Heat pump system, control method, and storage medium

Abstract

The application discloses a heat pump system, a control method and a storage medium, and relates to the technical field of heat pump systems, and specifically discloses a heat pump system, which comprises a compressor, an air-side heat exchanger and a water-side heat exchanger, the air-side heat exchanger is communicated with the air inlet of the compressor through a flow regulating valve, the flow regulating valve controls the refrigerant flow entering the compressor according to the difference between the exhaust temperature of the compressor and the outlet water temperature of the water-side heat exchanger, and the heat pump system further comprises an on-off control valve connected in parallel with the flow regulating valve.

Description

Technical Field

[0001] This invention relates to the field of air conditioning equipment technology, and particularly to heat pump systems, control methods, and storage media. Background Technology

[0002] Traditional split-type inverter heat pumps often use oil separators for reliable operation. The presence of the oil separator increases refrigerant flow resistance, and the oil return process requires a pressure difference, which the compressor motor must maintain. Therefore, the oil separator negatively impacts heat pump efficiency. Integrated inverter heat pumps, due to their shorter refrigerant flow path and smaller refrigerant charge, rarely experience oil shortages during stable operation. To improve heat pump efficiency, the oil separator is eliminated.

[0003] Before a heat pump starts in low-temperature winter conditions, the refrigerant liquefies within the air-side heat exchanger due to its low temperature. During startup, this refrigerant can easily carry a large amount of liquid back to the compressor, resulting in liquid in the compressor's intake air and low exhaust temperature. When the exhaust encounters the even colder oil sump, the temperature drops further, causing the refrigerant to liquefy and carrying away the compressor's lubricating oil, leading to oil shortage. Traditional heat pumps use vapor-liquid separators to address this issue during startup, but adding a vapor separator requires more space, negatively impacting the miniaturization design of integrated heat pumps. Summary of the Invention

[0004] To address the issue of oil shortage during low-temperature startup of heat pumps, this invention proposes a heat pump system and control method. An electromagnetic valve and an electronic expansion valve are added at the rear end of the air-side heat exchanger to replace the vapor-liquid separator. By controlling the refrigerant circulation volume, the exhaust gas is kept at a high temperature, ensuring that when the refrigerant encounters the low-temperature lubricating oil, it can quickly heat the oil, preventing the refrigerant from liquefying and mixing with the lubricating oil, thus diluting the lubricating oil, and preventing the refrigerant from flashing and carrying away the lubricating oil.

[0005] The technical solution adopted in this invention is to design a heat pump system, including a compressor, an air-side heat exchanger, and a water-side heat exchanger. The air-side heat exchanger is connected to the air inlet of the compressor through a flow regulating valve. The flow regulating valve controls the flow rate of refrigerant entering the compressor based on the difference between the exhaust temperature of the compressor and the outlet water temperature of the water-side heat exchanger. The invention also includes an on / off control valve connected in parallel with the flow regulating valve.

[0006] In some embodiments, the flow regulating valve is an electronic expansion valve.

[0007] In some embodiments, the on / off control valve is a solenoid valve.

[0008] A heat pump system control method is used in the heat pump system to determine whether the exhaust temperature minus the outlet water temperature is less than a first preset value. If so, close the on / off control valve and open the flow regulating valve to control the refrigerant flow, thereby reducing the refrigerant pressure. If not, determine whether the continuous running time of the compressor is greater than the preset time. If yes, close the flow regulating valve and open the on / off control valve. If not, determine whether the exhaust temperature minus the outlet water temperature is less than the second preset value. If yes, close the flow regulating valve and open the on / off control valve. If not, close the on / off control valve and open the flow regulating valve to control the refrigerant flow. The first preset value is less than the second preset value.

[0009] In some implementations, the flow regulating valve is an electronic expansion valve. If the electronic expansion valve is opened for the first time after the system is started, the number of steps to control the electronic expansion valve is equal to the rated number of steps of the electronic expansion valve * ((current compressor frequency - rated frequency) / rated frequency) * ((ambient temperature - rated ambient temperature) / rated ambient temperature).

[0010] In some implementations, the flow regulating valve is an electronic expansion valve. If the electronic expansion valve is not opened for the first time after the system is started, the number of steps to control the electronic expansion valve is equal to the current number of steps of the electronic expansion valve plus max(current number of steps of the electronic expansion valve / 100 * (exhaust temperature - outlet water temperature - 30); -15).

