Solar heat pump coupled multi-stage humidification dehumidification water treatment system and working method thereof

Abstract

A solar heat pump coupled multi-stage humidification and dehumidification water treatment system and a working method thereof, the system comprising a water treatment circulating subsystem, a solar hot water circulating subsystem and a compression heat pump circulating subsystem; the working method is that raw liquid is heated by solar prepared hot water and a compression heat pump condenser, sequentially enters two-stage humidifiers to exchange heat and mass with air, preheats air and discharges; circulating air sequentially undergoes two humidifications in the two-stage humidifiers, is gradually cooled and dehumidified in a pre-cooler, a dehumidifier and a heat pump evaporator, is preheated by the discharged raw liquid and then undergoes the next cycle, and condensed water obtained by condensing steam in the air is collected into a fresh water tank after heat exchange in a heat pump subcooler. The present application uses the hot raw liquid after one-stage humidification to complete two-stage humidification, uses a pre-cooler, high flow raw liquid and a heat pump evaporator to complete multi-stage dehumidification, and uses the solar hot water system to simultaneously introduce the heat pump system, thereby realizing all-weather fresh water supply demand.

Description

Technical Field

[0001] This invention belongs to the field of humidification and dehumidification water treatment technology, and relates to a multi-stage humidification and dehumidification water treatment system using solar energy and a heat pump coupled together, and its working method. Background Technology

[0002] Currently, commonly used wastewater treatment technologies, especially seawater desalination, mainly include three types: low-temperature multi-effect distillation, multi-effect flash evaporation, and reverse osmosis membranes. Among these, low-temperature multi-effect technology suffers from unstable low-temperature waste heat and low efficiency, resulting in actual operating costs far exceeding design costs. Furthermore, the equipment is large, leading to higher equipment costs. Multi-effect flash evaporation operates at high temperatures, making it prone to corrosion and scaling. Its operational flexibility is limited, typically operating at 80%–110% of its design value. Initial investment costs are high, requiring extensive initial construction work, and it consumes a lot of energy, necessitating joint operation with a thermal power plant. Reverse osmosis, however, has strict requirements for feedstock quality, resulting in high pretreatment costs. Moreover, reverse osmosis membranes are expensive, easily contaminated and damaged during use, and generally require replacement every 3–5 years. Considering all three commonly used water treatment technologies, there are issues with initial operating costs, strict requirements for feedstock, and unsuitability for small-scale freshwater supply needs. In remote islands and on ships, the demand for freshwater is usually small-scale and decentralized. The above three methods have low applicability. At the same time, the solar distillation water treatment technology, which has been widely used in the past, is difficult to be widely used due to its low thermal efficiency and low water production. In recent years, the humidification and dehumidification water treatment technology has developed rapidly. It is the best choice to solve small-scale freshwater needs because of its advantages such as flexible scale, low investment and applicability to decentralized water treatment needs.

[0003] Existing humidification and dehumidification water treatment technologies mostly rely on solar heating as their heat source. However, this is easily affected by weather conditions and cannot provide a stable supply of fresh water. Most of these systems are single-stage humidification and dehumidification systems, which have low energy efficiency and low fresh water production. Some systems use electric heating as the heat source for humidification and dehumidification, resulting in high energy consumption and high fresh water production costs. In contrast, an electrically driven heat pump system can recover 3 to 5 units of heat from humid air with just 1 unit of electricity. This system can provide a stable heat source with low energy consumption, while also cooling the humid air.

[0004] Therefore, there is an urgent need to develop a technology that can reduce the energy consumption of humidification and dehumidification systems and increase production. Consideration should be given to coupling solar heating technology with heat pump systems, which can save energy and protect the environment while providing a stable heat source for the system. Ideally, it should also overcome the problem of low energy consumption in single-stage systems by using multi-stage humidification and dehumidification systems to increase freshwater production and reduce system energy consumption. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of unstable heat source supply, low efficiency and low water production in humidification and dehumidification water treatment systems. By combining solar energy and heat pump technology, a two-stage solar heat pump coupled humidification and dehumidification water treatment system and its working method are proposed.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A solar-powered heat pump coupled multi-stage humidification and dehumidification water treatment system includes: a water treatment circulation subsystem, a solar water heating circulation subsystem, and a compression heat pump circulation subsystem. The water treatment circulation subsystem includes: a first water pump 1, a dehumidifier 2, a first three-way regulating valve 3, a precooler 4, a second three-way regulating valve 5, a solution heat exchanger 6, a condenser 7, a second humidifier 8, a second water pump 9, a first humidifier 10, a first fan 11, a second fan 12, a preheater 13, an evaporator 14, a subcooler 15, and a freshwater tank 16. The feed liquid is connected to the inlet a1 of the dehumidifier 2 via a pipeline through a flow regulating valve 23 and the first water pump 1. Outlet a2 of valve 2 is connected to inlet b1 of first three-way regulating valve 3 via a pipeline; outlet b3 of first three-way regulating valve 3 is directly connected to subsequent drainage equipment, while outlet b2 is connected to solution inlet c1 of precooler 4 via a pipeline. Solution outlet c2 of precooler 4 is connected to inlet d1 of second three-way regulating valve 5 via a pipeline; outlet d2 of second three-way regulating valve 5 is connected to inlet f1 of solution heat exchanger 6 via first solenoid valve 24 via a pipeline, and outlet d3 of second three-way regulating valve 5 is connected to inlet e1 of condenser 7 via a pipeline; outlet e2 of condenser 7 and outlet f2 of solution heat exchanger 6 are connected together via a pipeline to the first three-way regulating valve 3. The inlet g1 of the second humidifier 8 and the bottom outlet of the second humidifier 8 are connected to the inlet h1 of the first humidifier 10 via the second water pump 9. The bottom outlet of the first humidifier 10 is connected to the concentrated solution inlet i1 of the preheater 13 via a pipeline. The concentrated solution outlet i2 of the preheater 13 is connected to the subsequent drainage equipment via a pipeline through the first shut-off valve 26. Air is connected from the top air outlet of the second humidifier 8 to the air inlet c3 of the precooler 4 via a pipeline. The air outlet c4 of the precooler 4 is connected to the top air inlet of the dehumidifier 2 via a pipeline. The air outlet a3 of the dehumidifier 2 is connected to the top air inlet of the evaporator 14 via a pipeline. The air outlet a3 of the dehumidifier 2 is connected to the top air inlet of the evaporator 14 via a pipeline. Air outlet j1 is connected to air inlet i3 of preheater 13 via a pipeline. Air outlet i4 of preheater 13 is connected to air inlet h2 of first humidifier 10 via second fan 12 via a pipeline. Air outlet at the top of first humidifier 10 is connected to air inlet g2 of second humidifier 8 via first fan 11 via a pipeline to complete circulation. Condensate outlet at the bottom of dehumidifier 2 and condensate outlet at the bottom of evaporator 14 are connected to condensate inlet k3 of subcooler 15 via a pipeline. Condensate outlet k4 of subcooler 15 is connected to freshwater tank 16 via a pipeline. Bottom outlet of freshwater tank 16 is supplied to user via second shut-off valve 27 via a pipeline.

