Compression-absorption combined refrigeration and heat supply system and control method thereof

Abstract

The application discloses a compression-absorption combined refrigeration and heat supply system and a control method thereof. The system comprises an absorption heat exchange unit, a generator (1), a condenser (2), an absorber (4) and an evaporative condenser (6); a compression heat exchange unit, a compressor (9) and an evaporator (10); a cold water / waste heat water pipeline, which is divided into two parallel branches, a first branch passing through a first regulating valve (11) and the evaporative condenser (6) to a water outlet, and a second branch passing through a second regulating valve (12) and the evaporator (10) to the water outlet; a cooling water / heating water pipeline, which passes through the absorber (4) and the condenser (2) in sequence; a temperature sensor; and a controller, which is used for switching a refrigeration / heat supply mode, adjusting the opening degrees of the two regulating valves according to the water outlet temperature deviation, changing the flow ratio of the two branches and realizing continuous energy regulation of the absorption side and the compression side. The application can adaptively distribute cold and heat, and improve the energy efficiency and the water outlet temperature stability under all working conditions.

Description

Technical Field

[0001] This invention relates to the field of energy utilization and energy conservation technology, and in particular to a compression absorption combined refrigeration and heating system and its control method. Background Technology

[0002] In industries such as power generation, chemical engineering, pharmaceuticals, printing and dyeing, iron and steel coking, and non-ferrous metals, there are abundant medium- and high-temperature waste heat resources (such as process exhaust steam, steam, and medium- and high-temperature hot water). These industries also typically have needs for process cooling, air conditioning, and winter heating. Cooling and heating are key technologies for energy conservation in both residential and industrial sectors. Absorption heat pump units and electric compression heat pump units are currently the two most widely used technologies.

[0003] Absorption heat pump units can utilize waste heat to drive cooling or heating, offering the advantage of high primary energy utilization. However, their cooling / heating capacity decreases significantly when waste heat temperature fluctuates greatly or cooling water temperature is high, and output adjustment becomes difficult. Electric compression heat pump units offer advantages such as high energy efficiency ratio and flexible adjustment, but they consume high-grade electrical energy, and their energy efficiency decreases significantly under conditions of large temperature differences and high temperature rises.

[0004] To combine the advantages of both technologies, a combined compression and absorption heat pump unit has emerged in existing technologies. For example, a compression chiller and an absorption heat pump are coupled through a refrigerant three-way valve to achieve switching between winter and summer modes. In cooling mode, only the compression chiller operates, while in heating mode, the compression chiller and the absorption heat pump operate in series, utilizing the high-temperature rise characteristic of the absorption heat pump to increase the heating temperature.

[0005] However, the aforementioned compression-absorption combined unit still has the following drawbacks: First, the operating conditions are limited, and the control strategies are rudimentary. Existing combined units typically only achieve fixed mode switching between cooling and heating, and cannot finely and continuously adjust the output ratio of the absorption and compression sides based on continuous changes in operating parameters such as waste heat source temperature and cooling water temperature. Especially in non-circulating heat extraction scenarios (such as hot water storage bodies and soil heat storage bodies), the temperature of the waste heat source gradually decreases during the heat extraction process, and existing units struggle to adaptively adjust their operating strategies, resulting in low system energy efficiency or large fluctuations in outlet water temperature.

[0006] Second, the system relies on refrigerant switching, making system control complex. Existing combined units switch modes by changing the refrigerant flow direction through a three-way refrigerant valve. The controlled object is the refrigerant circuit, which results in high system complexity and makes it difficult to achieve continuous ratio adjustment of the output on the absorption and compression sides.

[0007] Third, there is a lack of closed-loop control based on outlet water temperature feedback. Existing combined units typically do not have outlet water temperature sensors or rely solely on preset fixed modes of operation, making it impossible to adjust the output ratio of the absorption and compression sides in real time according to actual load requirements, resulting in higher energy consumption under partial load.

[0008] Compression-absorption hybrid systems combine the waste heat utilization capabilities of absorption cycles with the adjustment flexibility of compression cycles, showing potential application value in waste heat recovery and combined cooling and heating systems. However, the sophistication of the operating strategies of existing hybrid systems still needs improvement, which to some extent limits further improvement in their energy efficiency. Therefore, developing a compression-absorption hybrid refrigeration and heating system and its operating strategy that can adapt to variable operating conditions and possess self-optimization capabilities is of positive significance for improving industrial waste heat utilization efficiency and reducing energy consumption. Summary of the Invention

[0009] The purpose of this invention is to provide a compression-absorption hybrid refrigeration and heating system and its control method. By setting up parallel pipelines between the absorption heat exchanger and the compression heat exchanger, and using a first and second regulating valve to direct the water to be treated in the chilled water / waste water pipeline to the evaporator-condenser side or the evaporator side, and coordinating with feedback regulation from temperature sensors and controllers, the system achieves continuous ratio adjustment of the output power on the absorption and compression sides. This solves the technical problems of existing hybrid units, such as single operating conditions, coarse control strategies, and inability to adapt to continuous changes in waste heat source temperature (especially the gradual temperature decrease in non-circulating heat extraction scenarios), leading to low system energy efficiency or large fluctuations in outlet water temperature. The system achieves the effect of adaptively adjusting the cooling capacity ratio of the absorption and compression sides based on the cooling water temperature in cooling mode, and adaptively adjusting the heat capacity ratio of the absorption and compression sides based on the waste water temperature in heating mode, thus realizing efficient and stable operation and improved overall energy efficiency under all operating conditions.