[0011] In some implementations, the first preset value is 30 degrees.

[0012] In some implementations, the second preset value is 35 degrees.

[0013] In some implementations, the preset duration is 5 minutes.

[0014] A storage medium storing one or more programs, which can be executed by one or more processors to implement the aforementioned heat pump system control method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The heat pump and control method of this invention eliminates the oil separator and vapor-liquid separator, replacing them with a solenoid valve and an electronic expansion valve added at the rear end of the air-side heat exchanger. This significantly reduces the space requirements of the heat pump system. Furthermore, during low-temperature startup in winter, by controlling the refrigerant circulation volume, the exhaust gas is kept at a high temperature. This ensures that when the refrigerant encounters the low-temperature lubricating oil, it can quickly heat the oil, preventing the refrigerant from liquefying and mixing with the lubricating oil, thus avoiding dilution and reduced lubrication. It also prevents the liquid refrigerant in the lubricating oil from flashing and carrying away the lubricating oil when it encounters the high-temperature gaseous refrigerant again. This achieves miniaturization of the integrated heat pump system and solves the reliability issues that come with miniaturization. Attached Figure Description

[0016] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. To illustrate the details and facilitate understanding of its principles, the drawings are not necessarily to scale, and similar reference numerals may describe similar components in different views. The accompanying drawings generally illustrate the embodiments discussed herein by way of example and not limitation. Wherein: Figure 1 This is a schematic diagram of a heat pump system.

[0017] Figure 2 This is a flowchart illustrating the control method of a heat pump system.

[0018] In the diagram, 1. Compressor; 2. Air-side heat exchanger; 3. Water-side heat exchanger; 4. First electronic expansion valve; 5. Four-way valve; 6. Outdoor pipe temperature sensor; 7. Ambient temperature sensor; 8. Inlet water temperature sensor; 9. Outlet water temperature sensor; 10. Exhaust temperature sensor; 11. Inlet temperature sensor; 12. Low-pressure switch; 13. High-pressure switch; 14. Second electronic expansion valve; 15. Solenoid valve. Detailed Implementation

[0019] The following are specific embodiments of the present invention, and the technical solution of the present invention will be further described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments, and the following embodiments do not limit the invention covered by the claims. Furthermore, not all combinations of the features described in the embodiments are necessary for the inventive solution.

[0020] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments. Example

[0021] A heat pump system is a system that uses heat pump technology to transfer energy, typically used for heating, cooling, and hot water applications. The working principle of a heat pump system is based on the heat pump cycle, which absorbs heat from a low-temperature region and then releases that heat to a high-temperature region by increasing its temperature.

[0022] An air source heat pump is a system that uses the heat energy in the air for heating and cooling. It absorbs low-temperature heat from the outdoor air through the principle of heat pump circulation, and then releases the heat into the building through compression and heating for heating, hot water, or cooling.

[0023] like Figure 1As shown, the heat pump system includes a compressor 1, an air-side heat exchanger 2 (evaporator), a water-side heat exchanger 3 (condenser), a first electronic expansion valve 4, a four-way valve 5, and other main components, as well as outdoor pipe temperature sensors 6, ambient temperature sensors 7, inlet water temperature sensors 8, outlet water temperature sensors 9, exhaust temperature sensors 10, suction temperature sensors 11, a low-pressure switch 12, and a high-pressure switch 13. The evaporator is located outdoors. Through the evaporator, the heat pump absorbs low-temperature heat from the outside air, evaporating the working fluid (usually refrigerant) into a gaseous state. The compressor compresses the low-temperature, low-pressure gas, increasing its temperature and pressure. The condenser heat pump releases heat into the room through the condenser, compressing the working fluid into a liquid. At this point, the liquid temperature is relatively high, suitable for heating or hot water supply. The expansion valve releases the high-pressure liquid, lowering its temperature and pressure, allowing it to re-enter the evaporator cycle. Air source heat pumps can provide heating in winter, cooling in summer, and also supply hot water. They are highly energy efficient by absorbing heat from the outside air, especially within a suitable temperature range. It requires no fuel combustion, reducing carbon emissions. It can provide both heating and cooling, making it suitable for various seasons and climate conditions.

