Heavy-duty ultra-low temperature air source heat pump heating unit

Abstract

The utility model discloses a kind of heavy-duty ultra-low temperature air source heat pump heating unit, belong to heat pump unit technical field, heavy-duty ultra-low temperature air source heat pump heating unit includes the refrigerant main circuit system for heating and the independent refrigerant auxiliary circuit system for defrosting, the defrosting evaporator of refrigerant auxiliary circuit system is set to the liquid accumulator inside of refrigerant main circuit system;Unit operating mode includes normal heating condition / heating and defrosting condition, can effectively realize on-demand precision defrosting or according to use demand cycle defrosting, and defrosting does not stop, improve heating stability and user comfort, avoid main compressor frequent start-stop, greatly prolong its service life, four-way valve is not set in unit, system pipeline is simple and reliable, effectively reduce the unit cost, improve economy.

Description

Technical Field

[0001] This utility model relates to the field of heat pump unit technology, and in particular to a heavy-duty ultra-low temperature air source heat pump heating unit. Background Technology

[0002] In large screw-type air source heat pump units, the outdoor heat exchanger typically uses a finned heat exchanger, composed of multiple sets of V-shaped fin units. During winter heating, as the unit operates for extended periods, frost forms on the finned heat exchanger, increasing thermal resistance and severely impacting heat exchange efficiency, thus deteriorating the unit's energy efficiency. Traditional air source heat pump heating units require shutting down the unit and switching it from heating to cooling cycle mode via a four-way reversing valve to defrost in order to remove frost and improve efficiency. Traditional air source heat pump heating units have the following shortcomings:

[0003] Switching from heating mode to defrost mode (i.e., cooling mode) causes the refrigerant to absorb heat from the user's hot water during defrosting, resulting in a drop in water temperature, a decrease in heating temperature, and instability in heating temperature. This, in turn, affects heating efficiency and reduces user comfort. Simultaneously, the compressor's frequent start-stop cycles between heating and defrost modes shorten its lifespan. During unit operation, the degree of frost buildup varies across heat exchange units. If some heat exchange units reach defrost conditions prematurely while others do not, the entire unit must be shut down for defrosting, increasing defrosting frequency, system instability, and defrosting operating costs. To meet defrosting requirements, heating units need four-way reversing valves to switch between cooling and heating modes. This increases the complexity of the system piping, especially in large air-source heat pump units where large four-way reversing valves are expensive, further increasing the overall cost of the heating unit. Utility Model Content

[0004] In view of this, the technical problem to be solved by this utility model is to provide a heavy-duty ultra-low temperature air source heat pump heating unit that can continue to heat without stopping during defrosting, thereby improving heating stability and user comfort, and extending the service life of the compressor.

[0005] To solve the above-mentioned technical problems regarding heavy-duty ultra-low temperature air source heat pump heating units, the technical solution of this utility model is: a heavy-duty ultra-low temperature air source heat pump heating unit, which includes: a refrigerant main circuit system for heating and a refrigerant auxiliary circuit system for defrosting;

[0006] The refrigerant main circuit system includes a main compressor, an oil-gas separator, a condenser, a liquid receiver, an economizer, a liquid distribution main pipe, a main electronic expansion valve, a heat exchange device, a gas collection main pipe, and a gas-liquid separator, all connected in series via refrigerant pipelines to form a closed-loop main circuit. The heat exchange device includes two or more heat exchange units arranged in parallel. Each heat exchange unit is connected to the liquid distribution main pipe via a liquid distribution branch pipe and to the gas collection main pipe via a gas collection branch pipe. The main electronic expansion valve is located on the liquid distribution branch pipe. Each heat exchange unit is equipped with a main solenoid valve group, which includes a liquid distribution solenoid valve located on the liquid distribution branch pipe and a gas collection solenoid valve located on the gas collection branch pipe.