[0010] To address the aforementioned problems, a first aspect of the present invention provides a compression-absorption combined refrigeration and heating system, characterized in that it comprises: an absorption heat exchanger unit having a generator 1, a condenser 2, an absorber 4, and an evaporative condenser 6; a compression heat exchange unit including a compressor 9 and an evaporator 10; a cold water / waste water pipeline divided into two parallel branches, the first branch passing through a first regulating valve 11 and the evaporative condenser 6 to the outlet, and the second branch passing through a second regulating valve 12 and the evaporator 10 to the outlet; a cooling water / heating water pipeline passing sequentially through the absorber 4 and the condenser 2; a temperature sensor disposed on the cold water / waste water pipeline and / or the cooling water / heating water pipeline for detecting the outlet water temperature supplied to users by the system; and a controller for switching the system between a cooling mode and a heating mode, receiving feedback signals from the temperature sensor, and adjusting the opening degree of the first regulating valve 11 and the second regulating valve 12 according to the deviation between a preset target outlet water temperature value and the measured value, thereby changing the flow ratio of the fluids in the two parallel branches of the cold water / waste water pipeline.

[0011] This invention, through an innovative parallel pipeline and regulating valve group design, sets up parallel pipelines between the absorption heat exchanger unit and the compression heat exchanger unit. This transforms the traditional single-mode switching refrigerant-side coupling method in compression-absorption composite systems into two independently controllable water flow distribution paths: the water to be treated is introduced to the evaporator-condenser side of the absorption heat exchanger unit for cooling via the first branch, and then introduced to the evaporator side of the compression heat exchanger unit for cooling via the second branch. The cooled water from both paths is then mixed and output at the outlet. Simultaneously, in conjunction with the proportional regulation of the first and second regulating valves and feedback control from temperature sensors, an intelligent control system is constructed that can adaptively adjust the output ratio of the absorption and compression sides based on the cooling water temperature, waste water temperature, and outlet water temperature between cooling and heating modes. This fundamentally solves the technical problems of existing composite units, such as single operating conditions, coarse control strategies, and inability to adapt to continuous changes in waste heat source temperature leading to low system energy efficiency or fluctuating outlet water temperature. This significantly improves the system's overall operating efficiency, load adaptability, and comprehensive energy-saving level.

[0012] Furthermore, the controller is configured in cooling mode as follows: when the cooling water temperature is lower than the first preset value, the first regulating valve 11 is kept open and the second regulating valve 12 is closed, and the absorption heat exchanger unit provides cooling alone; when the cooling water temperature is higher than the second preset value, the first regulating valve 11 is closed and the second regulating valve 12 is opened, and the compression heat exchanger unit provides cooling alone; when the cooling water temperature is between the first preset value and the second preset value, the opening degree of the first regulating valve 11 and the second regulating valve 12 is adjusted according to the deviation between the cold water outlet temperature and the preset target value of the cold water.

[0013] Furthermore, the controller is configured in heating mode as follows: when the waste water temperature is higher than the third preset threshold, the first regulating valve 11 is kept open and the second regulating valve 12 is kept closed, and the absorption heat exchanger unit provides heating alone; when the waste water temperature is lower than the fourth preset threshold, the first regulating valve 11 is closed and the second regulating valve 12 is opened, and the compression heat exchanger unit provides heating alone; when the waste water temperature is between the third preset threshold and the fourth preset threshold, the opening degree of the first regulating valve 11 and the second regulating valve 12 is adjusted according to the deviation between the heating water outlet temperature and the preset target value of the heating water.

[0014] Furthermore, the compressor 9 is any one of a scroll compressor, a screw compressor, or a centrifugal compressor.

[0015] Furthermore, the system also includes a digital twin simulation unit, which is communicatively connected to the controller. The digital twin unit simulates the system energy consumption under various combinations of opening degrees of the first regulating valve 11 and the second regulating valve 12 based on real-time collected data on waste hot water temperature, cooling water temperature, and load demand, and sends the optimal combination of opening degrees to the controller for execution.

[0016] Furthermore, the absorption heat exchanger unit is a two-stage absorption mode, including two absorbers 4 and two evaporators condensers 6, wherein the condensation heat of the compressor 9 is used as a high-temperature heat source to supply one of the evaporators condensers 6 to drive the absorber 4 corresponding to that evaporator condenser 6.

[0017] According to another aspect of the present invention, the present invention also provides a control method for a compression absorption combined refrigeration and heating system, used in the aforementioned compression absorption combined refrigeration and heating system. The control method includes: selecting a cooling mode or a heating mode according to actual needs; when the cooling mode is selected: introducing water to be cooled, cooling it through a first branch and / or a second branch to form cold water and then sending it out; adjusting the flow distribution ratio of the first branch and the second branch based on the deviation between the outlet temperature of the cold water and the preset target value of the cold water; when the heating mode is selected: introducing waste hot water, cooling it through the first branch and / or the second branch and then discharging it; simultaneously, heating water is sequentially heated through a first heating path and a second heating path and then sent out; controlling the start and stop of the heat source and the flow distribution ratio of the first branch and the second branch according to the temperature of the waste hot water, so as to adjust the heat ratio of the first heating path and the second heating path.

