Double-effect double-temperature-control heat pump unit and temperature control method thereof

Abstract

The invention relates to the technical field of heating, ventilation and air conditioning heat pumps, in particular to a double-effect double-temperature-control heat pump unit, and aims to solve the technical problem that a heat pump system in the prior art cannot realize independent and accurate temperature control on the cold side and the hot side. The system comprises a condenser, an evaporator, an electronic expansion valve, a compressor, a liquid spraying enthalpy increasing device, an anti-supercooling device and an intelligent full-automatic control system, and dynamic compensation and adjustment of the temperature of the cold side of the evaporator are achieved through the synergistic effect of the liquid spraying enthalpy increasing device and the anti-supercooling device in combination with a closed-loop feedback control strategy; meanwhile, independent setting and stable control over the temperature of the hot side are achieved through a heat adjusting device between the condenser and the compressor. The system has the advantages of high temperature control precision, high operation stability, high energy efficiency ratio, wide application range and the like, and is suitable for combined cooling and heating supply scenes with relatively high temperature control requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of heating, ventilation, air conditioning and heat pump, in particular to a dual-effect and dual-control warm heat pump unit and its temperature control method. Background Art

[0002] In the field of heating, ventilation, air conditioning and heat pump, most of the existing heat pump units are of the single-effect and single-temperature control type. In the refrigeration mode, only the temperature on the refrigeration side can be accurately controlled and set, and the temperature on the heating side cannot be controlled and set, resulting in ineffective precise heat supply on the heat side; in the heating mode, only the temperature on the heating side can be accurately controlled and set, and the temperature on the refrigeration side is uncontrollable, making it difficult to achieve precise cold supply on the cold side. This limitation makes it impossible for the existing heat pump units to build a combined cooling and heating supply system that meets the requirements of precise temperature control, and it cannot simultaneously meet the different temperature requirements of users for cooling and heating in practical applications. The energy utilization efficiency is low, and it cannot fully meet the needs of modern buildings and industrial fields for high-efficiency, intelligent and precise temperature control equipment, and there is an urgent need for technological innovation and improvement.

[0003] For example, some related technologies are disclosed in the prior art. The patent application with the publication number CN101900448B (applicant: Trane Air Conditioning Systems (China) Co., Ltd.; publication date: December 11, 2013) discloses a steam injection enhanced heat pump air conditioning and hot water unit. This technical solution enables the heat pump air conditioning and hot water unit to operate stably under the condition that the ambient temperature is as low as -15°C by introducing the steam injection enhanced heat pump technology, and raises the outlet temperature of domestic hot water to 63°C, thereby significantly improving the low-temperature heating performance, extending the service life of the equipment, and meeting the needs of building cooling, heating and domestic hot water throughout the year.

[0004] However, it still has the following technical problems: Although this technology improves the heating capacity of the system in a low-temperature environment, its control logic is still based on the traditional single-effect and single-temperature control mode, that is, when switching between the refrigeration or heating mode, only the temperature on the current side can be accurately controlled, and the simultaneous setting and adjustment of the temperatures on both the cold and hot sides cannot be achieved. Therefore, in the application scenarios that require combined cooling and heating supply, this system is difficult to meet the precise temperature control requirements of both the cold side and the hot side, resulting in reduced energy utilization efficiency, lagging system response, and insufficient control accuracy. In addition, due to the lack of a dynamic adjustment mechanism for the excess or deficiency of heat on the cold side of the evaporator, the system is prone to overcooling or undercooling phenomena under extreme load changes, affecting the overall operation stability and comfort.

[0005] For another example, a patent application with the publication number CN202002391U (applicant: Shandong Okai Air Conditioning Technology Co., Ltd.; publication date: October 5, 2011) discloses a liquid injection enhanced enthalpy heat pump water heater unit. Through the setting of an economizer, under the operating conditions of a relatively low evaporation temperature (lower than -25°C), part of the liquid refrigerant is throttled and evaporated to absorb heat, so that another part of the refrigerant obtains a subcooling effect and enters the compressor through a gas injection cycle, thereby increasing the refrigerating capacity, improving the refrigeration cycle efficiency of the compressor and reducing the exhaust temperature, so as to increase the system COP value.

