RU2818610C1 - Geothermal heat pump - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: invention relates to heating and cooling plants using low-potential heat sources. Geothermal heat pump comprises a heat pump plant and geothermal probes. Heat pump plant comprises compressor, oil separator, heat exchanger-condenser, liquid separator. Compressor outlet is communicated with oil separator inlet, the first output of which is connected to the input of the heat exchanger-condenser, and the second output is connected to the input of the compressor. Compressor inlet is also communicated with liquid separator outlet. First output of heat exchanger-condenser is connected to input of circulation pump of heating system, and the second output of the heat exchanger-condenser is connected through the electromagnetic valve to the inputs of the uncontrolled expansion valves, which in turn are interconnected with the geothermal probes. Each uncontrolled expansion valve is interconnected with a geothermal probe. Outlets of geothermal probes are combined in a manifold, the outlet of which is connected to the inlet of the liquid separator through a check valve. Geothermal probes are made vertical from polymer pipes, difference between the temperature at the inlet of the heat exchanger-condenser and the temperature of freon condensation is not less than 20 °C, while the temperature at the inlet of the heat exchanger-condenser is not more than 95 °C. Heat pump plant is equipped with controller, which is made with possibility of electromagnetic valve disconnection when compressor is switched off, as well as with the possibility of providing temperature control at the inlet to the heat exchanger-condenser and providing control of the temperature difference at the inlet to the heat exchanger-condenser and the freon condensation temperature.

EFFECT: providing operability of the system with deep probes (up to 150 m), reducing the area required for using the device, reducing the amount of freon.

3 cl, 1 dwg

Description

The invention relates to thermal power engineering, in particular to installations for heating and cooling premises using low-grade heat sources.

The invention RU2738527C1 is known, in which a heat pump installation for heating and cooling premises includes an internal heat exchanger with a fan connected by one pipeline to a four-way valve, the other to a capillary throttle; an external heat exchanger with a fan, connected by one pipeline to a four-way valve, the other to a capillary throttle; an electrically driven compressor connected by both pipelines to a four-way valve; four way valve; capillary-throttle; pipelines connecting the above-mentioned units into a single installation filled with the working fluid - freon, with the possibility of reversing its operation thanks to a four-way valve; characterized in that it includes a device for collecting soil heat - a soil probe in the form of plastic pipes filled with liquid non-freezing coolant, placed in pairs in vertical wells with a U-shaped connection of the pair of pipes at the bottom point of the well; an additional heat exchanger connected by one freon pipeline to a four-way valve, the other to a capillary-throttle, connecting the soil probe directly to the freon circuit of the installation; a circulation pump that drives the coolant through the soil probe; four solenoid valves controlled by an external thermostat, allowing to cut off an external or additional heat exchanger from the installation during operation.

The disadvantage of this technical solution is the complexity of the heat pump installation, the need to use a large amount of freon, high losses of freon, and the unreliability of the installation.

On the Russian market there are geothermal direct evaporation heat pumps of the "Sundue" brand, the "DROID"-SDU -INV series (https://sundue.ru/catalog/seriya-droid), containing a scroll compressor, an oil separator, a regenerative heat exchanger - a moisture separator ( whose task is to reheat the fren vapor before being sucked into the compressor), external air units with a large heat exchange surface and lamella pitch, a controller (providing control of the operation of external heat exchange circuits, including the direct evaporation circuit - DX circuit, as well as control of power lines and various modes, including temperature). The evaporation circuit of the specified technical solution is made of copper in a PVC sheath (https://sundue.ru/instr/011.pdf), which serves to combat corrosion of the copper probe (https://sundue.ru/news/podklyuchenie-dh -geotermalnogo-kontura-teplopreobrazovatelya-sundue-sdu-droid).

The disadvantage of this technical solution is the need to use a large area for the geothermal circuit, because the device does not allow the use of vertical geothermal probes, increased use of freon.

Geothermal direct evaporation heat pump brand "Sundue" series "DROID"-SDU -INV (https://sundue.ru/catalog/seriya-droid) was selected as a prototype.