[0018] This invention employs an innovative mode selection and segmented adjustment control method, implementing differentiated energy allocation strategies in cooling and heating modes respectively. This transforms the traditional coarse control approach of fixed mode switching in compression-absorption composite systems into an adaptive segmented adjustment logic based on either cooling water temperature (cooling mode) or waste water temperature (heating mode): In cooling mode, when the cooling water temperature is low, the first branch cools the water independently; when the cooling water temperature is high, the second branch cools the water independently; and when the cooling water temperature is between the two, the flow distribution ratio of the two branches is continuously adjusted according to the cold water outlet temperature deviation to achieve cooling capacity distribution. In heating mode, when the waste water temperature is high, the first branch provides heating independently; when the waste water temperature is low, the second branch provides heating independently. The two branches supply heat independently. When the temperature of the waste hot water is between the two, the flow distribution ratio of the two branches is continuously adjusted according to the temperature deviation of the heating water outlet to achieve heat distribution. At the same time, with the real-time feedback of the temperature sensor and the linkage control of the flow ratio, an intelligent operation strategy is built on the parallel water circuit architecture. This strategy can automatically adapt the output ratio of the absorption side and the compression side according to the temperature change of the waste heat source and the load demand of the user side. This fundamentally solves the technical problems of the existing composite unit, such as single operating conditions, coarse control strategy, and inability to adapt to the continuous drop in the temperature of the waste heat source in non-circulating heat extraction scenarios, which leads to low system energy efficiency or fluctuation in outlet water temperature. It significantly improves the system's adaptive adjustment capability, energy utilization efficiency and operational stability under all operating conditions.

[0019] Furthermore, when the cooling mode is selected, the following steps are specifically included: S1: Real-time acquisition of the outlet temperature of the chilled water and the temperature of the cooling water; S2: When the cooling water temperature is lower than the first preset value, control the first branch to open and the second branch to close, with the first branch cooling the water independently; S3: When the cooling water temperature is higher than the second preset value, control the first branch to close and the second branch to open, with the second branch cooling the water independently; S4: When the cooling water temperature is between the first preset value and the second preset value, adjust the flow distribution ratio of the first branch and the second branch according to the deviation between the outlet temperature of the chilled water and the preset target value of the chilled water.

[0020] Furthermore, when selecting the heating mode, the specific steps include: H1: Real-time acquisition of the outlet temperature of the heating water and the temperature of the residual hot water; H2: When the temperature of the residual hot water is higher than the third preset threshold, control the first branch to open and the second branch to close, with the first heating path providing heating alone; H3: When the temperature of the residual hot water is lower than the fourth preset threshold, control the first branch to close and the second branch to open, with the second heating path providing heating alone; H4: When the temperature of the residual hot water is between the third and fourth preset thresholds, adjust the flow distribution ratio of the first and second branches according to the deviation between the outlet temperature of the heating water and the preset target value of the heating water.

[0021] Furthermore, before adjusting the flow distribution, the total system energy consumption under various combinations of flow distribution ratios for the first and second branches is simulated using a digital twin, and the combination with the lowest energy consumption is selected as the execution instruction.

[0022] The above-described technical solution of the present invention has the following beneficial technical effects: 1. Full-condition adaptive adjustment for improved system energy efficiency: This invention achieves continuous proportional adjustment of the output from the absorption and compression sides by setting up parallel pipelines between the absorption heat exchanger and the compression heat exchanger, and by coordinating feedback adjustment with temperature sensors and controllers. In cooling mode, the cooling capacity ratio between the absorption and compression sides is automatically allocated according to the cooling water temperature; in heating mode, the heat capacity ratio between the absorption and compression sides is automatically allocated according to the waste water temperature. Compared with the existing coarse control method of composite units that can only perform fixed mode switching, this invention can adapt to the dynamic operating conditions of continuous changes in waste heat source temperature, significantly improving the overall energy efficiency of the system under all operating conditions.

[0023] 2. Adapting to non-circulating heat extraction scenarios and ensuring stable outlet water temperature: This invention is specifically designed for non-circulating waste heat sources such as hot water storage bodies and soil heat storage bodies, where the temperature gradually decreases unidirectionally during the heat extraction process. Through a three-zone adaptive control strategy (high-temperature zone operated solely by absorption, medium-temperature zone by a combination of both, and low-temperature zone operated solely by compression), this invention can maintain the user-side outlet water temperature consistently near the preset target value throughout the entire temperature change process of the waste heat source, avoiding the significant temperature fluctuations caused by changes in operating conditions in existing units.

[0024] 3. Reduced compressor power consumption and optimized operating costs: This invention prioritizes the use of absorption heat exchangers to handle the base load (driven by waste heat), supplementing the load only when waste heat is insufficient or cooling water temperature is too high. This achieves the principle of "waste heat priority, electric drive supplementation" for tiered energy utilization. Compared to existing solutions that rely solely on compression refrigeration, this invention significantly reduces compressor power consumption under the same cooling / heating output conditions, thereby lowering system operating costs.

[0025] 4. Dual-mode switching ensures continuous system operation: This invention allows for flexible switching between cooling and heating modes via a controller, enabling the same hardware system to meet users' year-round cooling and heating needs. When switching operating modes is required, no modifications to piping or equipment replacement are necessary; the process can be completed simply by switching modes using the controller. This ensures continuous and stable system operation, improving equipment utilization and economy.