[0008] The solar water heating subsystem includes: a solar water heater 33, an insulated water tank 20, a solution heat exchanger 6, a third water pump 21, and a three-way solenoid valve 20. Makeup water is supplied via a pipeline through a third shut-off valve 28 to the makeup water inlet n3 of the solar water heater 33. The hot water outlet n2 of the solar water heater 33 is connected via a pipeline to the inlet of the insulated water tank 20. The lower outlet of the insulated water tank 20 is connected via a pipeline through a second solenoid valve 25 to the inlet f3 of the solution heat exchanger 6. The outlet f4 of the solution heat exchanger 6 is connected via a pipeline through the third water pump 21 to the inlet m1 of the three-way solenoid valve 22. The outlet m3 of the three-way solenoid valve 22 is connected via a pipeline to the inlet n1 of the solar water heater 33, and the outlet m2 of the three-way solenoid valve 22 is connected via a pipeline to the subsequent drainage equipment.

[0009] The compression heat pump cycle subsystem includes: compressor 17, condenser 7, subcooler 15, liquid receiver 18, throttle valve 19, and evaporator 14; the refrigerant outlet of compressor 17 is connected to the refrigerant inlet e3 of condenser 7 through a pipeline, the refrigerant outlet e4 of condenser 7 is connected to the refrigerant inlet k1 of subcooler 15 through a pipeline, the refrigerant outlet k2 of subcooler 15 is connected to the inlet of liquid receiver 18 through a pipeline, the refrigerant outlet below liquid receiver 18 is connected to the refrigerant inlet j2 of evaporator 14 through throttle valve 19 through a pipeline, and the refrigerant outlet j3 of evaporator 14 is connected to the refrigerant inlet of compressor 17 through a pipeline.

[0010] Furthermore, a liquid level controller 29 is installed inside the insulated water tank 20, and the control signal of the liquid level controller 29 is connected to the first solenoid valve 24 and the second solenoid valve 25 respectively through wires.

[0011] Furthermore, a first temperature controller 30 is installed on the inlet g1 pipe of the second humidifier 8, and the control signal of the first temperature controller 30 is connected to the compressor 17 and the second three-way regulating valve 5 through wires.

[0012] Furthermore, a second temperature controller 31 is provided on the outlet j1 pipe of the evaporator 14, and the control signal of the second temperature controller 31 is connected to the flow regulating valve 23 through a wire.

[0013] Furthermore, a flow controller 32 is installed on the inlet c1 pipe of the precooler 4, and the control signal of the flow controller 32 is connected to the first three-way regulating valve 3 through the pipeline.

[0014] A method for operating a solar heat pump coupled multi-stage humidification and dehumidification water treatment system includes: a method for operating a water treatment circulation subsystem, a method for operating a solar water heating circulation subsystem, and a method for operating a compression heat pump circulation subsystem.

[0015] (1) Working method of water treatment circulation subsystem

[0016] During initial system operation: the first water pump 1, the third water pump 21, the first fan 11, and the second fan 12 are started. The first three-way regulating valve 3 and the second three-way regulating valve 5 are energized. The compressor 17 is started. The raw material liquid is pumped into the system by the first water pump 1, passes through the dehumidifier 2, the first three-way regulating valve 32, and the precooler 4, and then enters the second three-way regulating valve 5 for diversion. One path enters the solution heat exchanger 6 for heating and temperature rise, and the other path enters the condenser 7 for heating and temperature rise. After heating, they converge and spray in the second humidifier 8 to form a uniform high-temperature liquid film, which exchanges heat and mass with the air entering from the bottom. The air is enthalpy-enhanced and humidified, carrying water vapor to become hot and humid air, which is discharged from the top outlet of the second humidifier 8 and enters the precooler 4 to preheat the raw material liquid. When the set liquid level is reached in the second humidifier 8, the second water pump 9 is started and the first shut-off valve 26 is opened, and the system enters the normal operation stage.