[0007] The refrigerant auxiliary circuit system includes a defrosting compressor, the heat exchange device, a defrosting electronic expansion valve, and a defrosting evaporator, which are connected in series via refrigerant pipelines to form a closed-loop auxiliary circuit. The defrosting evaporator is located inside the liquid receiver. Each heat exchange unit is equipped with a defrosting solenoid valve group, which includes an inlet solenoid valve and a return solenoid valve. The inlet solenoid valve is located on the unit's inlet pipe, and the return solenoid valve is located on the unit's return pipe. The unit's inlet pipe is connected to the auxiliary circuit inlet main pipe, and the unit's return pipe is connected to the auxiliary circuit return main pipe.

[0008] The heavy-duty ultra-low temperature air source heat pump heating unit is further optimized as follows:

[0009] The heat exchange unit is a V-type heat exchanger. The lower end of the unit's steam inlet pipe extends out of the V-type heat exchanger, and the lower end of the unit's steam inlet pipe is connected to two steam inlet branch pipes. The two steam inlet branch pipes are respectively connected to the gas collecting branch pipes on both sides of the V-type heat exchanger. The lower end of the unit's liquid return pipe extends out of the V-type heat exchanger, and the lower end of the unit's liquid return pipe is connected to two liquid return branch pipes. The two liquid return branch pipes are respectively connected to the liquid distributing branch pipes on both sides of the V-type heat exchanger.

[0010] Furthermore, the V-type heat exchanger is a V-type finned tube heat exchanger.

[0011] The oil-gas separator is connected to the oil return port of the main compressor by a lubricating oil pipeline.

[0012] The reservoir and the economizer are connected by a main supply line and an auxiliary supply line for the economizer, and an auxiliary electronic expansion valve is installed in the auxiliary supply line for the economizer.

[0013] The economizer is connected to the main compressor by a gas supply line.

[0014] The main compressor is a high-power two-stage screw compressor.

[0015] After adopting the above technical solution, the present invention has achieved the following beneficial technical effects:

[0016] Because the heavy-duty ultra-low temperature air source heat pump heating unit of this utility model includes a refrigerant main circuit system for heating and an independent refrigerant auxiliary circuit system for defrosting, the control method of this utility model includes normal heating mode and heating and defrosting mode. In normal heating mode, the refrigerant auxiliary circuit system does not operate, and the refrigerant main circuit system operates to meet the user's heating needs. In heating and defrosting mode, only one heat exchange unit (defrosting unit) is in defrosting mode, and the refrigerant main circuit system where the other heat exchange units are located continues to operate for heating, providing heat to the heating user side to meet the heating needs. The defrosting mode has basically no impact on the overall heating effect of the unit, improving heating stability and user comfort. In addition, the main compressor is in a continuous heating operation state, avoiding frequent start-stop and greatly extending its service life.

[0017] Because the unit has an independent refrigerant auxiliary circuit system (i.e., defrosting system), the four-way reversing valve used for switching between cooling and heating modes during defrosting is no longer required. The system piping is simpler and more reliable, effectively reducing unit costs and improving economy.

[0018] Because the defrosting evaporator of the refrigerant auxiliary circuit system is located inside the receiver of the refrigerant main circuit system, the auxiliary refrigerant absorbs heat from the main refrigerant in the receiver within the defrosting evaporator. This satisfies the defrosting heat requirements of the unit's heat exchange unit (defrosting unit) while simultaneously lowering the temperature of the main refrigerant in the receiver, increasing its subcooling, and facilitating the absorption of more heat from the air by the main refrigerant in the heat exchange device. This effectively increases the main circuit's heating capacity and improves the unit's heating efficiency. The refrigerant auxiliary circuit system and the refrigerant main circuit system are both independent and interconnected, complementing each other. This not only meets the unit's need for uninterrupted defrosting heating but also improves the unit's heating efficiency, achieving remarkable results.