[0026] 5. Flexible and adaptable control strategies: The control method of this invention can select from various strategies, such as conventional feedback control or digital twin optimization control, according to actual needs. Specifically, the digital twin simulation unit can simulate the system energy consumption under various valve opening combinations based on real-time collected data on waste heat source temperature or waste hot water and cooling water temperatures, and load demand. It then selects the combination with the lowest energy consumption as the execution command, achieving self-optimizing system operation. Users can flexibly choose a suitable control scheme based on project scale, control accuracy requirements, and investment budget. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a compression absorption combined refrigeration and heating system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a two-stage absorption compression absorption composite refrigeration and heating system according to an embodiment of the present invention.

[0028] Figure label: 1: Generator; 2: Condenser; 3: Solution heat exchanger; 4: Absorber; 5: Dilute solution pump; 6: Evaporator-condenser; 7: Refrigerant pump; 8: Expansion valve; 9: Compressor; 10: Evaporator; 11: First regulating valve; 12: Second regulating valve. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0030] To address the problems of existing compression-absorption combined heat exchange units, such as limited operating conditions, rudimentary control strategies, and inability to adapt to continuous changes in waste heat source temperature (especially the gradual temperature decrease in non-circulating heat extraction scenarios), leading to low system efficiency or large fluctuations in outlet water temperature, this invention proposes a compression-absorption combined cooling and heating system and its control method. This system enables adaptive and continuous adjustment of the output on both the absorption and compression sides under different operating conditions. The invention employs a parallel pipeline between the absorption heat exchanger and the compression heat exchange unit, dividing the chilled water / waste water pipeline into two parallel branches. The first branch connects to the outlet via a first regulating valve and an evaporator-condenser, while the second branch connects to the outlet via a second regulating valve and an evaporator. The water to be treated is cooled by either the first or second branch to form chilled water, which is then sent to the outlet. Simultaneously, a temperature sensor installed on the chilled water / waste water pipeline detects the outlet water temperature. The controller receives the feedback signal from the temperature sensor and adjusts the opening degree of the first and second regulating valves based on the deviation between the preset target outlet water temperature value and the measured value, thereby changing the flow ratio of the fluids in the two branches. In cooling mode, the controller automatically allocates the cooling capacity ratio between the absorption and compression sides based on the cooling water temperature; in heating mode, the controller automatically allocates the heat capacity ratio between the absorption and compression sides based on the waste water temperature. This invention can significantly improve the system's operating efficiency and outlet water temperature stability under all operating conditions while achieving coordinated cooling / heating through absorption and compression, providing stable, economical, and efficient technical support for power generation, chemical industry, pharmaceutical industry, printing and dyeing, steel coking, non-ferrous metals, and residential heating.

[0031] The following is combined with Figure 1 and Figure 2 The present invention describes the compression absorption combined refrigeration and heating system and its control method provided by the present invention.

[0032] Figure 1 This is a schematic diagram of a compression absorption combined refrigeration and heating system according to an embodiment of the present invention.

[0033] like Figure 1 As shown, in some embodiments, the compression-absorption combined refrigeration and heating system includes an absorption heat exchanger unit, a compression heat exchanger unit, chilled water / waste water pipes, cooling water / heating water pipes, a temperature sensor, and a controller. The absorption heat exchanger unit includes a generator 1, a condenser 2, an absorber 4, and an evaporative condenser 6; the compression heat exchanger unit includes a compressor 9 and an evaporator 10.

[0034] The chilled water / waste hot water pipeline is divided into two parallel branches: the first branch connects to the outlet via the first regulating valve 11 and the evaporator-condenser 6, and the second branch connects to the outlet via the second regulating valve 12 and the evaporator 10. The water to be treated (cooling water in cooling mode, waste hot water in heating mode) enters the chilled water / waste hot water pipeline from the inlet, and flows through the first branch and / or the second branch depending on the valve opening status. After heat exchange in the evaporator-condenser 6 or the evaporator 10, it is delivered to the user from the outlet. This parallel water circuit structure allows the absorption heat exchanger and the compression heat exchanger unit to be adjusted independently, and the flow rates of the two branches can be controlled separately. This achieves continuous proportional output of cooling or heating capacity, avoiding the limitation of traditional composite units that can only perform fixed mode switching.

[0035] The cooling water / heating water pipeline passes sequentially through absorber 4 and condenser 2. In cooling mode, this pipeline serves as a cooling water pipeline, connecting to the cooling tower to remove the heat released by the absorber and condenser; in heating mode, this pipeline serves as a heating water pipeline, flowing sequentially through absorber 4 and condenser 2, where it is heated before being delivered to the user side to provide heating.

[0036] Temperature sensors can be installed on cold water / residual hot water pipes, or on cooling water / heating water pipes, or both, to detect the outlet water temperature supplied to users. In practical applications, one or more temperature sensors can be configured according to control requirements to detect the outlet water temperature supplied to users. The controller switches the system between cooling and heating modes and receives feedback signals from the temperature sensors. Based on the deviation between the preset outlet water temperature target value and the measured value, it dynamically adjusts the opening degree of the first regulating valve 11 and the second regulating valve 12 to change the flow ratio of the fluid in the two parallel branches of the cold water / residual hot water pipes. Through real-time feedback of the outlet water temperature and continuous adjustment of the valve opening, the system can quickly respond to load changes and operating condition fluctuations, stabilizing the outlet water temperature near the set value, effectively improving the quality and stability of cooling / heating supply.

