JP2012167902A - Geothermal heat pump device - Google Patents

Abstract

Provided is a geothermal heat pump device that prevents freezing of moisture in antifreeze liquid in an antifreeze liquid passage of a heat source side heat exchanger that functions as an evaporator during load operation.
In a geothermal heat pump device that performs a load operation in which a heat source side heat exchanger 7 functions as an evaporator and a load side heat exchanger 5 functions as a condenser to heat the load side, the compressor 4 is operated during the load operation. Is provided with control means 19 for controlling the opening degree of the decompression means 6 so that the discharge temperature of the refrigerant reaches a preset target discharge temperature, and the control means 19 is configured to control the temperature of the refrigerant on the heat source side heat exchanger 7 side during the load operation. The refrigerant temperature detected by the evaporating temperature detecting means 10 for detecting the temperature reaches a preset freezing temperature that is expected to start freezing of the water in the antifreeze liquid in the antifreeze liquid flow path 7b of the heat source side heat exchanger 7. If it judges, the target discharge temperature of the refrigerant | coolant discharged from the compressor 4 will be set to predetermined temperature lower than before, and it will control in the direction which opens the opening degree of the decompression means 6 so that it may become the said newly set target discharge temperature. I did it.
[Selection] Figure 2

Description

  The present invention relates to a geothermal heat pump device for preventing freezing of antifreeze liquid in an antifreeze liquid flow path of a heat source side heat exchanger functioning as an evaporator.

  Conventionally, in this type of geothermal heat pump device, as shown in FIG. 4, the compressor 101, the refrigerant flow path 102 a of the load side heat exchanger 102, the expansion valve 103, and the refrigerant flow path 104 a of the heat source side heat exchanger 104 The heat pump circuit 105 in which the refrigerant pipes are annularly connected, the antifreeze liquid flow path 104b of the heat source side heat exchanger 104, and the underground heat exchanger 106 installed in the ground are connected to the underground heat circulation circuit in an annular shape by the antifreeze liquid pipes. 107, a geothermal circulation pump 108 that circulates the antifreeze liquid in the geothermal circulation circuit 107, a load terminal 109 such as a floor heating panel, and a heating circulation liquid flow path 102b of the load-side heat exchanger 102 with a heating circulation liquid pipe. An annularly connected load-side circulation circuit 110 and a load-side circulation pump 111 that circulates the heating circulating fluid in the load-side circulation circuit 110 are provided. The heat source-side heat exchanger 104 is an evaporator, and the load-side heat exchange is performed. 102 is made to function as a condenser, it was to perform load operation of the heating operation or the like for heating the conditioned space at the load terminal 109. (For example, refer to Patent Document 1.)

JP 2005-30705 A

  By the way, in this conventional geothermal heat pump device, when the heating output rapidly increases during the heating operation by the load terminal 109, the temperature of the refrigerant on the heat source side heat exchanger 104 side as an evaporator is accordingly increased. If the temperature of the refrigerant on the heat source side heat exchanger 104 side falls below −10 ° C., for example, depending on the type of the heat exchanger, the antifreeze liquid flowing in the antifreeze liquid flow path 104b of the heat source side heat exchanger 104 The water begins to freeze, and ice gradually spreads on the inner wall of the antifreeze liquid flow path 104b.

  Then, as ice is stretched on the inner wall of the antifreeze liquid flow path 104b, the antifreeze liquid flow path 104b is closed, the circulation flow rate of the antifreeze liquid circulating in the underground heat circulation circuit 107 is reduced, and the heat in the heat source side heat exchanger 104 is reduced. Since the exchange amount becomes insufficient, the temperature drop of the refrigerant on the heat source side heat exchanger 104 side does not converge. As a result, there is a possibility that ice grows in the antifreeze liquid flow path 104b and the heat source side heat exchanger 104 is damaged.

