Vapor compression type heat pump system control and vapor compression type heat pump system

Abstract

The invention relates to the technical field of heating equipment, and provides a steam compression type heat pump system control method and a steam compression type heat pump system.The method comprises the steps that the running working medium flow is determined according to the obtained target preparation amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters and working medium attributes; obtaining a working medium injection amount according to the working medium flow; an evaporator, a compressor and a condenser are started, and a working medium storage device injects a working medium into the compressor according to the working medium injection amount; after running for preset unit time, obtaining the flow of the evaporator according to the obtained device liquid flow and evaporation gas flow of the gas-liquid separator; and adjusting the operation of the vapor compression heat pump system according to the evaporator flow and the operation working medium flow. The running condition of the steam compression type heat pump system is monitored and adjusted in real time, the fluctuation problem of the working medium flow in the steam compression type heat pump system due to environment change is reduced, and then the running stability of the steam compression type heat pump system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heating equipment, and in particular to a vapor compression heat pump system control method and a vapor compression heat pump system. Background Art

[0002] Steam compression heat pumps have high energy efficiency and strong temperature raising capability, and are recognized in the industry as the most efficient and environmentally friendly high-temperature hot water production device.

[0003] In the related art, a low-temperature working fluid is usually input into a steam compression heat pump system, and the working fluid undergoes cycles of evaporation, compression, condensation, etc. in the heat pump system. However, during the operation of the steam compression heat pump system, the flow rate of the working fluid may fluctuate due to factors such as environmental factors and changes in power supply, resulting in the instability of the steam compression heat pump system, which in turn affects the temperature of the hot water prepared by the steam compression heat pump and causes large fluctuations. Summary of the invention

[0004] The problem solved by the present invention is how to improve the operating stability of a steam compression heat pump.

[0005] In order to solve the above problems, the present invention provides a vapor compression heat pump system control method and a vapor compression heat pump system.

[0006] In a first aspect, the present invention provides a vapor compression heat pump system control method, based on the vapor compression heat pump system, the vapor compression heat pump system includes a working fluid storage device, an evaporator, a condenser, a liquid storage tank, a gas-liquid separator and a compressor; the vapor compression heat pump system control method includes:

[0007] Determine the operating working fluid flow rate according to the obtained target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters and working fluid properties, and obtain the working fluid injection amount according to the working fluid flow rate;

[0008] The evaporator, the compressor and the condenser are started, and the working fluid storage device injects working fluid into the compressor according to the working fluid injection amount;

[0009] After running for a preset unit time, the evaporator flow rate is obtained according to the liquid flow rate and the evaporated gas flow rate of the gas-liquid separator;

[0010] The operation of the vapor compression heat pump system is adjusted according to the evaporator flow and the operating working medium flow.

[0011] Optionally, the vapor compression heat pump system further includes an expansion valve; obtaining an adjustment strategy according to the evaporator flow and the operating working medium flow, and controlling the operation of the vapor compression heat pump system according to the adjustment strategy includes:

[0012] When the evaporator flow rate is less than or greater than the operating working medium flow rate, adjusting the opening of the expansion valve according to the difference between the evaporator liquid flow rate and the operating working medium flow rate;

[0013] When the liquid flow rate of the device increases, the power is adjusted according to the liquid flow rate of the device;

[0014] The evaporator is adjusted to operate according to the adjusted power.

[0015] Optionally, the vapor compression heat pump system further includes a sight glass; and the vapor compression heat pump system control method further includes:

[0016] Determine whether there are bubbles in the sight glass. If so, it is determined that there is a problem with the operating circuit of the condenser.

[0017] Optionally, before obtaining the evaporator flow rate according to the obtained liquid flow rate and evaporation gas flow rate of the gas-liquid separator, the method further comprises:

[0018] When the liquid level in the vessel decreases, the volume change of the liquid in the vessel is obtained according to the size of the gas-liquid separator and the change of the liquid level in the vessel;

[0019] The ratio of the volume change of the liquid in the vessel to the preset unit time is obtained to obtain the volume flow rate of the vessel;

[0020] The product of the volume flow rate of the vessel and the density of the working fluid is obtained to obtain the liquid flow rate of the vessel.

[0021] Optionally, the vapor compression heat pump system further comprises a liquid storage tank;

[0022] The starting of the evaporator, the compressor and the condenser, wherein the working medium storage device injects working medium into the compressor according to the working medium injection amount, comprises:

[0023] Obtaining a pre-storage working mass according to the storage capacity of the liquid storage tank, wherein the pre-storage working mass includes two-thirds of the storage capacity of the liquid storage tank;

[0024] The vapor compression heat pump system control method further includes:

[0025] The actual liquid level of the liquid storage tank is obtained, and when the actual liquid level is less than a preset dangerous liquid level, the pre-stored working mass of working fluid is added to the liquid storage tank.