[0024] Traditional split-type inverter heat pumps often use oil separators for reliable operation. The presence of the oil separator increases refrigerant flow resistance, and the oil return process requires a pressure difference, which the compressor motor must maintain. Therefore, the oil separator negatively impacts heat pump efficiency. Integrated inverter heat pumps, due to their shorter refrigerant flow path and smaller refrigerant charge, rarely experience oil shortages during stable operation. To improve heat pump efficiency, the oil separator is eliminated.

[0025] Before a heat pump starts in low-temperature winter conditions, the refrigerant liquefies within the air-side heat exchanger due to its low temperature. During startup, this refrigerant can easily carry a large amount of liquid back to the compressor, resulting in liquid in the compressor's intake air and low exhaust temperature. When the exhaust encounters the even colder oil sump, the temperature drops further, causing the refrigerant to liquefy and carrying away the compressor's lubricating oil, leading to oil shortage. Traditional heat pumps use vapor-liquid separators to address this issue during startup, but adding a vapor separator requires more space, negatively impacting the miniaturization design of integrated heat pumps.

[0026] To address the aforementioned issues, this embodiment employs a flow regulating valve connecting the air-side heat exchanger 2 and the air inlet of the compressor 1. This valve controls the refrigerant flow rate into the compressor 1 based on the difference between the compressor 1's exhaust temperature and the water outlet temperature of the water-side heat exchanger 3, effectively controlling the refrigerant circulation. By controlling the refrigerant circulation, the exhaust gas is kept at a high temperature, ensuring that the refrigerant can quickly heat the low-temperature lubricating oil upon contact. This prevents the refrigerant from liquefying and mixing with the lubricating oil, diluting the lubricating oil and reducing its lubrication effect. Simultaneously, it prevents the liquid refrigerant in the lubricating oil from flashing and carrying away the lubricating oil when it encounters the high-temperature gaseous refrigerant again. This achieves miniaturization of the integrated heat pump system and also solves the reliability issues arising from miniaturization.

[0027] It also includes an on / off control valve connected in parallel with the flow regulating valve. When the exhaust temperature minus the outlet water temperature is greater than a certain value, it indicates that the exhaust temperature of the compressor 1 has been rising continuously since it started, and the liquid discharge process of the air-side heat exchanger 2 has been completed. At this time, the oil sump of the compressor 1 has been heated, and the refrigerant will not liquefy when it enters the oil sump. Open the on / off control valve to release the entire suction flow of the compressor 1 and release the heating capacity of the unit.

[0028] In this embodiment, the flow regulating valve is a second electronic expansion valve 14, and the on / off control valve is a solenoid valve 15. The second electronic expansion valve facilitates precise control of the refrigerant circulation flow rate through a number of steps. The solenoid valve facilitates rapid switching between on and off states.

[0029] like Figure 2 As shown, the control method for the heat pump system is as follows: After receiving the start-up command, the heat pump unit determines whether the exhaust temperature minus the outlet water temperature is less than a first preset value. In this embodiment, the first preset value is 30 degrees.

[0030] If the exhaust temperature minus the outlet water temperature is less than 30 degrees Celsius, it indicates that the exhaust temperature is relatively low. In this case, the on / off control valve is closed, and the oil return control is activated. The flow regulating valve is opened to control the refrigerant flow, causing the refrigerant pressure to drop. By controlling the refrigerant circulation volume, the exhaust temperature is kept high, ensuring that when the refrigerant encounters the low-temperature lubricating oil, it can quickly heat the oil temperature. This prevents the refrigerant from liquefying and mixing with the lubricating oil, which would dilute the lubricating oil and reduce its lubrication effect. At the same time, it prevents the liquid refrigerant in the lubricating oil from flashing and carrying away the lubricating oil when it encounters the high-temperature gaseous refrigerant again.