[0019] This utility model relates to a heavy-duty ultra-low temperature air source heat pump heating unit. The main compressor adopts a high-power two-stage screw compressor, and the heat exchange device has multiple heat exchange units. It has a large heating / heat supply capacity, and the heating supply is not affected during defrosting. It can operate normally under ultra-low temperature conditions (below -25℃ is considered ultra-low temperature). It is particularly suitable for the heating needs of cold regions such as Northeast my country where the temperature reaches -40℃. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a heavy-duty ultra-low temperature air source heat pump heating unit according to an embodiment of this utility model (unit in normal heating condition);

[0021] Figure 2This is a schematic diagram of a heavy-duty ultra-low temperature air source heat pump heating unit according to an embodiment of this utility model (unit heating and defrosting mode);

[0022] Figure 3 yes Figure 2 Schematic diagram of the heat exchange unit in the diagram;

[0023] In the diagram: I. Refrigerant main circuit system; II. Refrigerant auxiliary circuit system;

[0024] 1. Heat exchange device; 101. Heat exchange unit; 111. Unit steam inlet pipe; 1111. Steam inlet branch pipe; 112. Unit liquid return pipe; 1121. Liquid return branch pipe;

[0025] 2. Main circuit electronic expansion valve;

[0026] 3. Main distribution pipe; 31. Branch distribution pipe;

[0027] 4. Main gas collecting pipe; 41. Branch gas collecting pipe;

[0028] 5. Condenser;

[0029] 6. Liquid reservoir;

[0030] 7. Oil-gas separator;

[0031] 8. Main compressor;

[0032] 9. Gas-liquid separator;

[0033] 10. Economical instruments;

[0034] 11. Auxiliary electronic expansion valve;

[0035] 12. Defrosting evaporator;

[0036] 13. Defrosting compressor;

[0037] 14. Defrosting electronic expansion valve;

[0038] A1, Steam inlet solenoid valve; A2, Liquid return solenoid valve; B1, Liquid distribution solenoid valve; B2, Gas collection solenoid valve; L1, Auxiliary steam inlet main pipe; L2, Auxiliary liquid return main pipe;

[0039] The arrows in the attached diagram indicate the direction of fluid flow. Detailed Implementation

[0040] The embodiments of this utility model will now be described in further detail and without limitation, with reference to the accompanying drawings.

[0041] like Figure 1 , Figure 2 and Figure 3As shown in the figure, the heavy-duty ultra-low temperature air source heat pump heating unit of this utility model includes: a refrigerant main circuit system I for heating, and an independent refrigerant auxiliary circuit system II for defrosting.

[0042] The refrigerant main circuit system I includes: a main compressor 8, an oil-gas separator 7, a condenser 5, a liquid receiver 6, an economizer 10, a liquid distribution main pipe 3, a main circuit electronic expansion valve 2, a heat exchange device 1, a gas collection main pipe 4, and a gas-liquid separator 9, which are connected in series through refrigerant pipelines to form a closed-loop main circuit.

[0043] The main compressor 8 is preferably a high-power two-stage screw compressor, such as the LT-S-65 / 32-A type compressor. The main compressor 8 is equipped with a low-pressure stage, an intermediate gas injection port, a lubricating oil return port, and a high-pressure stage. A lubricating oil pipeline connects the oil separator 7 to the lubricating oil return port of the main compressor 8, allowing the separated lubricating oil to return to the main compressor 8 for lubrication. A gas injection pipeline connects the economizer 10 to the intermediate gas injection port of the main compressor 8, allowing the auxiliary gas injection refrigerant from the economizer 10 to be introduced into the main compressor 8.

[0044] The reservoir 6 and the economizer 10 are connected by a main supply line and an auxiliary supply line for the economizer, and an auxiliary electronic expansion valve 11 is installed in the auxiliary supply line for the economizer.

[0045] The heat exchange device 1 includes two or more heat exchange units 101 connected in parallel (the figure shows five heat exchange units; obviously, the number of heat exchange units can be increased or decreased according to actual needs, for example, two, three, four, or more than five). Each heat exchange unit 101 is connected to the liquid distribution main pipe 3 through a liquid distribution branch pipe 31 and to the gas collection main pipe 4 through a gas collection branch pipe 41. The main electronic expansion valve 2 is installed on the liquid distribution branch pipe 31. Each heat exchange unit 101 is equipped with a main solenoid valve group, which includes a liquid distribution solenoid valve B1 installed on the liquid distribution branch pipe 31 and a gas collection solenoid valve B2 installed on the gas collection branch pipe 41.

