A heat recovery heat pump device and a control method of a heat recovery heat pump device

Abstract

The application provides a heat recovery type heat pump device and a control method of the heat recovery type heat pump device, and the heat recovery type heat pump device comprises a refrigerant circulation pipeline, a compressor, a first heat exchanger, a second heat exchanger, an external air branch and a liquid storage branch; an external air heat exchanger is arranged on the external air branch, the external air branch is provided with a first end and a second end, the first end is connected between the compressor and the first heat exchanger, and the second end is connected between the first heat exchanger and the second heat exchanger; a liquid storage device is arranged on the liquid storage branch, the liquid storage device is provided with an inlet side and an outlet side, the inlet side is connected between the second end and the second heat exchanger through a first pipeline, and the outlet side is connected between the second heat exchanger and the compressor through a second pipeline; wherein, a first control valve is arranged on the first pipeline, and a second control valve is arranged on the second pipeline. The application solves the technical problem that in the prior art, the excessive refrigerant liquid in the heat pump device is retained in the condenser, which leads to the increase of condensing temperature and the decrease of refrigeration system efficiency.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and more specifically, to a heat recovery heat pump device and a control method for the heat recovery heat pump device. Background Technology

[0002] In existing heat recovery heat pump systems, the required circulating refrigerant volume is greatest in the operating mode where the hot water heat exchanger acts as the condenser and the cold water heat exchanger acts as the evaporator (i.e., the cooling main operating mode). If the optimal circulating refrigerant volume for the cooling main operating mode is set to the charged refrigerant volume, then in other operating modes (cooling mode, heating mode, or heating main operating mode), there will be an excess of circulating refrigerant.

[0003] However, in actual use, there is a problem: in the existing technology, excess refrigerant liquid remains in the condenser of the heat pump device, which causes excessive supercooling of the high-pressure liquid, resulting in an increase in condensation temperature and a decrease in the efficiency of the refrigeration system. Summary of the Invention

[0004] This invention solves the technical problem in the prior art where excess refrigerant liquid remains in the condenser of a heat pump device, causing excessive supercooling of the high-pressure liquid, which in turn leads to an increase in condensation temperature and a decrease in the efficiency of the refrigeration system.

[0005] To address the aforementioned problems, this invention provides a heat recovery heat pump device comprising: a refrigerant circulation pipeline, a compressor, a first heat exchanger, a second heat exchanger, an external gas branch, and a liquid storage branch. The compressor, the first heat exchanger, and the second heat exchanger are sequentially connected via the refrigerant circulation pipeline. An external gas heat exchanger is provided on the external gas branch, which has a first end and a second end. The first end is connected between the compressor and the first heat exchanger, and the second end is connected between the first heat exchanger and the second heat exchanger. A liquid storage tank is provided on the liquid storage branch, which has an inlet side and an outlet side. The inlet side is connected to the second end and the second heat exchanger via a first pipe, and the outlet side is connected to the second heat exchanger and the compressor via a second pipe. A first control valve is provided on the first pipe, and a second control valve is provided on the second pipe. The opening and closing of the first and second control valves are controlled according to the refrigerant liquid requirements in the heat recovery heat pump device.

[0006] Compared with existing technologies, the technical effects achieved by this solution are as follows: Based on the refrigerant requirements of the heat recovery heat pump unit, the refrigerant capacity in the receiver can be controlled. Specifically, by controlling the opening and closing of the first and second control valves on the receiver branch, the inflow and outflow of refrigerant in the receiver are controlled, thereby ensuring that the circulating refrigerant volume in the heat recovery heat pump unit is always appropriate. Simultaneously, it prevents excess refrigerant from accumulating in the condenser, which could lead to excessive supercooling of the high-pressure liquid, increased condensing temperature, and decreased efficiency of the refrigeration system. Furthermore, when the heat pump unit malfunctions, the status of the receiver, the first control valve, and the second control valve can be checked for appropriate repairs and adjustments.

[0007] In one embodiment of the present invention, a high-pressure sensor is provided on the exhaust side of the compressor; a high-pressure liquid temperature sensor is provided on the second end; wherein, the high-pressure liquid subcooling degree is calculated by the data collected by the high-pressure sensor and the high-pressure liquid temperature sensor, thereby obtaining the refrigerant liquid requirement.

[0008] Compared with existing technologies, the technical effects achieved by this technical solution are as follows: In the operation of the heat recovery heat pump device, the high-pressure liquid subcooling degree is calculated based on the measurement values ​​of the high-pressure sensor and the high-pressure liquid temperature sensor. The refrigerant liquid demand in the heat recovery heat pump device can be accurately determined and obtained through the high-pressure liquid subcooling degree, making the refrigerant liquid demand more specific and accurate.