[0031] If the exhaust temperature minus the outlet water temperature is not less than 30 degrees Celsius, it indicates that the exhaust temperature is at a high temperature. Then, it is determined whether the compressor's continuous operating time exceeds a preset time (5 minutes in this embodiment). If the compressor's continuous operating time exceeds 5 minutes, the flow regulating valve is closed, the on / off control valve is opened, and the compressor's suction flow is fully released to unleash the unit's heating capacity. If the compressor's continuous operating time is not greater than 5 minutes, it is determined whether the exhaust temperature minus the outlet water temperature is less than a second preset value (35 degrees Celsius in this embodiment). If the exhaust temperature minus the outlet water temperature is less than 35 degrees Celsius, it indicates that the exhaust temperature is relatively low. Then, the on / off control valve is closed, oil return control is initiated, and the flow regulating valve is opened. The regulating valve controls the refrigerant flow, causing the refrigerant pressure to drop. By controlling the refrigerant circulation volume, the exhaust gas is kept at a high temperature, ensuring that when the refrigerant encounters the low-temperature lubricating oil, it can quickly heat the oil temperature. This prevents the refrigerant from liquefying and mixing with the lubricating oil, which would dilute the lubricating oil and reduce its lubrication effect. At the same time, it prevents the liquid refrigerant in the lubricating oil from flashing and carrying away the lubricating oil when it encounters the high-temperature gaseous refrigerant again. If the exhaust temperature minus the outlet water temperature is not less than 35 degrees, it means that the exhaust temperature has been rising continuously since the compressor started, and the air-side heat exchanger has completed the liquid drainage process. At this time, the compressor oil sump has been heated, and the refrigerant will not liquefy when entering the oil sump. Open the solenoid valve to release the compressor's suction flow and release the unit's heating capacity. If the second electronic expansion valve is opening for the first time after the system is powered on, the number of steps controlling the second electronic expansion valve is calculated as follows: Second electronic expansion valve rated steps * ((Current compressor frequency - Rated frequency) / Rated frequency) * ((Ambient temperature - Rated ambient temperature) / Rated ambient temperature). The number of steps for the second electronic expansion valve is determined by the ratio of the current compressor displacement and ambient temperature to the rated compressor displacement and ambient temperature. This is because the flow rate through the second electronic expansion valve is directly proportional to the compressor displacement, and the evaporator's evaporation rate is also directly proportional to the ambient temperature. Therefore, if the current frequency is lower than the rated frequency or the current ambient temperature is lower than the rated ambient temperature, the second electronic expansion valve needs to be closed less; conversely, it needs to be opened more.

[0032] If the second electronic expansion valve is not being opened for the first time after the system is powered on, then the number of steps controlling the second electronic expansion valve = the current number of steps of the second electronic expansion valve + max(the current number of steps of the second electronic expansion valve / 100 * (exhaust temperature - outlet water temperature - 30); -15). The flow rate of the second electronic expansion valve and the number of steps have a near-linear relationship with a slope greater than zero. The second electronic expansion valve usually has more than 500 steps. If the current number of steps is 100 and 500 respectively, then closing one step will affect the flow rate by 1% and 0.2% respectively. It can be seen that at 500 steps, closing one step will result in a very small adjustment and very insensitive adjustment. To ensure the sensitivity of the second electronic expansion valve at any number of steps, the current number of steps is divided by 100, that is, divided into 100 equal parts, so that the adjustment accuracy is consistent each time. Here, 100, 30, and 15 can be adjusted according to the actual system.

[0033] A storage medium storing one or more programs, which can be executed by one or more processors to implement the heat pump system control method.

[0034] Compressor oil return refers to the process of ensuring that the lubricating oil required for the normal operation of the compressor returns to the compressor's interior during operation. This is crucial because lubricating oil is essential for maintaining the compressor's normal operation, reducing friction, and cooling components.

[0035] During compressor operation, lubricating oil flows through the system along with the working fluid (usually refrigerant). As the working fluid passes through the evaporator, the lubricating oil also evaporates there and then enters the compressor along with the working fluid. To ensure good lubrication and cooling, it is necessary to return as much lubricating oil as possible to the compressor.

