Carnot battery system based on multi-stream heat exchange

Abstract

The invention belongs to the technical field of Carnot battery energy storage, and provides a Carnot battery system based on multi-stream heat exchange, which comprises an energy charging circulation loop including a compressor, a multi-stream air cooler, a first multi-stream heat regenerator, a throttle valve and an evaporator; and the energy release circulation loop comprises a condenser, a high-pressure working medium pump, a second multi-stream heat regenerator, a multi-stream heater and a turbine. The high-grade heat storage medium and the low-grade heat storage medium are used for storing the high-grade heat energy and the low-grade heat energy in the energy charging circulation and correspondingly used for conducting high-temperature heating and preheating on the working medium in the energy discharging circulation, so that the stored heat energy and the released heat energy are matched, the heat exchange end difference is reduced, and # imgabs0 # loss is reduced. And meanwhile, in the energy charging circulation, the first multi-strand heat regenerator divides a high-temperature side working medium into two parts which are used for heating a low-grade heat storage medium and a low-temperature side working medium correspondingly, and # imgabs 1 # loss in the heat regeneration process can be reduced. Therefore, the Carnot battery system based on multi-stream heat exchange can effectively reduce # imgabs2 loss of the system, so that the electricity-to-electricity conversion efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of Carnot battery energy storage, and in particular to a Carnot battery system based on multi-stream heat exchange. Background Art

[0002] As the global climate change problem becomes increasingly serious, countries have proposed carbon neutrality goals. China has pledged to reach the peak of carbon emissions around 2030, and gradually reduce the proportion of coal-fired power and increase the use of renewable energy. This transformation requires large-scale access to new energy sources such as wind power and photovoltaic power generation, but these energy sources are random, volatile and seasonally unbalanced, which brings balance problems to the power system. Energy storage technology is an important means to achieve a high proportion of new energy access to the power grid. It can improve the grid's ability to accept new energy, reduce peaks and fill valleys, participate in frequency and voltage regulation, and thus improve the overall efficiency and economy of the power system, which not only helps to improve the quality of electricity, but also reduces operating costs. In general, in order to achieve the stability of the power grid and the high penetration rate of renewable energy, low-cost, high-efficiency, large-capacity and environmentally friendly energy storage technology is needed. Carnot Battery (CB) is an energy storage system based on the Carnot cycle principle. It converts electrical energy into heat and cold energy for storage, and releases heat and cold energy in the power cycle to generate electricity when needed, thereby realizing the storage and conversion of electrical energy. The overall process flow of the Carnot battery is divided into a charging phase and a discharging phase, wherein the charging phase is a heat pump cycle and the discharging phase is a power generation cycle. This system is particularly suitable for dealing with the intermittent and unstable nature of renewable energy because it can store energy on a large scale and for a long time and has a high energy conversion efficiency.

[0003] CO2, as a common working medium in the Carnot battery system, stores and releases energy through the process of compression, storage, and expansion. Since the constant-pressure specific heat capacity of CO2 changes dramatically near the quasi-critical temperature and reaches its maximum value at the quasi-critical temperature, the thermal energy of the supercritical CO2 fluid is concentrated near the quasi-critical temperature in the heat pump cycle during the charging stage of the Carnot battery. However, the quasi-critical temperature of supercritical CO2 is different at different pressures. When the high-pressure side pressures of the Carnot battery charging process and the discharge process are different, the quality and quantity of the heat energy stored / released during the charging / discharging stage will be less adaptable, resulting in a higher heat exchange end difference under the limit of the minimum pinch point temperature, which increases the difference between the charging and discharging processes of the Carnot battery. This limits the power-to-electricity efficiency of the system. Summary of the invention

[0004] In view of the above problems, the present invention provides a Carnot battery system based on multi-stream heat exchange, which collects and stores high-grade thermal energy and low-grade thermal energy respectively in the charging stage, and heats and preheats the working fluid correspondingly in the discharging stage, so that the stored and released thermal energy are matched, effectively reducing the heat exchange end difference and reducing loss, thus improving the power-to-electricity efficiency of the entire system.