[0026] Optionally, the vapor compression heat pump system further comprises a flow meter disposed between the liquid storage tank and the evaporator, the flow meter being used to measure the flow rate of the condensing side working medium flowing into the evaporator; the vapor compression heat pump system control method further comprises:

[0027] The mass of the working medium on the evaporation side is obtained according to the evaporation gas flow rate, and the mass of the working medium on the condensation side is obtained according to the condensation gas flow rate;

[0028] Obtaining the sum of the mass of the working fluid on the evaporation side and the mass of the working fluid on the condensation side to obtain the mass of the circulating working fluid;

[0029] When the mass of the circulating working fluid is less than the working fluid injection amount, the working fluid replenishment amount is obtained according to the mass difference between the circulating working fluid mass and the working fluid injection amount, and at least one of the liquid storage tank and the working fluid storage device is controlled to output the working fluid according to the working fluid replenishment amount.

[0030] Optionally, when the mass of the circulating working fluid is less than the working fluid injection amount, obtaining a working fluid replenishment amount according to a mass difference between the mass of the circulating working fluid and the working fluid injection amount, and controlling at least one of the liquid storage tank and the working fluid storage device to output the working fluid according to the working fluid replenishment amount comprises:

[0031] Comparing the mass of the liquid in the tank with the amount of the working fluid added, wherein the mass of the liquid in the tank includes the mass of the working fluid in the liquid storage tank;

[0032] When the mass of the liquid in the tank is greater than or equal to the working fluid replenishment amount, controlling the liquid storage tank to output the working fluid according to the working fluid replenishment amount;

[0033] When the mass of the liquid in the tank is less than the amount of working fluid replenished, a difference between the mass of the liquid in the tank and the amount of working fluid replenished is generated, and the liquid storage tank is controlled to output all the working fluid, and the working fluid storage device outputs the working fluid according to the difference.

[0034] In a second aspect, the present invention provides a vapor compression heat pump system, comprising a working fluid storage device, an evaporator, a condenser, a liquid storage tank, a gas-liquid separator, a compressor and a controller, wherein the control module is used to implement the vapor compression heat pump system control method as described above.

[0035] Optionally, the vapor compression heat pump system further comprises a water storage tank, one end of which is used to be connected to a waste heat source, and the other end of which is connected to an inlet end of the evaporator.

[0036] Optionally, the vapor compression heat pump system further includes a straight-through joint, and the working fluid storage device, the evaporator, the condenser, the liquid storage tank, the gas-liquid separator, the expansion valve and the compressor are all connected via the straight-through joint.

[0037] The control method of the vapor compression heat pump system and the vapor compression heat pump system of the present invention have the following beneficial effects: the operating working fluid flow is determined according to the obtained target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters and working fluid properties, and the working fluid injection amount is obtained according to the working fluid flow, that is, the actual operating working fluid flow and working fluid injection amount of the vapor compression heat pump system are set according to the heat demand in the actual situation, and the evaporator, the compressor and the condenser are started, and the working fluid storage device injects the working fluid into the compressor according to the working fluid injection amount. When the working fluid in the vapor compression heat pump system circulates at the operating working fluid flow, the efficiency of the vapor compression heat pump system is optimal, and the working fluid is injected into the compressor according to the working fluid injection amount, so as to avoid the unloading or overloading phenomenon caused by too little or too much circulating working fluid in the vapor compression heat pump system. The preset unit time (for example, 1s) is run to obtain the liquid flow and the evaporated gas flow of the gas-liquid separator, and the actual working fluid flow accurately circulated in the vapor compression heat pump system is obtained, that is, the influence of the gas-liquid coexistence state of the working fluid on the flow measurement result is avoided, and the accuracy of the detection of the circulating working fluid flow in the vapor compression heat pump system is increased. According to the evaporator flow and the operating working fluid flow, for example, the evaporator flow in actual operation is compared with the operating working fluid flow in an ideal state, and the vapor compression heat pump system is adjusted according to the comparison result, and the operation of the vapor compression heat pump system is monitored and adjusted in real time to reduce the fluctuation problem of the working fluid flow in the vapor compression heat pump system due to environmental changes, thereby increasing the stability of the operation of the vapor compression heat pump system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic flow chart of a vapor compression heat pump system control method according to an embodiment of the present invention;

[0039] Figure 2 Schematic diagram of the structure of a vapor compression heat pump system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0041] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0042] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to"; the term "based on" means "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0043] It should be noted that the modifications of "one" and "plurality" mentioned in the present invention are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0044] The names of the messages or information exchanged between multiple devices in the embodiments of the present invention are only used for illustrative purposes, and are not used to limit the scope of these messages or information.

[0045] like Figure 1 As shown, a vapor compression heat pump system control method provided by an embodiment of the present invention is based on a vapor compression heat pump system, which is applied to a heating system, that is, preparing hot water.

