Heat pump system capable of preventing evaporator from freezing

Abstract

The invention relates to a heat pump system capable of preventing an evaporator from freezing, which comprises the following steps of: acquiring a plurality of water inlet temperatures Tin and evaporation temperatures To of the evaporator in a set period M; and the heat pump system is controlled to stop when the temperature change value delta To of the evaporation temperature To in the set period M is larger than the evaporation temperature change threshold # imgabs0 #. The temperature change condition of the evaporator can be effectively monitored, and the heat pump system is timely controlled to stop working when the freezing risk is detected, so that the evaporator is protected.

Description

Technical Field

[0001] The invention relates to the technical field of heat pump units, and in particular to a heat pump system for preventing an evaporator from freezing. Background Art

[0002] Evaporators are widely used due to their compact structure, high heat exchange efficiency and low water quality requirements. When the high-efficiency tank is used for evaporative heat exchange, the refrigerant circulating in the shell side vaporizes by absorbing the heat of the external water in the tube side, which cools the refrigerant. During normal operation, the external water flow rate matches the refrigerant vaporization amount to ensure that the external water temperature is appropriate so that the external water temperature meets the needs of the user end. However, if the external water supply system fails, resulting in an interruption or reduction in the external water flow, the continuous heat absorption of the refrigerant in the evaporator will cause the temperature of the water inside and outside the tube side to drop sharply. When the external water temperature is below zero, it will freeze and expand, which may burst the heat exchange tube, causing the refrigerant and external water to leak, causing the unit to interrupt operation and equipment damage, and even causing safety accidents.

[0003] In the prior art, a water flow switch is usually configured in the water circuit of the high-efficiency tank to detect the water flow status in real time. When the flow rate of external water does not reach the set value of the water flow switch, the water flow switch is disconnected and the unit is shut down at the same time, thereby avoiding damage to the high-efficiency tank. However, this method of configuring a water flow switch increases the cost and assembly workload of the system. In addition, the freezing risk of the evaporator is judged by detecting whether the inlet and outlet temperatures of the circulating water are lower than a set minimum temperature value, or the rate of decrease of the inlet and outlet temperatures. This method ignores the fact that when the amount of water in the system decreases or the water flow rate decreases, the evaporator may freeze even if the inlet temperature does not reach the low temperature threshold.

[0004] Therefore, there is an urgent need to design a system and method that can timely detect the risk of frostbite in the evaporator and respond quickly. Summary of the invention

[0005] Based on this, the object of the present invention is to overcome the defects or shortcomings of the prior art and provide a heat pump system that prevents evaporator freezing.

[0006] A heat pump system for preventing an evaporator from freezing comprises a compressor, a condenser, a throttling device and an evaporator connected in sequence by a refrigerant circulation pipeline, wherein the evaporator also comprises a water circulation pipeline for providing external water circulation, a first temperature sensor for detecting the water inlet temperature arranged in the water inlet pipeline of the evaporator, a second temperature sensor for detecting the evaporation temperature arranged in the refrigerant outlet pipeline of the evaporator, and a controller electrically connected to the compressor, the first temperature sensor and the second temperature sensor, wherein the controller performs antifreeze control of the evaporator in the following manner:

[0007] Obtain several water inlet temperatures Tin and evaporation temperatures To of the evaporator within the set period M. If the water inlet temperature Tin and the evaporation temperature To show a downward trend, and the temperature change value ΔT of the evaporation temperature To within the set period M o Greater than the evaporation temperature change threshold Control the heat pump system to shut down.

[0008] Compared with the prior art, the present invention can effectively monitor the temperature change of the evaporator and promptly control the heat pump system to stop working when the risk of freezing is detected, so as to protect the evaporator.

[0009] In one embodiment, m water inlet temperatures Tin and evaporation temperatures To of the evaporator are obtained at a set acquisition frequency F within a set period M; the water inlet temperature Tin sequence is obtained. And evaporation temperature To series

[0010] Among them, m represents the number of temperature values ​​collected within the set period M, and its value is

[0011] Specifically, m is not greater than The maximum integer.

[0012] In one embodiment, the sequence of determining the inlet water temperature Tin is from arrive Whether the overall trend is downward, and the evaporation temperature To series from arrive Is there an overall downward trend?

[0013] If yes, then further calculate the temperature change value ΔT of the evaporation temperature To within the set period M o .