[0037] The controller's control strategy in cooling mode is as follows: When the cooling water temperature is lower than the first preset value, the first regulating valve 11 remains open and the second regulating valve 12 remains closed, allowing the absorption heat exchanger unit to supply cooling independently. Preferably, taking the production of 7℃ chilled water as an example, the first preset value is between 15℃ and 25℃. That is, when the cooling water temperature is lower than the first preset value (e.g., within the range of 15℃ to 25℃), the absorption heat exchanger unit can meet the cooling demand independently, without needing to start the compressor, resulting in extremely low power consumption. At this time, all the water to be treated flows through the evaporator condenser 6, using waste heat to drive the absorption circulation to produce chilled water. Since there is no need to start the compressor, the power consumption is extremely low, making it particularly suitable for operating conditions with low cooling water temperatures. When the cooling water temperature is higher than the second preset value, the first regulating valve 11 is closed and the second regulating valve 12 is opened, allowing the compression heat exchanger unit to supply cooling independently. Preferably, taking the production of 7℃ chilled water as an example, the second preset value is between 28℃ and 32℃. When the cooling water temperature is higher than the second preset value (e.g., within the range of 28℃ to 32℃), the cooling capacity of the absorption heat exchanger is severely insufficient, requiring separate cooling from the compression heat exchanger to ensure the outlet water temperature remains stable at 7℃. At this time, the compressor is activated to ensure that chilled water of the required temperature can still be produced even under high cooling water temperatures. When the cooling water temperature is between the first and second preset values, the opening degree of the first regulating valve 11 and the second regulating valve 12 is simultaneously adjusted according to the deviation between the outlet water temperature and the preset target value. Preferably, taking the production of 7℃ chilled water as an example, when the cooling water temperature is between the first and second preset values, i.e., within the range of 25℃ to 28℃, the system enters the optimal adjustment range for combined cooling, continuously adjusting the opening degree of the two valves according to the outlet water temperature deviation: if the outlet water temperature is too high, the opening degree of the second regulating valve 12 is appropriately increased to increase the proportion of cooling capacity on the compression side; if the outlet water temperature is too low, the opening degree of the second regulating valve 12 is appropriately decreased to prioritize the use of cooling capacity on the absorption side. For example, when 7°C chilled water is required, the absorption heat exchanger unit operating alone can only produce 10°C chilled water. In this case, by adjusting the opening of the first regulating valve 11 and the second regulating valve 12, a portion of the water to be cooled is introduced into the evaporator 10 for further cooling. After cooling, it is mixed with another portion of the chilled water cooled by the absorption heat exchanger unit to achieve an outlet water temperature of 7°C. Through the coordinated adjustment of the two valves, the cooling capacity ratio between the absorption and compression sides can be continuously distributed, allowing the system to maintain efficient operation even under partial load and avoiding increased energy consumption caused by frequent compressor start-stop cycles.

[0038] The controller's control strategy in heating mode is as follows: When the waste water temperature is higher than the third preset threshold, the first regulating valve 11 remains open and the second regulating valve 12 remains closed, allowing the absorption heat exchanger unit to supply heat independently. Preferably, the third preset value is 25℃. That is, when the waste water temperature is higher than 25℃, the absorption heat exchanger unit can fully utilize the waste heat to produce heating water, the compressor is turned off, and the operating economy is optimal. At this time, the waste water temperature is relatively high, and the absorption heat exchanger unit can fully utilize the waste heat to produce heating water, the compressor is turned off, and the operating economy is optimal. When the waste water temperature is lower than the fourth preset threshold, the first regulating valve 11 is closed and the second regulating valve 12 is opened, allowing the compression heat exchanger unit to supply heat independently. Preferably, the fourth preset value is 15℃. That is, when the waste water temperature is lower than 15℃, the heating capacity of the absorption heat exchanger unit is insufficient, and the compressor starts as the main heat source to ensure heating reliability. When the waste water temperature is too low and the output of the absorption unit is insufficient, the compressor starts as the main heat source to ensure heating capacity. When the temperature of the residual hot water is between the third and fourth preset thresholds, the opening degree of the first regulating valve 11 and the second regulating valve 12 is adjusted synchronously according to the deviation between the outlet temperature of the heating water and the preset target value of the heating water. Preferably, when the temperature of the residual hot water is between 15℃ and 25℃, the system enters the combined heating zone, and the opening degree of the two valves is continuously adjusted according to the deviation of the outlet temperature of the heating water: if the outlet temperature is too low, the opening degree of the second regulating valve 12 is appropriately increased to increase the proportion of heat on the compression side; if the outlet temperature is too high, the opening degree of the second regulating valve 12 is appropriately decreased to prioritize the use of the waste heat on the absorption side.

[0039] Furthermore, in heating mode, when compressor 9 starts auxiliary heating, the controller can dynamically adjust the opening degree of the first regulating valve 11 and the second regulating valve 12 according to the rate of decrease of the waste water temperature and the current heating load demand. Specifically, when the waste water temperature decreases rapidly or the load demand is high, the controller appropriately increases the opening degree of the second regulating valve 12 to increase the heat supply on the compressor side; when the waste water temperature tends to be stable or the load demand is low, the controller prioritizes keeping the first regulating valve 11 open to maximize the utilization of the waste heat on the absorption side and reduce the energy consumption of compressor 9.