[0005] The present invention provides a Carnot battery system based on multi-stream heat exchange, comprising: a charging circulation loop, comprising a compressor, a multi-stream air cooler, a first multi-stream heat exchanger, a throttle valve and an evaporator connected in sequence, the evaporator is then connected to the compressor through the first multi-stream heat exchanger to form a loop, and a charging medium circulates in the charging circulation loop;

[0006] The energy release circulation loop includes a condenser, a high-pressure working medium pump, a second multi-stream heat exchanger, a multi-stream heater and a turbine connected in sequence. The turbine is connected to the condenser through the second multi-stream heat exchanger to form a loop. The energy release circulation loop has an energy release working medium circulating therein.

[0007] Among them, a high-grade heat storage medium also flows in the multi-stream air cooler, which absorbs and stores the high-grade heat energy in the charging medium after being compressed by the compressor.

[0008] A low-grade heat storage medium also flows in the first multi-stream heat regenerator, and the low-grade heat storage medium absorbs and stores the low-grade heat energy in the charging medium after absorbing heat in the multi-stream air cooler.

[0009] The second multi-stream heat regenerator receives low-grade heat storage medium with low-grade thermal energy, and preheats the exothermic medium by the low-grade thermal energy.

[0010] The multi-stream heater receives a high-grade heat storage medium with high-grade thermal energy, and heats the exothermic working fluid to a high-temperature state through the high-grade thermal energy so that the exothermic working fluid can enter the turbine to expand and do work.

[0011] According to the above technical solution, the high-grade heat energy in the compressed charging medium is collected and stored by the high-grade heat storage medium, and is correspondingly released to the multi-stream heater to heat the high-temperature of the releasing medium, and then the low-grade heat energy in the charging medium is collected by the low-grade heat storage medium, and is correspondingly released to the second multi-stream heat regenerator to preheat the releasing medium, so that the stored and released heat energy are matched, which can reduce the heat exchange end difference and reduce loss, thereby improving the power-to-electricity efficiency of the entire system.

[0012] In an optional technical solution of the present invention, a high-grade heat absorption channel is provided in the multi-stream air cooler, a high-grade heating channel is provided in the multi-stream heater, a high-grade heat storage medium flows through both the high-grade heat absorption channel and the high-grade heating channel, the high-grade heat absorption channel is also connected to a high-grade heat storage medium hot tank, and the high-grade heat storage medium with high-grade thermal energy is stored, and the high-grade heat storage medium hot tank is connected to the high-grade heating channel, and the high-grade heating channel is also connected to The high-grade heat storage medium cold tank stores the high-grade heat storage medium before absorbing heat and storing energy or after releasing high-grade heat energy, and the high-grade heat storage medium cold tank is connected with the high-grade heat absorption flow channel, and the high-grade heat storage medium circulates among the high-grade heat absorption flow channel, the high-grade heat storage medium hot tank, the high-grade heating flow channel and the high-grade heat storage medium cold tank, and absorbs the high-grade heat energy of the charging working fluid in the multi-stream air cooler, and releases the high-grade heat energy to the releasing working fluid in the multi-stream heater.

[0013] According to the technical solution, high-grade thermal energy is stored separately by providing a high-grade thermal storage medium hot tank and a high-grade thermal storage medium cold tank, thereby facilitating the independent circulation and use of high-grade thermal energy.

[0014] In an optional technical solution of the present invention, the number of high-grade heat absorption flow channels is multiple, and the number of high-grade heat storage medium hot tanks, high-grade heating flow channels and high-grade heat storage medium cold tanks matches the number of high-grade heat absorption flow channels, and are connected one-to-one.

[0015] According to this technical solution, by providing a plurality of high-quality heat absorption channels, the contact area with the energetic working fluid during heat exchange can be increased, thereby enhancing the heat exchange efficiency.

[0016] In an optional technical solution of the present invention, different types of high-grade heat storage media flow through each high-grade heat absorption flow channel to collect, store and circulate high-grade thermal energy at different temperatures.

[0017] According to the technical solution, by using different types of high-grade heat storage media, high-grade thermal energy at different temperatures can be collected and stored in segments, which is convenient for high-temperature heating of the working fluid in the energy release cycle, and further matches the stored and released thermal energy.