The technical result achieved by the invention is ensuring the operability of a geothermal heat pump with freon, containing a refrigeration circuit combined with geothermal probes, and a heating system circuit, with deep probes (up to 150 m), reducing the area required to use the device, reducing the amount of freon.

The claimed technical result is achieved due to the fact that in a geothermal heat pump containing a heat pump installation and geothermal probes, the heat pump installation contains a compressor, an oil separator, a heat exchanger-condenser, a liquid separator, and the output of the compressor is connected to the input of the oil separator, the first output of which is connected to the input heat exchanger-condenser, and the second output of the oil separator is connected to the input of the compressor, while the compressor input is also connected to the output of the liquid separator, the first output of the heat exchanger-condenser is connected to the input of the circulation pump of the heating system, and the second output of the heat exchanger-condenser is connected through an electromagnetic valve to the inputs of unregulated expansion valves, in turn, communicated with geothermal probes, while one unregulated expansion valve is connected with one geothermal probe, the outputs of the geothermal probes are combined in a manifold, the output of which is connected through a check valve to the inlet of the liquid separator, the geothermal probes are made vertical from polymer pipes, the difference between the temperature Tn at the inlet to the heat exchanger-condenser and the freon condensation temperature is at least 20ºC, while the temperature Tn at the inlet to the heat exchanger-condenser is no more than 95ºC, the heat pump unit is equipped with a controller, which is designed to ensure that the solenoid valve is turned off when switched off compressor, as well as with the ability to provide temperature control at the inlet to the heat exchanger-condenser and provide control of the temperature difference at the inlet to the heat exchanger-condenser and the freon condensation temperature.

Unregulated expansion valves are made in the form of capillary tubes.

The height of geothermal probes is up to 100 m.

The claimed invention is illustrated by the figure.

Positions on the figure:

1 - geothermal probes;

2 - compressor;

3 - oil separator;

4 - oil drain;

5 - heat exchanger-condenser;

6 - liquid separator;

7 - circulation pump;

8 - solenoid valve;

9 - unregulated expansion valves;

10 - collector;

11 - check valve;

12 – controller;

13 – heating system.

A geothermal heat pump containing a heat pump installation and geothermal probes 1, the heat pump installation contains a compressor 2, an oil separator 3, a heat exchanger-condenser 5, a liquid separator 6, and the output of the compressor 2 is connected to the input of the oil separator 3, the first output of which is connected to the input of the heat exchanger-condenser 5, and the second output of the oil separator 3 is connected to the input of the compressor 2, while the input of the compressor 2 is also connected to the output of the liquid separator 6, the first output of the heat exchanger-condenser 5 is connected to the input of the circulation pump 7 of the heating system, and the second output of the heat exchanger-condenser 5 through an electromagnetic valve 8 is connected to the inputs of unregulated expansion valves 9, communicated, in turn, with geothermal probes 1, while one unregulated expansion valve 9 is connected to one geothermal probe 1, the outputs of geothermal probes 1 are combined in a manifold 10, the output of which is communicated through a check valve 11 with the inlet of the liquid separator 6, geothermal probes 1 are made of vertical polymer pipes, the difference between the temperature Tn at the inlet to the heat exchanger-condenser 5 and the freon condensation temperature is at least 20ºC, while the temperature Tn at the inlet to the heat exchanger-condenser 5 is no more than 95ºC , the heat pump installation is equipped with a controller 12, which is configured to ensure that the solenoid valve 8 is turned off when the compressor 2 is turned off, as well as to provide control of the temperature at the inlet to the heat exchanger-condenser 5 and to provide control of the temperature difference at the inlet to the heat exchanger-condenser 5 and the condensation temperature Freon.

The claimed invention works as follows.

Compressor 2 pumps gaseous freon from the liquid separator 6, compresses it and directs it through the discharge pipeline to the float oil separator 3. At the outlet of compressor 2, gaseous freon partially contains lubricating oil, which it carries with it from compressor 2. In the oil separator 3, the separation process occurs oil contained in freon gas. Oil accumulates in oil separator 3 and, when it reaches the float-controlled level specified in the oil separator 3 device, it returns to the input of compressor 2 through the oil drain 4 (through which the second output of the oil separator and the compressor inlet are connected) to ensure constant lubrication of compressor 2. Gaseous freon from the oil separator 3 is sent through the discharge pipeline to the heat exchanger-condenser 5, where heat exchange occurs between gaseous freon and the coolant of the heating system 13, in which gaseous freon gives up its heat to the coolant, as a result, condensation of gaseous freon occurs and it turns into a liquid state. From the heating system 13, the coolant returns to the heat exchanger-condenser 5.