[0040] This three-stage adaptive adjustment strategy enables the system to meet heating demand with the lowest compressor power consumption throughout the entire process of waste heat resource change from abundant to insufficient, realizing the principle of tiered utilization of waste heat priority and electric drive to supplement the deficiency.

[0041] In this embodiment, compressor 9 can be any one of a scroll compressor, screw compressor, or centrifugal compressor. The specific selection can be determined based on system capacity, energy efficiency requirements, and investment budget. Different types of compressors can all be adapted to the control logic of this invention, ensuring the system's versatility and flexibility.

[0042] To further improve the system's operational economy, this embodiment preferably includes a digital twin simulation unit. This digital twin simulation unit is communicatively connected to the controller and can simulate the total system energy consumption under various combinations of opening degrees of the first regulating valve 11 and the second regulating valve 12 based on real-time collected data on waste water temperature, cooling water temperature, and load demand. It then sends the optimal opening degree combination to the controller for execution. Through digital twin technology, the system can pre-calculate the energy consumption results of different control strategies before the actual regulating valves, select the globally optimal solution, and thus further reduce operating costs. This is particularly suitable for applications with frequent load changes or large fluctuations in waste heat source temperature.

[0043] The above system has a particularly significant advantage in non-circulating heat extraction waste heat source scenarios (such as hot water storage bodies and soil heat storage bodies) because the temperature of such heat sources gradually decreases in one direction during the heat extraction process. This invention, through three-stage adaptive control, can maintain a stable outlet water temperature and maximize the utilization of waste heat throughout the entire heat extraction cycle, avoiding energy efficiency losses caused by frequent mode switching or compressor start-stop due to the drop in heat source temperature in traditional solutions.

[0044] The above embodiments of the present invention are only basic solutions. In actual applications, components can be added or adjusted according to specific needs, such as adding auxiliary equipment such as solution heat exchangers, refrigerant pumps, and expansion valves. These are all conventional designs in the field and do not affect the core protection scope of the present invention.

[0045] Figure 2 This is a schematic diagram of a two-stage absorption compression absorption composite refrigeration and heating system according to an embodiment of the present invention.

[0046] like Figure 2 As shown, in some embodiments, the absorption heat exchanger unit is further configured as a two-stage absorption mode to make fuller use of the condensing heat of the compressor 9 and improve the overall energy efficiency of the system.

[0047] In this two-stage absorption mode, the absorption heat exchanger unit includes two absorbers 4 and two evaporators / condensers 6. The first-stage absorber (i.e., the concentrated solution absorber paired with the low-temperature cold source) and the first-stage evaporator / condenser form a low-temperature stage cycle, while the second-stage absorber (i.e., the intermediate-stage absorber) and the second-stage evaporator / condenser form a high-temperature stage cycle.

[0048] The specific connection is as follows: the cold water / waste hot water pipeline is divided into two parallel branches. The first branch goes through the first regulating valve 11 and the first-stage evaporator-condenser 6 to the outlet, and the second branch goes through the second regulating valve 12 and the evaporator 10 of the compression heat exchange unit to the outlet. This part of the structure is the same as in the aforementioned embodiment. The difference is that the condensing heat of the compressor 9 is no longer used only to heat the heating circulating water, but is supplied as a high-temperature heat source to one of the evaporator-condensers 6 (i.e., the second-stage evaporator-condenser) to drive the absorber 4 (i.e., the second-stage absorber) corresponding to the evaporator-condenser 6.

[0049] The specific working process is as follows: The concentrated solution from generator 1 first enters the first-stage absorber, absorbing refrigerant vapor from the first-stage evaporator-condenser. The released heat of absorption is carried away by water in the cooling water / heating water pipes, forming an intermediate solution. The intermediate solution then enters the second-stage absorber, which is connected to the second-stage evaporator-condenser. The high-temperature refrigerant heat discharged from compressor 9 is introduced into the second-stage evaporator-condenser, heating the refrigerant water therein to cause it to evaporate. The generated refrigerant vapor enters the second-stage absorber and is absorbed by the intermediate solution. The released heat is also carried away by water in the cooling water / heating water pipes. Through this two-stage absorption design, the condensation heat of the compressor that would otherwise be wasted by the cooling water is effectively recovered and used to drive the second-stage absorption process, thereby increasing the driving force of the absorption cycle and enabling the system to operate efficiently even with limited waste heat resources.

[0050] In cooling mode, the two-stage absorption mode further enhances the cooling capacity generated by the low-temperature evaporator-condenser, enabling the absorption heat exchanger to produce chilled water at lower temperatures even when the cooling water temperature is high or the waste heat temperature is low. This reduces the cooling burden on the compression heat exchanger unit and further lowers the compressor's power consumption. In heating mode, the two-stage absorption mode utilizes the compressor's condensation heat and waste heat in a cascade manner. Water in the cooling / heating water pipes flows sequentially through the first-stage absorber, the second-stage absorber, and condenser 2, achieving a higher outlet water temperature to meet the heating needs of extremely cold regions or areas with large temperature differences.

[0051] This embodiment achieves the recovery and utilization of compressor condensation heat by configuring the absorption heat exchanger unit in a two-stage absorption mode, transforming the originally discarded low-temperature waste heat into a useful driving heat source, significantly improving the overall energy efficiency of the system, and is especially suitable for occasions with low waste heat resource quality or high requirements for user-side outlet water temperature.

