Low-energy-consumption control method for heat pump low-temperature dryer, electronic device and storage medium

Abstract

Provided are a low-energy-consumption control method for a heat pump low-temperature dryer, an electronic device, and a storage medium, belonging to the technical field of heat pump control. The present method, by means of controlling a compressor operating point and dehumidification performance of an evaporator, can achieve the goal of reducing overall device energy consumption. In a heat pump unit, the compressor, a condenser, an expansion valve and the evaporator are connected in sequence to form a refrigeration circulation loop; the compressor operating point comprises evaporation temperature and condensation temperature. First, an operating point with a COP value larger than a set value when preset evaporation temperature and condensation temperatures are satisfied is selected as an optimal operating point for the compressor. Then, structural design of the heat exchanger is conducted, so that a heat exchange volume of the heat exchanger can satisfy the requirement that the compressor operates at the optimal operating point. During operation of the heat pump low-temperature dryer, the operating state of the heat pump unit is dynamically adjusted in real time, so that the compressor is kept running at the optimal operating point.

Description

Low energy consumption control method for heat pump low-temperature drying equipment, electronic equipment and storage medium Technical Field

[0001] The present invention relates to a control method, in particular to a low-energy consumption control method for heat pump low-temperature drying equipment, electronic equipment and storage medium, belonging to the technical field of heat pump control. Background Art

[0002] Sludge treatment is the process of reducing, stabilizing and rendering sludge harmless by concentrating, conditioning, dehydrating, stabilizing, drying or incinerating it.

[0003] The heat pump low-temperature sludge drying system is a deep dehydration device that can effectively treat sludge with a moisture content of 85% or less to a minimum of 10%. Its operating principle is as follows: dry air is injected into a sealed drying chamber, removing moisture from the sludge through humidity exchange. The air is then condensed and removed using an evaporator. Simultaneously, the heat pump principle is used to recover the latent heat of condensation, which is used to heat the dry air and re-inject it into the drying chamber.

[0004] The heat pump unit is the core component of the heat pump low-temperature sludge drying equipment. In the heat pump unit, the compressor, condenser, liquid storage tank, high-temperature refrigerant filter, electronic expansion valve, evaporator and gas-liquid separator are connected in sequence to form a refrigeration cycle; the low-temperature and low-pressure refrigerant gas forms high-temperature and high-pressure gas after the compressor works, and the high-temperature and high-pressure gas enters the condenser to cool and form low-temperature and high-pressure refrigerant gas, while releasing heat to the air medium, and then passes through the liquid storage tank, high-temperature refrigerant filter and electronic expansion valve throttling to form low-temperature and low-pressure refrigerant liquid, and then enters the evaporator. The evaporator absorbs the latent heat in the air and turns the low-temperature and low-pressure refrigerant liquid into a low-temperature and low-pressure gas-liquid mixture. At the same time, the air is cooled and separated by the gas-liquid separator to form low-temperature and low-pressure refrigerant gas and then enters the compressor again, thus achieving a heat exchange refrigeration cycle.

[0005] In actual use, it was found that the overall energy consumption of heat pump low-temperature sludge drying equipment was relatively high. As the core component of heat pump low-temperature sludge drying equipment, the low operating point (COP) of the compressor in the heat pump unit (COP is the ratio of the cooling capacity achieved by the heat pump unit to the input power) was one of the main reasons for the high overall energy consumption of the equipment. Therefore, how to reduce the operating power of the compressor to reduce the overall energy consumption of the heat pump low-temperature sludge drying equipment was an urgent problem to be solved.

[0006] Summary of the Invention

[0007] In view of this, the present invention provides a low-energy consumption control method for a heat pump low-temperature drying device, which can achieve the purpose of reducing the overall energy consumption of the heat pump low-temperature drying device by controlling the operating point of the compressor and / or the dehumidification performance of the evaporator.