[0017] During normal system operation: The raw material liquid, after its flow rate is regulated by flow regulating valve 23, is pumped into the system by the first water pump 1. It passes through the dehumidifier 2 at a high flow rate, cooling and dehumidifying the humid air entering from the top inlet of dehumidifier 2. After the raw material liquid temperature is raised, its flow rate is regulated by the first three-way regulating valve 3 to maintain the optimal gas-liquid ratio for system water production. The flow rate then enters the precooler 4 through outlet b2 of the first three-way solenoid valve 3. The remaining raw material liquid is discharged from the system through outlet b3. The solution in the precooler 4 absorbs heat from the humid air and condenses, resulting in a significant temperature rise. It then continues to flow through the second three-way solenoid valve 5, where it is split into two streams: one entering the solution heat exchanger 6 to absorb heat from the high-temperature water in the solar water heating system, and the other entering the condenser 7 to absorb heat from the high-temperature refrigerant gas. These streams then converge and enter the second humidifier 8, where they are sprayed as a uniform high-temperature liquid film to exchange heat and mass with the humid air entering from the bottom. The remaining solution, which has not yet evaporated and whose temperature and concentration have not changed significantly, flows out from the bottom outlet of the second humidifier 8 and is pumped into the first humidifier 10 by the second water pump 9 for further spraying. The concentrated solution exchanges heat and mass with the air entering from the bottom. It then flows out from the bottom outlet of the first humidifier 10 into the preheater 13 to preheat the cold and humid air before being discharged from the system through the first shut-off valve 26. The cold and humid air in the preheater 13 absorbs heat from the concentrated solution and is then pressurized by the second fan 12 and sent into the first humidifier 12 to exchange heat and mass with the uniform high-temperature liquid film there. The resulting hot and humid air flows out from the top outlet and continues to pass through the first fan 11 into the second humidifier 8 to exchange heat and moisture with the high-temperature liquid film, increasing enthalpy and humidifying to become hot and humid air. The hot and humid air releases some sensible heat in the precooler 4 to preheat the raw material liquid. After the temperature drops below the dew point temperature, it continues to be passed sequentially into the dehumidifier 2 to be cooled and dehumidified by the high flow rate of raw material liquid and into the evaporator 14 to be cooled and dehumidified by the low-temperature, low-pressure refrigerant liquid. The temperature and humidity of the humid air are further reduced, and a large amount of fresh water is precipitated. The fresh water condensed in the dehumidifier 2 and the evaporator 14 enters the subcooler 15 and is heated to become hot water, which is then stored in the fresh water tank 16 for subsequent use.

[0018] (2) Working method of solar water heating circulation subsystem

[0019] On sunny days when solar heating conditions are met, the makeup water in the solar water heater 33 is heated by solar energy and stored in the insulated water tank 20. The high-temperature water in the insulated water tank 20 enters the solution heat exchanger 6 to release heat and heat the raw material liquid flowing through it. Then, it is pumped into the solar water heater 33 by the third water pump 21 through the outlet m3 of the three-way solenoid valve 22 for further heating and circulation. When the conditions for solar heating are not met at night, the high-temperature water stored in the insulated water tank 20 continues to flow into the solution heat exchanger 6 for heat exchange. The low-temperature water after heat exchange is discharged from the system by the third water pump 21 through the outlet m2 of the three-way solenoid valve 22.

[0020] (3) Working method of compression heat pump cycle subsystem

[0021] The high-temperature, high-pressure refrigerant gas generated by the compressor 17 enters the condenser 7, where it condenses and releases heat to heat the raw material liquid. It then continues to enter the subcooler 15 to increase the subcooling of the refrigerant while simultaneously heating the fresh water. The refrigerant flowing out of the subcooler 15 is fed into the liquid receiver 18. The refrigerant liquid flowing out of the bottom of the liquid receiver 18 enters the expansion valve 18 for throttling and then enters the evaporator 14 to absorb heat, cool, dehumidify, and produce fresh water. The refrigerant gas flowing out of the evaporator 14 is then fed into the compressor 17 for compression and enters the next cycle.

[0022] Furthermore, the first solenoid valve 24 and the second solenoid valve 25 are controlled by the liquid level controller 29. When the liquid level in the electric hot water tank 20 is lower than the set value, the first solenoid valve 24 and the second solenoid valve 25 are closed.

[0023] Furthermore, the compressor 17 is a variable frequency compressor, which, together with the second three-way regulating valve 15, is temperature controlled by the first temperature controller 30. The frequency of the compressor 17 and the opening degree of the outlet d1 of the second three-way regulating valve 5 are inversely proportional to the temperature of the raw material liquid at the inlet g1 of the second humidifier 8.

[0024] Furthermore, the flow regulating valve 23 is temperature-controlled by the second temperature controller 31, and the valve opening of the flow regulating valve 23 is inversely proportional to the temperature of the cold and humid air at the air outlet j1 of the evaporator 14; the first three-way regulating valve 3 is flow-controlled by the flow controller 31, and the valve opening of the outlet b2 of the first three-way regulating valve 3 is controlled so that the flow rate through the flow controller 31 is a set value.