[0046] The structure of the vapor compression heat pump system is as follows: Figure 2 As shown, it includes a working fluid storage device, an evaporator, a condenser, a liquid storage tank, a gas-liquid separator and a compressor, wherein Figure 2 The "IC" is an integrated circuit of the compressor, the working fluid storage device is connected to the compressor, the heating end of the evaporator is connected to a heat source (such as a hot water tank storage tank, etc.) to provide a heat exchange medium for the evaporator, the evaporation end of the evaporator is connected to the input end of the gas-liquid separator, the output end of the gas-liquid separator is connected to the input end of the compressor, the input end of the compressor is connected to the condenser, the condenser is also respectively connected to the inlet of the liquid storage tank, the water supply tank, and the heating system, the outlet of the liquid storage tank is connected to the evaporation end of the evaporator, and the heating end of the evaporator is connected to the drainage tank;

[0047] The vapor compression heat pump system control method comprises:

[0048] Step S1, determining the operating working fluid flow rate according to the acquired target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters and working fluid properties, and obtaining the working fluid injection amount according to the working fluid flow rate.

[0049] Specifically, first obtain the target amount of hot water, then obtain the target preparation heat required by the vapor compression heat pump system according to the target preparation heat, and determine the operation preparation heat within a preset unit time (e.g., 1s) by referring to the evaporator performance parameters, condenser performance parameters, and compressor performance parameters, such as the size and common power of the condenser, and the common operating power of the compressor. It should be noted that the power of the condenser and the operating power of the compressor can be adjusted according to actual conditions. For example, when the target preparation heat is large, the maximum or larger operating power can be selected under the condition that the condenser and the compressor are operating safely, so that the operation preparation heat prepared by the vapor compression heat pump system within the preset unit time is large, so as to improve the hot water preparation efficiency. Based on the operation preparation heat and the working fluid properties, such as the specific heat capacity of the working fluid, the operation working fluid flow required for the vapor compression heat pump system to generate the operation preparation heat is calculated. Based on the operation working fluid flow, the cycle time required for the working fluid to circulate once in the vapor compression heat pump system is obtained, and the operation working fluid flow is multiplied by the cycle time to obtain the working fluid injection amount required by the vapor compression heat pump system to meet the cyclic operation of the vapor compression heat pump system. For example, the cycle time required for the working fluid to circulate once in a vapor compression heat pump system is 10s, the preset unit time is 1s, and the operating working fluid flow rate is Qkg / s, then the working fluid injection amount is expressed as 10Qkg.

[0050] Step S2: starting the evaporator, the compressor and the condenser, and the working fluid storage device injects working fluid into the compressor according to the working fluid injection amount.

[0051] Specifically, the evaporator, compressor and condenser are started according to the evaporator operating parameters, compressor operating parameters and condenser operating parameters determined by the target production amount, and the working fluid storage device is controlled to inject working fluid into the compressor according to the working fluid injection amount, and the vapor compression heat pump system is started to prepare hot water.

[0052] The operation process of the vapor compression heat pump system includes:

[0053] The working fluid in the initial state (usually liquid, such as Freon, etc.) is stored in a working fluid storage device. When the vapor compression heat pump system is started, the working fluid storage device injects low-temperature and low-pressure liquid working fluid with a mass equal to the working fluid injection amount into the compressor.

[0054] The water storage tank provides hot water of a certain temperature to the evaporator so that the evaporator can operate for heat exchange. The low-temperature and low-pressure liquid working medium undergoes heat exchange in the evaporator, gradually evaporates and vaporizes, and turns into low-temperature and low-pressure steam or a working medium in a state where gas and liquid coexist at low temperature and low pressure, and enters the gas-liquid separator. The gas-liquid separator is used to separate low-temperature and low-pressure steam, or a working medium in a state where gas and liquid coexist at low temperature and low pressure, into a low-temperature and low-pressure gaseous working medium and a low-temperature and low-pressure liquid working medium, and stores the low-temperature and low-pressure liquid working medium, while the low-temperature and low-pressure gaseous working medium is injected into the compressor. The compressor compresses the low-temperature and low-pressure gaseous working medium. As the pressure increases, the temperature and pressure of the low-temperature and low-pressure gaseous working medium also rise, forming a high-temperature and high-pressure gaseous working medium, which is then injected into the condenser. The condenser condenses the high-temperature and high-pressure gaseous working medium, and uses the temperature of the high-temperature and high-pressure gaseous working medium to heat the low-temperature water provided by the water supply tank, so that the low-temperature water reaches the target preparation temperature, and outputs the heated hot water to the heating system. The high-temperature and high-pressure gaseous working medium is condensed by the condenser and converted into a low-temperature and high-pressure liquid working medium, wherein the heat required for the low-temperature water to reach the target preparation temperature from the initial temperature is equal to the operating preparation heat prepared by the vapor compression heat pump system during the cycle time. The low-temperature and high-pressure liquid working medium enters the liquid storage tank, which can store part of the low-temperature and high-pressure liquid working medium when the load of the vapor compression heat pump system is low, and part of the low-temperature and high-pressure liquid working medium flows through the expansion valve and is converted into a working medium in a state of low-temperature and low-pressure gas and liquid coexistence, and enters the evaporation end of the evaporator. The liquid storage tank can inject the stored low-temperature and high-pressure liquid working medium into the cycle when the load of the vapor compression heat pump system is high.

