Carnot cell coupling seawater desalination system and method with power generation and energy storage functions

Abstract

The invention provides a Carnot cell coupled seawater desalination system and method with power generation and energy storage functions, and the system comprises a heat pump module which is used for raising the temperature of low-grade heat of renewable energy sources to higher-temperature heat; the heat storage module is connected with the heat pump module and used for storing heat provided by the heat pump module; the organic Rankine cycle module is connected with the heat storage module and uses the heat released by the heat storage module to generate electricity; the seawater desalination module is used for carrying out seawater desalination through an evaporation and condensation technology, is connected with the heat storage module, and selectively utilizes renewable energy sources or electric power output by the organic Rankine cycle module to carry out seawater desalination according to the energy supply state, so that cooperative operation of heat energy storage and seawater desalination is realized; the system provided by the invention is simple in structure, integrated in function and stable in operation, and can synchronously realize flexible energy storage and fresh water supply.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seawater desalination, and in particular to a Carnot cell coupled seawater desalination system and method with power generation and energy storage. BACKGROUND

[0002] Remote areas (such as islands, deserts, and polar regions) have high extension costs of power grids due to geographical conditions, and energy supply is difficult. For example, only about 30% of islands in the Maldives have electricity, 600 million people in sub-Saharan Africa have no electricity, and offshore platforms rely on high-cost diesel power generation. At the same time, renewable energy (solar energy, wind energy, and tidal energy) is highly intermittent, and existing energy storage technologies (such as batteries and pumped storage) have short service lives and high resource dependence, making it difficult to meet the stable power supply needs of remote areas.

[0003] 40% of the world's population faces water shortages, and coastal areas rely on high-energy seawater desalination technology to alleviate the crisis, but traditional processes rely on stable power and are difficult to apply in areas without power grids or mobile scenarios, and the contradiction between fresh water supply and energy supply is prominent.

[0004] Existing energy storage and seawater desalination technologies are independent of each other, and the system is complex and has a single function, which cannot simultaneously solve the problem of "lack of electricity and water" in remote areas.

[0005] Therefore, there is an urgent need to develop a Carnot cell coupled seawater desalination system and method with power generation and energy storage that is simple in structure, integrated in function, and stable in operation, which can simultaneously achieve flexible energy storage and fresh water supply. SUMMARY

[0006] The purpose of the present application is to provide a Carnot cell coupled seawater desalination system and method with power generation and energy storage, which aims to solve the problems of energy storage difficulty and water shortage in remote areas and achieve the technical problem of coupling and integration of heat energy storage and seawater desalination functions.

[0007] To achieve the above-mentioned purpose, in a first aspect, the present application provides a Carnot cell coupled seawater desalination system with power generation and energy storage, comprising:

[0008] a heat pump module for upgrading the low-grade heat of renewable energy to higher temperature heat;

[0009] a heat storage module connected to the heat pump module for storing the heat provided by the heat pump module;

[0010] an organic Rankine cycle module connected to the heat storage module and generating electricity using the heat released by the heat storage module;

[0011] The seawater desalination module is used for seawater desalination through an evaporation condensation technology, is connected with the heat storage module, and selectively uses renewable energy or electric power output by the organic Rankine cycle module to perform seawater desalination according to an energy supply state, so that the heat energy storage and the seawater desalination are cooperatively operated.

[0012] As a further improvement of the above scheme, the heat pump module comprises:

[0013] a first compressor for compressing the working medium to increase its pressure and temperature;

[0014] a first evaporator, the outlet end of which is connected with the air inlet end of the first compressor, for absorbing heat from an external environment (such as air, a water source or an industrial waste heat source) to evaporate the working medium into a low-temperature and low-pressure gas state;

[0015] a first condenser, the hot side inlet end of which is connected with the air outlet end of the first compressor, for releasing the heat of the high-temperature and high-pressure gaseous working medium to an external heat sink (such as a heat storage module);

[0016] an expansion valve, which is arranged between the first evaporator and the first condenser, for adjusting the pressure and temperature of the working medium to form a closed circulation loop of the working medium among the evaporator, the compressor, the condenser and the expansion valve;

[0017] The heat pump module absorbs low-grade heat through the first evaporator, raises the low-grade heat to high-grade heat energy through the first compressor, releases the heat through the first condenser to realize energy conversion, and the expansion valve controls the throttling process of the working medium circulation to ensure stable operation of the system under variable working conditions.

[0018] As a further improvement of the above scheme, the heat storage module comprises:

[0019] a low-temperature tank for storing seawater with reduced temperature after heat exchange as a low-temperature heat energy storage unit;

[0020] a high-temperature tank for storing seawater with increased temperature after heating by the heat pump module as a high-temperature heat energy storage unit;

[0021] a first water pump, the inlet end of which is connected with the outlet end of the low-temperature tank, and the outlet end of which is connected with the cold side outlet end of the first condenser, for introducing the working medium in the low-temperature tank into the first condenser to absorb heat and deliver to the high-temperature tank;

[0022] a heat exchanger arranged between the low-temperature tank and the high-temperature tank, for realizing heat transfer between the high-temperature working medium and the low-temperature working medium;

[0023] a second water pump arranged between the high-temperature tank and the heat exchanger, for delivering the high-temperature working medium stored in the high-temperature tank to the heat exchanger to exchange heat and realize heat energy transfer from the high-temperature working medium to the low-temperature working medium.

[0024] The heat storage module realizes gradient storage and release of heat energy through the layered storage structure of the high-temperature tank and the low-temperature tank, promotes the transfer of heat energy from the high-temperature working medium to the low-temperature working medium through the heat exchanger, and ensures the controllable circulation of the working medium in the storage and exchange process through the directional transportation of the first water pump and the second water pump, thereby providing stable heat energy supply and adjustment capacity for the system.