[0009] In one embodiment of the present invention, the heat recovery heat pump device further includes: a heating branch, the heating branch having a first heating end and a second heating end, the first heating end and the first end being connected in parallel, and the second heating end being connected between a second heat exchanger and a compressor.

[0010] Compared with existing technologies, the technical effects achieved by this solution are as follows: When the outdoor gas heat exchanger is an evaporator (in which case the heat recovery heat pump device is in heating mode or main heating mode), the heating branch controls the refrigerant liquid on the compressor discharge side to pass through the condenser (here, the first heat exchanger) - evaporator (here, the outdoor gas heat exchanger and the second heat exchanger) and return to the compressor return gas side. When the evaporator includes an outdoor gas heat exchanger, the refrigerant flows out from the outdoor gas heat exchanger, flows through the heating branch, and returns to the compressor.

[0011] In one embodiment of the present invention, a switching element and a first throttling element are provided on the refrigerant circulation pipeline. The switching element is located at the first end, and the first throttling element is located at the second end and between the second heat exchanger. A second throttling element is also provided on the outside gas branch, which is located between the outside gas heat exchanger and the second end. A third switching valve is provided on the heating branch. A fourth switching valve is connected in parallel to both ends of the second throttling element.

[0012] Compared with existing technologies, the technical effects achieved by this solution are as follows: The superheat of the suction gas on the compressor return side is brought to a set value by adjusting the opening of the first throttling element; the temperature of the liquid passing through the first heat exchanger is brought to a set value by adjusting the opening of the second throttling element. The refrigerant flow rate from the compressor discharge side to the inlet of the first heat exchanger and the inlet of the outside gas heat exchanger is controlled by a switching element.

[0013] In one embodiment of the invention, the liquid receiver is also connected between the second heat exchanger and the compressor via a pressure relief branch.

[0014] Compared with existing technologies, the technical effect achieved by adopting this technical solution is that by setting up a pressure relief branch, it is easy to release pressure when the liquid reservoir exceeds the allowable pressure, thus avoiding damage to the liquid reservoir.

[0015] In one embodiment of the present invention, a pressure relief valve is provided on the pressure relief branch.

[0016] Compared with existing technologies, the technical effect achieved by adopting this technical solution is that the pressure relief valve can directly relieve pressure according to the pressure of the liquid reservoir.

[0017] In one embodiment of the present invention, the first heat exchanger is a hot water heat exchanger and the second heat exchanger is a cold water heat exchanger.

[0018] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: the first heat exchanger is a hot water heat exchanger, which is used as a condenser to release heat during operation; the second heat exchanger is a cold water heat exchanger, which is used as an evaporator to absorb heat during operation.

[0019] In one embodiment of the present invention, the heat recovery heat pump device further includes: a controller, which is used to receive the high-pressure liquid subcooling degree and control the opening and closing of the first control valve and the second control valve according to the high-pressure liquid subcooling degree.

[0020] Compared with existing technologies, the technical advantages achieved by this solution are as follows: Generally, the controller is electrically connected to the high-pressure sensor, high-pressure liquid temperature sensor, low-pressure sensor, and suction temperature sensor. The controller can achieve automatic control based on preset conditions, making it more convenient to use.

[0021] In another aspect, embodiments of the present invention also provide a control method for a heat recovery heat pump device, applied to the heat recovery heat pump device as described in Embodiment 1. The control method includes: obtaining the high-pressure liquid subcooling degree of the heat recovery heat pump device; controlling the opening and closing of a first control valve and a second control valve based on the high-pressure liquid subcooling degree and the magnitudes of a first subcooling degree threshold and a second subcooling degree threshold; controlling the first control valve to open and the second control valve to close when the high-pressure liquid subcooling degree is greater than the first subcooling degree threshold; and / or controlling the first control valve to close and the second control valve to open when the high-pressure liquid subcooling degree is less than the second subcooling degree threshold; and / or controlling both the first control valve and the second control valve to close when the high-pressure liquid subcooling degree is greater than or equal to the second subcooling degree threshold and less than or equal to the first subcooling degree threshold; wherein, the first subcooling degree threshold is greater than the second subcooling degree threshold.