[0055] Step S3: After running for a preset unit time, the evaporator flow rate is obtained according to the obtained liquid flow rate and evaporation gas flow rate of the gas-liquid separator.

[0056] Specifically, when the vapor compression heat pump system enters a stable operation state, after running for a preset unit time, the circulating working fluid flow rate circulating in the vapor compression heat pump system is obtained to monitor the working fluid flow rate in the vapor compression heat pump system. It should be noted that, ideally, the working fluid flow rate output by the evaporator is the working fluid flow rate input by the condenser, that is, the circulating working fluid flow rate of the entire heat pump system. Therefore, in this embodiment, the evaporator flow rate is used as the circulating working fluid flow rate of the entire heat pump system. After being processed by the evaporator, the low-temperature and low-pressure liquid working fluid may form a working fluid in a gas-liquid coexistence state. In the related art, the flow rate of the working fluid in the vapor compression heat pump system is usually monitored by a flow meter set at the outlet of the evaporator. However, affected by the gas-liquid coexistence state, the working fluid flow rate measured by the flow meter is not accurate, and thus the accurate evaporator flow rate in the vapor compression heat pump system cannot be obtained. Therefore, in this embodiment, the working fluid state is divided into liquid and gaseous states, and flow measurements are performed separately.

[0057] The specific process can be illustrated by an example: After the low-temperature and low-pressure liquid working medium is processed by the evaporator, the gas-liquid coexistence state of the working medium may be divided into liquid working medium and gaseous working medium after being processed by the gas-liquid separator. When the gas-liquid coexistence working medium appears, it means that the evaporator has not completely evaporated the input working medium, and the generated liquid working medium will be stored in the gas-liquid separator and will not participate in the next cycle. At this time, the circulating working medium flow participating in the next cycle is the evaporated gas flow output by the evaporator. When there is no gas-liquid coexistence working medium, the circulating working medium flow participating in the next cycle is the evaporated gas flow output by the evaporator.

[0058] Step S4: adjusting the operation of the vapor compression heat pump system according to the evaporator flow and the operating working medium flow.

[0059] Specifically, the working fluid flow rate actually participating in the circulation in the vapor compression heat pump system, i.e., the evaporator flow rate, is compared with the theoretical operating working fluid flow rate when the vapor compression heat pump system is operating smoothly, and the operation of each device in the vapor compression heat pump system is adjusted according to the comparison result to ensure that the working fluid flow rate in the vapor compression heat pump system is always in a stable state.

[0060] In this embodiment, the operating working fluid flow rate is determined according to the obtained target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters and working fluid properties, and the working fluid injection amount is obtained according to the working fluid flow rate, that is, the actual operating working fluid flow rate and working fluid injection amount of the vapor compression heat pump system are set according to the heat demand in the actual situation, and the evaporator, compressor and condenser are started, and the working fluid storage device injects the working fluid into the compressor according to the working fluid injection amount. When the working fluid in the vapor compression heat pump system circulates at the operating working fluid flow rate, the efficiency of the vapor compression heat pump system is optimal, and the working fluid is injected into the compressor according to the working fluid injection amount to avoid the loss of load or overload caused by too little or too much circulating working fluid in the vapor compression heat pump system. The preset unit time (for example, 1s) is run to obtain the liquid flow rate and the evaporated gas flow rate of the gas-liquid separator, and the actual working fluid flow rate circulating in the vapor compression heat pump system is accurately obtained, that is, the influence of the coexistence state of the working fluid gas and liquid on the flow measurement result is avoided, and the accuracy of the detection of the circulating working fluid flow rate in the vapor compression heat pump system is increased. According to the evaporator flow and the operating working fluid flow, for example, the evaporator flow in actual operation is compared with the operating working fluid flow in an ideal state, and the vapor compression heat pump system is adjusted according to the comparison result, and the operation of the vapor compression heat pump system is monitored and adjusted in real time to reduce the fluctuation problem of the working fluid flow in the vapor compression heat pump system due to environmental changes, thereby increasing the stability of the operation of the vapor compression heat pump system.

[0061] Optionally, the vapor compression heat pump system further includes an expansion valve; obtaining an adjustment strategy according to the evaporator flow and the operating working medium flow, and controlling the operation of the vapor compression heat pump system according to the adjustment strategy includes:

[0062] When the evaporator flow rate is less than or greater than the operating working medium flow rate, the opening of the expansion valve is adjusted according to the difference between the evaporator liquid flow rate and the operating working medium flow rate.

[0063] Specifically, when the evaporator flow rate is less than the operating working fluid flow rate, it means that the operating preparation heat prepared by the vapor compression heat pump system within the preset unit time is lower than the target preparation heat required to be prepared within the preset unit time, then the prepared hot water temperature will be lower than the target temperature, thereby obtaining the difference between the operating working fluid flow rate and the evaporator flow rate, and obtaining the adjustment value of the expansion valve opening based on the difference, and adjusting the expansion valve opening to increase the evaporator flow rate so that it is equal to the operating working fluid flow rate. Similarly, when the evaporator flow rate is greater than the operating working fluid flow rate, it means that the operating preparation heat prepared by the vapor compression heat pump system within the preset unit time is higher than the target preparation heat required to be prepared within the preset unit time, then the prepared hot water temperature will be higher than the target temperature, thereby obtaining the difference between the operating working fluid flow rate and the evaporator flow rate, and obtaining the adjustment value of the expansion valve opening based on the difference, and adjusting the expansion valve opening to reduce the evaporator flow rate so that it is equal to the operating working fluid flow rate.

