics performed using the computer program Excel, graph presented as figure 3.

Floor heat load in the first year of operation when the diameter of the outer tube of the heat exchanger (tubing) d₀=0.5 m is: when drilling depth h≈150 m, the cooling fluid in the casing pipe to a temperature of -16°C and the diameter of the cooled soil ≈6 m; drilling depth h≈100 m, respectively, -26°C and 8 PM On the second and each subsequent years of operation of the heating period which will begin with an increasingly thick chilled layer of soil, i.e. when increasing thermal resistance R. figure 3 shows the change of the diameter of the frozen soil and minimum temperatures well over 10 years of operation.

As follows from figure 3, on the 10th year, these figures will increase to ≈21 m and -25°C (well 150 m) and ≈21 m and -37°C (100 m). In the future, this pattern has a weak exponential in nature. There are an average over a year of transformation coefficients perfect reverse Carnot cycle heat pump, which shows that with decreasing temperature cooling (freezing) and with decreasing depth termocline conversion factors are reduced. For a real cycle with a coefficient of thermodynamic perfection ν=0.2 to 0.5 transformation ratio remains greater than unity.

On the obtained temperature values carry out the choice of low-temperature fluid, the working fluid loop and the heat pump. Next is drilling wells, installing without a clearance casing, mounting accessories termocline, pipelines, work inside the building: the connection of the heat pump, the drive power from the mains or from a system with wind power, thermal devices and automation systems in accordance with the construction norms and rules.

The device may have a separate primary is first closed loop with an adjustable liquid pump and heat exchanger, connected through pipes pipes with heat pump evaporator. This scheme is applicable when there is insufficient power pump primary circuit of the heat pump.

The device contains a low-temperature coolant of the primary circuit of a heat pump with a freezing temperature below the minimum temperature of the surrounding air space structures, for example FreeziumTM having a freezing temperature to -60°C [http://temper-t.narod.ru/Freeziumpdf.pdf], and the evaporation temperature of the working fluid of the secondary circuit, such as Freon R23, above the lower limit of its operating temperature range (-75°C) [the Internet. ["GeoPost-trade © 2009-2011]. Potential depletion of the ozone layer ODR=0 [http://www.freon-group.ru/freon_r23/]. These temperatures will not result in freezing of the coolant and the working fluid of the heat pump when installing the emergency stop equipment, the nominal temperature is selected according to the results of the calculations (figure 3).

The device freezes every soil permafrost, for example insular permafrost, taliks, because with sufficient tens of meters, the depth of the well thermospa is retained by the soil without additional fixtures and freezing near the casing is relatively fast (a few hours) after switching on the heat pump.

Termocline device is located, depending on the dimensions and configuration for the purpose of construction, in the centre of the base structure with bearing piles on the periphery or, being divided into less powerful, termocline mounted on its periphery, performing advanced carrier function of the pile.

The device uses the drive power for the heat pump and the regulated fluid pump from the mains or from wind power, providing continuous or discontinuous drive power.

1. Way year-round cooling, freezing of the soil Foundation and heating structures on permafrost soil in the permafrost zone, which includes the drilling of wells, the cooling of the ground, characterized in that year-round regulate the cooling and freezing of the soil Foundation and conducted year-round partial heat supply facilities by the heat cooled and frozen soil Foundation and surrounding soil layers, thus forming a primary circuit with a low temperature coolant of the heat pump, the working fluid of the heat pump has a boiling point lower by 10-30°C minimum temperature of the coolant of the primary circuit, the heat pump is fitted inside the building and supply heat conversion efficiency more units 1-3, and the coolant of the primary circuit of a heat pump them is no freezing temperature below the minimum temperature of the surrounding air space of the building up to -60°C, and the evaporation temperature of the working fluid of the secondary circuit above the lower limit of the working temperature range up to 75°C, while termocline set in the array base structure with bearing piles on the periphery or, being divided into less powerful, termocline establish on its periphery, performing advanced carrier function of the piles, and the coolant separated thermoskin served on insulated heat pipes to the total heat exchanger of the primary circuit of a heat pump or multiple heat pumps installed in different rooms of the building.

2. The method according to claim 1, characterized in that the coolant of the primary circuit is used FreeziumTM, and as the working fluid of the heat pump uses freon R23.

3. The method according to claim 1, characterized in that the Foundation soil Foundation can be any of the permafrost zone, for example insular permafrost, taliks.

4. Device for year-round cooling, freezing of the soil Foundation and heating structures on permafrost soil in the permafrost zone, containing mounted without clearance in a dirt hole plugged the bottom of the casing placed in her coaxial tube with an open bottom end, the gap between the pipes on the upper end of the casing pipe is plugged, the upper ends of Tr is b contain pipes, cavity tubes and pipes filled with coolant, characterized in that the device comprises a heat pump, low temperature heating circuit, the heating fluid is derived from the soil into the casing pipe, the inner pipe outside insulated pipes through insulated pipelines are connected with suction and delivery connections of the heat pump, forming a primary circuit, the working fluid of the heat pump has a boiling point lower by 10-30°C minimum temperature of the coolant of the primary circuit and the heat pump is located inside the building and carries out heat conversion efficiency greater than unity, the pipes the pipes are connected with an adjustable liquid pump and heat exchanger and form independent of the primary loop connected to the evaporator of the heat pump.

5. The device according to claim 4, characterized in that the driving power for the heat pump and the regulated fluid pump is consumed from the mains or from wind power.