[0014] In one embodiment, according to the inlet water temperature Tin sequence and evaporation temperature To series Perform linear fitting respectively to obtain the fitted straight line. By analyzing the slope of the fitted straight line, it can be determined whether the inlet water temperature Tin series and the evaporation temperature To series both show a downward trend:

[0015] If the slopes of the fitted straight lines are all negative, the temperature change value ΔT of the evaporation temperature To within the set period M is further calculated. o .

[0016] In one embodiment, by calculating the inlet water temperature Tin sequence Inlet water temperature With water inlet temperature The difference between Get the inlet water temperature difference ΔT in sequence Determine the inlet water temperature difference sequence The number of negative differences accounts for the inlet water temperature difference sequence ΔT in Is the ratio of the total number of differences greater than the first threshold, and by calculating the evaporation temperature To sequence The evaporation temperature With water inlet temperature The difference between Get the evaporation temperature difference ΔT o sequence Determine the evaporation temperature difference sequence ΔT o The number of negative internal differences accounts for the evaporation temperature difference ΔT o Whether the proportion of the total number of differences in the sequence is greater than the second threshold:

[0017] If the inlet water temperature difference sequence ΔT is satisfied in The ratio of the number of negative differences to the total number of differences is greater than the first threshold, and the evaporation temperature difference sequence ΔT o If the ratio of the number of negative differences to the total number of differences is greater than the second threshold, the temperature change value ΔT of the evaporation temperature To within the set period M is further calculated. o ;

[0018] Wherein, i represents the i-th inlet water temperature in the inlet water temperature Tin sequence and the i-th evaporation temperature in the evaporation temperature To sequence, and its value is i∈{1,2,...,m-1}.

[0019] In one embodiment, the temperature change value ΔT of the evaporation temperature To within the set period M is calculated. o , including calculation of evaporation temperature To series The first evaporation temperature and the mth evaporation temperature The difference between ΔT o .

[0020] In one embodiment, the period M is set to 60 seconds, and the collection frequency F is set to 5 seconds per acquisition.

[0021] In one embodiment, the evaporation temperature change threshold is set Take 10℃.

[0022] In addition, the present invention also provides a control method for preventing an evaporator from freezing, comprising:

[0023] S10 obtains m inlet water temperatures Tin and evaporation temperatures To of the evaporator at a set acquisition frequency F within a set period M; obtains the inlet water temperature Tin sequence And evaporation temperature To series

[0024] Among them, m represents the number of temperature values ​​collected within the set period M, and its value is

[0025] Specifically, m is not greater than The largest integer of ;

[0026] S20 determines the inlet water temperature Tin sequence from arrive Is the overall trend downward, and is the evaporation temperature To series from arrive Is there an overall downward trend?

[0027] If yes, execute step S30;

[0028] If no, execute step S10;

[0029] S30 calculates the evaporation temperature To sequence The first evaporation temperature and the mth evaporation temperature The difference between ΔT o , determine the difference ΔT o Whether the evaporation temperature change threshold is greater than the set value

[0030] If yes, the heat pump system is controlled to shut down;

[0031] If not, execute step S10.

[0032] In one embodiment, step S20 specifically includes: calculating the inlet water temperature Tin sequence Inlet water temperature With water inlet temperature The difference between Get the inlet water temperature difference ΔT in sequence Determine the inlet water temperature difference sequence ΔT in Whether the ratio of the number of negative differences to the total number of differences is greater than the first threshold, and by calculating the evaporation temperature To sequence The evaporation temperature With water inlet temperature The difference between Get the evaporation temperature difference ΔT o sequence Determine the evaporation temperature difference sequence ΔT o Whether the ratio of the number of inner negative differences to the total number of differences is greater than the second threshold:

[0033] If the inlet water temperature difference sequence ΔT is satisfied in The ratio of the number of negative differences to the total number of differences is greater than the first threshold, and the evaporation temperature difference sequence ΔT o If the ratio of the number of inner negative differences to the total number of differences is greater than the second threshold, step S30 is executed;

[0034] If not satisfied, execute step S10;

[0035] Wherein, i represents the i-th inlet water temperature in the inlet water temperature Tin sequence and the i-th evaporation temperature in the evaporation temperature To sequence, and its value is i∈{1,2,...,m-1}.

[0036] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the structure of a heat pump system for preventing evaporator freezing according to an embodiment of the present invention;

[0038] Figure 2 It is a structural schematic diagram of a control device for preventing evaporator freezing based on water inlet temperature and evaporation temperature according to an embodiment of the present invention;

[0039] Figure 3 The figure is a flow chart of a control method for preventing an evaporator from freezing according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The scheme of the present invention is described in detail below with reference to the accompanying drawings.