[0025] Compared with the prior art, the technical solution of the present invention has the following technical effects:

[0026] This system employs a solar-powered and heat pump-coupled heat source supply method. By controlling the flow rate of the heating feed liquid, it overcomes the influence of weather conditions, maximizing the utilization of solar energy while meeting the all-weather freshwater supply demand. The solution, still containing residual heat after the first-stage humidification, continues spraying to complete the second-stage humidification. The hot, humid air heats the low-flow feed liquid in the precooler, increasing its temperature upon entering the system. In the dehumidifier, it is cooled and dehumidified by a high-flow cooling water solution. By adjusting the feed liquid, the precooler achieves "low flow rate, high temperature difference," while the dehumidifier achieves "high flow rate, low temperature difference," maximizing the recovery of heat from the hot, humid air and improving cooling and dehumidification. The heat pump evaporator's second-stage dehumidification further reduces the temperature and humidity of the humid air, releasing more freshwater. Compared to single solar heating or heat pump humidification / dehumidification systems, this system can maintain stable operation while saving costs. By using different heating and cooling methods, it achieves two-stage humidification and two-stage dehumidification, improving energy utilization efficiency. The system of this invention consumes approximately 50 kWh / t of energy to produce fresh water, which is about 50% less than the existing single-stage humidification and dehumidification electric heating system, thus conforming to the current trend of energy development in society. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0028] In the diagram: 1 is the first water pump, 2 is the dehumidifier, 3 is the first three-way regulating valve, 4 is the precooler, 5 is the second three-way regulating valve, 6 is the solution heat exchanger, 7 is the condenser, 8 is the second humidifier, 9 is the first water pump, 10 is the second humidifier, 11 is the first fan, 12 is the second fan, 13 is the preheater, 14 is the evaporator, 15 is the subcooler, 16 is the freshwater tank, 17 is the compressor, 18 is the liquid storage tank, 19 is the throttle valve, 20 is the insulated water tank, 21 is the third water pump, 22 is the three-way solenoid valve, 23 is the flow regulating valve, 24 is the first solenoid valve, 25 is the second solenoid valve, 26 is the first shut-off valve, 27 is the second shut-off valve, 28 is the third shut-off valve, 29 is the liquid level controller, 30 is the first temperature controller, 31 is the second temperature controller, 32 is the flow controller, and 33 is the solar water heater. Detailed Implementation

[0029] To make the above-mentioned objectives, features, advantages, and technical solutions of the present invention more apparent and understandable, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1As shown, a solar heat pump coupled multi-stage humidification and dehumidification water treatment system includes: a water treatment circulation subsystem, a solar hot water circulation subsystem, and a compression heat pump circulation subsystem. The water treatment circulation subsystem further includes a raw material liquid circulation system, an air circulation system, and a condensate heating system, specifically composed of: a first water pump 1, a dehumidifier 2, a first three-way regulating valve 3, a precooler 4, a second three-way regulating valve 5, a solution heat exchanger 6, a condenser 7, a second humidifier 8, a second water pump 9, a first humidifier 10, a first fan 11, a second fan 12, a preheater 13, an evaporator 14, a subcooler 15, and a freshwater tank 16; the raw material liquid circulation system... The system connects to the inlet a1 of dehumidifier 2 via a pipeline through flow regulating valve 23 and the first water pump 1. The outlet a2 of dehumidifier 2 is connected to the inlet b1 of the first three-way regulating valve 3 via a pipeline. The outlet b3 of the first three-way regulating valve 3 is directly connected to the subsequent drainage equipment, while the outlet b2 is connected to the solution inlet c1 of precooler 4 via a pipeline. The solution outlet c2 of precooler 4 is connected to the inlet d1 of the second three-way regulating valve 5 via a pipeline. The outlet d2 of the second three-way regulating valve 5 is connected to the inlet f1 of solution heat exchanger 6 via a pipeline through the first solenoid valve 24. The outlet d3 of the second three-way regulating valve 5 is connected to the inlet e1 of condenser 7 via a pipeline. The outlet e2 of condenser 7 is connected to the inlet f1 of solution heat exchanger 6 via a pipeline through the first solenoid valve 24. The outlet f2 of the solution heat exchanger 6 is connected to the inlet g1 of the second humidifier 8 via a pipeline. The bottom outlet of the second humidifier 8 is connected to the inlet h1 of the first humidifier 10 via the second water pump 9. The bottom outlet of the first humidifier 10 is connected to the concentrated solution inlet i1 of the preheater 13 via a pipeline. The concentrated solution outlet i2 of the preheater 13 is connected to the subsequent drainage equipment via a pipeline and the first shut-off valve 26. Air is connected from the top air outlet of the second humidifier 8 to the air inlet c3 of the precooler 4 via a pipeline. The air outlet c4 of the precooler 4 is connected to the top air inlet of the dehumidifier 2 via a pipeline. The air outlet a3 of the dehumidifier 2 is connected to the top air inlet of the evaporator 14 via a pipeline. The air inlet and outlet j1 of the evaporator 14 are connected to the air inlet i3 of the preheater 13 via a pipeline. The air outlet i4 of the preheater 13 is connected to the air inlet h2 of the first humidifier 10 via a pipeline through the second fan 12. The top air outlet of the first humidifier 10 is connected to the air inlet g2 of the second humidifier 8 via a pipeline through the first fan 11 to complete the circulation. The condensate outlet at the bottom of the dehumidifier 2 and the condensate outlet at the bottom of the evaporator 14 are connected to the condensate inlet k3 of the subcooler 15 via a pipeline. The condensate outlet k4 of the subcooler 15 is connected to the freshwater tank 16 via a pipeline. The bottom outlet of the freshwater tank 16 is supplied to the user via a pipeline through the second shut-off valve 27.