[0006] However, there are often the following technical problems in practical applications: Although this technology realizes partial optimization of the refrigeration cycle of the compressor through an economizer, it does not involve effective control means for the temperature fluctuation on the cold side of the evaporator, and lacks a real-time compensation and adjustment mechanism for insufficient heat at the inlet of the evaporator or excessive heat at the outlet. This makes it difficult for the system to maintain the stability of the temperature on the cold side of the evaporator under the condition of frequent load changes, and it is easy to have problems such as large fluctuations in the cooling temperature and poor temperature control accuracy. At the same time, this system also does not solve the problem of independent temperature control on both sides in the scenario of combined heating and cooling, and cannot achieve an efficient operation mode of dual-purpose, which limits its applicability in occasions with high-precision temperature control requirements. Summary of the Invention

[0007] This application discloses a dual-effect and dual-temperature-controlled heat pump unit system, which can solve the above-mentioned existing technical problems to a certain extent. The system includes a condenser, an evaporator, an electronic expansion valve, a compressor, a liquid injection enhanced enthalpy device, a subcooling prevention device and a smart fully automatic control system. By setting a temperature sensor at the inlet of the evaporator and combining the liquid injection enhanced enthalpy device to deliver high-temperature medium to the cold side of the evaporator as needed, precise compensation temperature control when the heat is insufficient is realized; at the same time, a temperature sensor is set at the outlet of the evaporator, and the excess heat is bypassed over the evaporator and directly delivered to the inlet of the compressor in combination with the subcooling prevention device to realize precise adjustment temperature control when the heat is excessive. Through the synergistic effect of the above structural design and intelligent control strategy, this application can realize independent setting and synchronous adjustment of the temperatures on both the cold and hot sides, significantly improve the temperature control accuracy and operation efficiency of the system in the scenario of combined heating and cooling, and has multiple advantages such as energy saving, environmental protection and safety, and is especially suitable for industrial and commercial application fields with high requirements for temperature control. The present invention specifically adopts the following technical solutions.

[0008] Design a double-effect and double-control temperature heat pump unit, which includes an evaporator, a compressor, a condenser, and a throttle valve that are connected in sequence through pipelines in a cycle. It also includes a liquid injection and enthalpy increase device and an anti-subcooling device. One end of the liquid injection and enthalpy increase device is connected between the outlet of the compressor and the inlet of the condenser through a pipeline, and the other end is connected between the outlet of the throttle valve and the inlet of the evaporator through a pipeline; One end of the anti-subcooling device is connected between the outlet of the evaporator and the inlet of the compressor through a pipeline, and the other end is connected between the outlet of the throttle valve and the inlet of the evaporator through a pipeline;

[0009] It also includes temperature sensors respectively arranged at the inlet and outlet of the evaporator, and an automatic control system. The automatic control system adjusts the working states of the liquid injection and enthalpy increase device and the anti-subcooling device according to the feedback signals of the temperature sensors to achieve independent and precise temperature control on both the cold and hot sides;

[0010] The automatic control system includes a data acquisition module, a data processing module, and a control execution module. The data acquisition module is used to collect data from the temperature sensors at the inlet and outlet of the evaporator. The data processing module is used to calculate the required heat or excess heat based on the collected data and generate control instructions. The control execution module is used to control the operation of the liquid injection and enthalpy increase device and the anti-subcooling device according to the control instructions.

[0011] Preferably, the liquid injection and enthalpy increase device includes a regulating valve, and the regulating valve adjusts the flow rate of the high-temperature medium from the condenser to the evaporator according to the instructions of the automatic control system.

[0012] Preferably, the anti-subcooling device includes a bypass valve, and the bypass valve adjusts the bypass flow rate of the low-temperature medium from the outlet of the throttle valve to the inlet of the compressor according to the instructions of the automatic control system.

[0013] Preferably, the automatic control system further includes a human-machine interface for setting the target temperature values at the inlet and outlet of the evaporator and for displaying the operating parameters of the unit in real time.