[0008] The technical solution adopted by the present invention is: a low energy consumption control method for heat pump low temperature drying equipment,

[0009] The heat pump low-temperature drying equipment includes a heat exchanger and a heat pump unit. In the heat pump unit, a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected to form a refrigeration cycle. After the hot and humid air is heated by the heat exchanger under the action of a circulating fan, it passes through the evaporator and condenser of the heat pump unit in sequence to form dry hot air and enter the drying chamber of the heat pump low-temperature drying equipment. The characteristics are:

[0010] The operating point of the compressor includes: evaporation temperature and condensation temperature; first, the operating point where the COP value is greater than the set value under the conditions of the set evaporation temperature and condensation temperature is selected as the optimal operating point of the compressor, and the evaporation temperature and condensation temperature corresponding to the optimal operating point are set to be the optimal evaporation temperature and the optimal condensation temperature respectively;

[0011] Establishing a simulation model of the heat pump low-temperature drying equipment, the simulation model is used to simulate the air temperature and humidity gradient within the heat pump low-temperature drying equipment; adjusting the heat exchange capacity of the heat exchanger simulation unit in the simulation model so that the heat exchange capacity of the heat exchanger simulation unit can meet the requirements of the compressor operating at the optimal operating point, and obtaining the heat exchange capacity of the heat exchanger simulation unit in the simulation model at this time; and performing structural design on the heat exchanger based on the obtained heat exchange capacity;

[0012] During the operation of the heat pump low-temperature drying equipment, the operating state of the heat pump unit is dynamically adjusted in real time to keep the compressor operating at the optimal operating point.

[0013] As a preferred embodiment of the present invention, when there is only one alternative compressor, the operating point at which the COP value of the alternative compressor is the highest under the conditions of the set evaporation temperature and condensation temperature is selected as the optimal operating point;

[0014] When there are multiple alternative compressors: select the operating point with the highest COP value and the corresponding alternative compressor that can meet the set evaporating temperature and condensing temperature conditions from all alternative compressors; use the selected alternative compressor as the compressor of the heat pump unit, and use the corresponding operating point as the optimal operating point.

[0015] As a preferred embodiment of the present invention, during the operation of the heat pump low-temperature drying equipment, when the difference between the evaporation temperature of the heat pump unit and the optimal evaporation temperature exceeds the set range, the opening of the expansion valve is first adjusted. If, after the opening of the expansion valve is adjusted to the maximum opening or the minimum opening, the difference between the evaporation temperature and the optimal evaporation temperature still exceeds the set range, the evaporation temperature is further adjusted by adjusting the condenser subcooling, adjusting the circulating fan air volume, and adjusting the compressor speed.

[0016] As a preferred embodiment of the present invention, when further adjusting the evaporation temperature, the priority order is: adjusting the condenser subcooling degree - adjusting the circulation fan air volume - adjusting the compressor speed.

[0017] As a preferred embodiment of the present invention, during the operation of the heat pump low-temperature drying equipment, when the difference between the condensing temperature of the heat pump unit and the optimal condensing temperature exceeds a set range, the exhaust superheat of the compressor is first adjusted. If, after adjusting the exhaust superheat of the compressor, the difference between the condensing temperature and the optimal condensing temperature still exceeds the set range, the condensing temperature is further adjusted by adjusting the air volume of the circulating fan or adjusting the speed of the compressor.

[0018] As a preferred embodiment of the present invention, when the condensing temperature is further adjusted, the priority order is: adjusting the air volume of the circulating fan - adjusting the speed of the compressor.

[0019] As a preferred embodiment of the present invention, the relative humidity of the hot and humid air entering the evaporator of the heat pump unit is controlled to be 100%.

[0020] As a preferred embodiment of the present invention, in the simulation model of the heat pump low-temperature drying equipment, the heat exchange rate of the heat exchanger simulation unit in the simulation model is adjusted so that the heat exchange rate of the heat exchanger simulation unit can simultaneously meet the operating requirements of the compressor at the optimal operating point and the relative humidity of the hot and humid air in front of the evaporator is 100%, and then the heat exchange rate of the heat exchanger simulation unit in the simulation model at this time is obtained; based on the obtained heat exchange rate, the heat exchanger is structurally designed.

[0021] As a preferred embodiment of the present invention, during the operation of the heat pump low-temperature drying equipment, the humidity of the hot and humid air entering the evaporator is monitored in real time, and the operating status of the heat exchanger and the heat pump unit is dynamically adjusted in real time to keep the relative humidity of the hot and humid air entering the evaporator at 100%.

[0022] As a preferred embodiment of the present invention, during the operation of the heat pump low-temperature drying equipment, when the relative humidity of the hot and humid air in front of the evaporator deviates from the set 100%, the heat exchange rate of the heat exchanger is first adjusted. If the relative humidity of the hot and humid air in front of the evaporator still does not reach 100% when the heat exchange rate of the heat exchanger is adjusted to the maximum, the saturation of the air in front of the evaporator is further adjusted by adjusting the air volume of the circulating fan or adjusting the speed of the compressor.