[0041] like Figure 1 As shown, a heat pump system for preventing the evaporator from freezing of the present invention, the heat pump system 10 includes a compressor 11, a condenser 12, a throttling device 13 and an evaporator 14 which are connected in sequence by a refrigerant circulation pipeline, wherein the evaporator 14 also includes a water circulation pipeline for providing external water circulation, and the external water can come from various external water sources such as tap water, well water, return water, etc., which is used to exchange heat with the refrigerant in the refrigerant circulation pipeline.

[0042] It also includes a first temperature sensor 15 for detecting the water inlet temperature of the evaporator, a second temperature sensor 16 for detecting the evaporation pressure of the evaporator, and a controller (not shown); the first temperature sensor 15 and the second temperature sensor 16 are electrically connected or communicatively connected to the controller.

[0043] The first temperature sensor 15 is arranged on the water inlet pipe of the evaporator and is used to collect the water inlet temperature T of the evaporator. in , get the inlet water temperature T in ;

[0044] The second temperature sensor 16 is arranged on the refrigerant outlet pipe of the evaporator and is used to collect the evaporation temperature T of the evaporator. o , get the evaporation temperature T o ;

[0045] In some embodiments, a pressure sensor may be provided on the refrigerant outlet pipe of the evaporator to collect the evaporation pressure P of the evaporator. o , and then use the table lookup method to obtain the evaporation temperature T o .

[0046] See also Figures 2 to 3 The controller in the heat pump system 10 of the present invention includes a control device 20 for preventing the evaporator from freezing based on the water inlet temperature and the evaporation temperature, specifically including a temperature acquisition unit 21, an adjacent temperature difference calculation and judgment unit 22, a head and tail temperature difference calculation and judgment unit 23 and a heat pump unit control unit 24.

[0047] The temperature acquisition unit 21 is used to execute step S10: acquire m inlet water temperatures Tin and evaporation temperatures To of the evaporator at a set acquisition frequency F within a set period M; obtain the inlet water temperature Tin sequence And evaporation temperature To series

[0048] Among them, m represents the number of temperature values ​​collected within the set period M, and its value is

[0049] Specifically, m is not greater than The maximum integer.

[0050] In this application, the period M is set 1 Take 60 seconds and set the acquisition frequency F to 5 seconds / item.

[0051] The temperature change trend judgment unit 22 is used to execute step S20: judge the inlet water temperature Tin sequence from arrive Is the overall trend downward, and is the evaporation temperature To series from arrive Is there an overall downward trend?

[0052] If yes, execute step S30;

[0053] If not, execute step S10.

[0054] In one embodiment, by calculating the inlet water temperature Tin sequence Inlet water temperature With water inlet temperature The difference between Get the inlet water temperature difference ΔT in sequence Determine the inlet water temperature difference sequence ΔT in Whether the ratio of the number of negative differences to the total number of differences is greater than the first threshold, and by calculating the evaporation temperature To sequence The evaporation temperature With water inlet temperature The difference between Get the evaporation temperature difference ΔT o sequence Determine the evaporation temperature difference sequence ΔT o Whether the ratio of the number of inner negative differences to the total number of differences is greater than the second threshold:

[0055] If the inlet water temperature difference sequence ΔT is satisfied in The ratio of the number of negative differences to the total number of differences is greater than the first threshold, and the evaporation temperature difference sequence ΔT o If the ratio of the number of inner negative differences to the total number of differences is greater than the second threshold, step S30 is executed;

[0056] If the above conditions are not met, step S10 is executed.

[0057] Wherein, i represents the i-th inlet water temperature in the inlet water temperature Tin sequence and the i-th evaporation temperature in the evaporation temperature To sequence, and its value is i∈{1,2,...,m-1}.

[0058] Specifically, the first threshold and the second threshold are determined based on experience.

[0059] In one embodiment, according to the inlet water temperature Tin sequence and evaporation temperature To series Perform linear fitting to obtain a fitting straight line. By analyzing the slope of the fitting straight line, determine whether the inlet water temperature Tin series and the evaporation temperature To series both show a downward trend:

[0060] If the slopes of the fitted straight lines are all negative, then execute step S30;

[0061] If not, execute step S10.