[0046] Among them, the heat exchange unit 101 is optimized to be a V-type heat exchanger, and further, the V-type heat exchanger is preferably a V-type finned tube heat exchanger.

[0047] The refrigerant auxiliary circuit system II includes: a defrosting compressor 13 connected in series via refrigerant pipelines to form a closed-loop auxiliary circuit, the aforementioned heat exchange device 1, a defrosting electronic expansion valve 14, and a defrosting evaporator 12, with the defrosting evaporator 12 located inside the liquid receiver 6 of the refrigerant main circuit system I; each heat exchange unit 101 is provided with a defrosting solenoid valve group, which includes an inlet solenoid valve A1 and a return solenoid valve A2. The inlet solenoid valve A1 is located on the unit inlet pipe 111, and the return solenoid valve A2 is located on the unit return pipe 112. The unit inlet pipe 111 is connected to the auxiliary inlet pipe L1, and the unit return pipe 112 is connected to the auxiliary return pipe L2.

[0048] Specifically, the lower end of the unit steam inlet pipe 111 extends out of the V-shaped heat exchanger, and the lower end of the unit steam inlet pipe 111 is connected to two steam inlet branch pipes 1111, which are respectively connected to the gas collecting branch pipes 41 on both sides of the V-shaped heat exchanger; the lower end of the unit liquid return pipe 112 extends out of the V-shaped heat exchanger, and the lower end of the unit liquid return pipe 112 is connected to two liquid return branch pipes 1121, which are respectively connected to the liquid distribution branch pipes 31 on both sides of the V-shaped heat exchanger.

[0049] The heavy-duty ultra-low temperature air source heat pump heating unit of this utility model operates as follows when it is in normal heating mode and defrosting is not required:

[0050] like Figure 1As shown, during normal heating, all defrosting solenoid valve groups (steam inlet solenoid valve A1 and liquid return solenoid valve A2) of all heat exchange units 101 of heat exchange device 1 are closed, and the refrigerant auxiliary circuit system II does not operate. All main solenoid valve groups (liquid distribution solenoid valve B1 and gas collection solenoid valve B2) of all heat exchange units 101 are open, and the refrigerant main circuit system I operates: the low-temperature, low-pressure gaseous refrigerant separated by the gas-liquid separator 9 enters the main compressor 8. After being compressed in the low-pressure stage, the low-temperature, low-pressure gaseous refrigerant mixes with the auxiliary gas supply refrigerant of the economizer 10 and enters the high-pressure stage of the main compressor 8. After being compressed and separated by the oil-gas separator 7, the high-temperature, high-pressure refrigerant enters the condenser 5. The separated lubricating oil returns to the main compressor 8 through the lubricating oil pipeline to lubricate the main compressor 8. After the refrigerant releases heat to the hot water on the heating user side in the condenser 5 to achieve heating, it condenses into a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant is discharged into the liquid receiver 6. The liquid receiver 6 is equipped with a defrosting evaporator 12 for the independent defrosting system, an economizer auxiliary supply liquid port, and an economizer main supply liquid port. After the refrigerant is throttled and depressurized by the auxiliary electronic expansion valve 11, it evaporates in the economizer 10, cooling the main refrigerant of the economizer and increasing the subcooling of the main refrigerant. The superheated gaseous refrigerant in the auxiliary economizer circuit after evaporation and vaporization enters the main compressor 8's gas supply port through the gas supply pipeline to replenish the main compressor 8. The refrigerant in the main economizer circuit is evenly supplied to each heat exchange unit 101 after being throttled and depressurized by the refrigerant pipeline, the liquid distribution main pipe 3, each liquid distribution branch pipe 31, and the main circuit electronic expansion valve 2. In the heat exchange unit 101, it absorbs heat from the air and vaporizes. The low-temperature and low-pressure gaseous refrigerant that evaporates and vaporizes in the heat exchange unit 101 is collected by each gas collecting branch pipe 41 and the gas collecting main pipe 4, and then enters the gas-liquid separator 9 through the refrigerant pipeline. The low-temperature and low-pressure gaseous refrigerant separated by the gas-liquid separator 9 enters the low-pressure stage suction port of the main compressor 8 through the refrigerant pipeline. The refrigerant main circuit system II circulates in this way to achieve continuous and stable heating.