[0031] The solar water heating subsystem includes: a solar water heater 33, an insulated water tank 20, a solution heat exchanger 6, a third water pump 21, and a three-way solenoid valve 20. Makeup water is supplied via a pipeline through a third shut-off valve 28 to the makeup water inlet n3 of the solar water heater 33. The hot water outlet n2 of the solar water heater 33 is connected via a pipeline to the inlet of the insulated water tank 20. The lower outlet of the insulated water tank 20 is connected via a pipeline through a second solenoid valve 25 to the inlet f3 of the solution heat exchanger 6. The outlet f4 of the solution heat exchanger 6 is connected via a pipeline through the third water pump 21 to the inlet m1 of the three-way solenoid valve 22. The outlet m3 of the three-way solenoid valve 22 is connected via a pipeline to the inlet n1 of the solar water heater 33, and the outlet m2 of the three-way solenoid valve 22 is connected via a pipeline to the subsequent drainage equipment.

[0032] The compression heat pump cycle subsystem includes: compressor 17, condenser 7, subcooler 15, liquid receiver 18, throttle valve 19, and evaporator 14; the refrigerant outlet of compressor 17 is connected to the refrigerant inlet e3 of condenser 7 through a pipeline, the refrigerant outlet e4 of condenser 7 is connected to the refrigerant inlet k1 of subcooler 15 through a pipeline, the refrigerant outlet k2 of subcooler 15 is connected to the inlet of liquid receiver 18 through a pipeline, the refrigerant outlet below liquid receiver 18 is connected to the refrigerant inlet j2 of evaporator 14 through throttle valve 19 through a pipeline, and the refrigerant outlet j3 of evaporator 14 is connected to the refrigerant inlet of compressor 17 through a pipeline.

[0033] The insulated water tank 20 is equipped with a liquid level controller 29, and the control signal of the liquid level controller 29 is connected to the first solenoid valve 24 and the second solenoid valve 25 respectively through wires.

[0034] A first temperature controller 30 is installed on the inlet g1 pipe of the second humidifier 8. The control signal of the first temperature controller 30 is connected to the compressor 17 and the second three-way regulating valve 5 through wires.

[0035] A second temperature controller 31 is installed on the outlet j1 pipe of the evaporator 14, and the control signal of the second temperature controller 31 is connected to the flow regulating valve 23 through a wire.

[0036] A flow controller 32 is installed on the inlet c1 pipe of the precooler 4, and the control signal of the flow controller 32 is connected to the first three-way regulating valve 3 through the pipeline.

[0037] The present invention discloses a method for operating a solar heat pump coupled multi-stage humidification and dehumidification water treatment system, comprising a method for operating a water treatment circulation subsystem, a method for operating a solar water heating circulation subsystem, and a method for operating a compression heat pump circulation subsystem. The specific method steps are as follows:

[0038] (1) Working method of water treatment circulation subsystem

[0039] During initial system operation: the first water pump 1, the third water pump 21, the first fan 11, and the second fan 12 are started. The first three-way regulating valve 3 and the second three-way regulating valve 5 are energized. The compressor 17 is started. The raw material liquid is pumped into the system by the first water pump 1, passes through the dehumidifier 2, the first three-way regulating valve 32, and the precooler 4, and then enters the second three-way regulating valve 5 for diversion. One path enters the solution heat exchanger 6 for heating and temperature rise, and the other path enters the condenser 7 for heating and temperature rise. After heating, they converge and spray in the second humidifier 8 to form a uniform high-temperature liquid film, which exchanges heat and mass with the air entering from the bottom. The air is enthalpy-enhanced and humidified, carrying water vapor to become hot and humid air, which is discharged from the top outlet of the second humidifier 8 and enters the precooler 4 to preheat the raw material liquid. When the set liquid level is reached in the second humidifier 8, the second water pump 9 is started and the first shut-off valve 26 is opened, and the system enters the normal operation stage.

[0040] During normal system operation: The raw material liquid, after its flow rate is regulated by flow regulating valve 23, is pumped into the system by the first water pump 1. It passes through the dehumidifier 2 at a high flow rate, cooling and dehumidifying the humid air entering from the top inlet of dehumidifier 2. After the raw material liquid temperature is raised, its flow rate is regulated by the first three-way regulating valve 3 to maintain the optimal gas-liquid ratio for system water production. The flow rate then enters the precooler 4 through outlet b2 of the first three-way solenoid valve 3. The remaining raw material liquid is discharged from the system through outlet b3. The solution in the precooler 4 absorbs heat from the humid air and condenses, resulting in a significant temperature rise. It then continues to flow through the second three-way solenoid valve 5, where it is split into two streams: one entering the solution heat exchanger 6 to absorb heat from the high-temperature water in the solar water heating system, and the other entering the condenser 7 to absorb heat from the high-temperature refrigerant gas. These streams then converge and enter the second humidifier 8, where they are sprayed as a uniform high-temperature liquid film to exchange heat and mass with the humid air entering from the bottom. The remaining solution, which has not yet evaporated and whose temperature and concentration have not changed significantly, flows out from the bottom outlet of the second humidifier 8 and is pumped into the first humidifier 10 by the second water pump 9 for further spraying. The concentrated solution exchanges heat and mass with the air entering from the bottom. It then flows out from the bottom outlet of the first humidifier 10 into the preheater 13 to preheat the cold and humid air before being discharged from the system through the first shut-off valve 26. The cold and humid air in the preheater 13 absorbs heat from the concentrated solution and is then pressurized by the second fan 12 and sent into the first humidifier 12 to exchange heat and mass with the uniform high-temperature liquid film there. The resulting hot and humid air flows out from the top outlet and continues to pass through the first fan 11 into the second humidifier 8 to exchange heat and moisture with the high-temperature liquid film, increasing enthalpy and humidifying to become hot and humid air. The hot and humid air releases some sensible heat in the precooler 4 to preheat the raw material liquid. After the temperature drops below the dew point temperature, it continues to be passed sequentially into the dehumidifier 2 to be cooled and dehumidified by the high flow rate of raw material liquid and into the evaporator 14 to be cooled and dehumidified by the low-temperature, low-pressure refrigerant liquid. The temperature and humidity of the humid air are further reduced, and a large amount of fresh water is precipitated. The fresh water condensed in the dehumidifier 2 and the evaporator 14 enters the subcooler 15 and is heated to become hot water, which is then stored in the fresh water tank 16 for subsequent use.