[0018] In an optional technical solution of the present invention, a first low-grade flow channel is provided in the first multi-stream heat regenerator, and a second low-grade flow channel is provided in the second multi-stream heat regenerator. Low-grade heat storage medium flows through both the first low-grade flow channel and the second low-grade flow channel. The first low-grade flow channel is also connected to a low-grade heat storage medium hot tank to store low-grade heat storage medium with low-grade thermal energy. The low-grade heat storage medium hot tank is connected to the second low-grade flow channel, and the second low-grade flow channel is also connected to The low-grade heat storage medium cold tank stores the low-grade heat storage medium before absorbing heat and storing energy or after releasing low-grade heat energy, and the low-grade heat storage medium cold tank is connected with the first low-grade flow channel, and the low-grade heat storage medium circulates among the first low-grade flow channel, the low-grade heat storage medium hot tank, the second low-grade flow channel, and the low-grade heat storage medium cold tank, and absorbs the low-grade heat energy of the charging working fluid in the first multi-stream heat regenerator, and releases the low-grade heat energy to the releasing working fluid in the second multi-stream heat regenerator.

[0019] According to the technical solution, low-grade thermal energy is stored separately by providing a low-grade heat storage medium hot tank and a low-grade heat storage medium cold tank, thereby facilitating the independent circulation and use of low-grade thermal energy.

[0020] In an optional technical solution of the present invention, a first high-temperature side energetic working fluid flow channel, a second high-temperature side energetic working fluid flow channel and a low-temperature side energetic working fluid flow channel are provided in the first multi-stream heat exchanger, the inlets of the first high-temperature side energetic working fluid flow channel and the second high-temperature side energetic working fluid flow channel are both connected to the working fluid outlet of the multi-stream air cooler, the outlets of the first high-temperature side energetic working fluid flow channel and the second high-temperature side energetic working fluid flow channel are both connected to the working fluid inlet of the throttle valve, and the first high-temperature side energetic working fluid flow channel and the second high-temperature side energetic working fluid flow channel are uniformly connected to the working fluid inlet of the throttle valve. The charging medium after high-grade thermal energy is absorbed is passed through the first high-temperature side charging medium flow channel to exchange heat with the first low-grade flow channel, the inlet of the low-temperature side charging medium flow channel is connected with the working medium outlet of the evaporator, the outlet of the low-temperature side working medium flow channel is connected with the working medium inlet of the compressor, the charging medium that has successively expanded through the throttle valve and evaporated in the evaporator flows in the low-temperature side charging medium flow channel, the charging medium in the low-temperature side charging medium flow channel is reheated through the second high-temperature side charging medium flow channel, and is passed into the compressor.

[0021] According to the technical solution, the high-temperature side energetic working fluid is divided into two parts through the first high-temperature side energetic working fluid flow channel and the second high-temperature side energetic working fluid flow channel. The first high-temperature side energetic working fluid flow channel can exchange heat with the low-grade heat storage medium to store low-grade thermal energy. At the same time, the second high-temperature side energetic working fluid flow channel can directly use the low-grade thermal energy to recover the low-temperature side energetic working fluid, which can make full use of the low-grade thermal energy and effectively reduce the energetic working fluid in the process of heat recovery. damage.

[0022] In an optional technical solution of the present invention, a high-temperature side energy-releasing working fluid flow channel and a low-temperature side energy-releasing working fluid flow channel are provided in the second multi-stream heat regenerator, the inlet of the high-temperature side energy-releasing working fluid flow channel is connected with the working fluid outlet of the turbine, the outlet of the high-temperature side energy-releasing working fluid flow channel is connected with the working fluid inlet of the condenser, the high-temperature side energy-releasing working fluid flow channel has energy-releasing working fluid that has expanded and done work in the turbine flowing through the high-temperature side energy-releasing working fluid flow channel, and after releasing the residual heat, it is passed into the condenser, the inlet of the low-temperature side energy-releasing working fluid flow channel is connected with the working fluid outlet of the high-pressure working fluid pump, the outlet of the low-temperature side energy-releasing working fluid flow channel is connected with the working fluid inlet of the multi-stream heater, the low-temperature side energy-releasing working fluid flow channel has energy-releasing working fluid that has been pressurized by the high-pressure working fluid pump flowing through the low-temperature side energy-releasing working fluid flow channel, and is preheated by the low-grade thermal energy of the low-grade heat storage medium and the residual heat released by the energy-releasing working fluid in the high-temperature side energy-releasing working fluid flow channel.