[0062] The temperature change value calculation and judgment unit 23 is used to execute step S30: calculate the evaporation temperature To sequence The first evaporation temperature and the mth evaporation temperature The difference between ΔT o , determine the difference ΔT o Whether the evaporation temperature change threshold is greater than the set value

[0063] If yes, the heat pump system is controlled to shut down;

[0064] If not, execute step S10.

[0065] In this application, the evaporation temperature change threshold is set Take 10℃.

[0066] In addition, in this embodiment, the control device 20 for preventing the evaporator from freezing based on the water inlet temperature and the evaporation temperature is arranged in an electronic device, and the electronic device specifically includes a memory, a processor, a network interface and a system bus, wherein the memory, the processor and the network interface can communicate with each other through the system bus. The memory includes a non-volatile storage medium and an internal memory; the non-volatile storage medium stores an operating system and a computer program; the internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The processor is used to provide computing and control capabilities, and can call the logic instructions in the memory to execute the control method of the working state of the heat pump unit; the network interface is used to communicate with the outside world through a network connection.

[0067] The memory includes at least one type of readable storage medium, and the readable storage medium includes flash memory, hard disk, multimedia card, card-type memory (for example, SD or DX memory, etc.), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, etc. In some embodiments, the memory can be an internal storage unit of the controller, such as a hard disk or memory of the controller. In other embodiments, the memory can also be an external storage device of the controller, such as a plug-in hard disk equipped on the controller, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. The memory can also include both the internal storage unit of the controller and its external storage device.

[0068] In this embodiment, the memory is generally used to store an operating system and various application software installed in the control device 20, such as program codes of the control device 20. In addition, the memory can also be used to temporarily store various data that have been output or are to be output.

[0069] In some embodiments, the processor may be a central processing unit (CPU) microprocessor or other data processing chip. The processor is generally used to control the overall operation of the controller in the heat pump system, such as performing control and processing related to data interaction or communication with the controller in the heat pump system.

[0070] In this embodiment, the processor is used to run the program code or process data stored in the memory, for example, to run a control method for preventing the evaporator from freezing based on the water inlet temperature and the evaporation temperature of a controller in a heat pump system.

[0071] The network interface may include a wireless network interface or a wired network interface, which is generally used to establish a communication connection between the controller and other electronic devices. For example, the network interface is used to connect the control device 20 to an external data platform through a network, and to establish a data transmission channel and a communication connection between the control device 20 and the external data platform. The network may be an intranet, the Internet, a global system of mobile communications (GSM), a wideband code division multiple access (WCDMA), a 4G network, a 5G network, Bluetooth, a Wi-Fi or other wireless or wired network.

[0072] Compared with the prior art, the present invention can effectively monitor the temperature change of the evaporator and promptly control the heat pump system to stop working when the risk of freezing is detected, so as to protect the evaporator from frostbite.

[0073] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that, unless otherwise specified, "multiple" refers to two or more; the terms "first", "second", "third", etc. are only used to distinguish, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. The term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0074] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A heat pump system for preventing evaporator from freezing, comprising a compressor, a condenser, a throttling device and an evaporator connected in sequence by a refrigerant circulation pipeline, wherein the evaporator also includes a water circulation pipeline for providing external water circulation, and a first temperature sensor for detecting the inlet water temperature arranged in the water inlet pipeline of the evaporator, and a second temperature sensor for detecting the evaporation temperature arranged in the refrigerant outlet pipeline of the evaporator, and a controller electrically connected to the compressor, the first temperature sensor and the second temperature sensor, characterized in that: The controller performs evaporator antifreeze control in the following ways: Obtain several water inlet temperatures Tin and evaporation temperatures To of the evaporator within the set period M. If the water inlet temperature Tin and the evaporation temperature To show a downward trend, and the temperature change value ΔT of the evaporation temperature To within the set period M o Greater than the evaporation temperature change threshold Control the heat pump system to shut down.

2. The heat pump system for preventing evaporator freezing according to claim 1, characterized in that: Obtain several water inlet temperatures Tin and evaporation temperatures To of the evaporator within a set period M, including: Obtain m inlet water temperatures Tin and evaporation temperatures To of the evaporator at a set acquisition frequency F within a set period M; obtain the inlet water temperature Tin sequence And evaporation temperature To series Among them, m represents the number of temperature values ​​collected within the set period M, and its value is The m is not greater than The maximum integer.

3. The heat pump system for preventing evaporator freezing according to claim 2, characterized in that: Determine the inlet water temperature Tin sequence from arrive Whether the overall trend is downward, and the evaporation temperature To series from arrive Is there an overall downward trend? If yes, then further calculate the temperature change value ΔT of the evaporation temperature To within the set period M o .