[0022] Compared with existing technologies, the technical effects achieved by this solution are as follows: The high-pressure liquid subcooling degree is calculated based on the measurements from the high-pressure sensor and the high-pressure liquid temperature sensor. This high-pressure liquid subcooling degree allows for the determination of whether the circulating refrigerant quantity in the heat recovery heat pump device is within a reasonable range. When the high-pressure liquid subcooling degree is greater than the first subcooling degree threshold, it indicates that excess refrigerant is retained in the condenser, thus controlling the excess refrigerant to flow into the receiver. When the high-pressure liquid subcooling degree is less than the second subcooling degree threshold, it indicates that the refrigerant participating in the circulation in the heat pump device is insufficient, thus controlling the refrigerant to flow out of the receiver to participate in the circulation. When the high-pressure liquid subcooling degree is greater than or equal to the second subcooling degree threshold and less than or equal to the first subcooling degree threshold, it indicates that the amount of refrigerant participating in the circulation is reasonable, thus eliminating the need to adjust the refrigerant quantity in the receiver. By controlling the opening and closing of the first and second control valves on the liquid receiver side, the amount of refrigerant liquid participating in the circulation of the heat recovery heat pump device can be adjusted, thereby ensuring that the circulating refrigerant amount is always kept at the optimal value, thus maintaining the optimal efficiency of the heat recovery heat pump device at all times.

[0023] By adopting the technical solution of the present invention, the following technical effects can be achieved:

[0024] (1) By controlling the opening and closing of the first control valve and the second control valve on the liquid storage branch, the liquid inlet and outlet of the liquid storage tank are controlled, thereby achieving the effect that the circulating refrigerant quantity in the heat recovery heat pump device is always appropriate. At the same time, there will be no problem of excess refrigerant liquid remaining in the condenser, resulting in excessive high pressure liquid supercooling, rising condensing temperature, and reduced efficiency of the refrigeration system.

[0025] (2) The refrigerant demand in the heat recovery heat pump device can be accurately determined and obtained by the high-pressure liquid subcooling degree, making the refrigerant demand more specific and accurate. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the structure of a heat recovery heat pump device provided in Embodiment 1 of the present invention;

[0027] Figure 2 for Figure 1 A schematic diagram of the circuit of a medium-heat recovery heat pump unit in cooling mode;

[0028] Figure 3 for Figure 1 A schematic diagram of the circuit of a medium-heat recovery heat pump unit in the main cooling mode;

[0029] Figure 4 for Figure 1 A schematic diagram of the circuit of a medium-heat recovery heat pump unit in heating mode;

[0030] Figure 5 for Figure 1 A schematic diagram of the circuit of a medium-heat recovery heat pump unit in the main heating mode;

[0031] Figure 6 for Figure 1 A schematic diagram of the circuit in which excess refrigerant retained in the hot water heat exchanger flows into the liquid receiver in the heating mode of a medium heat recovery heat pump unit.

[0032] Figure 7 for Figure 1 A schematic diagram of the circuit in which the refrigerant stored in the receiver is supplied to the circulation pipeline in the main heating mode of the medium heat recovery heat pump unit.

[0033] Figure 8 A flowchart of a control method for a heat recovery heat pump device provided in Embodiment 2 of the present invention;

[0034] Explanation of reference numerals in the attached figures:

[0035] 100. Refrigerant circulation piping; 102. First throttling element; 105. Switching end; 106. First switching valve; 107. Second switching valve; 110. Compressor; 111. High-pressure sensor; 112. Low-pressure sensor; 113. Suction temperature sensor; 120. First heat exchanger; 121. First temperature sensor; 130. Second heat exchanger; 131. Second temperature sensor; 200. Outside air branch; 21. First end; 22. Second... End; 203, High-pressure liquid temperature sensor; 205, Second throttling element; 206, Fourth switching valve; 210, External air heat exchanger; 31-First liquid storage end; 32-Second liquid storage end; 310, Liquid storage tank; 311, First pipeline; 312, Second pipeline; 313, First control valve; 314, Second control valve; 315, Pressure relief branch; 316, Pressure relief valve; 400, Heating branch; 42, Second heating end; 403, Third switching valve. Detailed Implementation

[0036] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] See Figure 1 This is a structural schematic diagram of a heat recovery heat pump device provided in the first embodiment of the present invention, combined with... Figures 2-7 The heat recovery heat pump device includes: a refrigerant circulation pipeline 100, a compressor 110, a first heat exchanger 120, a second heat exchanger 130, an outside gas branch 200, and a liquid storage branch. The compressor 110, the first heat exchanger 120, and the second heat exchanger 130 are connected sequentially through the refrigerant circulation pipeline 100. An outside gas heat exchanger 210 is provided on the outside gas branch 200. The outside gas branch 200 has a first end 21 and a second end 22. The first end 21 is connected between the compressor 110 and the first heat exchanger 120, and the second end 22 is connected between the first heat exchanger 120 and the second heat exchanger 130. Between the heat exchangers 130; a liquid storage tank 310 is provided on the liquid storage branch, the liquid storage tank 310 has an inlet side and an outlet side, and the inlet side is connected to the second end 22 and the second heat exchanger 130 through the first pipe 311; the outlet side is connected to the second heat exchanger 130 and the compressor 110 through the second pipe 312; wherein, a first control valve 313 is provided on the first pipe 311 and a second control valve 314 is provided on the second pipe 312; the opening and closing of the first control valve 313 and the second control valve 314 are controlled according to the refrigerant liquid demand in the heat recovery heat pump device.