[0064] When the liquid flow rate of the device increases, the power is adjusted according to the liquid flow rate of the device;

[0065] The evaporator is adjusted to operate according to the adjusted power.

[0066] Specifically, when the liquid flow rate increases, it means that the evaporator has not completely evaporated the input working fluid. At this time, the adjustment power of the evaporator can be obtained according to the generated liquid flow rate, that is, the adjustment power of the evaporator is increased, and the evaporator is controlled to operate according to the adjustment power to ensure complete evaporation of the working fluid.

[0067] Optionally, the vapor compression heat pump system further includes a sight glass; and the vapor compression heat pump system control method further includes:

[0068] Determine whether there are bubbles in the sight glass. If so, it is determined that there is a problem with the operating circuit of the condenser.

[0069] Specifically, when there are bubbles in the sight glass, it means that the condenser has not completely evaporated the input working fluid. In this case, there is a problem with the operation of the condenser. The adjustment power of the condenser can be increased to ensure that the working fluid is completely condensed. Alternatively, there may be a lack of working fluid, the pressure drop of the drying filter is too high to cause blockage, insufficient supercooling, etc., and corresponding adjustments can be made.

[0070] Furthermore, a flow meter may be provided at the inlet of the expansion valve to obtain the evaporator flow rate flowing into the evaporator. The evaporator flow rate minus the storage tank flow rate is the condensing gas working medium output flow rate. The condenser working medium output flow rate and the evaporated gas flow rate are compared. If the condenser working medium output flow rate is less than the evaporated gas flow rate, it means that there is a problem with the pipeline between the gas-liquid separator and the condenser outlet flow meter, that is, the operating circuit of the condenser, and an early warning is issued to remind the operator to handle it; if the evaporator flow rate is greater than the evaporated gas flow rate, it means that there is a problem with the pipeline between the expansion valve inlet flow meter and the gas-liquid separator, that is, the operating circuit of the evaporator, and an early warning is issued to remind the operator to handle it.

[0071] Optionally, before obtaining the evaporator flow rate according to the obtained liquid flow rate and evaporation gas flow rate of the gas-liquid separator, the method further comprises:

[0072] When the liquid level in the vessel decreases, the volume change of the liquid in the vessel is obtained according to the size of the gas-liquid separator and the change of the liquid level in the vessel;

[0073] The ratio of the volume change of the liquid in the vessel to the preset unit time is obtained to obtain the volume flow rate of the vessel;

[0074] The product of the volume flow rate of the vessel and the density of the working fluid is obtained to obtain the liquid flow rate of the vessel.

[0075] Specifically, the gas-liquid separator can be a tank body or a box body, etc. In this embodiment, the gas-liquid separator is a tank structure, so the liquid volume of the gas-liquid separator can be calculated using the following formula:

[0076] V=π(D / 2) 2 △h,

[0077] Among them, V represents the change in liquid volume, D represents the inner diameter of the gas-liquid separator tank, and △h represents the height of the liquid level change in the gas-liquid separator, that is, the height to which the liquid level is lowered.

[0078] It should be noted that the embodiment of the present invention is to obtain the liquid flow rate of the vapor compression heat pump system when it runs for a preset unit time. Therefore, after obtaining the liquid volume change of the device, it is necessary to obtain the volume flow rate of the device according to the preset unit time, which is expressed by the formula:

[0079] Q Vliq =V / △t,

[0080] Among them, Q Vliq Indicates the volume flow rate of the device, and △t represents the preset unit time.

[0081] Then, according to the volume flow rate of the device and the working fluid density ρ, the mass flow rate of the liquid, that is, the liquid flow rate of the device, is obtained, which is expressed by the formula:

[0082] Q mliq=ρQ Vliq .

[0083] In addition, the evaporator flow rate Q mliq＝ Q mliq +Q mgas， Q mgas Indicates the evaporation gas flow rate in kg / m 3 , Q mliq Indicates the liquid flow rate.

[0084] Optionally, the vapor compression heat pump system further comprises a liquid storage tank;

[0085] The starting of the evaporator, the compressor and the condenser, wherein the working medium storage device injects working medium into the compressor according to the working medium injection amount, comprises:

[0086] A pre-storage working mass is obtained according to the storage capacity of the liquid storage tank, wherein the pre-storage working mass includes two-thirds of the storage capacity of the liquid storage tank.

[0087] Specifically, the pre-stored working fluid stored in the liquid storage tank is used to adjust the working fluid circulating in the vapor compression heat pump system. For example, the liquid storage tank can store part of the low-temperature and high-pressure liquid working fluid when the load of the vapor compression heat pump system is low, and inject the stored low-temperature and high-pressure liquid working fluid into the circulation when the load of the vapor compression heat pump system is high.

