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

Abstract

The present invention relates to the technical field of heating equipment, and provides a vapor compression heat pump system control method and a vapor compression heat pump system. The method includes determining an operating working fluid flow rate based on an acquired target hot water production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters, and working fluid properties, and obtaining a working fluid injection amount based on the operating working fluid flow rate; starting the evaporator, compressor, and condenser, and injecting working fluid into the compressor according to the working fluid injection amount through a working fluid storage device; after a preset unit time of operation, obtaining an evaporator flow rate based on the acquired liquid flow rate and evaporated gas flow rate of a gas-liquid separator; and adjusting the operation of the vapor compression heat pump system based on the evaporator flow rate and the operating working fluid flow rate. The present invention monitors and adjusts the operation of the vapor compression heat pump system in real time, reduces fluctuations in the working fluid flow rate in the system due to environmental changes, and increases the stability of the operation of the vapor compression heat pump system.

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 capabilities, and are recognized in the industry as the most efficient and environmentally friendly high-temperature hot water production device.

[0003] In related technologies, a low-temperature working fluid is typically fed into a vapor compression heat pump system, where it undergoes cycles of evaporation, compression, and condensation. However, during operation, the working fluid flow rate can fluctuate due to factors such as environmental factors and power supply variations. This can lead to unstable operation of the vapor compression heat pump system and, in turn, significant fluctuations in the temperature of the hot water produced by the vapor compression heat pump. 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] 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 method for controlling a vapor compression heat pump system. The method is based on 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 an expansion valve. The method comprises:

[0007] Determining an operating working fluid flow rate based on the acquired target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters, and working fluid properties, and obtaining a working fluid injection amount based on the operating working fluid flow rate, wherein the target production amount includes a total amount of hot water required to be produced;

[0008] Starting the evaporator, the compressor, and the condenser, and injecting the working fluid into the compressor from the working fluid storage device 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, adjusting the operation of the vapor compression heat pump system according to the evaporator flow and the operating working medium flow 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 includes:

[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] Obtaining the ratio of the volume change of the liquid in the container to the preset unit time to obtain the container volume flow rate;

[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 includes a liquid storage tank;

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

[0023] Obtaining a pre-stored working mass according to the storage capacity of the liquid storage tank, wherein the pre-stored 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 lower than a preset dangerous liquid level, the pre-stored working amount of working fluid is added to the liquid storage tank.

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

[0027] Obtaining the mass of the working medium on the evaporation side according to the evaporation gas flow rate, and obtaining the mass of the working medium on the condensation side 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 circulating working fluid mass and the working fluid injection amount, and controlling at least one of the liquid storage tank and the working fluid storage device to output working fluid according to the working fluid replenishment amount includes:

[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 working fluid replenishment amount, a difference between the mass of the liquid in the tank and the working fluid replenishment amount 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, an expansion valve and a controller, wherein the controller is used to implement the vapor compression heat pump system control method as described above.

[0035] Optionally, the vapor compression heat pump system further 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.

[0036] Optionally, the vapor compression heat pump system further includes a straight-through joint, 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.

[0037] The beneficial effects of the vapor compression heat pump system control method and the vapor compression heat pump system of the present invention are: determining the operating working fluid flow rate based on the obtained target production amount of hot water, evaporator performance parameters, condenser performance parameters, compressor performance parameters and working fluid properties, and obtaining the working fluid injection amount based on the operating working fluid flow rate, that is, setting the actual operating working fluid flow rate and working fluid injection amount of the vapor compression heat pump system according to the heat demand in actual conditions, and starting the evaporator, compressor and condenser, and the working fluid storage device injecting 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 load loss or overload in the vapor compression heat pump system due to too little or too much circulating working fluid. The system runs for a preset unit time (e.g., 1 second) to obtain the liquid flow rate and evaporation gas flow rate of the gas-liquid separator, accurately obtaining the actual working fluid flow rate circulating in the vapor compression heat pump system. This avoids the influence of the coexistence of working fluid gas and liquid on the flow measurement results, thereby increasing the accuracy of the detection of the circulating working fluid flow rate in the vapor compression heat pump system. Based on the evaporator flow rate and the operating working fluid flow rate, for example, the evaporator flow rate in actual operation is compared with the operating working fluid flow rate under ideal conditions. Based on the comparison results, the vapor compression heat pump system is adjusted, and the operation of the vapor compression heat pump system is monitored and adjusted in real time. This reduces the fluctuation of the working fluid flow rate 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 Schematic diagram of a 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] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below with reference to 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 construed as being limited to the embodiments described herein. Instead, 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 for illustrative purposes only 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 "multiple" mentioned in the present invention are illustrative rather than restrictive. 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, an embodiment of the present invention provides a vapor compression heat pump system control method, which is based on a vapor compression heat pump system. The system is applied to a heating system, that is, to prepare 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, a compressor and an expansion valve, 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 storage tank, etc.) to provide a heat exchange medium for the evaporator, the evaporating 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 further connected to the inlet of the liquid storage tank, the water supply tank, and the heating system respectively, the outlet of the liquid storage tank is connected to the inlet of the expansion valve, the outlet of the expansion valve is connected to the evaporating end of the evaporator, and the heating end of the evaporator is connected to the drain tank;