[0039] In one specific embodiment, a new liquid storage branch is added to a conventional heat pump device. By controlling the inlet and outlet flow rates of the liquid storage tank 310, the amount of circulating refrigerant in the heat recovery heat pump device is controlled. This avoids excessive circulating refrigerant in the heat recovery heat pump device, which would cause refrigerant liquid to stagnate in the condenser, thus reducing the efficiency of the heat pump system. Accordingly, based on the refrigerant liquid requirements of the heat recovery heat pump device, the refrigerant liquid capacity in the liquid storage tank 310 can be controlled. Specifically, by controlling the opening and closing of the first control valve 313 and the second control valve 314 on the liquid storage branch, the inlet and outlet flow rates of the liquid storage tank 310 are controlled, thereby achieving the effect of always having an appropriate amount of circulating refrigerant in the heat recovery heat pump device. At the same time, it prevents excess refrigerant liquid from stagnating in the condenser, which would lead to excessive supercooling of the high-pressure liquid, an increase in condensing temperature, and a decrease in the efficiency of the refrigeration system. Furthermore, when the heat pump device malfunctions, the status of the liquid storage tank 310, the first control valve 313, and the second control valve 314 can be checked for appropriate repairs and adjustments.

[0040] The first liquid storage end 31 is one end of the first pipe 311, and the first liquid storage end 31 is connected to the refrigerant circulation pipe 100 between the second end 22 and the second heat exchanger 130; the second liquid storage end 32 is one end of the second pipe 312, and the second liquid storage end 32 is connected to the refrigerant circulation pipe 100 between the second heat exchanger 130 and the compressor 110.

[0041] Furthermore, a high-pressure sensor 111 is provided on the exhaust side of the compressor 110; a high-pressure liquid temperature sensor 203 is provided on the second end 22; wherein, the high-pressure liquid subcooling degree is calculated by the data collected by the high-pressure sensor 111 and the high-pressure liquid temperature sensor 203, thereby obtaining the refrigerant liquid requirement.

[0042] Specifically, during the operation of the heat recovery heat pump device, the high-pressure liquid subcooling degree is calculated based on the measured values ​​of the high-pressure sensor 111 and the high-pressure liquid temperature sensor 203. The refrigerant liquid demand in the heat recovery heat pump device can be accurately determined and obtained through the high-pressure liquid subcooling degree, making the refrigerant liquid demand more specific and accurate.

[0043] Furthermore, the heat recovery heat pump device also includes: a heating branch 400, which is provided with a first heating end and a second heating end 42. The first heating end and the first end 21 are connected in parallel, and the second heating end 42 is connected between the second heat exchanger 130 and the compressor 110.

[0044] Specifically, the first heating end and the first end 21 are connected in parallel, so that the heating branch 400 is used to control the refrigerant liquid on the exhaust side of the compressor 110 to pass through the condenser (here, the first heat exchanger 120) and the evaporator (here, the outside gas heat exchanger 210 and the second heat exchanger 130) and return to the return gas side of the compressor 110. When the evaporator includes the outside gas heat exchanger 210, the refrigerant flows out of the outside gas heat exchanger 210, flows through the heating branch 400 and returns to the compressor 110.

[0045] Preferably, the second liquid storage end 32 is located on the refrigeration branch 400.

[0046] Furthermore, the refrigerant circulation pipeline 100 is equipped with a switching element and a first throttling element 102. The switching element is located at the first end 21, and the first throttling element 102 is located at the second end 22 between the second heat exchanger 130. The outside air branch 200 is also equipped with a second throttling element 205, which is located between the outside air heat exchanger 210 and the second end 22. The heating branch 400 is equipped with a third switching valve 403. A fourth switching valve 206 is connected in parallel to both ends of the second throttling element 205.

[0047] Specifically, the opening of the first throttling element 102 is adjusted to make the suction superheat of the compressor 110 return side reach the set value; the opening of the second throttling element 205 is adjusted to make the temperature of the liquid exchanging heat through the first heat exchanger 120 reach the set value. The refrigerant flow rate of the refrigerant discharged from the compressor 110 discharge side to the inlet of the first heat exchanger 120 and the inlet of the outside air heat exchanger 210 is controlled by the switching element.