[0088] The vapor compression heat pump system control method further includes:

[0089] The actual liquid level of the liquid storage tank is obtained, and when the actual liquid level is less than a preset dangerous liquid level, the pre-stored working mass of working fluid is added to the liquid storage tank.

[0090] Specifically, a liquid level meter may be provided in the liquid storage tank to monitor the liquid level count value in real time to obtain the actual liquid level of the liquid storage tank.

[0091] Optionally, the vapor compression heat pump system further comprises a flow meter disposed between the liquid storage tank and the evaporator, the flow meter being used to measure the flow rate of the condensing side working medium flowing into the evaporator; the vapor compression heat pump system control method further comprises:

[0092] The working medium mass on the evaporation side is obtained according to the evaporation gas flow rate, and the working medium mass on the condensation side is obtained according to the working medium flow rate on the condensation side.

[0093] The sum of the working fluid mass on the evaporation side and the working fluid mass on the condensation side is obtained to obtain the circulating working fluid mass.

[0094] Specifically, in a vapor compression heat pump system, the stability of the working fluid quality is a key factor to ensure the efficient, safe and reliable operation of the system. Stable working fluid quality means that in the evaporator and condenser, the working fluid can fully exert its heat exchange capacity under the corresponding state, optimize the heat transfer, improve the overall thermal efficiency of the system, help maintain a suitable pressure and temperature range, ensure that the compressor and other equipment operate under the best working conditions, reduce the risk of failure, etc. Therefore, it is necessary to monitor not only the circulating working fluid flow rate, but also the circulating working fluid quality. The working fluid quality on the evaporation side is obtained according to the evaporation gas flow rate, and the working fluid quality on the condensation side is obtained according to the working fluid flow rate on the condensation side. For example, after obtaining the evaporation gas flow rate and the working fluid flow rate on the condensation side within a preset unit time, the ratio of the cycle time required for the working fluid to circulate once in the vapor compression heat pump system to the preset unit time is obtained, and the product of the evaporation gas flow rate and the working fluid flow rate on the condensation side and the ratio is obtained respectively, and the working fluid quality on the evaporation side and the working fluid quality on the condensation side circulating in the vapor compression heat pump system are obtained, and the circulating working fluid quality is obtained by summing.

[0095] When the mass of the circulating working fluid is less than the working fluid injection amount, the working fluid replenishment amount is obtained according to the mass difference between the circulating working fluid mass and the working fluid injection amount, and at least one of the liquid storage tank and the working fluid storage device is controlled to output the working fluid according to the working fluid replenishment amount.

[0096] Specifically, since a working fluid with a mass equal to the working fluid injection amount is injected when the vapor compression heat pump system is started, the situation where the mass of the circulating working fluid is greater than the working fluid injection amount will not occur in the vapor compression heat pump system. When the mass of the circulating working fluid is less than the working fluid injection amount, it indicates that the working fluid in the vapor compression heat pump system is lost, etc. In order not to affect the change in the output heat of the heat pump system, a certain mass of working fluid needs to be added to the circulating working fluid. The working fluid injection amount is subtracted from the mass of the circulating working fluid to obtain the working fluid replenishment amount, and the devices that may store the working fluid, such as the liquid storage tank and the working fluid storage device, are controlled to output the working fluid according to the working fluid replenishment amount, so as to ensure that the quality of the working fluid participating in the circulation is always in a stable state.

[0097] Optionally, when the mass of the circulating working fluid is less than the working fluid injection amount, obtaining a working fluid replenishment amount according to a mass difference between the mass of the circulating working fluid and the working fluid injection amount, and controlling at least one of the liquid storage tank and the working fluid storage device to output the working fluid according to the working fluid replenishment amount comprises:

[0098] Comparing the mass of the liquid in the tank with the amount of the working fluid added, wherein the mass of the liquid in the tank includes the mass of the working fluid in the liquid storage tank;

[0099] When the mass of the liquid in the tank is greater than or equal to the working fluid replenishment amount, controlling the liquid storage tank to output the working fluid according to the working fluid replenishment amount;

[0100] When the mass of the liquid in the tank is less than the amount of working fluid replenished, a difference between the mass of the liquid in the tank and the amount of working fluid replenished is generated, and the liquid storage tank is controlled to output all the working fluid, and the working fluid storage device outputs the working fluid according to the difference.

[0101] Specifically, when the mass of the liquid in the tank is less than the amount of working fluid replenished, it may mean that the current mass of the circulating working fluid is insufficient to produce the target production amount, and it is necessary to increase the mass of the working fluid, or increase the operating power of the evaporator, condenser, etc. However, since the optimal operating state is calculated based on the conditions of each device and the target production amount before starting the evaporator, condenser and other devices, if the operating power of each device is adjusted at this time, it may cause problems such as overload of each device, affecting the service life of the vapor compression heat pump system. At this time, a certain amount of working fluid is replenished to meet the preparation requirements of the vapor compression heat pump system, that is, the difference between the mass of the liquid in the tank and the amount of working fluid replenished is calculated, the liquid storage tank is controlled to output all the working fluid, the working fluid storage device is controlled to output the working fluid to the compressor according to the difference, and the sum of the difference and the circulating working fluid mass is obtained to update the working fluid injection amount, so that in the subsequent working fluid quality monitoring, the circulating working fluid mass adjusted this time is used as the judgment standard to avoid judgment errors.