[0023] As a preferred embodiment of the present invention, when the relative humidity of the hot and humid air before the evaporator is further adjusted, the priority order is: adjusting the air volume of the circulation fan - adjusting the speed of the compressor.

[0024] As a preferred embodiment of the present invention, during the operation of the heat pump low-temperature drying equipment, the pressure at the front end of the condenser is monitored in real time. When the pressure at the front end of the condenser is greater than a set value, the superheat of the evaporator is adjusted.

[0025] As a preferred embodiment of the present invention, a heat exchange unit is provided between the compressor and the condenser of the heat pump unit. If the pressure at the front end of the condenser is still greater than the set value after adjusting the superheat of the evaporator, the heat exchange capacity of the heat exchange unit is increased to reduce the pressure at the front end of the condenser.

[0026] In addition, the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above control method when executing the computer program.

[0027] In addition, the present invention also provides a computer-readable storage medium having a computer program stored thereon, and the computer program implements the steps of the above control method when executed by a processor. Beneficial effects:

[0028] (1) The present invention can effectively reduce the operating power of the compressor and increase the cooling capacity of the compressor by controlling the operating point of the compressor in the heat pump unit, thereby achieving the purpose of reducing the overall energy consumption of the heat pump low-temperature drying equipment.

[0029] (2) In order to ensure that the compressor can operate at the optimal operating point, the heat exchanger is first optimized, thereby ensuring that the compressor can operate at the optimal operating point from the hardware structure.

[0030] (3) During the operation of the heat pump low-temperature drying equipment, the evaporation temperature and condensation temperature of the heat pump unit are monitored in real time, and the compressor operating point is corrected by real-time dynamic adjustment of the heat pump unit operating status.

[0031] (4) When the present invention dynamically adjusts the operating status in real time to correct the operating point, it gives priority to using an adjustment method that is easy to implement and does not have any incidental impact on other parameters, such as expansion valve opening, superheat and subcooling; secondly, it adopts adjustment methods such as fan air volume and compressor frequency conversion.

[0032] (5) In addition, the present invention can improve the dehumidification latent heat ratio of the evaporator by controlling the hot and humid air entering the evaporator in the heat pump unit to saturated air with a relative humidity of 100%, thereby achieving the purpose of reducing energy consumption; experiments have shown that by maintaining the relative humidity of the hot and humid air in front of the evaporator at 100%, the dehumidification latent heat ratio of the evaporator can be increased from 75% to 85%.

[0033] (6) In the present invention, in order to ensure that the relative humidity of the hot and humid air entering the evaporator is 100%, the heat exchanger is first optimized to ensure that the heat exchange capacity of the heat exchanger can meet the requirements from the hardware perspective.

[0034] (7) During the operation of the heat pump low-temperature drying equipment, the saturation of the evaporator's hot and humid air is monitored in real time, and dynamic correction is performed according to the set correction logic to ensure that the relative humidity of the hot and humid air entering the evaporator can be maintained at 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a diagram showing the composition and working principle of the heat exchanger and heat pump unit in the heat pump low-temperature drying equipment;

[0036] FIG2 is a schematic diagram of a method for controlling the refrigeration performance of a compressor;

[0037] Figure 3 is a control logic diagram of the compressor operating point;

[0038] FIG4 is a logic diagram of the heat pump unit operation state adjustment to ensure that the relative humidity of the hot and humid air before the evaporator is maintained at 100%. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0040] Example 1:

[0041] This embodiment provides a low-energy consumption control method for heat pump low-temperature drying equipment. By controlling the operating point of the compressor in the heat pump unit, it can effectively reduce the operating power of the compressor and increase the cooling capacity of the compressor, thereby achieving the purpose of reducing the overall energy consumption of the heat pump low-temperature drying equipment.

[0042] As shown in Figure 1, the heat pump low-temperature drying equipment includes a heat exchanger and a heat pump unit. In the heat pump unit, the compressor, condenser, expansion valve, and evaporator are connected in sequence to form a refrigeration cycle loop; the hot and humid air is heat exchanged through the heat exchanger under the action of the circulating fan, and then passes through the evaporator and condenser in the heat pump unit in sequence to form dry hot air and enter the drying chamber of the heat pump low-temperature drying equipment.