[0048] Preferably, the switching element can be a three-way switching valve, which controls the refrigerant flow from the compressor 110 to the inlet of the first heat exchanger 120 and the inlet of the outside air heat exchanger 210. The switching element may further include: a first switching valve 106 and a second switching valve 107, which control the refrigerant flow from the discharge side of the compressor 110 to the inlet of the first heat exchanger 120 and the inlet of the outside air heat exchanger 210 by controlling the opening and closing of the first switching valve 106 and the second switching valve 107 respectively; one side of the first switching valve 106 is connected to the discharge side of the compressor 110, and the other side of the first switching valve 106 is connected to the inlet of the first heat exchanger 120; one side of the second switching valve 107 is connected to the discharge side of the compressor 110, and the other side of the second switching valve 107 is connected to the first end 21. The first switching valve 106 and the second switching valve 107 are connected in parallel at the switching end by setting a switching end 105 on the refrigerant circulation pipeline 100 on the discharge side of the compressor 110. When the first switching valve 106 is open, the refrigerant on the discharge side of the compressor 110 flows through the first switching valve 106 to the inlet of the first heat exchanger 120; when the second switching valve 107 is open, the refrigerant on the discharge side of the compressor 110 flows through the second switching valve 107 to the inlet of the outside air heat exchanger 210. Preferably, the first switching valve 106 is located on the refrigerant circulation pipeline 100 between the switching end 105 and the first heat exchanger 120, and the second switching valve 107 is located on the refrigerant circulation pipeline 100 between the switching end 105 and the first end 21.

[0049] Preferably, the first throttling element 102 is disposed on the refrigerant circulation pipeline 100 between the first liquid storage end 31 and the second heat exchanger 130; the third switching valve 403 is disposed on the heating branch 400 between the first end 21 and the second liquid storage end 32.

[0050] like Figure 2 As shown, when the heat recovery heat pump device is in cooling mode, it absorbs heat from the second liquid (cold water) through the second heat exchanger 130 to handle the cooling load. At the same time, the heat absorbed from the cold water and the total amount of compression work are released to the outside air through the outside air heat exchanger 210. At this time, the first switching valve 106 is closed, the second switching valve 107 is open, the third switching valve 403 is closed, the fourth switching valve 206 is open, the first throttling element 102 is open, and the second throttling element 205 is closed.

[0051] like Figure 3As shown, when the heat recovery heat pump device is in the main cooling mode, while absorbing heat from the second liquid (cold water) through the second heat exchanger 130 to handle the cooling load, a portion of the heat absorbed from the cold water and the total compression workload is released to the outside air through the outside air heat exchanger 210, and the remaining portion is released to the first liquid (warm water) through the first heat exchanger 120 to handle the heating load. At this time, the first switching valve 106 is open, the second switching valve 107 is open, the third switching valve 403 is closed, the fourth switching valve 206 is closed, and the first throttling element 102 and the second throttling element 205 are both open.

[0052] like Figure 4 As shown, when the heat recovery heat pump device is in heating mode, it absorbs heat from the outer ring through the outside air heat exchanger 210. The heat absorbed from the outside air and the workload of the compressor 110 are combined and released to the first liquid (warm water) through the first heat exchanger 120 to handle the heating load. At this time, the first switching valve 106 is open, the second switching valve 107 is closed, the third switching valve 403 is closed, the fourth switching valve 206 is closed, the first throttling element 102 is closed, and the second throttling element 205 is open.

[0053] like Figure 5 As shown, when the heat recovery heat pump device is in the main heating mode, it absorbs heat from the second liquid (cold water) through the second heat exchanger 130 to handle the cooling load, and absorbs heat from the outside air through the outside air heat exchanger 210. At the same time, the heat absorbed from the cold water, the heat absorbed from the outside air, and the workload of the compressor 110 are combined and released to the first liquid (warm water) through the first heat exchanger 120 to handle the heating load. At this time, the first switching valve 106 is open, the second switching valve 107 is closed, the third switching valve 403 is open, the fourth switching valve 206 is closed, and the first throttling element 102 and the second throttling element 205 are both open.

[0054] Furthermore, the liquid receiver 310 is also connected between the second heat exchanger 130 and the compressor 110 via a pressure relief branch 315.

[0055] Specifically, the reservoir 310 is also connected to the second reservoir end 32 via a pressure relief branch 315; by setting the pressure relief branch 315, it is easy to release pressure when the reservoir 310 exceeds the allowable pressure, thus avoiding damage to the reservoir 310.

[0056] Furthermore, a pressure relief valve 316 is installed on the pressure relief branch 315.

[0057] Specifically, the pressure relief valve 316 is a one-way valve with an opening pressure. It will automatically open when the pressure in the reservoir 310 exceeds its opening pressure, thereby achieving pressure relief. The pressure relief valve 316 can directly relieve pressure according to the pressure in the reservoir 310.