[0102] In a second aspect, an embodiment of the present invention further provides a vapor compression heat pump system, comprising a working fluid storage device, an evaporator, a condenser, a liquid storage tank, a gas-liquid separator, a compressor and a controller, wherein the control module is used to implement the vapor compression heat pump system control method as described above.

[0103] Specifically, Figure 2 As shown, the vapor compression heat pump system also includes a filter and a sight glass. The inlet of the filter is connected to the outlet of the liquid storage tank. The filter is used to filter and absorb moisture in the working fluid, and to block impurities in the system so that the working fluid cannot pass through, thereby preventing the system pipeline from being blocked by ice and dirt.

[0104] In order to monitor the operation of the vapor compression heat pump system, 9 temperature measuring points, 5 pressure measuring points, and 4 flow measuring points are set in the vapor compression heat pump system, and 9 temperature sensors are set accordingly, such as Figure 2 The "T" in the heat pump system can accurately measure the temperature of each key node in the heat pump system to observe the temperature changes at each point in the system; 5 pressure sensors, such as Figure 2 The "P" in the heat pump system can accurately measure the pressure of each key node in the heat pump system to observe the pressure changes at each point in the system; 4 flow meters, such as remote float flow meters, such as Figure 2The "F" in the figure is a flow meter in the working fluid cycle that measures the flow at each point. It can measure the flow at each key node of the heat pump system to observe the flow changes at each point in the system. Figure 2 The "W" in the figure is a power meter, which measures the active power of the compressor electrical signal and then calculates the power consumption of the compressor.

[0105] Optionally, the vapor compression heat pump system also includes a water storage tank, one end of the water storage tank is used to be connected to the waste heat source, and the other end is connected to the inlet end of the evaporator. The water storage tank is provided with a temperature regulator, and the temperature regulator is used to adjust the temperature of the medium in the water storage tank.

[0106] Specifically, in recent years, data centers have experienced explosive growth, and at the same time, they are also facing huge challenges in energy conservation and environmental protection. It is inevitable to try to explore new energy-saving and consumption-reducing technologies. The energy consumption optimization of data centers focuses on the high-power and low-energy consumption cooling system of data centers. For the low-temperature waste heat generated by data centers, a steam compression heat pump in the waste heat heating technology is used to process it. One end of the water storage tank in the steam compression heat pump is connected to the waste heat source of the data center, providing a heat exchange basis for the evaporator, realizing resource recycling, and excess hot water can also be stored in the water storage tank. However, since the temperature of the waste heat generated by the data center is not stable, the temperature may change in the water storage tank, which will cause the temperature of the medium (such as water) to be unstable, which may affect the heat exchange efficiency of the evaporator. Therefore, a temperature adjuster is set to adjust the temperature of the medium stored in the water storage tank so that the temperature is uniform, ensuring the heat exchange efficiency of the evaporator, and thus improving the operating stability of the steam compression heat pump system.

[0107] Optionally, the vapor compression heat pump system further includes a straight-through joint, and the working fluid storage device, the evaporator, the condenser, the liquid storage tank, the gas-liquid separator, the expansion valve and the compressor are all connected via the straight-through joint.

[0108] Specifically, since the current steam compression heat pump needs to be manufactured according to the use requirements and the corresponding working fluid (such as Freon, ammonia, etc.), and the manufacturing cost is high, the steam compression heat pump can usually only meet the specific working fluid requirements, resulting in its single function. When the intermediate components of the steam compression heat pump are damaged, it is often necessary to exceed the pipeline or replace the entire steam compression heat pump, and the maintenance operation is complicated and the cost is high. Therefore, unlike the welded integrated heat pump system, this embodiment uses a straight-through connector to connect the working fluid storage device, evaporator, condenser, liquid storage tank, gas-liquid separator, expansion valve and the compressor, and the corresponding equipment can be replaced according to different working conditions and working fluid requirements, such as replacing compressors of different power models, different types of working fluids, etc., to achieve adjustable combinations between the various structures of the steam compression heat pump system, thereby increasing the versatility of the heat pump system.

[0109] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A vapor compression heat pump system control method, characterized in that: Based on a vapor compression heat pump system, the vapor compression heat pump system includes a working fluid storage device, an evaporator, a condenser, a liquid storage tank, a gas-liquid separator and a compressor; The vapor compression heat pump system control method comprises: Determine the operating working fluid flow rate according to the obtained target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters and working fluid properties, and obtain the working fluid injection amount according to the working fluid flow rate; The evaporator, the compressor and the condenser are started, and the working fluid storage device injects working fluid into the compressor according to the working fluid injection amount; After running for a preset unit time, the evaporator flow rate is obtained according to the liquid flow rate and the evaporated gas flow rate of the gas-liquid separator; The operation of the vapor compression heat pump system is adjusted according to the evaporator flow and the operating working medium flow.