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

[0048] Step S1: Determine the operating working fluid flow rate based on the acquired target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters, and working fluid properties, and obtain the working fluid injection amount based on the operating working fluid flow rate, wherein the target production amount includes the total amount of hot water required to be produced.

[0049] Specifically, a target hot water production rate is first determined. Based on the target production rate, the target heat production required by the vapor compression heat pump system is then calculated. Based on the target heat production rate, the operating heat production rate per a preset unit time (e.g., 1 second) is determined, taking into account evaporator, condenser, and compressor performance parameters, such as the condenser's size and typical power, and the compressor's typical operating power. It should be noted that the condenser power and compressor operating power can be adjusted based on actual conditions. For example, when the target heat production rate is high, a maximum or higher operating power can be selected, provided the condenser and compressor are operating safely, to maximize the operating heat production by the vapor compression heat pump system within the preset unit time, thereby improving hot water production efficiency. Based on the operating heat production rate and working fluid properties, such as the working fluid's specific heat capacity, the operating working fluid flow rate required for the vapor compression heat pump system to generate the operating heat production rate is calculated. Based on the operating working fluid flow rate, the cycle time required for the working fluid to circulate once through the vapor compression heat pump system is determined. The operating working fluid flow rate is multiplied by the cycle time to determine the required working fluid injection rate to ensure the system's cyclic operation. For example, if 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 injecting the working fluid into the compressor from the working fluid storage device 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) 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 at a certain temperature to the evaporator so that the evaporator can operate and perform heat exchange. The low-temperature, low-pressure liquid working medium undergoes heat exchange in the evaporator, gradually evaporating and vaporizing, turning into low-temperature, low-pressure steam or a low-temperature, low-pressure gas-liquid coexisting state working medium, and then enters the gas-liquid separator. The gas-liquid separator is used to separate the low-temperature, low-pressure steam or the low-temperature, low-pressure gas-liquid coexisting state working medium into a low-temperature, low-pressure gaseous working medium and a low-temperature, low-pressure liquid working medium, and store the low-temperature, low-pressure liquid working medium while injecting the low-temperature, low-pressure gaseous working medium into the compressor. The compressor compresses the low-temperature, low-pressure gaseous working medium. As the pressure increases, the temperature and pressure of the low-temperature, low-pressure gaseous working medium also rise, forming a high-temperature, high-pressure gaseous working medium, which is then injected into the condenser. The condenser condenses the high-temperature, high-pressure gaseous working fluid, and uses the temperature of the high-temperature, high-pressure gaseous working fluid to heat the low-temperature water provided by the water supply tank, so that the low-temperature water reaches the target preparation temperature. The heated hot water is then output to the heating system. The high-temperature, high-pressure gaseous working fluid is condensed by the condenser and converted into a low-temperature, high-pressure liquid working fluid. The heat required for the low-temperature water to reach the target preparation temperature from the initial temperature is equal to the operating heat prepared by the vapor compression heat pump system during the cycle time. The low-temperature, high-pressure liquid working fluid enters the liquid storage tank. When the load of the vapor compression heat pump system is low, the liquid storage tank can store part of the low-temperature, high-pressure liquid working fluid, while part of the low-temperature, high-pressure liquid working fluid flows through the expansion valve and is converted into a low-temperature, low-pressure gas-liquid coexisting state, entering the evaporation end of the evaporator. When the load of the vapor compression heat pump system is high, the liquid storage tank can inject the stored low-temperature, high-pressure liquid working fluid into the cycle.