[0043] As shown in FIG2 , the principle of the compressor refrigeration performance control method is as follows: first, the optimal operating point of the compressor is determined; then, the heat exchanger is designed so that the heat exchange capacity of the heat exchanger can meet the requirements of the compressor operating at the optimal operating point; then, during the operation of the heat pump low-temperature drying equipment, the heat pump unit is controlled to keep the compressor operating at the optimal operating point; in this scheme, operating at the optimal operating point means that the temperature difference with the optimal operating point is within a set range (such as the temperature difference is within ±5%), and the ideal state is consistent with the optimal operating point (that is, the temperature difference with the optimal operating point is 0).

[0044] The operating points of the compressor include: evaporation temperature and condensation temperature, where the evaporation temperature is the compressor's inlet temperature and the condensation temperature is the compressor's outlet temperature; this operating point corresponds to the compressor's operating COP; for low-temperature sludge drying equipment, an outlet air temperature above 65°C is important for ensuring that the sludge quickly enters the constant speed stage, so the condensation temperature must be greater than or equal to 65°C; after simulation, the optimal evaporation temperature is around 30°C.

[0045] Based on this, to reduce the power consumption of the heat pump unit, it is necessary to increase the compressor's operating COP. When the compressor is not replaced (i.e., there is only one backup compressor), select an operating point where the compressor's COP is greater than the set value, with a condensing temperature greater than or equal to 65°C and an evaporating temperature around 30°C. This operating point is then used as the optimal operating point, and the evaporating and condensing temperatures corresponding to the optimal evaporation and condensing temperatures are set to the optimal evaporation and condensing temperatures, respectively. In this case, the compressor's COP is increased solely by changing the compressor's operating point.

[0046] When a compressor can be replaced (i.e., multiple alternative compressors are available), you can select from multiple different compressors (different brands and / or models) an operating point that satisfies the conditions of a condensing temperature greater than or equal to 65°C, an evaporating temperature around 30°C, and a COP value greater than the set value. The selected compressor is then used, and the corresponding operating point is used as the optimal operating point. This approach improves the compressor's COP by selecting a compressor and operating point.

[0047] As an example, the operating point with the highest compressor COP value can be selected as the optimal operating point. For example, for a compressor of the same brand and model (such as a Copeland 12P), the COP value is 3.31 at an operating point of 30°C / 80°C (i.e., evaporating temperature 30°C, condensing temperature 80°C); and 5.51 at an operating point of 30°C / 65°C. Therefore, 30°C / 65°C is selected as the optimal operating point.

[0048] As another example, the COP values ​​corresponding to various operating points that meet the conditions of a condensing temperature greater than or equal to 65°C and an evaporating temperature of approximately 30°C are sorted from large to small, and the operating points with COP values ​​in the top 50% can be selected as the optimal operating points.

[0049] After determining the optimal operating point, the compressor is guaranteed to operate at the optimal operating point by optimizing the heat exchanger and controlling the operating status of the heat pump unit, that is, the difference between the evaporation temperature and the optimal evaporation temperature is controlled within the set range, and the difference between the condensation temperature and the optimal condensation temperature is controlled within the set range.

[0050] In the circulating air path of the heat pump low-temperature drying equipment, the circulating hot and humid air passes through the heat exchanger (specifically a water-cooled heat exchanger in this solution) under the action of the circulating fan, and then passes through the evaporator and condenser in the heat pump unit in turn to form circulating dry hot air that is blown into the drying chamber.

[0051] In order to ensure that the compressor can operate at the optimal operating point, the heat exchanger is first structurally designed to optimize the heat exchange rate of the heat exchanger (i.e., optimize the design of the heat exchanger) to ensure that the heat exchange rate of the heat exchanger can meet the requirements when the compressor operates at the optimal operating point during the operation of the heat pump unit. The method for optimizing the heat exchange rate of the heat exchanger is as follows: DYMOLA is used to establish a simulation model of the heat pump low-temperature drying equipment, and the air temperature and humidity gradient in the heat pump low-temperature drying equipment is digitally simulated by the simulation model. The heat exchange rate required by the heat exchanger when the compressor is operating at the optimal operating point can be obtained through the digital simulation (i.e., when using DYMOLA digital simulation, the heat exchange rate of the heat exchanger simulation unit in the simulation model is adjusted so that the heat exchange rate of the heat exchanger simulation unit can meet the requirements of the compressor operating at the optimal operating point, and the heat exchange rate of the heat exchanger simulation unit in the simulation model at this time is obtained); based on the heat exchange rate of the heat exchanger simulation unit obtained, the structure and size of the heat exchanger are determined, and the heat exchanger is structurally designed according to the structural size, thereby ensuring that the compressor can operate at the optimal operating point from the hardware structure.