  In order to solve the above-mentioned problems, the present invention is particularly configured in claim 1 in which the compressor, the refrigerant flow path of the load side heat exchanger, the pressure reducing means, and the refrigerant flow path of the heat source side heat exchanger are annularly formed by refrigerant piping. A heat pump circuit connected to the heat source, an antifreeze liquid flow path of the heat source side heat exchanger and a ground heat exchanger installed in the ground in an annular shape by an antifreeze pipe, and the underground heat circulation A ground heat circulation pump that circulates the antifreeze liquid in the circuit, and an evaporating temperature detection means that detects the temperature of the refrigerant on the heat source side heat exchanger side, and collects the ground heat by the ground heat exchanger, In the geothermal heat pump apparatus that performs a load operation in which the heat source side heat exchanger functions as an evaporator and the load side heat exchanger functions as a condenser to heat the load side, the compressor is operated during the load operation. Target discharge temperature with preset discharge temperature Control means for controlling the opening degree of the decompression means so that the refrigerant temperature detected by the evaporation temperature detection means during the load operation is such that the refrigerant temperature of the antifreeze liquid is When it is determined that the preset freezing temperature that is expected to start freezing has been reached, the target discharge temperature is set to a predetermined temperature lower than before, and the pressure is reduced to the newly set target discharge temperature. The opening degree of the means was controlled in the opening direction.

  According to a second aspect of the present invention, the control means sets in advance that the refrigerant temperature detected by the evaporating temperature detecting means is expected to start freezing of water in the antifreeze liquid in the antifreeze liquid flow path during the load operation. If it is determined that the set freezing temperature has been reached, the target discharge temperature is set to a predetermined lower temperature, and the opening of the decompression means is controlled to open so as to reach the newly set target discharge temperature, and the compressor Control was made to increase the frequency of

  According to the first aspect of the present invention, in the control means, the refrigerant temperature detected by the evaporating temperature detecting means is set in advance during the load operation so that the freezing of the water in the antifreeze liquid is expected to start in the antifreeze liquid flow path. If the target freezing temperature is determined to be reached, the target discharge temperature is set to a predetermined temperature lower than before, and the opening of the decompression means is controlled to open so as to reach the newly set target discharge temperature. The temperature of the refrigerant on the side heat exchanger side rises, the freezing of the antifreeze liquid flow path of the heat source side heat exchanger during load operation can be prevented, and damage to the heat source side heat exchanger can be prevented in advance. .

  According to the second aspect of the present invention, the control means sets the refrigerant temperature detected by the evaporating temperature detecting means in a load operation in advance so that freezing of water in the antifreeze liquid is expected to start in the antifreeze liquid flow path. When it is determined that the freezing temperature has been reached, the target discharge temperature is set lower by a predetermined temperature, the opening degree of the decompression means is controlled to be opened to reach the newly set target discharge temperature, and the frequency of the compressor is increased. By controlling so that the temperature of the refrigerant on the heat source side heat exchanger side rises, it is possible to prevent freezing of the antifreeze liquid flow path of the heat source side heat exchanger and to prevent stable heating output without lowering the heating output Can be obtained and does not impair the usability.

The schematic block diagram of one Embodiment of this invention. The flowchart which shows the freeze prevention operation | movement of the antifreeze liquid flow path of the heat source side heat exchanger of the same embodiment. The time chart showing the movement of each parameter at the time of heating operation of the same embodiment. The schematic block diagram of the conventional geothermal heat pump apparatus.

Next, a geothermal heat pump device according to a first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the geothermal heat pump device of the present embodiment is roughly composed of a heat pump unit 1, a geothermal heat exchange unit 2, and a load heat exchange unit 3.

  The heat pump unit 1 circulates a variable capacity compressor 4 for compressing a refrigerant and a high-temperature refrigerant discharged from the compressor 4, and heat exchange between the high-temperature refrigerant and a heat medium on the load side of the load heat exchange unit 3. From the refrigerant flow path 5a of the load side heat exchanger 5 as a condenser for performing the above, the expansion valve 6 as pressure reducing means for depressurizing the refrigerant flowing out from the refrigerant flow path 5a of the load side heat exchanger 5, and the expansion valve 6 A refrigerant flow path 7a of a heat source side heat exchanger 7 serving as an evaporator that circulates the decompressed low temperature refrigerant and exchanges heat between the low temperature refrigerant and the heat medium on the heat source side of the underground heat exchange unit 2, Are connected in an annular shape by refrigerant piping to form a heat pump circuit 8. In addition, as a refrigerant | coolant of the heat pump unit 1, arbitrary refrigerant | coolants, such as a carbon dioxide refrigerant | coolant and a HFC refrigerant | coolant, can be used. Further, 9 is a discharge temperature sensor as discharge temperature detecting means for detecting the temperature of the refrigerant discharged from the compressor 4, and 10 is a refrigerant pipe on the heat source side heat exchanger 7 side from the expansion valve 6 to the compressor 4. That is, it is an evaporating temperature sensor as evaporating temperature detecting means provided in the low pressure side refrigerant pipe and detecting the temperature of the low pressure side refrigerant.