[0025] As a further improvement of the above scheme, the hot measuring outlet end of the first condenser is connected with the inlet end of the high-temperature tank, for delivering the working medium absorbing the heat released by the first condenser to the high-temperature tank to store heat.

[0026] As a further improvement of the above scheme, the Carnot cell coupled seawater desalination system with power generation and energy storage also includes a waste heat recovery module for collecting heat energy outside the system, such as waste heat of a ship generator, solar energy, etc.

[0027] The waste heat recovery module is connected with the first evaporator to provide a heat source for the first evaporator.

[0028] And / or, the waste heat recovery module is connected with the low-temperature tank to preheat the low-temperature seawater in the low-temperature tank.

[0029] As a further improvement of the above scheme, the organic Rankine cycle module includes:

[0030] A working medium pump, the outlet end of which is connected with the cold side inlet of the heat exchanger, for delivering the circulating working medium to the heat exchanger for heat exchange to increase the temperature of the working medium;

[0031] An expander, the inlet side of which is connected with the cold side outlet of the heat exchanger, for receiving the high-temperature and high-pressure working medium heated by the heat exchanger and converting the heat energy of the working medium into mechanical energy;

[0032] A second condenser, the outlet end of which is connected with the inlet end of the working medium pump, and the inlet end of which is connected with the outlet end of the expander, for condensing the low-pressure working medium discharged by the expander into liquid state, forming a closed circulation loop of the working medium among the working medium pump, the heat exchanger, the expander and the second condenser;

[0033] The organic Rankine cycle module receives the heat of the high-temperature working medium from the heat storage module through the heat exchanger, converts the heat energy into mechanical energy output by the expander, releases the heat of the working medium and condenses it by the second condenser, and returns the pressurized working medium to the heat exchanger by the working medium pump, thereby realizing continuous conversion of heat energy into mechanical energy and providing stable power output capacity for the system.

[0034] As a further improvement of the above scheme, the seawater desalination module includes:

[0035] a fourth water pump, an inlet end of which is connected to an outlet end of the high-temperature tank, for conveying the high-temperature seawater stored in the heat storage module to the seawater desalination module;

[0036] a second evaporator, a seawater inlet end of which is connected to an outlet end of the fourth water pump, for receiving the high-temperature seawater in the high-temperature tank and evaporating water in the seawater into water vapor through heat exchange;

[0037] a second compressor, an exhaust end of which is connected to a hot side inlet end of the second evaporator, for sending the working medium into the second evaporator after being pressurized and heated, so that the seawater is evaporated and the high-temperature seawater is cooled by heat released by the working medium;

[0038] a third condenser, an outlet end of which is connected to an air inlet end of the second compressor, and a steam inlet end of which is connected to a steam output port of the second evaporator, for exchanging heat between the water vapor and the low-temperature working medium, so that the water vapor is condensed into high-purity liquid water, and the low-temperature working medium is heated after absorbing heat;

[0039] The seawater desalination module conveys seawater to the second evaporator through the fourth water pump, uses the second compressor to drive the working medium to circulate to provide heat for seawater evaporation, can directly use clean energy to drive when energy supply is sufficient, can use the heat energy provided by the organic Rankine cycle module to drive when energy supply is insufficient, and condenses the water vapor into liquid fresh water through the third condenser to realize the seawater desalination function and provide stable fresh water supply capacity for the system.

[0040] In a second aspect, the application also provides a running method of the seawater desalination system coupled with the Carnot cell for power generation and energy storage according to the first aspect, and the steps include:

[0041] a heat storage mode: when energy supply is sufficient or the electricity price is low, the first compressor is started to drive the working medium to complete the heat pump cycle, and the first condenser releases heat to the heat storage module; at the same time, the first water pump is started to make the low-temperature seawater flow through the first condenser to be heated and turned into high-temperature seawater and stored in the high-temperature tank;

[0042] a power generation mode: when energy supply is insufficient or the electricity price is high, the second water pump is started to make the high-temperature seawater flow through the heat exchanger, and the working medium pump is started to make the working medium enter the expander to generate power after being heated by the heat exchanger;

[0043] a desalination mode: the fourth water pump is started to lead the high-temperature seawater to the second evaporator, and the second compressor is started to pressurize and heat the working medium to be sent into the second evaporator under the drive of electricity, so that the seawater is evaporated by heat released by the working medium, and the water vapor enters the third condenser to form high-purity liquid water by condensation;

[0044] Power generation and desalination parallel mode: simultaneously start the second water pump, the working medium pump, the second compressor and the fourth water pump, and make the high-temperature seawater branch to the heat exchanger and the second evaporator to complete power generation and desalination respectively;

[0045] Heat storage and desalination parallel mode: simultaneously start the first compressor, the first water pump, the second compressor and the fourth water pump, store heat under the action of the first condenser and the first water pump, and introduce the high-temperature tank seawater to the second evaporator by the fourth water pump to evaporate and condense water.

[0046] As a further improvement of the above scheme, in the heat storage mode, the first compressor drives the working medium to form a closed cycle between the first evaporator, the first condenser and the expansion valve, so that the heat of the low-temperature heat source is raised to high-temperature heat and released to the heat storage module through the first condenser, and the first water pump delivers the low-temperature seawater to the first condenser to absorb heat and then stores it in the high-temperature tank.

[0047] As a further improvement of the above scheme, in the power generation mode, the second water pump delivers the high-temperature seawater in the high-temperature tank to the heat exchanger, the working medium pump delivers the working medium of the organic Rankine cycle to the heat exchanger to absorb heat and then enters the expander, the expander converts the heat energy of the working medium into mechanical energy and outputs electric power, and the working medium after work is condensed by the second condenser and then circulated back to the heat exchanger by the working medium pump.