4. The heat pump system for preventing evaporator freezing according to claim 3, characterized in that: According to the inlet water temperature Tin sequence and evaporation temperature To series Linear fitting is performed separately to obtain the fitting straight line. By analyzing the slope of the fitting straight line, it is determined whether the inlet water temperature Tin series and the evaporation temperature To series both show a downward trend: If the slopes of the fitted straight lines are all negative, the temperature change value ΔT of the evaporation temperature To within the set period M is further calculated. o .

5. The heat pump system for preventing evaporator freezing according to claim 3, characterized in that: By calculating the inlet water temperature Tin series Inlet water temperature With water inlet temperature The difference between Get the inlet water temperature difference ΔT in sequence Determine the inlet water temperature difference sequence ΔT in The number of negative differences accounts for the inlet water temperature difference sequence ΔT in Is the ratio of the total number of differences greater than the first threshold, and by calculating the evaporation temperature To sequence The evaporation temperature With water inlet temperature The difference between Get the evaporation temperature difference ΔT o sequence Determine the evaporation temperature difference sequence ΔT o The number of negative internal differences accounts for the evaporation temperature difference ΔT o Whether the proportion of the total number of differences in the sequence is greater than the second threshold: If the inlet water temperature difference sequence ΔT is satisfied in The ratio of the number of negative differences to the total number of differences is greater than the first threshold, and the evaporation temperature difference sequence ΔT o If the ratio of the number of negative differences to the total number of differences is greater than the second threshold, the temperature change value ΔT of the evaporation temperature To within the set period M is further calculated. o ; Wherein, i represents the i-th inlet water temperature in the inlet water temperature Tin sequence and the i-th evaporation temperature in the evaporation temperature To sequence, and its value is i∈{1,2,...,m-1}.

6. The heat pump system for preventing evaporator freezing according to claims 3-5, characterized in that: Calculate the temperature change value ΔT of the evaporation temperature To within the set period M o , including: calculation of evaporation temperature To series The first evaporation temperature and the mth evaporation temperature The difference between ΔT o .

7. The heat pump system for preventing evaporator freezing according to claim 6, characterized in that: Set the period M to 60 seconds and the acquisition frequency F to 5 seconds per acquisition.

8. The heat pump system for preventing evaporator freezing according to claim 7, characterized in that: Set evaporation temperature change threshold Take 10℃.

9. An antifreeze control method for an evaporator, characterized in that: The following steps are involved: S10 obtains m inlet water temperatures Tin and evaporation temperatures To of the evaporator at a set acquisition frequency F within a set period M; obtains the inlet water temperature Tin sequence And evaporation temperature To series Among them, m represents the number of temperature values ​​collected within the set period M, and its value is The m is not greater than The largest integer of ; S20 determines the inlet water temperature Tin sequence from arrive Is the overall trend downward, and is the evaporation temperature To series from arrive Is there an overall downward trend? If yes, execute step S30; If no, execute step S10; S30 calculates the evaporation temperature To sequence The first evaporation temperature and the mth evaporation temperature The difference between ΔT o , determine the difference ΔT o Whether the evaporation temperature change threshold is greater than the set value If yes, the heat pump system is controlled to shut down; If not, execute step S10.

10. The antifreeze control method for an evaporator according to claim 9, characterized in that: Step S20 specifically includes: calculating the inlet water temperature Tin sequence Inlet water temperature With water inlet temperature The difference between Get the inlet water temperature difference ΔT in sequence Determine the inlet water temperature difference sequence ΔT in Whether the ratio of the number of negative differences to the total number of differences is greater than the first threshold, and by calculating the evaporation temperature To sequence The evaporation temperature With water inlet temperature The difference between Get the evaporation temperature difference ΔT o sequence Determine the evaporation temperature difference sequence ΔT o Whether the ratio of the number of inner negative differences to the total number of differences is greater than the second threshold: If the inlet water temperature difference sequence ΔT is satisfied in The ratio of the number of negative differences to the total number of differences is greater than the first threshold, and the evaporation temperature difference sequence ΔT o If the ratio of the number of inner negative differences to the total number of differences is greater than the second threshold, step S30 is executed; If not satisfied, execute step S10; Wherein, i represents the i-th inlet water temperature in the inlet water temperature Tin sequence and the i-th evaporation temperature in the evaporation temperature To sequence, and its value is i∈{1,2,...,m-1}.

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