[0052] Furthermore, the two-stage absorption mode does not change the control strategy and parallel water circuit structure in the aforementioned embodiments. The controller can still flexibly adjust the opening degree of the first regulating valve 11 and the second regulating valve 12 according to parameters such as cooling water temperature, waste water temperature, and outlet water temperature to achieve output ratio adjustment between the absorption side and the compression side. Users can choose between the basic mode and the two-stage absorption mode according to actual project needs, or pre-configure the two-stage absorption mode in this system to cope with different waste heat resource conditions and load requirements.

[0053] It should be noted that, Figure 2 In the two-stage absorption structure shown, the two absorbers and two evaporators / condensers can be integrated into a single absorption heat exchanger housing, or they can be assembled from independent modules. The condensing heat of compressor 9 can be transferred to the second-stage evaporator / condenser via heat exchange coils or an external heat exchanger. All multi-stage absorption structures implemented using the principles of this invention fall within the scope of protection of this invention.

[0054] The present invention also provides a control method for a compression absorption combined refrigeration and heating system. This method is used in the aforementioned system and can flexibly select the refrigeration mode or the heating mode according to actual needs, and adaptively adjust the flow distribution ratio of the two branches to optimize the energy ratio between different paths and achieve efficient and stable operation under all working conditions.

[0055] In cooling mode, water to be cooled is introduced, and after being cooled through the first branch and / or the second branch, it becomes chilled water and is then delivered. The controller dynamically adjusts the flow distribution ratio of the first and second branches based on the deviation between the chilled water outlet temperature and the preset target value. Specifically, when cooling mode is selected, the control process includes the following steps: real-time acquisition of the chilled water outlet temperature and the cooling water temperature; when the cooling water temperature is lower than the first preset value, the first branch is opened and the second branch is closed, allowing the first branch to cool the water independently, eliminating the need to start a heat source, resulting in extremely low power consumption and full utilization of waste heat resources; when the cooling water temperature is higher than the second preset value, the first branch is closed and the second branch is opened, allowing the second branch to cool the water independently, ensuring stable production of chilled water at the required temperature even under high cooling water temperature conditions; when the cooling water temperature is between the first and second preset values, the flow distribution ratio of the first and second branches is adjusted according to the deviation between the chilled water outlet temperature and the preset target value, ensuring continuous proportional output of cooling capacity from the first and second branches. Through this three-stage adaptive adjustment, the system can avoid frequent start-up and shutdown of the heat source, reduce energy consumption, and at the same time stabilize the outlet water temperature near the set value, significantly improving the cooling quality.

[0056] In heating mode, waste hot water is introduced and discharged after being cooled through the first branch and / or the second branch. Simultaneously, heating water is heated sequentially through the first and second heating paths before being sent out. The controller controls the start / stop of the heat source and the flow distribution ratio of the first and second branches based on the temperature of the waste hot water to rationally allocate the heat ratio between the first and second heating paths. The specific steps are as follows: The outlet temperature of the heating water and the temperature of the waste hot water are acquired in real time; when the waste hot water temperature is higher than a third preset threshold, the first branch is opened and the second branch is closed, with the first heating path providing heating alone, and the heat source not operating, achieving pure waste heat heating with the lowest operating cost; when the waste hot water temperature is lower than a fourth preset threshold, the first branch is closed and the second branch is opened, with the second heating path providing heating alone, and the heat source starting as the main heat source to ensure heating reliability; when the waste hot water temperature is between the third and fourth preset thresholds, the flow distribution ratio of the first and second branches is adjusted according to the deviation between the outlet temperature of the heating water and the preset target value of the heating water. This three-stage strategy prioritizes the use of waste heat throughout the entire process of waste heat resources changing from abundant to insufficient, and only uses heat sources to assist when waste heat is insufficient. This approach minimizes heat source energy consumption while ensuring heating demand, achieving a balance between energy conservation and reliability.

[0057] During the adjustment process of the aforementioned cooling or heating modes, the controller can also simulate the total system energy consumption under various combinations of flow distribution ratios for the first and second branches using a digital twin unit before adjusting the flow distribution, and select the combination with the lowest energy consumption as the execution command. Based on real-time collected data on waste water temperature, cooling water temperature, and load demand, the digital twin unit pre-simulates the energy consumption results of different control schemes, thereby selecting the globally optimal flow distribution ratio. This optimized control is particularly suitable for scenarios with frequent load changes or large fluctuations in waste heat source temperature, further reducing operating costs, improving system energy efficiency, and avoiding the tediousness and uncertainty of manual parameter tuning.

[0058] In summary, the control method of this invention achieves adaptive and refined operation of the compression-absorption hybrid system through mode selection, three-stage segmented adjustment of cooling / heating, closed-loop feedback of outlet water temperature, and optional digital twin optimization. Compared with the coarse control of existing hybrid units that can only perform fixed mode switching, this invention significantly reduces the operating power consumption of the heat source while ensuring the stability of the outlet water temperature, and improves the overall energy efficiency under all operating conditions. It has the advantages of reliable control and significant energy-saving effect.

[0059] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects. For example, A and / or B indicates that there are three possible relationships: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article indicates that the related objects before and after it are in an "or" relationship.