[0048] As a further improvement of the above scheme, in the desalination mode, the fourth water pump delivers the high-temperature seawater in the high-temperature tank to the second evaporator, the second compressor pressurizes and heats the working medium under the drive of electric power and then sends it into the second evaporator, the working medium releases heat to the high-temperature seawater to evaporate the seawater into water vapor, and the water vapor enters the third condenser to exchange heat with the low-temperature working medium to condense into high-purity liquid water and output.

[0049] As a further improvement of the above scheme, in the power generation and desalination parallel mode, the flow distribution of the second water pump and the fourth water pump is adjusted to control the proportion of the high-temperature seawater branched to the heat exchanger and the second evaporator, so that the power generation and desalination functions are cooperatively operated.

[0050] As a further improvement of the above scheme, in the heat storage and desalination parallel mode, when the first compressor drives the working medium to complete the heat pump cycle, the high-temperature seawater in the high-temperature tank is introduced to the second evaporator by the fourth water pump to heat and evaporate, the water vapor enters the third condenser to be condensed by the low-temperature working medium to form high-purity liquid water, and the synchronous operation of heat energy storage and fresh water production is realized.

[0051] Due to the adoption of the above technical scheme, the application has the following beneficial effects:

[0052] The application provides a seawater desalination system coupled with a Carnot battery for power generation and energy storage, which combines a heat pump module, a heat storage module, an organic Rankine cycle module and a seawater desalination module, and realizes the collaborative operation of heat energy storage and seawater desalination for the problem of coexistence of unstable energy supply and shortage of fresh water resources in remote areas. Specifically, the heat pump module can upgrade low-grade heat such as solar energy, industrial waste heat or marine facility waste heat to high-temperature heat and send it to the heat storage module for storage. Since the heat pump module can directly utilize renewable energy or waste heat without relying on external stable power grids, it can obtain and store heat energy on site in scenarios such as islands, deserts and polar regions where the extension cost of power grids is high or there is no power grid coverage, thereby alleviating the difficulty of energy supply.

[0053] The heat storage module completes the preservation and release of heat between the high-temperature tank and the low-temperature tank, so that the system stores heat when the energy supply is sufficient or the electricity price is low, and generates power by the organic Rankine cycle module when the energy supply is insufficient or the electricity price is high. This combination of features enables intermittent solar energy and wind energy to be converted into dispatchable heat energy when there is a surplus, thereby stably outputting power when there is a lack of energy, overcoming the limitations of existing energy storage technologies such as short service life and high resource dependence.

[0054] The organic Rankine cycle module uses the high-temperature heat released by the heat storage module as a driving source, and outputs electric power through the expansion of the working medium after heat absorption, thereby replacing the high-cost diesel power generation mode of offshore platforms and the like, thereby reducing fuel transportation costs and carbon emissions and improving the economy and sustainability of energy use in remote areas.

[0055] The seawater desalination module can directly utilize clean energy to drive the compressor when the energy supply is sufficient, and can be switched to be driven by the electric power output by the organic Rankine cycle module when the energy supply is insufficient. This selective driving mode solves the problem that traditional desalination technologies rely on stable power and are difficult to apply in scenarios without power grids or on the move, so that the system can produce water in environments lacking fixed power sources such as ships and disaster relief.

[0056] The high-temperature seawater of the heat storage module can be used for power generation by the organic Rankine cycle module and evaporation of seawater by the seawater desalination module, realizing multipurpose utilization of the same heat source. For example, in the power generation + desalination mode or the heat storage + desalination mode, the high-temperature seawater is divided to participate in different processes, avoiding waste of heat energy and improving the comprehensive utilization efficiency of limited resources in remote areas.

[0057] The application has simple structure and high functional integration, and effectively solves the complex problem of coexistence of lack of electricity and lack of water in remote areas through the combination of features such as heat pump temperature rise and heat storage, cross-period scheduling of the heat storage module, organic Rankine cycle power generation and on-demand driving of seawater desalination, thereby realizing stable power and fresh water supply without relying on high-cost power grids or fossil fuels. BRIEF DESCRIPTION OF DRAWINGS

[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0059] Figure 1 This is a schematic diagram of a Carnot battery coupled with a seawater desalination system that combines power generation and energy storage, as disclosed in this invention.

[0060] Figure label:

[0061] 1. First compressor; 2. First condenser; 3. Expansion valve; 4. First evaporator; 5. Low-temperature tank; 6. First water pump; 7. High-temperature tank; 8. Second water pump; 9. Heat exchanger; 10. Expander; 11. Second condenser; 12. Working fluid pump; 13. Fourth water pump; 14. Second compressor; 15. Second evaporator; 16. Third condenser; 17. Freshwater pump.

[0062] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0065] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0066] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0067] Example 1

[0068] like Figure 1 As shown, this invention provides a Carnot battery-coupled seawater desalination system that combines power generation and energy storage, comprising a heat pump module, a thermal storage module, an organic Rankine cycle module, and a seawater desalination module. The heat pump module uses renewable energy sources (such as solar thermal collectors, industrial waste heat, or waste heat from marine facilities) or low-grade environmental heat sources as input, raising the low-grade heat to high-grade heat; the thermal storage module receives and stores this high-grade heat; the organic Rankine cycle module extracts heat from the thermal storage module when power generation is needed, converting the thermal energy into electrical energy; the seawater desalination module uses high-temperature water or electrical energy to drive the evaporation and condensation process to achieve seawater desalination. The modules are connected according to the flow of heat and matter, forming a switchable operating mode.

[0069] Specifically, the heat pump module includes a first evaporator 4, a first compressor 1, a first condenser 2, and an expansion valve 3. The working fluid can be R1233zd or cyclopentane. During operation, the working fluid absorbs low-grade heat in the first evaporator 4 and evaporates into a gaseous state. After being pressurized and heated by the first compressor 1, it enters the first condenser 2. In the first condenser 2, it releases heat to the high-temperature tank 7 of the heat storage module and condenses into a liquid state. Then, it is depressurized by the expansion valve 3 and returns to the evaporator, forming a closed loop. Through this loop, dispersed, low-grade usable heat can be concentrated and elevated into high-temperature heat and sent to the heat storage module for subsequent long-term storage and utilization.