  The load side heat exchanger 5 and the heat source side heat exchanger 7 are configured by a plate heat exchanger, and the plate heat exchanger includes a plurality of heat transfer plates stacked, and a refrigerant channel and a fluid for circulating the refrigerant. The fluid flow paths to be circulated are alternately formed with each heat transfer plate as a boundary.

  The underground heat exchanging section 2 is installed in the ground as a heat source for heating the refrigerant flowing through the antifreeze liquid flow path 7b of the heat source side heat exchanger 7 and the refrigerant flow path 7a of the heat source side heat exchanger 7. A ground heat circulation circuit 12 in which a plurality of underground heat exchangers 11 connected in parallel are connected in an annular shape by an antifreeze pipe, and an antifreeze liquid in which ethylene glycol, propylene glycol or the like is added to the ground heat circulation circuit 12 as a heat medium. And a ground heat circulation pump 13 with a variable rotation speed.

  Here, in the underground heat exchanging unit 2, when performing a load operation described later, the underground heat exchanger 11 collects the underground heat from the underground, and the antifreeze liquid with the heat is discharged from the underground heat circulation pump. 13 is supplied to the antifreeze liquid flow path 7 b of the heat source side heat exchanger 7. Then, the refrigerant flowing through the refrigerant flow path 7a and the antifreeze liquid flowing through the antifreeze liquid flow path 7b flow in the heat source side heat exchanger 7 so as to face each other, and heat is exchanged by the underground heat exchanger 11. The generated underground heat is pumped to the refrigerant side of the heat pump unit 1 to heat the refrigerant, and the heat source side heat exchanger 7 functions as an evaporator.

  In addition, the load heat exchanging section 3 has a heating circulation liquid pipe connected to the heating circulation liquid flow path 5b of the load side heat exchanger 5 and a load terminal 14 such as a floor heating panel for heating the air-conditioned space. A load-side circulation circuit 15, a load-side circulation pump 16 that circulates the heating circulating fluid in the load-side circulation circuit 15, and a load-side circulation circuit 15 that branches for each load terminal 14 are provided to the load terminal 14 by opening and closing thereof. And a heat operated valve 17 (17a, 17b) for controlling the supply of the heating circulating fluid. A load temperature sensor 18 is provided in the load side circulation circuit 15 and serves as a load temperature detection means for detecting the temperature of the heating circulation liquid flowing from the load terminal 14 into the heating circulation liquid flow path 5b of the load side heat exchanger 5. is there.

  A remote control (not shown) is installed in each air-conditioned space heated by the load terminal 14, and when the remote controller instructs to heat the air-conditioned space, the compressor 4 and the underground heat circulation are provided. Driving of the pump 13 and the load side circulation pump 16 is started, and the heat source side heat exchanger 7 functions as an evaporator and the load side heat exchanger 5 functions as a condenser to heat the load side. Heating operation is performed. During the heating operation, in the load side heat exchanger 5, the refrigerant circulating in the refrigerant flow path 5a of the load side heat exchanger 5 and the heating circulating liquid flowing in the heating circulation liquid path 5b of the load side heat exchanger 5 Flows oppositely, heat exchange is performed to heat the heating circulating fluid, and the heated heating circulating fluid is sent to the load terminal 14 via the thermal valve 17 to heat the air-conditioned space instructed by the remote controller. To do.

  19 receives the inputs of the discharge temperature sensor 9, the evaporation temperature sensor 10, the load temperature sensor 18, and signals from the remote controller, and each of the compressor 4, the expansion valve 6, the underground heat circulation pump 13, and the load side circulation pump 16. It is a control means which has the microcomputer which controls the drive of an actuator.