[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 operating state, after running for a preset unit time, the circulating working fluid flow rate of 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 coexisting 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 evaporator outlet. However, due to the influence of the gas-liquid coexisting state, the working fluid flow rate measured by the flow meter is not accurate, and thus it is impossible to obtain the accurate evaporator flow rate in the vapor compression heat pump system. 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, low-pressure liquid working medium is processed by the evaporator, the gas-liquid coexistence state is formed. After the working medium is processed by the gas-liquid separator, the gas-liquid coexistence state may be separated into liquid working medium and gas working medium. When gas-liquid coexistence occurs, it means that the evaporator has not completely evaporated the input working medium. The resulting 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 rate participating in the next cycle is the boil-off gas flow rate output by the evaporator. If the gas-liquid coexistence does not exist, the circulating working medium flow rate participating in the next cycle is the boil-off gas flow rate 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 actual working fluid flow rate involved 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, an operating working fluid flow rate is determined based on the target hot water production output, evaporator performance parameters, condenser performance parameters, compressor performance parameters, and working fluid properties. The working fluid injection rate is then determined based on the operating working fluid flow rate. Specifically, the actual operating working fluid flow rate and working fluid injection rate for the vapor compression heat pump system are set based on actual heat demand. The evaporator, compressor, and condenser are then started, and a working fluid storage device injects working fluid into the compressor according to the working fluid injection rate. 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 optimized. Injecting working fluid into the compressor according to the working fluid injection rate avoids load loss or overload in the vapor compression heat pump system due to insufficient or excessive circulating working fluid. The system is operated for a preset unit time (e.g., 1 second) to obtain the liquid flow rate and evaporated gas flow rate of the gas-liquid separator, accurately obtaining the actual working fluid flow rate circulating in the vapor compression heat pump system. This prevents the influence of the coexistence of gas and liquid working fluid on flow measurement results, thereby increasing the accuracy of circulating working fluid flow detection in the vapor compression heat pump system. 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. 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, adjusting the operation of the vapor compression heat pump system according to the evaporator flow and the operating working medium flow 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 is less than the operating working fluid flow, 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 and the evaporator flow, 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 so that it is equal to the operating working fluid flow. Similarly, when the evaporator flow is greater than the operating working fluid flow, 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 and the evaporator flow, 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 so that it is equal to the operating working fluid flow.

[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 medium. 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 can be increased, and the evaporator can be controlled to operate according to the adjusted power to ensure that the working medium is completely evaporated.

[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, if bubbles are present in the sight glass, it indicates that the condenser is not completely evaporating the incoming working fluid. This indicates a problem with the condenser's operation and requires increasing the condenser's adjustment power to ensure complete condensation of the working fluid. Alternatively, there may be a lack of working fluid, a high pressure drop across the filter drier causing blockage, or insufficient subcooling. These issues can be addressed and adjusted accordingly.

[0070] Furthermore, a flow meter can be installed at the inlet of the expansion valve to obtain the evaporator flow rate flowing into the evaporator. The evaporator flow rate minus the liquid storage tank flow rate is the condenser 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 indicates 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 indicates 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 includes:

[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] Obtaining the ratio of the volume change of the liquid in the container to the preset unit time to obtain the container volume flow rate;

[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 or a box. In this embodiment, the gas-liquid separator is a tank structure. Therefore, 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 of the liquid level drop.

[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 is running for a preset unit time. Therefore, after obtaining the volume change of the liquid in the device, it is necessary to obtain the volume flow rate of the device according to the preset unit time, which can be 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, the mass flow rate of the liquid is obtained according to the volume flow rate of the device and the working fluid density ρ, that is, the liquid flow rate of the device, which can be expressed as follows:

[0082] Q mliq=ρQ Vliq .

[0083] Additionally, 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 includes a liquid storage tank;

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

[0086] A pre-stored working mass is obtained according to the storage capacity of the liquid storage tank, wherein the pre-stored 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 lower than a preset dangerous liquid level, the pre-stored working amount of working fluid is added to the liquid storage tank.

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

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

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

[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 in ensuring the efficient, safe, and reliable operation of the system. Stable working fluid quality means that the working fluid can fully utilize its heat exchange capacity in the evaporator and condenser under the corresponding conditions, which can optimize heat transfer, improve the overall thermal efficiency of the system, help maintain the appropriate pressure and temperature range, ensure that the compressor and other equipment operate under optimal conditions, and reduce the risk of failure. 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 based on the evaporation gas flow rate, and the working fluid quality on the condensation side is obtained based on 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. The product of the evaporation gas flow rate and the working fluid flow rate on the condensation side and the ratio is obtained, and the evaporation gas flow rate and the working fluid flow rate on the condensation side are obtained to obtain 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.