[0041] (2) Working method of solar water heating circulation subsystem

[0042] On sunny days when solar heating conditions are met, the makeup water in the solar water heater 33 is heated by solar energy and stored in the insulated water tank 20. The high-temperature water in the insulated water tank 20 enters the solution heat exchanger 6 to release heat and heat the raw material liquid flowing through it. Then, it is pumped into the solar water heater 33 by the third water pump 21 through the outlet m3 of the three-way solenoid valve 22 for continued heating and circulation. When the conditions for solar heating are not met at night, the high-temperature water stored in the insulated water tank 20 continues to flow into the solution heat exchanger 6 for heat exchange. The low-temperature water after heat exchange is discharged from the system by the third water pump 21 through the outlet m2 of the three-way solenoid valve 22.

[0043] (3) Working method of compression heat pump cycle subsystem

[0044] The high-temperature, high-pressure refrigerant gas generated by the compressor 17 enters the condenser 7, where it condenses and releases heat to heat the raw material liquid. It then continues to enter the subcooler 15 to increase the subcooling of the refrigerant while simultaneously heating the fresh water. The refrigerant flowing out of the subcooler 15 is fed into the liquid receiver 18. The refrigerant liquid flowing out from the bottom of the liquid receiver 18 enters the expansion valve 18 for throttling and then enters the evaporator 14 to absorb heat, cool, dehumidify, and produce fresh water. The refrigerant gas flowing out of the evaporator 14 is then fed into the compressor 17 for compression and enters the next cycle.

[0045] The first solenoid valve 24 and the second solenoid valve 25 are controlled by the liquid level controller 29. When the liquid level in the electric hot water tank 20 is lower than the set value, it means that the hot water in the insulated water tank 20 is insufficient to supply the solution heat exchanger 6 to heat the raw material liquid. Then the first solenoid valve 24 and the second solenoid valve 25 are closed, and the raw material liquid is heated by the heat pump condenser.

[0046] The compressor 17 is a variable frequency compressor, which, together with the second three-way regulating valve 15, is temperature controlled by the first temperature controller 30. The frequency of the compressor 17 and the opening degree of the outlet d1 of the second three-way regulating valve 5 are inversely proportional to the temperature of the raw material liquid at the inlet g1 of the second humidifier 8. When the temperature of the raw material liquid entering the second humidifier 8 is low, it is necessary to adjust the second three-way regulating valve to increase the flow rate into the condenser, and at the same time increase the compressor frequency to increase the heating capacity of the heat pump condenser.