  The control means 19 controls the frequency of the compressor 4 so that the temperature of the heating circulating fluid detected by the load temperature sensor 18 becomes the set target heating temperature during the heating operation, for example, the detection of the load temperature sensor 18. When the temperature of the heating circulating fluid is lower than the set target heating temperature, the frequency of the compressor 4 is controlled to increase.

  Further, the control means 19 sets the target discharge temperature of the refrigerant discharged from the compressor 4 based on the set temperature of the load terminal 14 set by the remote controller during the heating operation, and the discharge temperature sensor 9 The opening degree of the expansion valve 6 is controlled to open and close so that the temperature of the refrigerant discharged from the compressor 4 to be detected becomes the set target discharge temperature. For example, the refrigerant discharge temperature detected by the discharge temperature sensor 9 is set. When the temperature drops below the target discharge temperature, the opening degree is controlled to close.

  Further, during the heating operation, the control means 19 controls the rotation speed of the geothermal circulation pump 13 so that the low-pressure side refrigerant temperature detected by the evaporation temperature sensor 10 becomes the set target evaporation temperature, for example, When the refrigerant temperature on the low-pressure side detected by the evaporation temperature sensor 10 falls below the set target evaporation temperature, control is performed to increase the rotation speed of the underground heat circulation pump 13.

Next, the antifreezing operation of the antifreeze liquid channel 7b during the heating operation of the embodiment shown in FIG. 1 will be described based on the flowchart shown in FIG. 2 and the time chart shown in FIG.
When the load terminal 14 instructs the heating of the air-conditioned space by the remote controller, the control means 19 starts driving the compressor 4, the geothermal circulation pump 13, and the load-side circulation pump 16, and the heating operation is started. Is done. When the heating operation is started, the load-side heat exchanger 5 exchanges heat between the heating circulation liquid circulated by the load-side circulation pump 16 and the high-temperature and high-pressure refrigerant discharged from the compressor 4, and is heated. The liquid is supplied to the load terminal 14 to heat the air-conditioned space, and in the heat source side heat exchanger 7, the antifreeze liquid that is circulated by the geothermal circulation pump 13 and collects the underground heat through the underground heat exchanger 11. The low-temperature and low-pressure refrigerant discharged from the expansion valve 6 exchanges heat, and the refrigerant is heated and evaporated by underground heat.

  During this heating operation, the control means 19 sets the target discharge temperature of the refrigerant discharged from the compressor 4, the target evaporation temperature of the refrigerant on the heat source heat exchanger 7 side (low pressure side), and the target heating temperature on the load side, During the heating operation, the opening of the expansion valve 6 is controlled to open and close so that the temperature of the refrigerant discharged from the compressor 4 detected by the discharge temperature sensor 9 becomes the set target discharge temperature, and detected by the evaporation temperature sensor 10. The rotational speed of the geothermal circulation pump 13 is controlled so that the refrigerant temperature on the low-pressure side becomes the set target evaporation temperature, and the temperature of the heating circulating fluid detected by the load temperature sensor 18 becomes the set target heating temperature. Thus, the frequency of the compressor 4 is controlled.

  During the heating operation, the heating output may suddenly increase due to a rise immediately after the start of the heating operation or an increase in the number of operating load terminals 14, and in this case, the heating output is shown at times t <b> 1 to t <b> 2 in FIG. 3. Thus, the temperature of the refrigerant | coolant by the side of the heat source side heat exchanger 7 falls rapidly with the rapid increase in heating output. When a plate-type heat exchanger is used as the heat source side heat exchanger 7, the antifreeze liquid flowing through the antifreeze liquid passage 7b is cooled by the refrigerant across the heat transfer plate from both sides of the antifreeze liquid passage 7b. The temperature of the antifreeze liquid decreases rapidly, the water in the antifreeze liquid freezes in a short time, and the antifreeze liquid flow path 7b is gradually blocked.

  Therefore, during the heating operation, the control means 19 is expected that the refrigerant temperature detected by the evaporation temperature sensor 10 is lower than the target evaporation temperature, and the freezing of the water in the antifreeze liquid is started in the antifreeze liquid flow path 7b. It is determined whether or not a predetermined freezing temperature set in advance, for example, −10 ° C. has been reached (step S1), and the refrigerant temperature detected by the evaporation temperature sensor 10 is −10 as in the period up to time t2 in FIG. If it is determined that the temperature has not reached ° C, the process of step S1 is repeated to continue the heating operation so far, and the refrigerant temperature detected by the evaporation temperature sensor 10 is -10 ° C as shown at time t2 in FIG. If it is determined that the value has reached, it is determined whether or not the rotation speed of the underground heat circulation pump 13 is the upper limit rotation speed (step S2).