[0070] The thermal storage module comprises a high-temperature tank 7 and a low-temperature tank 5, each equipped with a corresponding pump. The high-temperature tank 7 receives the exothermic working fluid or heat transfer medium from the first condenser 2 of the heat pump module, storing the heat in the form of sensible or latent heat. The low-temperature tank 5 temporarily stores the heated low-temperature medium, i.e., low-temperature seawater. The pumps are used to drive the medium between the tanks or to other modules under different operating conditions. The outlet of the high-temperature tank 7 can be connected to an organic Rankine cycle module or a seawater desalination module, enabling on-demand heat release. This dual-tank structure facilitates stratified heat storage and stable supply, reducing the impact of temperature fluctuations on downstream modules.

[0071] The organic Rankine cycle module includes a second condenser 11, a heat exchanger 9, an expander 10, and a working fluid pump 12. The working fluid can be cyclopentane, R245fa, or R1233zd. In power generation mode, high-temperature seawater or a heat transfer medium in the high-temperature tank 7 is pumped to the heat exchanger 9, heating the organic working fluid to a high-temperature, high-pressure state. The working fluid then enters the expander 10 to perform work, driving the generator to output electricity. After performing work, the working fluid enters the second condenser 11 to release heat and condense, and is then pressurized and returned to the heat exchanger 9 by the working fluid pump, forming a cycle. This module can continuously generate electricity using the heat from the thermal storage module, making up for the power shortage during renewable energy off-peak periods or peak electricity price periods.

[0072] The seawater desalination module employs evaporation-condensation technology, comprising a second evaporator 15, a third condenser 16, a second compressor 14, and a water circulation pump. When energy is sufficient, the second compressor 14, driven by clean energy, pressurizes and heats the working fluid before sending it to the second evaporator 15, causing the flowing seawater to evaporate. The evaporated water vapor enters the third condenser 16, where it exchanges heat with the low-temperature working fluid and condenses into high-purity liquid fresh water. When energy is insufficient, the compressor can be driven by electricity output from the organic Rankine cycle module. The high-temperature water source for the seawater desalination module can be supplied by the high-temperature tank 7 of the thermal storage module, thus forming a thermal linkage with the thermal storage module and reducing additional heating energy consumption.

[0073] The system can select between thermal storage, power generation, desalination, or a combination of modes of operation based on energy supply and demand. For example, when there is sufficient sunlight or waste heat and electricity prices are low, the heat pump module and thermal storage module work to store heat in the high-temperature tank 7; when there is no sunlight or during peak electricity demand, the organic Rankine cycle module is activated to generate electricity; when fresh water is needed and energy permits, the seawater desalination module is activated, and high-temperature seawater can be diverted for both power generation and desalination, achieving multi-purpose utilization of thermal energy.

[0074] This invention utilizes a heat pump module to enhance and store low-grade heat, a thermal storage module to achieve cross-period heat scheduling, an organic Rankine cycle module to generate electricity on demand, and a seawater desalination module to flexibly select driving energy sources, forming a compact, functionally integrated, and stable coupled system. This system can simultaneously provide electricity and fresh water in remote, grid-free, or water-scarce environments, alleviating the contradiction between local energy and water resource supply.

[0075] In a preferred embodiment, in the heat pump module, the outlet end of the first evaporator 4 is connected to the inlet end of the first compressor 1 to send the low-temperature, low-pressure gaseous working fluid that has absorbed external heat into the compressor; the exhaust end of the first compressor 1 is connected to the hot-side inlet end of the first condenser 2 to allow the high-temperature, high-pressure gaseous working fluid to enter the condenser; the cold-side outlet end of the first condenser 2 is connected to the inlet side of the high-temperature tank 7 of the heat storage module (or connected to the high-temperature tank 7 via a heat transfer circuit) to release the heat of the working fluid to the heat storage medium; the expansion valve 3 is located between the first evaporator 4 and the first condenser 2 to control the working fluid to drop from the condensing pressure to the evaporating pressure, and to form a closed loop of the working fluid between the evaporator, compressor, condenser and expansion valve 3.

[0076] During operation, the first evaporator 4 absorbs low-grade heat from the external environment (such as air, water, or industrial waste heat sources), causing the liquid working fluid to evaporate into a low-temperature, low-pressure gaseous state, which then enters the inlet of the first compressor 1 through its outlet. The first compressor 1 compresses this gaseous working fluid, increasing its pressure and temperature, transforming it into a high-temperature, high-pressure gaseous state, which is then discharged from its exhaust end into the hot-side inlet of the first condenser 2. After entering the first condenser 2, the working fluid exchanges heat with an external heat sink (the high-temperature tank 7 of the heat storage module or its heat transfer medium) on the hot side, releasing heat and condensing itself into a high-pressure liquid state. Subsequently, the working fluid is throttled and depressurized by the expansion valve 3, its temperature drops, and it re-enters the first evaporator 4 to absorb heat and evaporate, completing one cycle.

[0077] Through the aforementioned structural connections and circulation process, the first evaporator 4 can utilize dispersed, low-grade available heat (such as surplus solar heat during the day or industrial waste heat). The first compressor 1 elevates this heat to high-grade thermal energy, which is then sent to the thermal storage module for storage by the first condenser 2. This arrangement ensures a stable heat source for the system during renewable energy off-peak periods, which can be used for subsequent organic Rankine cycle power generation or seawater desalination, thereby alleviating energy supply difficulties in remote areas caused by high grid extension costs. The expansion valve 3 plays a role in stabilizing throttling and controlling the working fluid state in the circuit. It can adapt to changes in evaporation and condensation temperatures, ensuring stable system operation under varying conditions and preventing efficiency drops or equipment damage due to sudden pressure changes.