[0047] The flow regulating valve 23 is temperature-controlled by the second temperature controller 31. The valve opening of the flow regulating valve 23 is inversely proportional to the temperature of the cold and humid air at the air outlet j1 of the evaporator 14. When the temperature of the hot and humid air at the outlet of the evaporator 14 is high, it is necessary to increase the flow rate of the cooling raw material liquid in the dehumidifier to enhance dehumidification. The first three-way regulating valve 3 is flow-controlled by the flow controller 31. The valve opening of the outlet b2 of the first three-way regulating valve 3 is controlled so that the flow rate through the flow controller 31 is the set value, maintaining the optimal gas-liquid ratio of the system.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solar heat pump coupled multi-stage humidification and dehumidification water treatment system, comprising: The system comprises a water treatment circulation subsystem, a solar water heating circulation subsystem, and a compression heat pump circulation subsystem. The water treatment circulation subsystem includes: a first water pump (1), a dehumidifier (2), a first three-way regulating valve (3), a precooler (4), a second three-way regulating valve (5), a solution heat exchanger (6), a condenser (7), a second humidifier (8), a second water pump (9), a first humidifier (10), a first fan (11), a second fan (12), a preheater (13), an evaporator (14), a subcooler (15), and a freshwater tank (16). The raw material liquid is connected to the inlet (a1) of the dehumidifier (2) via a pipeline through a flow regulating valve (23) and the first water pump (1). The outlet (a2) of the dehumidifier (2) is connected to the first three-way regulating valve via a pipeline. The inlet (b1) of the regulating valve (3); the outlet (b3) of the first three-way regulating valve (3) is directly connected to the subsequent drainage equipment, and the outlet (b2) is connected to the solution inlet (c1) of the precooler (4) through a pipeline. The solution outlet (c2) of the precooler (4) is connected to the inlet (d1) of the second three-way regulating valve (5) through a pipeline. The outlet (d2) of the second three-way regulating valve (5) is connected to the inlet (f1) of the solution heat exchanger (6) through a pipeline via the first solenoid valve (24). The outlet (d3) of the second three-way regulating valve (5) is connected to the inlet (e1) of the condenser (7) through a pipeline. The outlet (e2) of the condenser (7) and the outlet (f2) of the solution heat exchanger (6) are connected together through a pipeline to the inlet of the second humidifier (8). The bottom outlet of the second humidifier (8) is connected to the inlet (h1) of the first humidifier (10) via the second water pump (9). The bottom outlet of the first humidifier (10) is connected to the concentrated solution inlet (i1) of the preheater (13) via a pipeline. The concentrated solution outlet (i2) of the preheater (13) is connected to the subsequent drainage equipment via the first shut-off valve (26) via a pipeline. Air is connected from the top air outlet of the second humidifier (8) to the air inlet (c3) of the precooler (4) via a pipeline. The air outlet (c4) of the precooler (4) is connected to the top air inlet of the dehumidifier (2) via a pipeline. The air outlet (a3) ​​of the dehumidifier (2) is connected to the top air inlet of the evaporator (14) via a pipeline. The air outlet of the evaporator (14) is connected to the top air inlet of the evaporator (14). (j1) is connected to the air inlet (i3) of the preheater (13) through a pipeline. The air outlet (i4) of the preheater (13) is connected to the air inlet (h2) of the first humidifier (10) through a pipeline via the second fan (12). The top air outlet of the first humidifier (10) is connected to the air inlet (g2) of the second humidifier (8) through a pipeline via the first fan (11) to complete the circulation. The condensate outlet at the bottom of the dehumidifier (2) and the condensate outlet at the bottom of the evaporator (14) are connected to the condensate inlet (k3) of the subcooler (15) through a pipeline. The condensate outlet (k4) of the subcooler (15) is connected to the fresh water tank (16) through a pipeline. The bottom outlet of the fresh water tank (16) is supplied to the user through a pipeline via the second shut-off valve (27). The solar water heating subsystem includes: a solar water heater (33), an insulated water tank (20), a solution heat exchanger (6), a third water pump (21), and a three-way solenoid valve (22); the makeup water is connected to the makeup water inlet (n3) of the solar water heater (33) via a pipeline through a third shut-off valve (28), the hot water outlet (n2) of the solar water heater (33) is connected to the inlet of the insulated water tank (20) via a pipeline, the lower outlet of the insulated water tank (20) is connected to the inlet (f3) of the solution heat exchanger (6) via a pipeline through a second solenoid valve (25), the outlet (f4) of the solution heat exchanger (6) is connected to the inlet (m1) of the three-way solenoid valve (22) via a pipeline through the third water pump (21); the outlet (m3) of the three-way solenoid valve (22) is connected to the inlet (n1) of the solar water heater (33) via a pipeline, and the outlet (m2) of the three-way solenoid valve (22) is connected to the subsequent drainage equipment via a pipeline; The compression heat pump cycle subsystem includes: a compressor (17), a condenser (7), a subcooler (15), a liquid receiver (18), a throttle valve (19), and an evaporator (14); the refrigerant outlet of the compressor (17) is connected to the refrigerant inlet (e3) of the condenser (7) through a pipeline, the refrigerant outlet (e4) of the condenser (7) is connected to the refrigerant inlet (k1) of the subcooler (15) through a pipeline, the refrigerant outlet (k2) of the subcooler (15) is connected to the inlet of the liquid receiver (18) through a pipeline, the refrigerant outlet below the liquid receiver (18) is connected to the refrigerant inlet (j2) of the evaporator (14) through a pipeline via the throttle valve (19), and the refrigerant outlet (j3) of the evaporator (14) is connected to the refrigerant inlet of the compressor (17) through a pipeline; The insulated water tank (20) is equipped with a liquid level controller (29), and the control signal of the liquid level controller (29) is connected to the first solenoid valve (24) and the second solenoid valve (25) respectively through wires; The inlet (g1) pipe of the second humidifier (8) is equipped with a first temperature controller (30), and the control signal of the first temperature controller (30) is connected to the compressor (17) and the second three-way regulating valve (5) respectively through wires; A second temperature controller (31) is installed on the outlet (j1) pipe of the evaporator (14), and the control signal of the second temperature controller (31) is connected to the flow regulating valve (23) through a wire; A flow controller (32) is installed on the inlet (c1) pipe of the precooler (4), and the control signal of the flow controller (32) is connected to the first three-way regulating valve (3) through the pipe.