Heat exchanger-condenser 5 can be either remote or placed in the body of the heat pump unit. From the heat exchanger-condenser 5, liquid freon is directed through a pipeline through an electromagnetic valve 8 controlled by a controller 12 and supplied to a restriction device, the function of which is performed by unregulated expansion valves (for example, capillary tubes) 9. Unregulated expansion valves 9 are connected to vertical probes of the geothermal circuit ( geothermal probes 1), with one unregulated expansion valve 9 connected to one corresponding geothermal probe 1.

Liquid freon through unregulated expansion valves 9, expanding at their outlet, enters geothermal probes 1, which serve as an evaporator. A plastic pipe (for example, low-density polyethylene) with a length of up to 100 meters and a diameter of 16 to 32 mm is used as a geothermal probe 1. The ends of the geothermal probes 1 are combined in a collector 10, which can be located inside the body of the heat pump installation, which makes it possible to reduce the dimensions of the inventive geothermal heat pump. In geothermal probes 1, liquid freon boils. The use of polymer (for example, plastic) as a material for geothermal probes is due to the fact that polymer (plastic), unlike metal, has lower thermal conductivity, and therefore the process of heat extraction from the ground occurs more slowly (than when using metal ). As a result of the use of polymer (plastic) pipes for geothermal probes 1, boiling of liquid freon is ensured gradually and evenly with the same temperature of -5°C along the entire length of the corresponding geothermal probe 1, which in turn makes it possible to reduce the amount of freon used in the freon circuit in 5 times and reduce the number of geothermal probes used 1 by 2.5 times. At the same time, in metal pipes, heat extraction occurs quickly, and therefore freon boils immediately, more intensely and unevenly (not along the entire length with the same temperature), which requires the use of a larger amount of freon. As a result of the boiling of liquid freon in polymer (plastic) geothermal probes 1, a vapor-liquid mixture is formed (that is, liquid freon formed during boiling), which is supplied through a check valve 11 to the liquid separator 6, where the freon boils to a gaseous state, which is then pumped out by a compressor 2. Moreover, if liquid freon reaches the boiler (liquid separator 6), then it clearly carries oil dissolved in it, which oil separator 3, installed after compressor 2, could not remove, preventing oil from accumulating in probe 1.

The supply of freon in liquid state to the liquid separator 6 is ensured by maintaining the difference between the discharge temperature of compressor 2 (at the inlet to the heat exchanger-condenser 5) and the condensation temperature of freon (inside the heat exchanger-condenser 5) of at least 20°C. The condensation temperature is determined indirectly through the condensation pressure Pk (at the condenser inlet) according to known dependencies (https://www.xiron.ru/content/view/10/27/). In this case, the upper limit of the discharge temperature (the temperature at the inlet to the heat exchanger-condenser 5) should be no more than 95°C, since exceeding this limit will lead to premature boiling of freon, which will result in a shortage of freon, and it will not reach the liquid state. liquid separator 6, as a result of which an emergency situation will occur and the system will stop.

If the difference between the discharge temperature of compressor 2 (the temperature at the inlet to the heat exchanger-condenser 5) and the freon condensation temperature inside the heat exchanger-condenser 5 is less than 20°C, then the circulation pump 7 located in the heating system will turn off, which will lead to an increase in the freon condensation temperature, due to the lack of heat transfer to the coolant. In addition, if the specified temperature difference is less than 20°C, this will also lead to insufficient evaporation of liquid freon, which, if it enters compressor 2, can damage it due to dilution of the oil in compressor 2, and can also cause hydraulic shock in it . The specified difference between the discharge temperature of compressor 2 and the freon condensation temperature is controlled by controller 12, which can be either remote or located in the body of the heat pump unit.