2. The vapor compression heat pump system control method according to claim 1, characterized in that: The vapor compression heat pump system further includes an expansion valve; obtaining an adjustment strategy based on the evaporator flow and the operating working medium flow, and controlling the operation of the vapor compression heat pump system according to the adjustment strategy includes: When the evaporator flow rate is less than or greater than the operating working medium flow rate, adjusting the opening of the expansion valve according to the difference between the evaporator liquid flow rate and the operating working medium flow rate; When the liquid flow rate of the device increases, the power is adjusted according to the liquid flow rate of the device; The evaporator is adjusted to operate according to the adjusted power.

3. The vapor compression heat pump system control method according to claim 1, characterized in that: The vapor compression heat pump system further includes a sight glass; the vapor compression heat pump system control method further includes: Determine whether there are bubbles in the sight glass. If so, it is determined that there is a problem with the operating circuit of the condenser.

4. The vapor compression heat pump system control method according to claim 1, characterized in that: Before obtaining the evaporator flow rate according to the obtained liquid flow rate and evaporation gas flow rate of the gas-liquid separator, the method further includes: When the liquid level in the vessel decreases, the volume change of the liquid in the vessel is obtained according to the size of the gas-liquid separator and the change of the liquid level in the vessel; The ratio of the volume change of the liquid in the vessel to the preset unit time is obtained to obtain the volume flow rate of the vessel; The product of the volume flow rate of the vessel and the density of the working fluid is obtained to obtain the liquid flow rate of the vessel.

5. The vapor compression heat pump system control method according to claim 1, characterized in that: The vapor compression heat pump system also includes a liquid storage tank; The starting of the evaporator, the compressor and the condenser, wherein the working medium storage device injects working medium into the compressor according to the working medium injection amount, comprises: Obtaining a pre-storage working mass according to the storage capacity of the liquid storage tank, wherein the pre-storage working mass includes two-thirds of the storage capacity of the liquid storage tank; The vapor compression heat pump system control method further includes: The actual liquid level of the liquid storage tank is obtained, and when the actual liquid level is less than a preset dangerous liquid level, the pre-stored working mass of working fluid is added to the liquid storage tank.

6. The vapor compression heat pump system control method according to claim 5, characterized in that: The vapor compression heat pump system further includes a flow meter disposed between the liquid storage tank and the evaporator, the flow meter being used to measure the flow rate of the condensing side working medium flowing into the evaporator; the vapor compression heat pump system control method further includes: The mass of the working medium on the evaporation side is obtained according to the evaporation gas flow rate, and the mass of the working medium on the condensation side is obtained according to the condensation gas flow rate; Obtaining the sum of the mass of the working fluid on the evaporation side and the mass of the working fluid on the condensation side to obtain the mass of the circulating working fluid; When the mass of the circulating working fluid is less than the working fluid injection amount, the working fluid replenishment amount is obtained according to the mass difference between the circulating working fluid mass and the working fluid injection amount, and at least one of the liquid storage tank and the working fluid storage device is controlled to output the working fluid according to the working fluid replenishment amount.

7. The vapor compression heat pump system control method according to claim 6, characterized in that: When the mass of the circulating working fluid is less than the working fluid injection amount, obtaining the working fluid replenishment amount according to the mass difference between the mass of the circulating working fluid and the working fluid injection amount, and controlling at least one of the liquid storage tank and the working fluid storage device to output the working fluid according to the working fluid replenishment amount comprises: Comparing the mass of the liquid in the tank with the amount of the working fluid added, wherein the mass of the liquid in the tank includes the mass of the working fluid in the liquid storage tank; When the mass of the liquid in the tank is greater than or equal to the working fluid replenishment amount, controlling the liquid storage tank to output the working fluid according to the working fluid replenishment amount; When the mass of the liquid in the tank is less than the amount of the working fluid replenished, a difference between the mass of the liquid in the tank and the amount of the working fluid replenished is generated, and the liquid storage tank is controlled to output all the working fluid, and the working fluid storage device outputs the working fluid according to the difference.

8. A vapor compression heat pump system, characterized in that: It comprises a working fluid storage device, an evaporator, a condenser, a liquid storage tank, a gas-liquid separator, a compressor and a controller, and the control module is used to implement the vapor compression heat pump system control method as described in any one of claims 1-7.

9. The vapor compression heat pump system according to claim 8, characterized in that: It also includes a water storage tank, one end of which is used to connect to the waste heat source, and the other end is connected to the inlet end of the evaporator. The water storage tank is provided with a temperature regulator, and the temperature regulator is used to adjust the temperature of the medium in the water storage tank.

10. The vapor compression heat pump system according to claim 8, characterized in that: It also includes a straight-through connector, through which the working fluid storage device, the evaporator, the condenser, the liquid storage tank, the gas-liquid separator, the expansion valve and the compressor are all connected.

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