[0051] When the heavy-duty ultra-low temperature air source heat pump heating unit of this utility model requires defrosting and continuous heating, it can adopt an on-demand precise defrosting mode or a cyclical shift defrosting mode.

[0052] The on-demand precision defrosting mode is as follows:

[0053] like Figure 2 and Figure 3 As shown, when one of the heat exchange units 101 in the unit (with Figure 2As shown in the diagram, taking the first heat exchange unit on the left as an example, when defrosting is required due to the defrosting conditions, the heat exchange unit is designated as the defrosting unit. The defrosting solenoid valve group (inlet solenoid valve A1 and return solenoid valve A2) of the defrosting unit is opened, and the main circuit solenoid valve group (distribution solenoid valve B1 and gas collection solenoid valve B2) of the defrosting unit is disconnected. The defrosting unit does not participate in the heating of the refrigerant main circuit system I. The refrigerant auxiliary circuit system II, where the defrosting unit is located, operates as follows: the low-temperature, low-pressure gas-liquid mixture of refrigerant, after being throttled and depressurized by the defrosting electronic expansion valve 14, enters the defrosting evaporator 12, where it absorbs heat from the main refrigerant in the receiver 6 and evaporates. The low-temperature, low-pressure auxiliary refrigerant vapor in the defrosting system enters the defrosting compressor 13 through the refrigerant pipeline. The high-temperature, high-pressure refrigerant, after compression, enters the V-type heat exchanger of the defrosting unit through the auxiliary inlet manifold L1, the unit inlet manifold 111, the inlet solenoid valve A1, and the two inlet branch pipes 1111, releasing heat to heat the frost layer and defrost. The refrigerant vapor condenses into a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant enters the defrosting evaporator 12 after being throttled and depressurized by the two return manifolds 1121, the return solenoid valve A2, the unit return manifold 112, the auxiliary return manifold L2, and the defrosting electronic expansion valve 14. The auxiliary refrigerant circulates back and forth, completing the independent defrosting of the defrosting unit.

[0054] During defrosting, except for the defrosting unit, all other heat exchange units in the unit (shown in the diagram, from left to right: the second heat exchange unit, the third heat exchange unit, the fourth heat exchange unit, and the fifth heat exchange unit) have their defrosting solenoid valve groups (steam inlet solenoid valve A1 and liquid return solenoid valve A2) completely disconnected. The main circuit solenoid valve groups (liquid distribution solenoid valve B1 and gas collection solenoid valve B2) of the remaining heat exchange units are all opened. The refrigerant main circuit system I, where the remaining heat exchange units are located, is running. The high-temperature and high-pressure gaseous refrigerant releases heat to the heating user side in the condenser 5, achieving continuous and stable heating without stopping the machine during defrosting.

[0055] The cyclical defrosting mode is as follows:

[0056] After the unit starts up and runs for a period of time (T1), from left to right, it will... Figure 2 The first group of heat exchange units is used as the defrosting unit, and defrosting is performed on it (refer to the on-demand precise defrosting mode described above), with a defrosting time of T2. After the unit continues to run for a period of time T1, the second group of heat exchange units is used as the defrosting unit, and defrosting is performed on it (refer to the first group of heat exchange units), with a defrosting time of T2; ... and so on, completing the defrosting of the third, fourth, and fifth groups of heat exchange units, that is, all heat exchange units are defrosted and defrosted in turn, completing one defrosting cycle of the unit. Depending on actual needs, if necessary, the unit can continue to be defrosted in this cycle. The unit running time T1 can be set, for example, to 1 hour; the defrosting time T2 can be set, for example, to 0.1 hours.

[0057] Obviously, due to the influence of climate conditions and / or air temperature and humidity, the unit operating time T1 and defrosting time T2 are not fixed, but need to be flexibly set or adjusted according to the user's actual usage time and the user's usage environment, and are not limited to them.