[0078] In a preferred embodiment, the thermal storage module further includes a heat exchanger 9, and the pumps include a first water pump 6 and a second water pump 8. The low-temperature tank 5 stores seawater whose temperature has decreased after heat exchange, serving as a low-temperature thermal energy storage unit; the high-temperature tank 7 stores seawater whose temperature has increased after being heated by a heat pump module or an organic Rankine cycle module, serving as a high-temperature thermal energy storage unit. The inlet end of the first water pump 6 is connected to the outlet end of the low-temperature tank 5, and its outlet end is connected to the cold-side inlet end of the first condenser 2, used to transport the seawater (or heat transfer medium) in the low-temperature tank 5 to the first condenser 2 for further heating before sending it to the high-temperature tank 7. The heat exchanger 9 is disposed between the low-temperature tank 5 and the high-temperature tank 7 to realize heat transfer between the media in the two tanks. The second water pump 8 is disposed between the high-temperature tank 7 and the heat exchanger 9, used to transport the high-temperature seawater (or heat transfer medium) in the high-temperature tank 7 to the heat exchanger 9 for heat exchange with the low-temperature side medium, thereby realizing the transfer of thermal energy from the high-temperature side to the low-temperature side.

[0079] In thermal storage mode, the heat pump module raises the low-grade heat and then transfers it to the seawater delivered from the low-temperature tank 5 by the first water pump 6 and output from the cold side via the first condenser 2, raising its temperature before sending it to the high-temperature tank 7 for storage. The hot water in the high-temperature tank 7 can be extracted as needed in power generation or desalination modes. If the system needs to adjust the temperature between tanks or recover waste heat, the second water pump 8 can be activated to send the high-temperature seawater from the high-temperature tank 7 to the heat exchanger 9, where it exchanges heat with the low-temperature seawater on the low-temperature tank 5 side, raising the temperature on the low-temperature side and lowering the temperature on the high-temperature side, achieving internal heat reuse and temperature balance. The cooled seawater can be returned to the low-temperature tank 5, while the high-temperature water can re-enter the high-temperature tank 7 or enter the downstream heat consumption stage.

[0080] The output of the high-temperature tank 7 of the thermal storage module can be connected to an organic Rankine cycle module to convert thermal energy into electrical energy; it can also be connected to a seawater desalination module to provide the heat required for evaporation. The low-temperature tank 5 recovers the seawater after it releases heat and can then be reheated by the heat pump module, forming a closed or semi-closed cycle, reducing the burden of external water intake and drainage. This heat-water linkage design allows the same batch of seawater to be used multiple times in the thermal storage, power generation, and desalination stages, improving resource utilization efficiency and aligning with the invention's goal of achieving coordinated energy and freshwater supply in environments with power and water shortages.

[0081] In a preferred embodiment, the waste heat recovery module is used to collect low-grade or waste heat energy from outside the system, such as waste heat generated by ship generators or heat energy output from solar collectors. The waste heat recovery module can be independently equipped with a heat exchanger or heat pipe assembly to capture and export heat from external heat sources. The waste heat recovery module has two optional connection paths: first, it connects to the first evaporator 4 of the heat pump module, using the recovered heat energy as one of the heat sources for the first evaporator 4, allowing the working fluid to absorb this heat and evaporate in the evaporator; second, it connects to the low-temperature tank 5 of the heat storage module, used to preheat the low-temperature seawater before it enters the heat pump module, thereby reducing the heating load of the heat pump module. The two connection methods can be selected or used simultaneously depending on the type of heat source and energy consumption strategy on site.

[0082] When the system's environment has available external waste heat or solar energy, the waste heat recovery module first collects and transfers this heat. If connected to the first evaporator 4, the external heat flow enters the heat absorption circuit of the first evaporator 4, heating the working fluid together with the existing environmental heat source (such as air or water), causing it to evaporate into a low-temperature, low-pressure gaseous state in the evaporator, before entering the compressor for pressurization and heating. If connected to the low-temperature tank 5, the external heat flow preheats the low-temperature seawater that is about to enter the heat pump cycle in the low-temperature tank 5, increasing the initial temperature of the cold-side medium entering the first condenser 2, reducing the temperature difference for the heat pump module, and thus saving compression power consumption. The preheated seawater can be sent by the first water pump 6 to the first condenser 2 for further heating and then sent to the high-temperature tank 7 for storage.

[0083] The heat supplied by the waste heat recovery module, together with the heat pump module and the thermal storage module, forms a pre-heat supply, which can maintain the thermal storage module's charging capacity when renewable energy is insufficient. This ensures the stable output of the organic Rankine cycle module in power generation mode, or the continuous operation of the seawater desalination module in desalination mode. Since this module utilizes an external heat source that was not originally used by the system, it expands the system's heat input channels without increasing fossil fuel consumption, which aligns with the invention's goal of achieving coordinated energy and freshwater supply through localized and diversified heat sources.

[0084] In a preferred embodiment, the organic Rankine cycle module further includes a second condenser 11, and the working fluid pump is a working fluid pump 12. The outlet end of the working fluid pump 12 is connected to the cold side inlet of the heat exchanger 9, and is used to transport the circulating working fluid (such as cyclopentane, R245fa, R1233zd, etc., organic working fluids) to the heat exchanger 9 for heat exchange, thereby raising the temperature of the working fluid; the cold side outlet of the heat exchanger 9 is connected to the inlet side of the expander 10, and the heated high-temperature and high-pressure working fluid is sent into the expander 10; the outlet end of the expander 10 is connected to the inlet end of the second condenser 11, so that the low-pressure working fluid after work enters the second condenser 11; the outlet end of the second condenser 11 is connected to the inlet end of the working fluid pump 12, and the condensed liquid working fluid is sent back to the working fluid pump 12, thereby forming a closed loop of working fluid between the working fluid pump 12, the heat exchanger 9, the expander 10, and the second condenser 11.