[0060] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A compression-absorption combined refrigeration and heating system, characterized in that, include: An absorption heat exchanger unit has a generator (1), a condenser (2), an absorber (4) and an evaporative condenser (6). A compression heat exchange unit includes a compressor (9) and an evaporator (10). The cold water / residual hot water pipe is divided into two parallel branches. The first branch goes through the first regulating valve (11) and the evaporator condenser (6) to the outlet, and the second branch goes through the second regulating valve (12) and the evaporator (10) to the outlet. The cooling water / heating water pipe passes through the absorber (4) and the condenser (2) in sequence. A temperature sensor is installed on the cold water / residual hot water pipe and / or the cooling water / heating water pipe to detect the outlet water temperature supplied to the user by the system. The controller is used to switch the system between cooling mode and heating mode, and to receive feedback signals from the temperature sensor. It adjusts the opening degree of the first regulating valve (11) and the second regulating valve (12) according to the deviation between the preset target value of the outlet water temperature and the measured value, so as to change the flow ratio of the fluid in the two parallel branches of the cold water / residual hot water pipeline.

2. The system according to claim 1, characterized in that, The controller is configured in cooling mode as follows: When the cooling water temperature is lower than the first preset value, the first regulating valve (11) is kept open and the second regulating valve (12) is closed, and the absorption heat exchanger unit provides cooling separately. When the cooling water temperature is higher than the second preset value, the first regulating valve (11) is closed and the second regulating valve (12) is opened, and the cooling is supplied separately by the compression heat exchange unit. When the cooling water temperature is between the first preset value and the second preset value, the opening degree of the first regulating valve (11) and the second regulating valve (12) is adjusted according to the deviation between the cold water outlet temperature and the cold water preset target value.

3. The system according to claim 1, characterized in that, The controller is configured in heating mode as follows: When the temperature of the waste hot water is higher than the third preset threshold, the first regulating valve (11) is kept open and the second regulating valve (12) is kept closed, and the absorption heat exchanger unit provides heat separately. When the temperature of the residual hot water is lower than the fourth preset threshold, the first regulating valve (11) is closed and the second regulating valve (12) is opened, and the heat is supplied separately by the compression heat exchange unit. When the temperature of the residual hot water is between the third preset threshold and the fourth preset threshold, the opening degree of the first regulating valve (11) and the second regulating valve (12) is adjusted according to the deviation between the heating water outlet temperature and the heating water preset target value.

4. The system according to claim 1, characterized in that, The compressor (9) is any one of a scroll compressor, a screw compressor, or a centrifugal compressor.

5. The system according to claim 1, characterized in that, The system also includes a digital twin simulation unit, which is communicatively connected to the controller. The digital twin unit simulates the system energy consumption under various combinations of opening degrees of the first regulating valve (11) and the second regulating valve (12) based on real-time collected data on waste water temperature, cooling water temperature and load demand, and sends the optimal combination of opening degrees to the controller for execution.

6. The system according to claim 1, characterized in that, The absorption heat exchanger unit is a two-stage absorption mode, including two absorbers (4) and two evaporators (6). The condensation heat of the compressor (9) is used as a high-temperature heat source to supply one of the evaporators (6) to drive the absorber (4) corresponding to the evaporator (6).

7. A control method for a compression-absorption combined refrigeration and heating system, characterized in that, For use in the system according to any one of claims 1 to 6, comprising: Choose either cooling or heating mode based on actual needs; When the cooling mode is selected: water to be cooled is introduced, cooled by the first branch and / or the second branch to form cold water and then sent out; the flow distribution ratio of the first branch and the second branch is adjusted based on the deviation between the outlet temperature of the cold water and the preset target value of the cold water. When the heating mode is selected: waste hot water is introduced, cooled and discharged after passing through the first branch and / or the second branch; at the same time, heating water is heated and sent out after passing through the first heating path and the second heating path in sequence; according to the temperature of the waste hot water, the start and stop of the heat source and the flow distribution ratio of the first branch and the second branch are controlled to adjust the heat ratio of the first heating path and the second heating path.

8. The control method according to claim 7, characterized in that, When selecting a cooling mode, the specific steps are as follows: S1: Real-time acquisition of cold water outlet temperature and cooling water temperature; S2: When the cooling water temperature is lower than the first preset value, control the first branch to open and the second branch to close, so that the first branch can cool down independently. S3: When the cooling water temperature is higher than the second preset value, control the first branch to close and the second branch to open, so that the second branch can cool down independently. S4: When the cooling water temperature is between the first preset value and the second preset value, adjust the flow distribution ratio of the first branch and the second branch according to the deviation between the outlet water temperature and the preset target value of the cooling water.

9. The control method according to claim 7, characterized in that, When selecting a heating mode, specifically Includes the following steps: H1: Real-time acquisition of the outlet temperature of heating water and the temperature of residual hot water; H2: When the temperature of the residual hot water is higher than the third preset threshold, the first branch is opened and the second branch is closed, and the first heating path supplies heat independently. H3: When the temperature of the residual hot water is lower than the fourth preset threshold, control the first branch to close and the second branch to open, so that the second heating path can supply heat independently. H4: When the temperature of the residual hot water is between the third preset threshold and the fourth preset threshold, the flow distribution ratio of the first branch and the second branch is adjusted according to the deviation between the outlet temperature of the heating water and the preset target value of the heating water.

10. The control method according to claim 7, characterized in that, Before adjusting the flow distribution, the total system energy consumption under various combinations of flow distribution ratios for the first and second branches is simulated using a digital twin, and the combination with the lowest energy consumption is selected as the execution instruction.

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