[0023] According to the technical solution, while using low-grade thermal energy to preheat the exothermic working fluid, the exothermic working fluid is also preheated by using the waste heat of the exothermic working fluid after expansion and work through the high-temperature side exothermic working fluid flow channel, thereby achieving full utilization of thermal energy.

[0024] In an optional technical solution of the present invention, a cold storage medium flows through both the evaporator and the condenser, and the evaporator and the condenser are also connected to a cold storage medium hot tank and a cold storage medium cold tank for storing the cold storage medium. The evaporator, the cold storage medium cold tank, the condenser, and the cold storage medium hot tank are connected in sequence to form a loop for circulating the cold storage medium. The cold storage medium releases heat in the evaporator to evaporate the energy-charging working fluid, and absorbs heat in the condenser to cool the energy-releasing working fluid.

[0025] In an optional technical solution of the present invention, the charging working fluid and the discharging working fluid are both CO2, the charging cycle loop and the discharging cycle loop are both transcritical cycles, and the pressure on the high-pressure side is greater than the critical pressure of CO2, and the pressure on the low-pressure side is lower than the critical pressure of CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a Carnot battery system based on multi-stream heat exchange in an embodiment of the present invention.

[0027] Figure numerals: charging circulation loop 100, compressor 1, multi-stream air cooler 2, high-grade heat absorption flow channel 21, first multi-stream heat regenerator 3, low-temperature side charging working medium flow channel 31, throttle valve 4, evaporator 5, energy release circulation loop 200, condenser 6, high-pressure working medium pump 7, second multi-stream heat regenerator 8, low-temperature side energy release working medium flow channel 81, high-temperature side energy release working medium flow channel 82, multi-stream heater 9, high-grade heating flow channel 91, turbine 10, high-grade heat storage medium hot tank 11, high-grade heat storage medium cold tank 12, low-grade heat storage medium hot tank 13, low-grade heat storage medium cold tank 14, cold storage medium cold tank 15, cold storage medium hot tank 16. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Figure 1 It is a schematic structural diagram of a Carnot battery system based on multi-stream heat exchange in an embodiment of the present invention.

[0030] like Figure 1 As shown, a Carnot battery system based on multi-stream heat exchange of the present invention includes a charging cycle loop 100 and a discharging cycle loop 200.

[0031] The charging circulation loop 100 includes a compressor 1, a multi-stream air cooler 2, a first multi-stream heat regenerator 3, a throttle valve 4 and an evaporator 5 which are connected in sequence. The evaporator 5 is then connected to the compressor 1 through the multi-stream heat regenerator 3 to form a loop. Charging working fluid circulates in the charging circulation loop 100.

[0032] The energy release circulation loop 200 includes a condenser 6, a high-pressure working fluid pump 7, a second multi-stream heat regenerator 8, a multi-stream heater 9 and a turbine 10 which are connected in sequence. The turbine 10 is then connected to the condenser 6 through the second multi-stream heat regenerator 8 to form a loop. Energy release working fluid circulates in the energy release circulation loop 200.

[0033] A high-grade heat storage medium also flows in the multi-stream air cooler 2 , and the high-grade heat storage medium absorbs and stores the high-grade heat energy in the charging medium compressed by the compressor 1 .

[0034] A low-grade heat storage medium also flows in the first multi-stream heat regenerator 3 , and the low-grade heat storage medium absorbs and stores the low-grade heat energy in the charging medium after absorbing heat in the multi-stream air cooler 2 .

[0035] The second multi-stream regenerator 8 receives the low-grade heat storage medium having low-grade thermal energy, and preheats the exothermic working medium by the low-grade thermal energy.

[0036] The multi-stream heater 9 receives a high-grade heat storage medium having high-grade thermal energy, and heats the exothermic working medium by the high-grade thermal energy to a high-temperature state where the exothermic working medium can enter the turbine 10 to expand and do work.

[0037] The high-grade heat storage medium is used to store the high-temperature and high-pressure charging medium generated by compression, and correspondingly releases it to the multi-stream heater 9 to heat the high-temperature discharging medium. The low-grade heat storage medium is then used to collect the low-grade heat energy, and correspondingly releases it to the second multi-stream regenerator 8 to preheat the discharging medium. This achieves matching of the stored and released heat energy, which can reduce the heat exchange end difference and reduce loss, thereby improving the power-to-electricity efficiency of the entire system.