[0014] A temperature control method for a double-effect and double-control temperature heat pump unit includes the following steps:

[0015] S1: The temperature sensor at the inlet of the evaporator monitors the temperature at the inlet of the evaporator in real time. When it is detected that the temperature at the inlet of the evaporator is lower than the set temperature, the automatic control system automatically calculates the required heat;

[0016] S2: The automatic control system uses the PID control strategy according to the required heat calculated in step S1 to control the liquid injection and enthalpy increase device to transport the high-temperature medium on the inlet side of the condenser to the cold-temperature medium at the inlet of the evaporator to compensate for the insufficient heat on the cold side of the evaporator;

[0017] S3: Monitor the temperature at the outlet of the evaporator in real time through the evaporator outlet temperature sensor. When it is detected that the temperature at the outlet of the evaporator is higher than the set temperature, the automatic control system automatically calculates the excess heat;

[0018] S4: The automatic control system controls the anti-subcooling device to directly transport the excess heat calculated in step S3 from the outlet of the throttle valve to the inlet of the compressor, without entering the evaporator again, reducing the flow rate of the heat absorption medium, adjusting the excessive heat on the cold side of the evaporator, and achieving precise temperature control on both the hot and cold sides.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. The present invention realizes the precise setting and control of the temperatures on the hot and cold sides of the heat pump unit, breaks through the limitation of traditional single-effect single-temperature control, can meet different operating conditions on both the hot and cold sides simultaneously, realizes combined heat and cold supply, achieves the effect of one machine with two uses, and improves the functional diversity and practicality of the equipment.

[0021] 2. The present invention works in coordination with the automatic control system through the liquid injection and enthalpy increase device and the anti-subcooling device. While the precise temperature control on the cold side meets the refrigeration demand, the heat on the hot side can be obtained for free, and the cooling load on the hot side during the refrigeration of the conventional refrigerator is saved. It is a low-carbon or even negative-carbon product for the heating system, significantly improves the energy utilization efficiency, is of great significance in energy conservation and emission reduction, and reduces the operating cost.

[0022] 3. The automatic control system integrates data acquisition, processing, and execution modules, automatically adjusts the working states of the liquid injection and enthalpy increase device and the anti-subcooling device according to the feedback signal of the temperature sensor, and realizes intelligent and precise temperature control. The human-machine interface is convenient for users to set the target temperature value and view the operating parameters of the unit in real time, with convenient and intuitive operation, and improves the user experience. Description of the Drawings

[0023] Figure 1 is the overall structural schematic diagram of the present invention;

[0024] The reference numerals in the figure are: 1 evaporator, 2 compressor, 3 condenser, 4 liquid injection and enthalpy increase device, 5 anti-subcooling device, 6 throttle valve. Detailed Embodiments

[0025] The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0026] Embodiment 1

[0027] A double-effect and double-control temperature heat pump unit, as Figure 1As shown in the figure, it includes an evaporator 1, a compressor 2, a condenser 3, and a throttle valve 6 that are sequentially connected in a loop through pipelines. The core components of the heat pump unit, namely the evaporator 1, the compressor 2, the condenser 3, and the throttle valve 6, are circulated through pipelines to transfer heat under the action of the refrigerant, which is the same as the principle of ordinary heat pump units. It also includes a liquid injection and enthalpy increase device 4 and an anti-subcooling device 5. One end of the liquid injection and enthalpy increase device 4 is connected between the outlet of the compressor 2 and the inlet of the condenser 3 through a pipeline, and the other end is connected between the outlet of the throttle valve 6 and the inlet of the evaporator 1 through a pipeline; One end of the anti-subcooling device 5 is connected between the outlet of the evaporator 1 and the inlet of the compressor 2 through a pipeline, and the other end is connected between the outlet of the throttle valve 6 and the inlet of the evaporator 1 through a pipeline;

[0028] It also includes temperature sensors respectively arranged at the inlet and outlet of the evaporator 1, and an automatic control system. The automatic control system adjusts the working states of the liquid injection and enthalpy increase device 4 and the anti-subcooling device 5 according to the feedback signals of the temperature sensors to achieve independent and precise temperature control on both the cold and hot sides;

[0029] The liquid injection and enthalpy increase device 4 includes a regulating valve. The regulating valve adjusts the flow rate of the high-temperature medium from the condenser 3 to the evaporator 1 according to the instructions of the automatic control system. The liquid injection and enthalpy increase device 4 is based on the principle of on-demand adjustment. When the heat on the cold side of the evaporator 1 is insufficient, it introduces high-temperature medium from the condenser 3 side to compensate for the heat.