[0058] Furthermore, the first heat exchanger 120 is a hot water heat exchanger, and the second heat exchanger 130 is a cold water heat exchanger.

[0059] Specifically, the first heat exchanger 120 is a hot water heat exchanger, used as a condenser to release heat during operation; the first heat exchanger 120 is a cold water heat exchanger, used as an evaporator to absorb heat during operation.

[0060] Furthermore, the compressor 110 is also equipped with a low-pressure sensor 112 and a suction temperature sensor 113 on the return side.

[0061] Specifically, the superheat of compressor 110 intake is calculated based on the measured values ​​of low pressure sensor 112 and intake temperature sensor 113.

[0062] Furthermore, the heat recovery heat pump device also includes a controller, which receives the high-pressure liquid subcooling and controls the opening and closing of the first control valve 313 and the second control valve 314 according to the high-pressure liquid subcooling.

[0063] Specifically, under normal circumstances, the controller is electrically connected to the high-pressure sensor 111, the high-pressure liquid temperature sensor 203, the low-pressure sensor 112, and the suction temperature sensor 113. The controller can be configured to achieve automatic control based on preset conditions, making it more convenient to use.

[0064] Preferably, a first temperature sensor 121 is provided at the liquid outlet of the first heat exchanger 120, and a second temperature sensor 131 is provided at the liquid outlet of the second heat exchanger 130. The controller is electrically connected to the first temperature sensor 121 and the second temperature sensor 131. The speed of the compressor 110 is adjusted to make the measured value of the second temperature sensor 131 reach the set value, and the opening of the second throttling element 205 is adjusted to make the measured value of the first temperature sensor 121 reach the set value.

[0065]

Example 2

[0066] See Figure 8 This embodiment also provides a control method for a heat recovery heat pump device, applied to the heat recovery heat pump device as in Embodiment 1. The control method includes:

[0067] Step S100: Obtain the high-pressure liquid subcooling degree of the heat recovery heat pump device;

[0068] Step S200: Control the opening and closing of the first control valve and the second control valve according to the high-pressure liquid subcooling degree and the magnitude of the first subcooling degree threshold and the second subcooling degree threshold;

[0069] Step S310: When the high-pressure liquid subcooling degree is greater than the first subcooling degree threshold, control the first control valve to open and the second control valve to close; and / or

[0070] Step S320: When the high-pressure liquid subcooling degree is less than the second subcooling degree threshold, control the first control valve to close and the second control valve to open; and / or

[0071] Step S330: When the high-pressure liquid subcooling degree is greater than or equal to the second subcooling degree threshold and less than or equal to the first subcooling degree threshold, both the first control valve and the second control valve are closed.

[0072] Among them, the first supercooling threshold is greater than the second supercooling threshold.

[0073] In one specific embodiment, the high-pressure liquid subcooling degree is calculated based on the measurements from the high-pressure sensor and the high-pressure liquid temperature sensor. This high-pressure liquid subcooling degree determines whether the circulating refrigerant quantity in the heat recovery heat pump device is within a reasonable range: when the high-pressure liquid subcooling degree is greater than a first subcooling degree threshold, it indicates that excess refrigerant is retained in the condenser, therefore the excess refrigerant is controlled to flow into the receiver; when the high-pressure liquid subcooling degree is less than a second subcooling degree threshold, it indicates that the refrigerant participating in the circulation is insufficient, therefore the refrigerant in the receiver is controlled to flow out to participate in the circulation; when the high-pressure liquid subcooling degree is greater than or equal to the second subcooling degree threshold and less than or equal to the first subcooling degree threshold, it indicates that the refrigerant quantity participating in the circulation is reasonable, therefore there is no need to adjust the refrigerant quantity in the receiver. By controlling the opening and closing of the first and second control valves on the receiver side, the refrigerant quantity participating in the circulation of the heat recovery heat pump device is adjusted, thereby ensuring that the circulating refrigerant quantity is always at its optimal value, thus maintaining the optimal efficiency of the heat recovery heat pump device at all times.

[0074] Specifically, the refrigerant flow path volume of the cold water heat exchanger and the warm water heat exchanger using plate heat exchangers is set to 1.0 [L], and the refrigerant flow path volume of the external air heat exchanger using plate-fin tube heat exchangers is about 4.0 [L] according to the general design of heat pump devices.

[0075] Regardless of the type of refrigerant used, when the refrigeration system is operating within the normal range, the refrigerant liquid level in the evaporator is approximately 20% of the refrigerant flow path volume, and the refrigerant liquid level in the condenser is approximately 30% of the refrigerant flow path volume.