[0038] A high-grade heat absorption channel 21 is provided in the multi-stream air cooler 2, and a high-grade heating channel 91 is provided in the multi-stream heater 9. High-grade heat storage medium flows through both the high-grade heat absorption channel 21 and the high-grade heating channel 91. The high-grade heat absorption channel 21 is also connected to a high-grade heat storage medium hot tank 11, which stores high-grade heat storage medium with high-grade thermal energy, and the high-grade heat storage medium hot tank 11 is connected to the high-grade heating channel 91. The high-grade heating channel 91 is also connected to a high-grade heat storage medium cold tank 12, which stores high-grade heat storage medium before heat absorption and energy storage or after high-grade thermal energy release, and the high-grade heat storage medium cold tank 12 is connected to the high-grade heat absorption channel 21.

[0039] The high-grade heat storage medium circulates among the high-grade heat absorption channel 21, the high-grade heat storage medium hot tank 11, the high-grade heating channel 91, and the high-grade heat storage medium cold tank 12, and absorbs the high-grade thermal energy of the charging medium in the multi-stream air cooler 2, and releases the high-grade thermal energy to the releasing medium in the multi-stream heater 9.

[0040] The first multi-stream heat exchanger 3 is provided with a first low-grade flow channel (not shown in the figure), and the second multi-stream heat exchanger 8 is provided with a second low-grade flow channel (not shown in the figure), and low-grade heat storage medium flows in both the first low-grade flow channel and the second low-grade flow channel. The first low-grade flow channel is also connected to a low-grade heat storage medium hot tank 13, which stores low-grade heat storage medium with low-grade thermal energy, and the low-grade heat storage medium hot tank 13 is connected to the second low-grade flow channel, and the second low-grade flow channel is also connected to a low-grade heat storage medium cold tank 14, which stores low-grade heat storage medium before absorbing heat and storing energy or after releasing low-grade thermal energy, and the low-grade heat storage medium cold tank 14 is connected to the first low-grade flow channel.

[0041] The low-grade heat storage medium circulates among the first low-grade flow channel, the low-grade heat storage medium hot tank 13, the second low-grade flow channel, and the low-grade heat storage medium cold tank 14, and absorbs the low-grade thermal energy of the charging medium in the first multi-stream heat regenerator 3, and releases the low-grade thermal energy to the releasing medium in the second multi-stream heat regenerator 8.

[0042] By arranging a high-grade heat storage medium hot tank 11, a high-grade heat storage medium cold tank 12 and a low-grade heat storage medium hot tank 13, a low-grade heat storage medium cold tank 14, high-grade thermal energy and low-grade thermal energy are stored separately, so that high-grade thermal energy and low-grade thermal energy can be collected, stored and released separately in the charging / discharging stage.

[0043] Furthermore, the number of high-grade heat absorption channels 21 is multiple, and the number of high-grade heat storage medium hot tank 11, high-grade heating channel 91 and high-grade heat storage medium cold tank 12 matches the number of high-grade heat absorption channels 21, and they are connected one by one. By providing multiple high-grade heat absorption channels 21, the contact area during heat exchange with the charging medium can be increased, thereby enhancing the heat exchange efficiency.

[0044] Furthermore, different types of high-grade heat storage media flow in each high-grade heat absorption flow channel 21, and the mass flow rates are different, so as to collect, store and circulate high-grade thermal energy at different temperatures. By using different types of high-grade heat storage media, high-grade thermal energy at different temperatures can be collected and stored in stages, which is convenient for high-temperature heating of the working fluid in the energy release cycle, and further matches the stored and released thermal energy.

[0045] In this embodiment, the multi-stream air cooler 2 is provided with two high-grade heat absorption channels 21, and two high-grade heat storage medium hot tanks 11, high-grade heating channels 91 and high-grade heat storage medium cold tanks 12 are provided, and are connected one by one to form two high-grade heat storage medium circulation loops. Among them, the high-grade heat storage media used are high-pressure water and low-temperature molten salt, respectively, to collect and use high-grade thermal energy at different temperatures. At the same time, the low-grade heat storage medium uses normal pressure water to collect and use low-grade thermal energy.