[0052] However, in the actual operation process, due to various interferences, it cannot be guaranteed that the compressor can operate stably at the optimal operating point. Based on this, it is necessary to further perform real-time dynamic adjustment of the operating status (i.e., correction of the optimal operating point).

[0053] In this embodiment, in order to achieve the correction of the optimal operating point, sensors are respectively configured at positions set on the circulating air circuit and the refrigerant gas circulating circuit to perform real-time monitoring of the working status.

[0054] Circulating air path: Air temperature and humidity sensors are installed at the air inlet and outlet of the evaporator, the air inlet and outlet of the condenser, and the air outlet of the heat exchanger (the temperature and humidity sensors are also used to monitor the saturation of the circulating air at the corresponding positions).

[0055] Refrigerant gas circulation circuit: Temperature sensors are installed at the inlet and outlet of the compressor to monitor the refrigerant gas temperature at the inlet and outlet of the compressor (i.e., the evaporation temperature and condensation temperature of the heat pump unit) in real time. The evaporation temperature of the heat pump unit is monitored in real time through temperature sensor A, and the condensation temperature of the heat pump unit is monitored in real time through temperature sensor B. A high-pressure side pressure sensor (let it be pressure sensor A) is provided on the front end pipeline of the condenser, and a low-pressure side pressure sensor (let it be pressure sensor B) is provided on the front end pipeline of the evaporator. In this way, the temperature and pressure of the refrigerant gas at each state point can be monitored, thereby judging the working status of the compressor.

[0056] During the operation of the heat pump unit, the evaporation temperature and condensation temperature of the heat pump unit are monitored in real time through temperature sensor A and temperature sensor B. When the difference between the evaporation temperature or condensation temperature and the temperature corresponding to the optimal operating point exceeds the set range, the various components in the heat pump unit are adjusted to achieve real-time adjustment of the evaporation temperature and condensation temperature, thereby ensuring that the compressor can stably operate at the optimal operating point. As shown in Figure 3, specifically:

[0057] When the evaporation temperature deviates from the optimal evaporation temperature (i.e., the difference from the optimal evaporation temperature exceeds the set range), the expansion valve opening is prioritized for adjustment. Adjusting the expansion valve opening regulates the refrigerant gas flow and pressure. Adjusting the refrigerant gas flow can adjust the evaporator's heat exchange rate, while adjusting the refrigerant gas pressure can adjust the evaporation temperature. However, adjustment of the expansion valve opening is limited by the expansion valve's structure. If the evaporation temperature still deviates from the optimal evaporation temperature after the expansion valve opening is adjusted to the maximum or minimum opening, further adjustment of the evaporation temperature can be achieved by adjusting the condenser subcooling, the circulating fan air volume, or the compressor speed. The condenser subcooling can only be adjusted within a certain range (e.g., only around 5K). Adjusting the condenser subcooling can control the temperature and pressure of the refrigerant gas flowing through the expansion valve. Adjusting the circulating fan air volume uses variable frequency control, which can control the air flow through the condenser and evaporator, thereby changing the heat exchange rate. The compressor is a variable frequency compressor, and adjusting the compressor speed can adjust the pressure and temperature of the refrigerant gas after compression.

[0058] When the evaporating temperature is further adjusted in the above manner, the priority order is: adjusting the condenser subcooling - adjusting the fan air volume - adjusting the compressor speed, that is, the evaporating temperature is fine-tuned by adjusting the condenser subcooling. When the evaporating temperature is at the optimal evaporating temperature after adjusting the condenser subcooling (that is, the deviation from the optimal evaporating temperature is within the set range), no other adjustments are required; otherwise, the circulating fan air volume is further adjusted. If the evaporating temperature is at the optimal evaporating temperature after adjusting the circulating fan air volume (that is, the deviation from the optimal evaporating temperature is within the set range), no other adjustments are required. Otherwise, the compressor speed is further adjusted.

[0059] When the condensing temperature deviates from the optimal condensing temperature (that is, the difference from the optimal condensing temperature exceeds the set range), the exhaust superheat of the compressor is adjusted first. Adjusting the exhaust superheat of the compressor can control the temperature and pressure of the refrigerant gas in front of the condenser; but the exhaust superheat of the compressor can only be adjusted within a certain range (such as only within 5K); when the condensing temperature still deviates from the optimal condensing temperature after adjusting the exhaust superheat of the compressor, the condensing temperature can be further adjusted by adjusting the circulating fan air volume and adjusting the compressor speed. The priority order is: adjusting the circulating fan air volume-adjusting the compressor speed.