  In Step 2, when the control means 19 determines that the rotation speed of the geothermal circulation pump 13 is not the upper limit rotation speed, the rotation speed of the geothermal circulation pump 13 is set to the upper limit rotation speed (Step S3). After a predetermined time has elapsed, the process returns to step S1. On the other hand, if it is determined in step S2 that the rotation speed of the underground heat circulation pump 13 is the upper limit rotation speed, the target discharge temperature of the refrigerant discharged from the compressor 4 is set to the current target discharge temperature at time t2 in FIG. A temperature (for example, 80 ° C.) is set to a predetermined temperature, for example, a temperature lower by 15 ° C. (60 ° C.) (step S4), and the discharge temperature detected by the discharge temperature sensor 9 is set to a newly set target discharge temperature (= The opening degree of the expansion valve 6 is controlled to open so that the current target discharge temperature is 85 ° C.-predetermined temperature 15 ° C. = 60 ° C., and the control means 19 is the heating circulating fluid detected by the load temperature sensor 18. Control is performed to increase the frequency of the compressor 4 so that the temperature becomes the set target heating temperature.

  Then, the control means 19 predicts in advance that the refrigerant temperature detected by the evaporation temperature sensor 10 is higher than the predetermined freezing temperature and lower than the target evaporation temperature, and freezing of the antifreeze liquid is expected to be eliminated in the antifreeze liquid flow path 7b. It is determined whether or not a predetermined set freezing temperature, for example, −5 ° C. has been reached (step S5), and the refrigerant temperature detected by the evaporating temperature sensor 10 as in the period from time t2 to t3 in FIG. If it is determined that the temperature does not reach -5 ° C, the process of step S5 is repeated, and it is determined that the refrigerant temperature detected by the evaporation temperature sensor 10 has reached -5 ° C as shown at time t3 in FIG. In this case, the target discharge temperature of the refrigerant discharged from the compressor 4 is set to a predetermined temperature, for example, 15 ° C. higher than the current target discharge temperature, that is, the target discharge temperature 65 ° C. set in Step S4 (step S4). S6) The heating operation is performed in a state where the opening degree of the expansion valve 6 is closed and the heating output is increased so that the discharge temperature detected by the discharge temperature sensor 9 becomes a newly set target discharge temperature. Is to continue.

  In the antifreezing operation of the antifreeze liquid channel 7b during the heating operation described above, the control means 19 determines that the refrigerant temperature detected by the evaporation temperature sensor 10 is frozen during the heating operation so that the water in the antifreeze liquid is frozen in the antifreeze liquid channel 7b. When it is determined that the predetermined freezing temperature that is expected to be started has been reached, the target discharge temperature of the refrigerant discharged from the compressor 4 is set to a predetermined temperature lower than before and detected by the discharge temperature sensor 9 By controlling the opening of the expansion valve 6 so that the discharged temperature becomes the newly set target discharge temperature, the refrigerant temperature on the low pressure side rises, and during the heating operation, the heat source side heat exchanger 7 can prevent the water in the antifreeze liquid from freezing and prevent the heat source side heat exchanger 7 from being damaged.

  Further, the target discharge temperature of the refrigerant discharged from the compressor 4 is set to a temperature lower than the predetermined temperature, and the discharge temperature detected by the discharge temperature sensor 9 becomes the newly set target discharge temperature. Controlling the opening degree of the expansion valve 6 in the opening direction, and controlling the frequency of the compressor 4 to increase so that the temperature of the heating circulating fluid detected by the load temperature sensor 18 becomes the set target heating temperature. Thus, the refrigerant temperature on the low pressure side rises, so that the water in the antifreeze liquid can be prevented from freezing in the antifreeze liquid flow path 7b of the heat source side heat exchanger 7, and the antifreeze liquid flow path 7b is being prevented from freezing. By increasing the frequency of the compressor 4, it is possible to obtain a stable heating output without lowering the heating output and not to deteriorate the feeling of use.