[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 of a mass equal to the working fluid injection amount is injected into the vapor compression heat pump system at startup, the situation in which 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 there has been a loss of working fluid in the vapor compression heat pump system. In order not to affect 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. Devices that may contain working fluid, such as liquid storage tanks and working fluid storage devices, are controlled to output working fluid according to the working fluid replenishment amount to ensure that the quality of the working fluid involved 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 circulating working fluid mass and the working fluid injection amount, and controlling at least one of the liquid storage tank and the working fluid storage device to output working fluid according to the working fluid replenishment amount includes:

[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 working fluid replenishment amount, a difference between the mass of the liquid in the tank and the working fluid replenishment amount 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 the working fluid mass needs to be increased, or the operating power of the evaporator, condenser, etc. needs to be increased. 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 mass 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, an expansion valve and a controller, wherein the controller is used to implement the vapor compression heat pump system control method as described above.

[0103] Specifically, if 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. 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, so as 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 that measures the flow at each point in the working medium cycle. It can measure the flow at each key node of the heat pump system in order 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 further 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, and a temperature regulator is provided on the water storage tank, and the temperature regulator is used to adjust the temperature of the medium in the water storage tank.

[0106] Specifically, data centers have experienced explosive growth in recent years, yet they also face significant challenges in energy conservation and environmental protection. Exploring new energy-saving and consumption-reducing technologies is essential. Data center energy optimization focuses on high-power, low-energy cooling systems. Vapor-compression heat pumps, a type of waste heat heating technology, are used to process the low-temperature waste heat generated by data centers. One end of the water storage tank in a vapor-compression heat pump is connected to the data center's waste heat source, providing a heat exchange foundation for the evaporator and enabling resource reuse. Excess hot water can also be stored in the water storage tank. However, since the temperature of waste heat generated by data centers is unstable, temperature fluctuations in the water storage tank can cause temperature instability in the medium (e.g., water), potentially affecting the heat exchange efficiency of the evaporator. Therefore, a temperature regulator is provided to uniformly regulate the temperature of the medium stored in the water storage tank, ensuring heat exchange efficiency for the evaporator and improving the operational stability of the vapor-compression heat pump system.

[0107] Optionally, the vapor compression heat pump system further includes a straight-through joint, 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.

[0108] Specifically, because current vapor compression heat pumps require structural design and manufacturing based on usage requirements and corresponding working fluids (such as Freon, ammonia, etc.), and their manufacturing costs are high, vapor compression heat pumps can usually only meet specific working fluid requirements, resulting in a single function. When intermediate components of the vapor compression heat pump are damaged, it is often necessary to replace the pipeline or the entire vapor compression heat pump, which is complex and costly to repair. Therefore, unlike the welded integrated heat pump system, this embodiment uses straight-through connectors to connect the working fluid storage device, evaporator, condenser, liquid storage tank, gas-liquid separator, expansion valve, and the compressor. 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 vapor 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, a compressor and an expansion valve; The vapor compression heat pump system control method includes: Determining an operating working fluid flow rate based on the acquired target production amount, evaporator performance parameters, condenser performance parameters, compressor performance parameters, and working fluid properties, and obtaining a working fluid injection amount based on the operating working fluid flow rate, wherein the target production amount includes a total amount of hot water required to be produced; Starting the evaporator, the compressor, and the condenser, and injecting the working fluid into the compressor from the working fluid storage device 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 adjusting the operation of the vapor compression heat pump system according to the evaporator flow and the operating working medium flow comprises: 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, wherein: The vapor compression heat pump system further includes a sight glass; and 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, wherein: 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; Obtaining the ratio of the volume change of the liquid in the container to the preset unit time to obtain the container volume flow rate; 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, wherein: The vapor compression heat pump system further includes a liquid storage tank; The starting of the evaporator, the compressor, and the condenser, wherein the working medium storage device injects the working medium into the compressor according to the working medium injection amount, comprises: Obtaining a pre-stored working mass according to the storage capacity of the liquid storage tank, wherein the pre-stored 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 lower than a preset dangerous liquid level, the pre-stored working amount 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: Obtaining the mass of the working medium on the evaporation side according to the evaporation gas flow rate, and obtaining the mass of the working medium on the condensation side 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 circulating working fluid mass 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 working fluid replenishment amount, a difference between the mass of the liquid in the tank and the working fluid replenishment amount 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: The heat pump system comprises a working fluid storage device, an evaporator, a condenser, a liquid storage tank, a gas-liquid separator, a compressor, an expansion valve and a controller, wherein the controller is used to implement the vapor compression heat pump system control method according to any one of claims 1 to 7.

9. The vapor compression heat pump system according to claim 8, wherein: It also includes a water storage tank, one end of which is connected to the waste heat source, and the other end is connected to the inlet end of the evaporator. A temperature regulator is provided on the water storage tank, 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, wherein: It also includes a straight-through joint, through which the working medium 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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