[0060] Example 2:

[0061] On the basis of the above-mentioned Example 1, given that the dehumidification latent heat ratio of the existing heat pump unit evaporator (the dehumidification latent heat ratio refers to the air dehumidification amount on both sides of the evaporator converted into heat / air enthalpy difference, that is, the proportion of the total cooling capacity of the compressor used for dehumidification) is relatively low (0.73 to 0.75), the efficiency of the cooling capacity evaporation dehumidification is low, and thus multiple compressors and fans need to be installed, resulting in high overall energy consumption of the equipment. In order to achieve low energy consumption, a method for improving the dehumidification performance of the evaporator is further provided. The dehumidification latent heat ratio of the evaporator is increased by increasing the relative humidity of the air before the evaporator. During operation, the operating state of the heat pump unit is dynamically adjusted in real time to keep the relative humidity of the air before the evaporator at the set value. This can reduce the number of compressors and fans used, thereby achieving the purpose of reducing energy consumption.

[0062] First, by optimizing the design of the heat exchanger and making real-time dynamic adjustments during operation, the relative humidity of the hot and humid air in front of the evaporator is maintained at 100% (i.e., the hot and humid air in front of the evaporator is saturated air with a relative humidity of 100%), thereby increasing the dehumidification latent heat ratio of the evaporator from 75% to 85%.

[0063] In the heat pump low-temperature drying equipment, the circulating hot and humid air passes through the heat exchanger (specifically a water-cooled heat exchanger in this solution) under the action of the circulating fan, and then passes through the evaporator and condenser in the heat pump unit in sequence to form circulating dry hot air and blown into the drying chamber.

[0064] To ensure that the hot and humid air entering the evaporator is air with a relative humidity of 100%, that is, saturated air, the heat exchanger is first optimized to ensure that the heat exchange capacity of the heat exchanger can meet the requirements when the relative humidity of the air before the evaporator is 100%. That is, when optimizing the heat exchanger in the above-mentioned embodiment 1, the requirement for the relative humidity of the air before the evaporator is added; that is, when using DYMOLA digital simulation, the heat exchange capacity of the heat exchanger simulation unit in the simulation model is adjusted so that the heat exchange capacity of the heat exchanger simulation unit can simultaneously meet the requirements of the compressor operating at the optimal operating point and the relative humidity of the air before the evaporator being 100%, and the heat exchange capacity of the heat exchanger simulation unit in the simulation model at this time is obtained; based on the obtained heat exchange capacity of the heat exchanger simulation unit, the structure and size of the heat exchanger are determined, and the heat exchanger is structurally designed according to the structure and size, thereby ensuring that the compressor can operate at the optimal operating point and the relative humidity of the air before the evaporator is 100% from the hardware structure.

[0065] However, in actual operation, due to various interferences, the relative humidity of the air before the evaporator cannot be guaranteed to be maintained at 100%. Based on this, real-time dynamic adjustment of the operating state (ie, correction) is further performed.

[0066] In the circulating air path, humidity sensors are installed on the pipes before and after the heat exchanger and at the evaporator air inlet (the position where the humid hot air enters the evaporator) to monitor the humidity of the humid hot air before entering the evaporator in real time. During the operation of the heat pump unit, the humidity sensor at the evaporator air inlet monitors the humidity of the air before the evaporator in real time, and then obtains the air saturation at this position. When the difference between the relative humidity of the air at this position and the set 100% exceeds the set range, the various components in the heat pump unit are adjusted to achieve real-time adjustment of the saturation of the humid hot air before the evaporator, thereby keeping the relative humidity of the air before the evaporator at the set 100%. Specifically:

[0067] When the relative humidity of the hot and humid air before the evaporator deviates from the set 100% (i.e., the difference from the set 100% exceeds the set error range), the heat exchanger's heat transfer capacity is preferentially adjusted, thereby achieving preliminary adjustment of the relative humidity of the hot and humid air before the evaporator. However, the heat exchanger's heat transfer capacity is limited by its structural dimensions. If the heat exchanger's heat transfer capacity is adjusted to maximum, but the relative humidity of the hot and humid air before the evaporator still deviates from the set 100%, further adjustment of the relative humidity of the hot and humid air before the evaporator can be achieved by adjusting the circulating fan air volume and the compressor speed. The circulating fan air volume is adjusted using variable frequency control, which controls the air flow through the condenser and evaporator, thereby varying the heat transfer capacity. The compressor is a variable frequency compressor, and adjusting the compressor speed adjusts the pressure and temperature of the refrigerant gas after compression. (Adjusting the compressor speed changes the compressor's cooling capacity and heating capacity. For example, reducing the compressor's cooling capacity reduces the evaporator's dehumidification capacity, gradually increasing the air humidity and indirectly affecting the relative humidity.)