[0076] Therefore, under normal operating conditions in cooling mode, the chilled water heat exchanger, which acts as the evaporator, holds 1.0 × 20% = 0.2 [L], and the outside air heat exchanger, which acts as the condenser, holds 4.0 × 30% = 1.2 [L], for a total of 0.2 + 1.2 = 1.4 [L] of refrigerant liquid.

[0077] Under normal operating conditions in the main cooling mode, the chilled water heat exchanger, which acts as the evaporator, holds 1.0 × 20% = 0.2 [L], the outdoor air heat exchanger, which acts as the condenser, holds 4.0 × 30% = 1.2 [L], and the warm water heat exchanger holds 1.0 × 30% = 0.3 [L], for a total of 0.2 + 1.2 + 0.3 = 1.7 [L] of refrigerant liquid.

[0078] Under normal operating conditions in heating mode, the outer ring heat exchanger, which acts as the evaporator, holds 4.0 × 20% = 0.8 [L], and the warm water heat exchanger, which acts as the condenser, holds 1.0 × 30% = 0.3 [L], for a total of 1.1 [L] of refrigerant liquid.

[0079] Under normal operating conditions in the main heating mode, the cold water heat exchanger, which acts as the evaporator, holds 1.0 × 20% = 0.2 [L], the outdoor air heat exchanger holds 4.0 × 20% = 0.8 [L], and the warm water heat exchanger, which acts as the condenser, holds 1.0 × 30% = 0.3 [L], for a total of 0.2 + 0.8 + 0.3 = 1.3 [L] of refrigerant liquid.

[0080] At this point, when the device is filled with 1.7 [L] of refrigerant based on the main cooling mode with the largest refrigerant liquid holding capacity, the cooling mode will have 1.7-1.4=0.3 [L], the heating mode will have 1.7-1.1=0.6 [L], and the main heating mode will have 1.7-1.3=0.4 [L] of excess refrigerant liquid.

[0081] Excess refrigerant liquid remains in the condenser, causing excessive supercooling of the high-pressure liquid and an increase in condensation temperature, resulting in a significant decrease in the efficiency of the refrigeration system.

[0082] Therefore, this invention calculates the supercooling degree of the high-pressure liquid based on the measured values ​​of the high-pressure sensor and the high-pressure liquid temperature sensor. When the calculated supercooling degree is higher than the allowable value, the first control valve opens and the second control valve closes. When the calculated supercooling degree is lower than the allowable value, the first control valve closes and the second control valve opens. When the calculated supercooling degree is within the allowable range, the first control valve closes and the second control valve closes. This maintains the supercooling degree of the high-pressure liquid within the allowable range at all times, preventing excess refrigerant liquid from remaining in the condenser, which would cause the supercooling degree of the high-pressure liquid to become too high, leading to an increase in condensing temperature and a significant decrease in the efficiency of the refrigeration system.

[0083] As shown below, in order to illustrate the effects of the present invention, detailed physical laws are temporarily ignored, and the explanation is carried out solely based on the discussed model.

[0084] As mentioned above, the excess refrigerant in heating mode is 0.6 [L]. This excess refrigerant remains in the hot water heat exchanger, causing an abnormal rise in condensation temperature. Simultaneously, the efficiency of the refrigeration system deteriorates, and the calculated value of the high-pressure liquid subcooling exceeds the allowable value. At this point, after the first control valve opens and the second control valve closes, the excess refrigerant remaining in the hot water heat exchanger flows into the liquid receiver (…). Figure 7 The calculated value of the high-pressure liquid subcooling gradually decreases. When the amount of refrigerant flowing into the receiver reaches 0.6 [L], the calculated value of the high-pressure liquid subcooling enters the allowable range, the condensing temperature drops to the normal value, and the efficiency of the refrigeration system increases. Therefore, the first control valve closes, cutting off the flow of refrigerant into the receiver.