The controller 12 also controls the movement of freon throughout the system as follows. When compressor 2 is turned off, liquid freon tends to flow into the coldest part of the system - into geothermal probes 1 and accumulate in their lower part, which leads to a failure in the system due to the fact that under normal operating conditions of the geothermal heat pump, liquid freon cannot be lifted from the geothermal probes 1. To prevent the flow of liquid freon into geothermal probes 1, an electromagnetic valve 8 is used at the inlet to the geothermal probes 1 (before the unregulated expansion valves 9) and a check valve 11 at the outlet of the geothermal probes 1. When the compressor 2 is turned on, these valves ensure the passage of freon into in one given direction, and when compressor 2 is turned off, solenoid valve 8 is locked, because check valve 11 does not allow the reverse flow of liquid freon (towards the geothermal probes 1).

In this way, the freon is stored at the top of the geothermal heat pump - in the heat pump unit, and not in the coldest place (geothermal probes 1).

In the claimed invention, the compressor 2 is turned off when the specified temperature of the coolant or the specified temperature of the heated (cooled) room is reached, while the achievement of the specified temperature conditions is also controlled by the controller 12.

Thus, as a result of the implementation of the claimed invention, the amount of freon is reduced (compared to metal probes), the operability of the geothermal heat pump is ensured with deep probes and with a smaller amount of freon, the number of used geothermal probes is reduced by 2.5 times, and motion control is also provided freon and preventing its migration to the coldest place (geothermal probes) when the compressor is turned off.

Reducing the amount of freon, ensuring operability with deep probes and reducing the number of geothermal probes are also achieved through the use of geothermal probes made of polymer (plastic) pipes, which, having lower thermal conductivity compared to metal, and when planting probes to a depth of more than 20 meters without the use of oil-lifting pipes loops, make it possible to ensure the boiling of liquid freon in geothermal probes gradually and evenly with the same temperature of -5°C along the entire length of the corresponding geothermal probe while maintaining the difference between the compressor discharge temperature and the freon condensation temperature of at least 20°C by means of a controller.

Controlling the movement of freon and preventing its migration into geothermal probes when the compressor is turned off is ensured by placing an adjustable solenoid valve at the inlet to the probes and a check valve at the outlet of the probes, in which, at the moment the compressor is turned off, the solenoid valve is locked, freon is redirected from one valve to another and is stored in the heat pump housing rather than in probes.

Thus, the claimed invention achieves the technical result of ensuring the operation of a geothermal heat pump with deep probes and a smaller amount of freon.

Claims (3)

1. A geothermal heat pump containing a heat pump installation and geothermal probes, the pumping installation contains a compressor, an oil separator, a heat exchanger-condenser, a liquid separator, and the output of the compressor is connected to the input of the oil separator, the first output of which is connected to the input of the heat exchanger-condenser, and the second output of the oil separator communicated with the input of the compressor, while the compressor input is also connected with the output of the liquid separator, the first output of the heat exchanger-condenser is connected with the input of the circulation pump of the heating system, and the second output of the heat exchanger-condenser is connected through an electromagnetic valve with the inputs of unregulated expansion valves, communicated in turn with geothermal probes, while one unregulated expansion valve is connected to one geothermal probe, the outputs of the geothermal probes are combined in a manifold, the output of which is connected through a check valve to the inlet of the liquid separator, the geothermal probes are made vertical from polymer pipes, the difference between the temperature at the inlet to the heat exchanger is condenser and the freon condensation temperature is at least 20°C, while the temperature at the inlet to the heat exchanger-condenser is no more than 95°C, the heat pump unit is equipped with a controller, which is designed to ensure that the solenoid valve is turned off when the compressor is turned off, as well as to ensure controlling the temperature at the inlet to the heat exchanger-condenser and ensuring control of the temperature difference at the inlet to the heat exchanger-condenser and the freon condensation temperature. 2. Geothermal heat pump according to claim 1, characterized in that the unregulated expansion valves are made in the form of capillary tubes. 3. Geothermal heat pump according to claim 1, characterized in that the height of geothermal probes is up to 100 m.