[0068] When the evaporation temperature is further adjusted using the above method, the priority order is: adjusting the fan air volume - adjusting the compressor speed, that is, adjusting the circulating fan air volume is preferably used to fine-tune the saturation of the hot and humid air in front of the evaporator. When the relative humidity of the hot and humid air in front of the evaporator reaches 100% after adjusting the circulating fan air volume, no other adjustments are required. Otherwise, the compressor speed is further adjusted, as shown in Figure 4.

[0069] Example 3:

[0070] On the basis of the above-mentioned embodiment 1 or embodiment 2, an emergency adjustment method during the operation of the heat pump unit is further provided.

[0071] To ensure the safe operation of the heat pump unit, a water monitor heat exchanger (a type of shell and tube heat exchanger) is installed between the compressor and the condenser.

[0072] During the operation of the heat pump unit, when pressure sensor A detects that the pressure at the front end of the condenser is greater than the set threshold, it enters the emergency adjustment state. In the emergency adjustment state, the evaporator superheat is adjusted first (the high condenser pressure corresponds to a high temperature, and the temperature needs to be lowered, so the superheat needs to be reduced), but the evaporator superheat can only be adjusted within a certain range (such as only about 8K can be adjusted); if after adjusting the evaporator superheat, the pressure at the front end of the condenser is still greater than the set threshold, the heat exchange capacity of the water cannon heater is increased to prevent the temperature and pressure of the condenser from being too high.

[0073] Example 4:

[0074] This embodiment provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the control methods of embodiments 1 to 3 are implemented.

[0075] Example 5:

[0076] This embodiment provides a storage medium storing a computer program. When the computer program is executed by one or more processors, the control methods of Embodiments 1 to 3 are implemented.

[0077] The storage medium may be implemented by any type of volatile or non-volatile storage device, or a combination thereof.

[0078] The above content is a further detailed description of the present invention in conjunction with specific embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A low energy consumption control method for a heat pump low temperature drying device, wherein the heat pump low temperature drying device comprises a heat exchanger and a heat pump unit, wherein a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected to form a refrigeration cycle loop; after the humid hot air is heat exchanged by the heat exchanger under the action of a circulating fan, it sequentially passes through the evaporator and the condenser in the heat pump unit to form dry hot air and enter the drying chamber of the heat pump low temperature drying device; the method is characterized in that: The operating point of the compressor includes: evaporation temperature and condensation temperature; firstly, the operating point where the COP value is greater than the set value under the conditions of the set evaporation temperature and condensation temperature is selected as the optimal operating point of the compressor, and the evaporation temperature and condensation temperature corresponding to the optimal operating point are respectively the optimal evaporation temperature and the optimal condensation temperature; Establish a simulation model of the heat pump low-temperature drying equipment, the simulation model is used to simulate the air temperature and humidity gradient in the heat pump low-temperature drying equipment; adjust the heat exchange capacity of the heat exchanger simulation unit in the simulation model so that the heat exchange capacity of the heat exchanger simulation unit can meet the demand of the compressor operating at the optimal operating point, and obtain the heat exchange capacity of the heat exchanger simulation unit in the simulation model at this time; based on the obtained heat exchange capacity, perform structural design on the heat exchanger; During the operation of the heat pump low-temperature drying equipment, the operating state of the heat pump unit is dynamically adjusted in real time to keep the compressor running at the optimal operating point.

2. The low energy consumption control method for heat pump low temperature drying equipment according to claim 1, characterized in that: When there is only one alternative compressor, the operating point with the highest COP value of the alternative compressor under the conditions of set evaporation temperature and condensation temperature is selected as its optimal operating point; When there are multiple different alternative compressors: select from all the alternative compressors the operating point with the highest COP value that can meet the set evaporating temperature and condensing temperature conditions and the corresponding alternative compressor; use the selected alternative compressor as the compressor of the heat pump unit, and use the corresponding operating point as the optimal operating point.