[0058] In summary, this utility model's heavy-duty ultra-low temperature air source heat pump heating unit is equipped with a main refrigerant circuit system for heating and an independent auxiliary refrigerant circuit system for defrosting. It can perform precise defrosting on demand or cyclical defrosting according to usage requirements, without shutting down the unit during defrosting, thus improving heating stability and user comfort. It avoids frequent start-stop of the main compressor, greatly extending its service life. The unit does not include a four-way reversing valve, resulting in a simple and reliable system piping, effectively reducing unit costs and improving economy. The defrosting evaporator and economizer auxiliary refrigerant significantly increase the subcooling of the main refrigerant circuit, effectively increasing the main circuit's heating capacity and improving the unit's heating efficiency.

Claims

1. A heavy-duty ultra-low temperature air source heat pump heating unit, characterized in that, The heavy-duty ultra-low temperature air source heat pump heating unit includes: a refrigerant main circuit system for heating and a refrigerant auxiliary circuit system for defrosting; The refrigerant main circuit system includes: a main compressor, an oil-gas separator, a condenser, a liquid receiver, an economizer, a liquid distribution main pipe, a main electronic expansion valve, a heat exchange device, a gas collection main pipe, and a gas-liquid separator, all connected in series via refrigerant pipelines to form a closed-loop main circuit. The heat exchange device includes two or more heat exchange units arranged in parallel. Each heat exchange unit is connected to the liquid distribution main pipe via a liquid distribution branch pipe and to the gas collection main pipe via a gas collection branch pipe. The main electronic expansion valve is located on the liquid distribution branch pipe. Each heat exchange unit is equipped with a main solenoid valve group, which includes a liquid distribution solenoid valve located on the liquid distribution branch pipe and a gas collection solenoid valve located on the gas collection branch pipe. The refrigerant auxiliary circuit system includes: a defrosting compressor forming a closed-loop auxiliary circuit via refrigerant pipelines, the heat exchange device, a defrosting electronic expansion valve, and a defrosting evaporator, wherein the defrosting evaporator is disposed inside the liquid receiver; each heat exchange unit is provided with a defrosting solenoid valve group, the defrosting solenoid valve group including a steam inlet solenoid valve and a liquid return solenoid valve, the steam inlet solenoid valve being disposed on the unit steam inlet pipe, the liquid return solenoid valve being disposed on the unit liquid return pipe, the unit steam inlet pipe being connected to the auxiliary circuit steam inlet main pipe, and the unit liquid return pipe being connected to the auxiliary circuit liquid return main pipe.

2. The heavy-duty ultra-low temperature air source heat pump heating unit as described in claim 1, characterized in that, The heat exchange unit is a V-type heat exchanger. The lower end of the unit's steam inlet pipe extends out of the V-type heat exchanger, and the lower end of the unit's steam inlet pipe is connected to two steam inlet branch pipes. The two steam inlet branch pipes are respectively connected to the gas collecting branch pipes on both sides of the V-type heat exchanger. The lower end of the unit's liquid return pipe extends out of the V-type heat exchanger, and the lower end of the unit's liquid return pipe is connected to two liquid return branch pipes. The two liquid return branch pipes are respectively connected to the liquid distributing branch pipes on both sides of the V-type heat exchanger.

3. The heavy-duty ultra-low temperature air source heat pump heating unit as described in claim 2, characterized in that, The V-type heat exchanger is a V-type finned tube heat exchanger.

4. The heavy-duty ultra-low temperature air source heat pump heating unit as described in claim 1, characterized in that, A lubricating oil pipeline is connected between the oil-gas separator and the oil return port of the main compressor.

5. The heavy-duty ultra-low temperature air source heat pump heating unit as described in claim 1, characterized in that, The reservoir and the economizer are connected by a main supply line and an auxiliary supply line for the economizer, and an auxiliary electronic expansion valve is installed in the auxiliary supply line for the economizer.

6. The heavy-duty ultra-low temperature air source heat pump heating unit as described in claim 1, characterized in that, An air supply line is connected between the economizer and the main compressor.

7. The heavy-duty ultra-low temperature air source heat pump heating unit as described in claim 1, characterized in that, The main compressor is a high-power two-stage screw compressor.

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