  Further, the control means 19 increases the target discharge temperature to a predetermined temperature without waiting for the refrigerant temperature detected by the evaporation temperature sensor 10 to rise to the target evaporation temperature in the processing of Step S5 and Step S6. The expansion valve 6 is controlled so as to close the opening, but if the antifreeze flow path 7b is freed, the heat exchange efficiency in the heat source side heat exchanger 7 is increased, and the low pressure side is gradually increased. This is because the refrigerant reaches a target evaporation temperature without waiting for the above-described change of the target discharge temperature and the opening degree control of the expansion valve 6 to reach the target evaporation temperature.

  The present invention is not limited to the embodiment described above. In this embodiment, a plurality of underground heat exchangers 11 are installed in the ground and connected in parallel to each other. The intermediate heat exchangers 11 may be connected in series with each other. If a plurality of underground heat exchangers 11 are not installed and desired heat collection is possible from the ground, the underground heat exchanger 11 is 1 Only a book may be installed.

  In the present embodiment, the underground heat exchanger 11 is installed in the ground, and the underground heat exchanger 11 is directly buried in the ground to collect the underground heat. What installs 11 in a well and heat-collects from the well water heated by the underground heat is also contained in what installs the underground heat exchanger 11 in the underground.

  In the present embodiment, the heating medium circulation type heating operation in which the load terminal 14 such as a floor heating panel heats the room as the air-conditioned space is used as the load operation, but load-side heat exchange is performed in the room as the air-conditioned space. An indoor unit (not shown) having a unit 5 may be provided, and a heating operation in which the high-temperature refrigerant discharged from the compressor 4 in the indoor unit directly exchanges heat with room air and heats the room by blowing air may be used as a load operation. In addition, the load terminal 14 may be a hot water storage tank (not shown) for storing hot water used for hot water supply or the like, and a boiling operation for boiling hot water in the hot water storage tank may be a load operation. Various modifications are possible without departing from the scope of the invention, and this is not disturbed.

DESCRIPTION OF SYMBOLS 4 Compressor 5 Load side heat exchanger 5a Refrigerant flow path of load side heat exchanger 6 Expansion valve 7 Heat source side heat exchanger 7a Refrigerant flow path of heat source side heat exchanger 7b Antifreeze liquid flow path of heat source side heat exchanger 8 Heat pump Circuit 10 Evaporation temperature sensor 11 Underground heat exchanger 12 Underground heat circulation circuit 13 Underground heat circulation pump 19 Control means

Claims (2)

  Compressor, refrigerant flow path of load side heat exchanger, decompression means, heat pump circuit in which refrigerant flow path of heat source side heat exchanger is annularly connected by refrigerant piping, antifreeze liquid flow path and underground of said heat source side heat exchanger A ground heat circulation circuit in which a geothermal heat exchanger installed in a ring is connected in an annular shape by an antifreeze pipe, a ground heat circulation pump that circulates the antifreeze liquid in the ground heat circulation circuit, and the heat source side heat exchanger side And evaporating temperature detecting means for detecting the temperature of the refrigerant, collecting ground heat by the underground heat exchanger, causing the heat source side heat exchanger to function as an evaporator, and the load side heat exchanger In a geothermal heat pump device that performs a load operation that functions as a condenser and heats the load side, the decompression means is opened so that the discharge temperature of the compressor becomes a preset target discharge temperature during the load operation. Control means for controlling the degree of The means determines that, during the load operation, the refrigerant temperature detected by the evaporating temperature detecting means has reached a preset freezing temperature at which freezing of moisture in the antifreeze liquid is expected to start in the antifreeze liquid flow path. Then, the target discharge temperature is set to a predetermined temperature lower than before, and the opening of the decompression means is controlled to open in such a way as to be the newly set target discharge temperature. Thermal heat pump device.   The control means, during the load operation, the refrigerant temperature detected by the evaporation temperature detection means has reached a preset freezing temperature that is expected to start freezing of water in the antifreeze liquid in the antifreeze liquid flow path. The target discharge temperature is set lower than the predetermined temperature, and the opening of the decompression means is controlled to be opened so that the newly set target discharge temperature is reached, and the frequency of the compressor is increased. The geothermal heat pump device according to claim 1, wherein the geothermal heat pump device is provided.

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