2. A method for operating a solar heat pump coupled multi-stage humidification and dehumidification water treatment system according to claim 1, characterized in that, This includes the operating methods of the water treatment circulation subsystem, the solar water heating circulation subsystem, and the compression heat pump circulation subsystem: (1) Working method of water treatment circulation subsystem When the system is running for the first time: the first water pump (1), the third water pump (21), the first fan (11), and the second fan (12) are started. The first three-way regulating valve (3) and the second three-way regulating valve (5) are powered on. The compressor (17) is started. The raw material liquid is pumped into the system by the first water pump (1), passes through the dehumidifier (2), the first three-way regulating valve (3), and the precooler (4), and then enters the second three-way regulating valve (5) for diversion. One path enters the solution heat exchanger (6) for heating and temperature rise, and the other path enters the condenser (7) for heating and temperature rise. After heating, they are combined and sprayed in the second humidifier (8) to form a uniform high-temperature liquid film and exchange heat and mass with the air entering from the bottom. The air is enthalpy-enhanced and humidified, carrying water vapor to become hot and humid air. It is discharged from the top outlet of the second humidifier (8) and enters the precooler (4) to preheat the raw material liquid. When the set liquid level is reached in the second humidifier (8), the second water pump (9) is started and the first shut-off valve (26) is opened. The system enters the normal operation stage. During normal system operation: the raw material liquid is pumped into the system by the first water pump (1) after the flow rate is regulated by the flow regulating valve (23). It passes through the dehumidifier (2) at a high flow rate, cooling and dehumidifying the humid air entering from the top inlet of the dehumidifier (2). After the temperature of the raw material liquid is raised, the flow rate is regulated by the first three-way regulating valve (3). The flow rate used to maintain the optimal gas-liquid ratio of the system water production is entered into the precooler (4) through the outlet (b2) of the first three-way solenoid valve (3). The remaining raw material liquid is discharged from the system through the outlet (b3). The solution in the precooler (4) absorbs heat. After the humid air condenses and gains a significant temperature rise, it continues to flow into the second three-way solenoid valve (5) for diversion. The humid air then enters the solution heat exchanger (6) to absorb heat from the high-temperature water in the solar water heating system, and enters the condenser (7) to absorb heat from the high-temperature refrigerant gas. Afterward, the humid air merges and flows into the second humidifier (8), where it is sprayed into a uniform high-temperature liquid film for heat and mass exchange with the humid air entering from the bottom. The solution that has not yet evaporated and whose temperature and concentration have not changed significantly flows out from the bottom outlet of the second humidifier (8) and is pumped into the first humidifier (10) by the second water pump (9) for further processing. The spray exchange of heat and mass with the air entering from the bottom, and the concentrated solution flows out from the bottom outlet of the first humidifier (10) into the preheater (13) to preheat the hot and humid air before being discharged from the system through the first shut-off valve (26); the cold and humid air in the preheater (13) absorbs the heat of the concentrated solution and is then pressurized by the second fan (12) and sent into the first humidifier (10) to exchange heat and mass with the uniform high-temperature liquid film therein, and the resulting hot and humid air flows out from the top outlet and continues to pass through the first fan (11) into the second humidifier (8) to exchange heat and mass with the high-temperature solution, increasing enthalpy. The humid air becomes hot and humid air. The hot and humid air releases some sensible heat to preheat the raw material liquid in the precooler (4). After the temperature drops below the dew point temperature, it continues to be passed into the dehumidifier (2) to be cooled and dehumidified by the high flow rate of raw material liquid and into the evaporator (14) to be cooled and dehumidified by the low temperature and low pressure refrigerant liquid. The temperature and humidity of the humid air are further reduced, and a large amount of fresh water is precipitated. The fresh water generated by the condensation of the dehumidifier (2) and the evaporator (14) enters the subcooler (15) and is heated into hot water, which is then stored in the fresh water tank (16) for subsequent use. (2) Working method of solar water heating circulation subsystem On a sunny day when the conditions for solar heating are met, the replenishment water in the solar water heater (33) is heated by solar energy and stored in the insulated water tank (20). The high-temperature water in the insulated water tank (20) enters the solution heat exchanger (6) to release heat and heat the raw material liquid flowing through it. Then, it is pumped into the solar water heater (33) by the third water pump (21) through the outlet (m3) of the three-way solenoid valve (22) to continue heating and circulating. When the conditions for solar heating are not met at night, the high-temperature water stored in the insulated water tank (20) continues to flow into the solution heat exchanger (6) for heat exchange. The low-temperature water after heat exchange is discharged from the system by the third water pump (21) through the outlet (m2) of the three-way solenoid valve (22). (3) Working method of compression heat pump cycle subsystem The high-temperature and high-pressure refrigerant gas generated by the compressor (17) enters the condenser (7) to condense and release heat to heat the raw material liquid. After that, it continues to enter the subcooler (15) to increase the subcooling degree of the refrigerant and heat the fresh water. The refrigerant flowing out of the subcooler (15) is connected to the liquid storage tank (18). The refrigerant liquid flowing out of the bottom of the liquid storage tank (18) enters the throttling valve (19) for throttling and then enters the evaporator (14) to absorb heat, cool and dehumidify to produce fresh water. The refrigerant gas flowing out of the evaporator (14) is fed into the compressor (17) for compression and enters the next cycle.

3. The operation method of the solar heat pump coupled multi-stage humidification and dehumidification water treatment system according to claim 2, characterized in that, The first solenoid valve (24) and the second solenoid valve (25) are controlled by the liquid level controller (29). When the liquid level in the insulated water tank (20) is lower than the set value, the first solenoid valve (24) and the second solenoid valve (25) are closed.

4. The operation method of the solar heat pump coupled multi-stage humidification and dehumidification water treatment system according to claim 2, characterized in that, The compressor (17) is a variable frequency compressor, which, together with the second three-way regulating valve (5), is temperature controlled by the first temperature controller (30). The frequency of the compressor (17) and the opening degree of the outlet (d1) of the second three-way regulating valve (5) are inversely proportional to the temperature of the raw material liquid at the inlet (g1) of the second humidifier (8).

5. The operation method of the solar heat pump coupled multi-stage humidification and dehumidification water treatment system according to claim 2, characterized in that, The flow regulating valve (23) is temperature controlled by the second temperature controller (31), and the valve opening of the flow regulating valve (23) is inversely proportional to the temperature of the cold and humid air at the air outlet (j1) of the evaporator (14); the first three-way regulating valve (3) is flow controlled by the flow controller (31), and the valve opening of the outlet (b2) of the first three-way regulating valve (3) is controlled so that the flow through the flow controller (31) is the set value.

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