[0030] The anti-subcooling device 5 includes a bypass valve. The bypass valve adjusts the bypass flow rate of the low-temperature medium from the outlet of the throttle valve 6 to the inlet of the compressor 2 according to the instructions of the automatic control system. When the heat on the cold side of the evaporator 1 is excessive, the anti-subcooling device 5 bypasses the low-temperature medium to reduce the flow rate of the heat-absorbing medium entering the evaporator 1 to adjust the heat.

[0031] The automatic control system includes a data acquisition module, a data processing module, a control execution module, and a human-machine interface. The data acquisition module is used to collect data from the temperature sensors at the inlet and outlet of the evaporator 1. The data processing module is used to calculate the required heat or excess heat based on the collected data and generate control instructions. The control execution module is used to control the operation of the liquid injection and enthalpy increase device 4 and the anti-subcooling device 5 according to the control instructions. The automatic control system collects data through the temperature sensors arranged at the inlet and outlet of the evaporator 1, and through the cooperation of the data acquisition, processing, and execution modules, precisely controls the liquid injection and enthalpy increase device 4 and the anti-subcooling device 5 to achieve independent and precise temperature control on both the cold and hot sides. The human-machine interface is used to set the target temperature values at the inlet and outlet of the evaporator 1 and display the operating parameters of the unit in real time.

[0032] The working process of the present invention: First, the operator sets the target temperature values at the inlet and outlet of the evaporator 1 through the human-machine interface. During operation, the data acquisition module continuously collects data from the temperature sensors at the inlet and outlet of the evaporator 1.

[0033] In the refrigeration mode, when the inlet temperature sensor of the evaporator 1 monitors that the inlet temperature is lower than the set temperature, the data processing module is activated and calculates the heat to be supplemented based on the collected data. Subsequently, the control execution module of the automatic control system controls the opening of the regulating valve in the liquid injection and enthalpy-increasing device 4 according to the PID control strategy, so that the high-temperature medium on the inlet side of the condenser 3 flows from between the outlet of the compressor 2 and the inlet of the condenser 3 to between the outlet of the throttle valve 6 and the inlet of the evaporator 1 through the pipeline according to the calculated heat, and is transported to the cold-temperature medium at the inlet of the evaporator 1 to compensate for the insufficient heat on the cold side of the evaporator 1 and ensure that the cold-side temperature meets the refrigeration requirements. When the outlet temperature sensor of the evaporator 1 monitors that the outlet temperature is higher than the set temperature, the data processing module calculates the excess heat. The control execution module controls the opening of the bypass valve in the subcooling prevention device 5, directly transports the excess heat from the outlet of the throttle valve 6 to the inlet of the compressor 2, and no longer allows this part of the heat to enter the evaporator 1, reducing the flow rate of the heat-absorbing medium entering the evaporator 1, thereby adjusting the situation of excessive heat on the cold side of the evaporator 1 and maintaining the stability of the cold-side temperature.

[0034] In the heating mode, the system also monitors the inlet and outlet temperatures of the evaporator 1 through temperature sensors. The excess heat on the cold side is processed by the subcooling prevention device 5 to prevent the evaporator 1 from being subcooled and affecting the heating efficiency; on the hot side, the liquid injection and enthalpy-increasing device 4 and other components work together to accurately control the hot-side temperature. At the same time, the heat generated on the hot side can be directly utilized without additional cooling, improving the energy utilization efficiency, realizing combined cooling and heating, and having the advantages of energy conservation and emission reduction for the heating system.