[0085] In power generation mode, the high-temperature tank 7 of the thermal storage module delivers high-temperature water (or heat transfer medium) to the hot side of the heat exchanger 9, while the working fluid pump 12 simultaneously delivers liquid working fluid to the cold side inlet of the heat exchanger 9. The cold-side working fluid exchanges heat with the high-temperature water on the hot side in the heat exchanger 9, absorbing heat and becoming a high-temperature, high-pressure state, before entering the inlet of the expander 10 from the cold-side outlet. The expander 10 receives this high-temperature, high-pressure working fluid, converting its internal energy into mechanical energy (which can drive a generator to output electricity). During expansion, the pressure and temperature of the working fluid decrease, becoming low-pressure, low-temperature wet steam or a gas-liquid mixture, which then enters the second condenser 11. The second condenser 11 condenses the working fluid into a liquid state through heat exchange with an ambient cold source (such as air or cooling water), completing the heat release process. The liquid working fluid returns from the outlet of the second condenser 11 to the inlet of the working fluid pump 12, is pressurized again, and sent back to the heat exchanger 9 to begin the next cycle.

[0086] The organic Rankine cycle module's heat source comes from the thermal storage module, which can be supplemented by a heat pump module to boost low-grade heat or by waste heat captured by the waste heat recovery module, forming a chain of heat source acquisition → heating and storage → heat release and power generation. The generated electricity can be used for local loads and can also drive the compressor of the seawater desalination module in desalination mode, achieving synergy between power generation and desalination. Because the working fluid circulation loop is closed and relies on the thermal storage module for heat release, the system can continuously generate electricity without an external power grid, making it particularly suitable for remote locations such as islands, offshore platforms, and deserts.

[0087] In a preferred embodiment, the seawater desalination module further includes a fourth water pump 13 and a freshwater pump 17. The inlet end of the fourth water pump 13 is connected to the outlet end of the high-temperature tank 7 of the thermal storage module, and is used to transport the high-temperature seawater stored in the high-temperature tank 7 to the seawater desalination module; the seawater inlet end of the second evaporator 15 is connected to the outlet end of the fourth water pump 13, and is used to receive the high-temperature seawater and evaporate the water in the seawater into water vapor through heat exchange; the exhaust end of the second compressor 14 is connected to the hot side inlet of the second evaporator 15, and is used to pressurize and heat the working fluid before sending it into the second evaporator 15, where the working fluid releases heat on the hot side to evaporate the seawater and releases heat to the high-temperature seawater at the same time; the outlet end of the third condenser 16 is connected to the air inlet end of the second compressor 14, and the steam inlet end is connected to the steam outlet of the second evaporator 15, where the water vapor exchanges heat with the low-temperature working fluid, causing the water vapor to condense into high-purity liquid water, and the low-temperature working fluid absorbs heat and returns to the second compressor 14 after heating, forming a working fluid circulation loop.

[0088] In desalination mode, the fourth water pump 13 delivers high-temperature seawater from the high-temperature tank 7 to the second evaporator 15. The second compressor 14, driven by electricity, pressurizes and heats the working fluid, discharging it from the exhaust end into the hot-side inlet of the second evaporator 15. The working fluid releases heat on the hot side within the second evaporator 15, causing the flowing seawater to evaporate and produce water vapor. The water vapor enters the steam inlet of the third condenser 16 from the steam outlet of the second evaporator 15. In the third condenser 16, the water vapor exchanges heat with the low-temperature working fluid, releasing latent heat and condensing into liquid fresh water, which is then discharged from the outlet and transported to the desired location by the freshwater pump 17. The low-temperature working fluid absorbs heat, its temperature rises, and it returns to the inlet of the second compressor 14, completing the working fluid cycle.

[0089] The high-temperature seawater in the desalination module originates from the thermal storage module, whose heat can be supplemented by a heat pump module to boost low-grade heat or by waste heat captured by a waste heat recovery module, forming a closed loop of heat energy collection → storage → utilization. The produced freshwater can be used for local domestic or industrial purposes, alleviating water resource pressure in coastal areas or islands. The desalination and power generation processes can be carried out in parallel. For example, in the parallel mode of power generation and desalination, the high-temperature seawater can be diverted to achieve multi-purpose utilization of the same heat source, improve the overall energy efficiency of the system, and align with the goal of this invention to achieve coordinated energy and freshwater supply in remote environments.

[0090] Example 2

[0091] The present invention also provides an operation method for a Carnot battery coupled with a seawater desalination system that combines power generation and energy storage as described in Example 1, the steps of which include:

[0092] Thermal storage mode: When energy supply is sufficient or electricity prices are low, the first compressor 1 is started, creating a closed loop between the first evaporator 4, the first condenser 2, and the expansion valve 3. This process raises low-grade heat from the external environment to high-temperature heat, which is then released to the thermal storage module via the first condenser 2. Simultaneously, the first water pump 6 is started, transporting low-temperature seawater to the first condenser 2 to absorb heat and heat it to high-temperature seawater, which is then stored in the high-temperature tank 7. This mode utilizes surplus or inexpensive energy to store thermal energy in advance in the form of high-temperature seawater, providing a reserve heat source for subsequent power generation or desalination, and alleviating energy constraints in areas without power grids or with high fuel transportation costs.