3. The low energy consumption control method for heat pump low temperature drying equipment according to claim 1 or 2, characterized in that: During the operation of the heat pump low-temperature drying equipment, when the difference between the evaporation temperature of the heat pump unit and the optimal evaporation temperature exceeds the set range, the opening of the expansion valve is first adjusted. If the difference between the evaporation temperature and the optimal evaporation temperature still exceeds the set range after the opening of the expansion valve is adjusted to the maximum opening or the minimum opening, the evaporation temperature is further adjusted by adjusting one or more of the following methods: adjusting the subcooling of the condenser, adjusting the air volume of the circulating fan, and adjusting the speed of the compressor.

4. The low energy consumption control method for heat pump low temperature drying equipment according to claim 3, characterized in that: When further adjusting the evaporating temperature, the priority order is: adjusting the condenser subcooling - adjusting the circulation fan air volume - adjusting the compressor speed.

5. The low energy consumption control method for heat pump low temperature drying equipment according to claim 1 or 2, characterized in that: During the operation of the heat pump low-temperature drying equipment, when the difference between the condensing temperature of the heat pump unit and the optimal condensing temperature exceeds the set range, the exhaust superheat of the compressor is first adjusted. If the difference between the condensing temperature and the optimal condensing temperature still exceeds the set range after adjusting the exhaust superheat of the compressor, the condensing temperature is further adjusted by adjusting the air volume of the circulating fan or adjusting the speed of the compressor.

6. The low energy consumption control method of heat pump low temperature drying equipment according to claim 5, characterized in that: When further adjusting the condensing temperature, the priority order is: adjusting the circulation fan air volume - adjusting the compressor speed.

7. The low energy consumption control method for heat pump low temperature drying equipment according to claim 1, characterized in that: The relative humidity of the hot and humid air entering the evaporator in the heat pump unit is controlled to be 100%.

8. The low energy consumption control method for heat pump low temperature drying equipment according to claim 7, characterized in that: In the simulation model of the heat pump low-temperature drying equipment, the heat exchange rate of the heat exchanger simulation unit in the simulation model is adjusted so that the heat exchange rate of the heat exchanger simulation unit can simultaneously meet the operating requirements of the compressor operating at the optimal operating point and the relative humidity of the hot and humid air in front of the evaporator being 100%, and then the heat exchange rate of the heat exchanger simulation unit in the simulation model at this time is obtained; based on the obtained heat exchange rate, the heat exchanger is structurally designed.

9. The low energy consumption control method for heat pump low temperature drying equipment according to claim 8, characterized in that: During the operation of the heat pump low-temperature drying equipment, the humidity of the hot and humid air entering the evaporator is monitored in real time, and the operating status of the heat exchanger and the heat pump unit is dynamically adjusted in real time to keep the relative humidity of the hot and humid air entering the evaporator at 100%.

10. The low energy consumption control method of heat pump low temperature drying equipment according to claim 9, characterized in that: During the operation of the heat pump low-temperature drying equipment, when the relative humidity of the hot and humid air in front of the evaporator deviates from the set 100%, the heat exchange rate of the heat exchanger is first adjusted. If the relative humidity of the hot and humid air in front of the evaporator still does not reach 100% when the heat exchange rate of the heat exchanger is adjusted to the maximum, the relative humidity of the hot and humid air in front of the evaporator is further adjusted by adjusting the air volume of the circulating fan or adjusting the speed of the compressor.

11. The low energy consumption control method for heat pump low temperature drying equipment according to claim 10, characterized in that: When further adjusting the relative humidity of the hot and humid air before the evaporator, the priority order is: adjusting the circulation fan air volume - adjusting the compressor speed.

12. The low energy consumption control method for heat pump low temperature drying equipment according to any one of claims 1 or 2 or 7-10, characterized in that: During the operation of the heat pump low-temperature drying equipment, the pressure at the front end of the condenser is monitored in real time. When the pressure at the front end of the condenser is greater than a set value, the superheat of the evaporator is adjusted.

13. The low energy consumption control method of heat pump low temperature drying equipment according to claim 12, characterized in that: A heat exchange unit is set between the compressor and the condenser of the heat pump unit. If the pressure at the front end of the condenser is still greater than the set value after adjusting the superheat of the evaporator, the heat exchange capacity of the heat exchange unit is increased to reduce the pressure at the front end of the condenser.

14. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 13 are implemented.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 13 are implemented.

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