[0035] Embodiment 2

[0036] A temperature control method for a double-effect and dual-temperature heat pump unit includes the following steps:

[0037] S1: The inlet temperature of the evaporator 1 is continuously monitored by the temperature sensor at the inlet of the evaporator 1. When it is monitored that the inlet temperature of the evaporator 1 is lower than the set temperature, the automatic control system automatically calculates the required heat;

[0038] S2: The automatic control system uses the PID control strategy according to the required heat calculated in step S1 to control the liquid injection and enthalpy-increasing device 4 to transport the high-temperature medium on the inlet side of the condenser 3 to the cold-temperature medium at the inlet of the evaporator 1 to compensate for the insufficient heat on the cold side of the evaporator 1;

[0039] S3: The outlet temperature of the evaporator 1 is continuously monitored by the temperature sensor at the outlet of the evaporator 1. When it is monitored that the outlet temperature of the evaporator 1 is higher than the set temperature, the automatic control system automatically calculates the excess heat;

[0040] S4: The automatic control system controls the anti-subcooling device 5 to directly transport the excess heat calculated in step S3 from the outlet of the throttle valve 6 to the inlet of the compressor 2, without entering the evaporator 1 anymore, reducing the flow rate of the heat absorption medium, regulating the excessive heat on the cold side of the evaporator 1, and achieving precise temperature control on both the cold and hot sides.

[0041] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A double-effect and double-control warm pump unit, characterized in that, It includes an evaporator, a compressor, a condenser, and a throttle valve that are connected in sequence through a pipeline in a cycle. It also includes a liquid injection and enthalpy increase device and an anti-subcooling device. One end of the liquid injection and enthalpy increase device is connected between the outlet of the compressor and the inlet of the condenser through a pipeline, and the other end is connected between the outlet of the throttle valve and the inlet of the evaporator through a pipeline; One end of the anti-subcooling device is connected between the outlet of the evaporator and the inlet of the compressor through a pipeline, and the other end is connected between the outlet of the throttle valve and the inlet of the evaporator through a pipeline; It also includes temperature sensors respectively arranged at the inlet and outlet of the evaporator, and an automatic control system. The automatic control system adjusts the working states of the liquid injection and enthalpy increase device and the anti-subcooling device according to the feedback signals of the temperature sensors to achieve independent and precise temperature control on both the cold and hot sides; The automatic control system includes a data acquisition module, a data processing module, and a control execution module. The data acquisition module is used to acquire the data of the temperature sensor at the inlet of the evaporator and the temperature sensor at the outlet of the evaporator. The data processing module is used to calculate the required heat or excess heat according to the acquired data and generate a control instruction. The control execution module is used to control the working of the liquid injection and enthalpy increase device and the anti-subcooling device according to the control instruction.

2. The double-effect and double-control warm heat pump unit according to claim 1, characterized in that: The liquid injection and enthalpy increase device includes a regulating valve, and the regulating valve adjusts the flow rate of the high-temperature medium from the condenser to the evaporator according to the instruction of the automatic control system.

3. The double-effect and double-control warm heat pump unit according to claim 1, characterized in that: The anti-subcooling device includes a bypass valve, and the bypass valve adjusts the bypass flow rate of the low-temperature medium from the outlet of the throttle valve to the inlet of the compressor according to the instruction of the automatic control system.

4. The double-effect and double-control warm heat pump unit according to claim 1, wherein: The automatic control system also includes a human-machine interface for setting the target temperature values at the inlet and outlet of the evaporator and for displaying the operation parameters of the unit in real time.

5. A temperature control method for a double-effect and double-control warm heat pump unit according to any one of claims 1 to 4, characterized in that, It includes the following steps: S1: The temperature sensor at the inlet of the evaporator is used to monitor the temperature at the inlet of the evaporator in real time. When it is monitored that the temperature at the inlet of the evaporator is lower than the set temperature, the automatic control system automatically calculates the required heat; S2: The automatic control system uses the PID control strategy according to the required heat calculated in step S1 to control the liquid injection and enthalpy increase device to deliver the high-temperature medium on the inlet side of the condenser to the cold-temperature medium at the inlet of the evaporator to compensate for the insufficient heat on the cold side of the evaporator; S3: The temperature sensor at the outlet of the evaporator is used to monitor the temperature at the outlet of the evaporator in real time. When it is monitored that the temperature at the outlet of the evaporator is higher than the set temperature, the automatic control system automatically calculates the excess heat; S4: The automatic control system controls the anti-subcooling device to directly deliver the excess heat calculated in step S3 from the outlet of the throttle valve to the inlet of the compressor without entering the evaporator, reducing the flow rate of the heat-absorbing medium and adjusting the excessive heat on the cold side of the evaporator to achieve precise temperature control on both the cold and hot sides.

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