[0093] Power generation mode: When energy supply is insufficient or electricity prices are high, the second water pump 8 is activated to flow high-temperature seawater from the high-temperature tank 7 through the heat exchanger 9. Simultaneously, the working fluid pump 12 is activated to send the organic Rankine cycle working fluid into the heat exchanger 9 to absorb heat and increase its temperature. The heated working fluid then enters the expander 10 to perform work, converting thermal energy into mechanical energy and outputting electricity. After performing work, the working fluid enters the second condenser 11 to condense into a liquid state, and is then returned to the heat exchanger 9 by the working fluid pump 12, forming a cycle. This mode utilizes the high-temperature heat released by the thermal storage module to continuously generate electricity, making up for the power gap during renewable energy off-peak periods or peak electricity demand, and reducing dependence on diesel power generation, etc.

[0094] Desalination Mode: The fourth water pump 13 is activated to draw high-temperature seawater from the high-temperature tank 7 to the second evaporator 15. When power is available, the second compressor 14 is activated to pressurize and heat the working fluid before sending it into the second evaporator 15. The working fluid releases heat, causing the seawater to evaporate into water vapor. The water vapor enters the third condenser 16, where it exchanges heat with the low-temperature working fluid and condenses into high-purity liquid water, which is then output. This mode allows the compressor to be driven directly by renewable energy sources when energy is abundant, and by electricity provided by the power generation mode when energy is insufficient, thus achieving continuous water production in mobile or remote scenarios without a stable power grid.

[0095] Parallel power generation and desalination mode: The second water pump 8, working fluid pump 12, second compressor 14, and fourth water pump 13 are simultaneously activated, diverting high-temperature seawater to heat exchanger 9 and second evaporator 15. Seawater flowing through heat exchanger 9 heats the organic Rankine cycle working fluid to generate electricity. Seawater flowing into the second evaporator 15 is reheated and evaporated, with the steam condensed in the third condenser 16 to produce water. By adjusting the flow distribution between the second water pump 8 and the fourth water pump 13, the power ratio for power generation and desalination can be controlled, enabling synergistic operation of both functions and improving the overall utilization efficiency of high-temperature seawater.

[0096] Parallel thermal storage and desalination mode: The first compressor 1, the first water pump 6, the second compressor 14, and the fourth water pump 13 are simultaneously activated. The first compressor 1 drives the heat pump cycle, which, under the action of the first condenser 2 and the first water pump 6, converts low-temperature seawater and low-grade heat into high-temperature seawater, which is then stored in the high-temperature tank 7. The fourth water pump 13 then leads the high-temperature seawater from the high-temperature tank 7 to the second evaporator 15 for heating and evaporation. The water vapor is condensed by the third condenser 16 to form high-purity liquid water. This mode allows desalination to occur simultaneously with heat storage, achieving synchronous thermal energy storage and freshwater production, reducing system idle time, and improving overall resource utilization.

[0097] The aforementioned modes, through the combination of features such as heat pump modules to enhance and store low-grade heat, thermal storage modules for cross-period scheduling, organic Rankine cycle modules for on-demand power generation, and seawater desalination modules for flexible drive mode selection, enable the system to achieve coordinated energy and freshwater supply in areas lacking electricity and water. The modes can be switched on demand or operated in parallel, making full use of localized and diverse heat and power sources, avoiding long-term dependence on high-cost power grids or fossil fuels, thus structurally effectively supporting the invention's goal of solving the combined problems of "electricity and water shortage" in remote areas.

[0098] This invention couples a Carnot battery with evaporative condensation desalination technology, enabling the use of multiple energy sources such as solar, wind, and industrial waste heat. This improves energy efficiency and reduces fossil fuel combustion and ecological costs. The Carnot battery offers advantages such as low cost, high stability, no pollution, and superior cycle performance compared to lithium batteries, achieving efficient energy storage. The evaporative condensation desalination technology features simple equipment, good cycle performance, low cost, and high-purity water, meeting freshwater needs in various scenarios. The system can store heat when energy is abundant and generate electricity when energy is scarce. The electricity can be supplied externally or used for desalination, achieving coordinated energy and freshwater supply and balancing peak and off-peak electricity prices to improve economic efficiency. The overall equipment has a simple structure, complete functions, and flexible operation, facilitating deployment in decentralized scenarios such as ships, islands, and desert oases. This significantly reduces investment in local power plants and freshwater equipment, effectively alleviating power and water shortages in remote areas.

[0099] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A Carnot battery coupled seawater desalination system that combines power generation and energy storage, characterized in that, include: Heat pump modules are used to heat low-grade heat from renewable energy sources into heat at higher temperatures; A heat storage module, connected to the heat pump module, is used to store the heat provided by the heat pump module; An organic Rankine cycle module is connected to the thermal storage module and generates electricity using the heat released by the thermal storage module. The seawater desalination module is used to desalinate seawater through evaporation and condensation technology. It is connected to the thermal storage module and selectively uses renewable energy or the electricity output from the organic Rankine cycle module to desalinate seawater according to the energy supply status, so as to realize the coordinated operation of thermal energy storage and seawater desalination.

2. The Carnot battery-coupled seawater desalination system with both power generation and energy storage as described in claim 1, characterized in that, The heat pump module includes: The first compressor is used to compress the working fluid to increase its pressure and temperature; The first evaporator, whose outlet end is connected to the inlet end of the first compressor, is used to absorb heat from the external environment and evaporate the working fluid into a low-temperature, low-pressure gaseous state. The first condenser has its hot-side inlet end connected to the exhaust end of the first compressor, and is used to release the heat of the high-temperature and high-pressure gaseous working fluid to an external heat sink. An expansion valve is located between the first evaporator and the first condenser to regulate the working fluid pressure and temperature, forming a closed loop of the working fluid between the evaporator, compressor, condenser and expansion valve.