[0036] An electronic expansion valve is a device that regulates refrigerant flow through an electronic control system. It is commonly used in refrigeration and air conditioning systems to ensure accurate and flexible control of refrigerant flow, thereby maintaining system stability and efficiency. Step control of an electronic expansion valve refers to adjusting the refrigerant flow by changing the valve's opening degree, thus achieving precise system control. This step control is typically implemented using a motor or stepper motor on the electronic expansion valve, which controls the valve's opening degree in discrete steps. Electronic expansion valves can be designed with multiple discrete steps; by adjusting these steps, the valve's opening degree can be changed, thereby adjusting the refrigerant flow. Because electronic expansion valves are regulated by an electronic control system, very precise flow control can be achieved. This is crucial for maintaining system performance under varying load conditions. The step control of electronic expansion valves allows them to adapt to different operating conditions and environmental conditions, ensuring effective system operation under various loads and temperatures. Precise step control helps the system operate more efficiently, improving energy efficiency and reducing energy consumption. The step control of electronic expansion valves typically has a fast response speed, quickly adapting to changes in system requirements.

[0037] The specific embodiments described herein are merely illustrative examples illustrating the spirit of the invention. Those skilled in the art can make various modifications or additions to the described embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0038] Although this document uses a number of technical terms, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention. The order of actions, steps, etc., in the apparatus and methods shown in the specification and drawings can be implemented in any order unless otherwise expressly specified, and provided that the output of a preceding process is not used in a subsequent process. Similar sequential terms used for descriptive convenience (e.g., "firstly," "next," "secondly," "again," "then," etc.) do not imply that the actions must be performed in such an order.

[0039] Those skilled in the art will understand that all directional references (e.g., above, below, up, down, down, top, bottom, left, right, vertical, horizontal, etc.) are used descriptively in the drawings to aid the reader's understanding and do not imply (e.g., a limitation on the scope of the invention as defined by the appended claims) a limitation on the location, orientation, or use of the invention, but are merely for the purpose of facilitating the description of this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation. The directional terms "inside" and "outside" refer to inside or outside relative to the outline of the respective component itself.

[0040] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0041] Additionally, some vague terms (e.g., substantially, certain, generally, etc.) may refer to slight inaccuracies or minor deviations in conditions, quantities, values, or dimensions, some of which are within manufacturing tolerances or limits. It should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components; unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application.

Claims

1. A heat pump system control method, used in a heat pump system, the heat pump system including a compressor, an air-side heat exchanger, and a water-side heat exchanger, wherein the air-side heat exchanger is connected to the compressor inlet via a flow regulating valve, the flow regulating valve controlling the refrigerant flow rate into the compressor based on the difference between the compressor exhaust temperature and the water outlet temperature of the water-side heat exchanger, and further including an on / off control valve connected in parallel with the flow regulating valve, characterized in that: Determine if the exhaust temperature minus the outlet water temperature is less than the first preset value. If so, close the on / off control valve and open the flow regulating valve to control the refrigerant flow, thereby reducing the refrigerant pressure. If not, determine whether the continuous running time of the compressor is greater than the preset time. If yes, close the flow regulating valve and open the on / off control valve. If not, determine whether the exhaust temperature minus the outlet water temperature is less than the second preset value. If yes, close the flow regulating valve and open the on / off control valve. If not, close the on / off control valve and open the flow regulating valve to control the refrigerant flow. The first preset value is less than the second preset value.

2. The heat pump system control method according to claim 1, characterized in that, The on / off control valve is a solenoid valve.

3. The heat pump system control method according to claim 1, characterized in that, The flow regulating valve is an electronic expansion valve. If the electronic expansion valve is opened for the first time after the system is started, the number of steps to control the electronic expansion valve is equal to the rated number of steps of the electronic expansion valve * ((current frequency of the compressor - rated frequency) / rated frequency) * ((ambient temperature - rated ambient temperature) / rated ambient temperature).

4. The heat pump system control method according to claim 1, characterized in that, The flow regulating valve is an electronic expansion valve. If the electronic expansion valve is not opened for the first time after the system is turned on, the number of steps to control the electronic expansion valve = the current number of steps of the electronic expansion valve + max(current number of steps of the electronic expansion valve / 100 * (exhaust temperature - outlet water temperature - 30); -15).

5. The heat pump system control method according to claim 1, characterized in that, The first preset value is 30 degrees.

6. The heat pump system control method according to claim 1, characterized in that, The second preset value is 35 degrees.

7. The heat pump system control method according to claim 1, characterized in that, The preset duration is 5 minutes.

8. A storage medium, characterized in that, The storage medium stores one or more programs, which can be executed by one or more processors to implement the heat pump system control method according to any one of claims 1 to 7.

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