[0085] Then the state switches to the main heating mode. As above, the excess refrigerant in the main heating mode is 0.4 [L]. The current refrigerant stored in the receiver is 0.6 [L], therefore the circulating refrigerant amount is reduced by 0.6 - 0.4 = 0.2 [L]. Heating capacity decreases, refrigeration system efficiency deteriorates, and the calculated value of the high-pressure liquid subcooling degree is less than the allowable value. At this time, the first control valve closes, and the second control valve opens, supplying the refrigerant stored in the receiver to the circulation pipeline (…). Figure 8 The calculated value of the high-pressure liquid subcooling gradually increases. When the refrigerant quantity in the receiver reaches 0.4 [L], the calculated value of the high-pressure liquid subcooling enters the set range, the condensing temperature rises to the normal value, and the efficiency of the refrigeration system increases. Therefore, the first control valve closes, cutting off the outflow of refrigerant from the receiver.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat recovery type heat pump device, characterized in that, The heat recovery type heat pump device includes: The refrigerant circulation pipeline (100), compressor (110), first heat exchanger (120), second heat exchanger (130), outside gas branch (200) and liquid storage branch are connected in sequence through the refrigerant circulation pipeline (100); An external air heat exchanger (210) is provided on the external air branch (200). The external air branch (200) is provided with a first end (21) and a second end (22). The first end (21) is connected between the compressor (110) and the first heat exchanger (120), and the second end (22) is connected between the first heat exchanger (120) and the second heat exchanger (130). A liquid storage device (310) is provided on the liquid storage branch. The liquid storage device (310) has an inlet side and an outlet side. The inlet side is connected to the second end (22) and the second heat exchanger (130) through a first pipe (311). The outlet side is connected to the second heat exchanger (130) and the compressor (110) through a second pipe (312). The first pipe (311) is provided with a first control valve (313), and the second pipe (312) is provided with a second control valve (314); the opening and closing of the first control valve (313) and the second control valve (314) are controlled according to the refrigerant liquid demand in the heat recovery heat pump device. A first temperature sensor (121) is provided at the liquid outlet of the first heat exchanger (120), and a second temperature sensor (131) is provided at the liquid outlet of the second heat exchanger (130). The controller is electrically connected to the first temperature sensor (121) and the second temperature sensor (131). The speed of the compressor (110) is adjusted to make the measured value of the second temperature sensor (131) reach the set value. The opening of the second throttling element (205) is adjusted to make the measured value of the first temperature sensor (121) reach the set value.

2. The heat recovery heat pump device according to claim 1, characterized in that, The compressor (110) is equipped with a high-pressure sensor (111) on the exhaust side; The second end (22) is equipped with a high-pressure liquid temperature sensor (203); The high-pressure liquid subcooling degree is calculated by collecting data from the high-pressure sensor (111) and the high-pressure liquid temperature sensor (203), thereby obtaining the refrigerant liquid requirement.

3. The heat recovery heat pump device according to claim 1, characterized in that, The heat recovery heat pump device also includes: A heating branch (400) is provided with a first heating end and a second heating end (42). The first heating end and the first end (21) are connected in parallel, and the second heating end (42) is connected between the second heat exchanger (130) and the compressor (110).

4. The heat recovery heat pump device according to claim 3, characterized in that, The refrigerant circulation pipeline (100) is provided with a switching element and a first throttling element (102). The switching element is located at the first end (21), and the first throttling element (102) is located between the second end (22) and the second heat exchanger (130). The external air branch (200) is also provided with a second throttling element (205), which is located between the external air heat exchanger (210) and the second end (22); A third switching valve (403) is provided on the heating branch (400); A fourth switching valve (206) is connected in parallel across the two ends of the second throttling element (205).

5. The heat recovery heat pump device according to claim 1, characterized in that, The liquid reservoir (310) is also connected between the second heat exchanger (130) and the compressor (110) via a pressure relief branch (315).

6. The heat recovery heat pump device according to claim 5, characterized in that... A pressure relief valve (316) is installed on the pressure relief branch (315).

7. The heat recovery heat pump device according to any one of claims 1-6, characterized in that, The first heat exchanger (120) is a hot water heat exchanger, and the second heat exchanger (130) is a cold water heat exchanger.

8. The heat recovery heat pump device according to claim 1, characterized in that, The compressor (110) is also equipped with a low-pressure sensor (112) and a suction temperature sensor (113) on the suction side.

9. The heat recovery heat pump device according to claim 2, characterized in that, The heat recovery heat pump device further includes a controller, which is used to receive the high-pressure liquid subcooling degree and control the opening and closing of the first control valve (313) and the second control valve (314) according to the high-pressure liquid subcooling degree.

10. A control method for a heat recovery heat pump device, characterized in that, The control method is applied to the heat recovery heat pump device as described in any one of claims 1-9, and the control method includes: Obtain the high-pressure liquid subcooling degree of the heat recovery heat pump device; The opening and closing of the first control valve and the second control valve are controlled according to the high-pressure liquid supercooling degree and the magnitude of the first supercooling degree threshold and the second supercooling degree threshold. When the high-pressure fluid subcooling degree is greater than the first subcooling threshold, the first control valve is opened and the second control valve is closed; and / or When the high-pressure fluid subcooling degree is less than the second subcooling threshold, the first control valve is closed and the second control valve is opened; and / or When the high-pressure liquid subcooling degree is greater than or equal to the second subcooling degree threshold and less than or equal to the first subcooling degree threshold, both the first control valve and the second control valve are closed. Wherein, the first supercooling threshold is greater than the second supercooling threshold.

Images