3. A Carnot battery coupled seawater desalination system with both power generation and energy storage as described in claim 2, characterized in that, The thermal storage module includes: Low-temperature tanks are used to store seawater whose temperature has decreased after heat exchange, serving as low-temperature thermal energy storage units. High-temperature tanks are used to store seawater whose temperature has increased after being heated by a heat pump module, serving as high-temperature thermal energy storage units. The first water pump has its inlet end connected to the outlet end of the low-temperature tank and its outlet end connected to the cold side outlet end of the first condenser. It is used to introduce the working fluid in the low-temperature tank into the first condenser to absorb heat and transport it to the high-temperature tank. A heat exchanger is installed between the low-temperature tank and the high-temperature tank to realize the heat transfer between the high-temperature working fluid and the low-temperature working fluid; The second water pump is installed between the high-temperature tank and the heat exchanger to transport the high-temperature working fluid stored in the high-temperature tank to the heat exchanger for heat exchange, thereby realizing the transfer of heat energy from the high-temperature working fluid to the low-temperature working fluid.

4. A Carnot battery coupled seawater desalination system with both power generation and energy storage as described in claim 3, characterized in that, The organic Rankine cycle module includes: A working fluid pump, the outlet of which is connected to the cold side inlet of the heat exchanger, is used to transport the circulating working fluid to the heat exchanger for heat exchange and to increase the working fluid temperature. An expander, whose inlet side is connected to the cold side outlet of the heat exchanger, is used to receive the high-temperature and high-pressure working fluid heated by the heat exchanger and convert the thermal energy of the working fluid into mechanical energy. The second condenser has its outlet end connected to the inlet end of the working fluid pump and its inlet end connected to the outlet end of the expander. It is used to condense the low-pressure working fluid discharged from the expander into a liquid state, forming a closed loop of working fluid between the working fluid pump, heat exchanger, expander and second condenser.

5. A Carnot battery coupled seawater desalination system combining power generation and energy storage according to claim 3, characterized in that, The seawater desalination module includes: The fourth water pump, whose inlet end is connected to the outlet end of the high-temperature tank, is used to transport the high-temperature seawater stored in the thermal storage module to the seawater desalination module. The second evaporator has its seawater inlet end connected to the outlet end of the fourth water pump. It is used to receive the high-temperature seawater in the high-temperature tank and evaporate the water in the seawater into water vapor through heat exchange. The second compressor has its exhaust end connected to the hot side inlet of the second evaporator. It is used to pressurize and heat the working fluid and send it into the second evaporator. The heat released by the working fluid causes the seawater to evaporate and release heat to the high-temperature seawater. The third condenser has its outlet end connected to the inlet end of the second compressor and its steam inlet end connected to the steam outlet of the second evaporator. It is used to exchange heat between water vapor and low-temperature working fluid, so that the water vapor is condensed into high-purity liquid water, while the low-temperature working fluid absorbs heat and rises in temperature.

6. A Carnot battery coupled seawater desalination system combining power generation and energy storage according to any one of claims 3-5, characterized in that, The Carnot battery-coupled seawater desalination system, which combines power generation and energy storage, also includes a waste heat recovery module for collecting heat energy from outside the system. The waste heat recovery module is connected to the first evaporator to provide it with a heat source; And / or, the waste heat recovery module is connected to the cryogenic tank for preheating the cryogenic seawater inside.

7. A method for operating a Carnot battery coupled with a seawater desalination system that combines power generation and energy storage as described in any one of claims 1-4, characterized in that, The steps include: Thermal storage mode: When energy supply is sufficient or electricity price is low, the first compressor is started to drive the working fluid to complete the heat pump cycle, and release heat to the thermal storage module through the first condenser; at the same time, the first water pump is started to make low temperature seawater flow through the first condenser to absorb heat and heat up to high temperature seawater and store it in the high temperature tank. Power generation mode: When energy supply is insufficient or electricity price is high, the second water pump is started to make high temperature seawater flow through the heat exchanger, and the working fluid pump is started to make the working fluid heat up through the heat exchanger and then enter the expander to do work and generate electricity. Desalination mode: The fourth water pump is started to draw high-temperature seawater to the second evaporator, and the second compressor is started under electric drive to pressurize and heat the working fluid and send it into the second evaporator. The working fluid releases heat to evaporate the seawater, and the water vapor enters the third condenser and is condensed to form high-purity liquid water. Parallel power generation and desalination mode: The second water pump, the second compressor, the working fluid pump, and the fourth water pump are started simultaneously to divert the high-temperature seawater to the heat exchanger and the second evaporator to complete power generation and desalination respectively; Parallel mode of heat storage and desalination: The first compressor, the second compressor, the first water pump and the fourth water pump are started at the same time. Heat is stored under the action of the first condenser and the first water pump, and the high-temperature seawater in the tank is led to the second evaporator by the fourth water pump to evaporate and condense water.

8. The operating method according to claim 5, characterized in that, In the desalination mode, the fourth water pump delivers the high-temperature seawater from the high-temperature tank to the second evaporator. The second compressor, driven by electricity, pressurizes and heats the working fluid and sends it into the second evaporator. The working fluid releases heat to the high-temperature seawater, causing the seawater to evaporate into water vapor. The water vapor enters the third condenser, exchanges heat with the low-temperature working fluid, and condenses into high-purity liquid water, which is then output.

9. The operating method according to claim 5, characterized in that, In the parallel power generation and desalination mode, the proportion of high-temperature seawater diverted to the heat exchanger and the second evaporator is controlled by adjusting the flow distribution of the second and fourth water pumps, thereby achieving coordinated operation of power generation and desalination functions.

10. The operating method according to claim 5, characterized in that, In the parallel mode of thermal storage and desalination, when the first compressor drives the working fluid to complete the heat pump cycle, the high-temperature seawater in the high-temperature tank is led to the second evaporator by the fourth water pump for heating and evaporation. The water vapor enters the third condenser and is condensed by the low-temperature working fluid to form high-purity liquid water, thus realizing the simultaneous operation of thermal energy storage and freshwater production.

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