[0046] Furthermore, the heat storage medium is not limited to common sensible heat storage fluids such as high-pressure water and molten salt, but also includes latent heat storage fluids such as paraffin, salts (such as sodium nitrate, sodium acetate), organic compounds, etc., as well as thermochemical heat storage fluids.

[0047] In some embodiments, the first low-grade flow channel, the low-grade heat storage medium hot tank 13, the second low-grade flow channel, and the low-grade heat storage medium cold tank 14 can also be set to multiple and connected one by one, so as to improve the heat exchange efficiency. And low-grade heat energy of different temperatures can also be collected by using different low-grade heat storage media.

[0048] The first multi-stream heat regenerator 3 is provided with a first high-temperature side energetic working medium flow channel (not shown in the figure), a second high-temperature side energetic working medium flow channel (not shown in the figure) and a low-temperature side energetic working medium flow channel 31. The inlets of the first high-temperature side energetic working medium flow channel and the second high-temperature side energetic working medium flow channel are both connected to the working medium outlet of the multi-stream air cooler 2, and the outlets of the first high-temperature side energetic working medium flow channel and the second high-temperature side energetic working medium flow channel are both connected to the working medium inlet of the throttle valve 4. The energetic medium after high-grade thermal energy is absorbed flows through the first high-temperature side energetic working medium flow channel and the second high-temperature side energetic working medium flow channel, and the low-grade thermal energy in the energetic medium is collected by heat exchange between the first high-temperature side energetic working medium flow channel and the first low-grade flow channel.

[0049] The inlet of the low-temperature side energizing working fluid flow channel 31 is connected to the working fluid outlet of the evaporator 5, and the outlet of the low-temperature side energizing working fluid flow channel is connected to the working fluid inlet of the compressor 1. The energizing working fluid that has been expanded by the throttle valve 4 and evaporated by the evaporator 5 in sequence flows in the low-temperature side energizing working fluid flow channel 31. The energizing working fluid in the low-temperature side energizing working fluid flow channel 31 is reheated through the second high-temperature side energizing working fluid flow channel and is passed into the compressor 1.

[0050] The energetic working fluid that has absorbed high-grade thermal energy through the multi-stream air cooler 2 is diverted through the first high-temperature side energetic working fluid flow channel and the second high-temperature side energetic working fluid flow channel. A portion of the energetic working fluid exchanges heat with the first low-grade flow channel through the first high-temperature side energetic working fluid flow channel, collecting and storing low-grade thermal energy; the other portion of the energetic working fluid regenerates heat to the energetic working fluid in the low-temperature side energetic working fluid flow channel 31 through the second high-temperature side energetic working fluid flow channel, making full use of the low-grade thermal energy of the energetic working fluid, which can effectively reduce the energetic working fluid regeneration process. damage.

[0051] The second multi-stream heat regenerator 8 is provided with a high-temperature side energy-releasing working fluid flow channel 82 and a low-temperature side energy-releasing working fluid flow channel 81. The inlet of the high-temperature side energy-releasing working fluid flow channel 82 is connected to the working fluid outlet of the turbine 10, and the outlet of the high-temperature side energy-releasing working fluid flow channel 82 is connected to the working fluid inlet of the condenser 6.

[0052] The high-temperature side energy-releasing medium flow passage 82 is filled with energy-releasing medium that has expanded and done work in the turbine 10, and is passed into the condenser 6 after releasing the residual heat. The inlet of the low-temperature side energy-releasing medium flow passage 81 is connected to the working medium outlet of the high-pressure working medium pump 7, and the outlet of the low-temperature side energy-releasing medium flow passage 81 is connected to the working medium inlet of the multi-stream heater 9. The low-temperature side energy-releasing medium flow passage 81 is filled with energy-releasing medium that has been pressurized by the high-pressure working medium pump 7, and is preheated by the low-grade heat energy of the low-grade heat storage medium and the residual heat released by the energy-releasing medium in the high-temperature side energy-releasing medium flow passage 82.

[0053] The waste heat of the exothermic medium after expansion and work can be utilized through the high-temperature side exothermic medium flow channel 82, and the exothermic medium in the low-temperature side exothermic medium flow channel 81 can be preheated together with the low-grade thermal energy, thereby achieving full utilization of thermal energy.

[0054] In addition, in this embodiment Figure 1 The shapes and positions of the various flow channels illustrated are for illustrative purposes only and should not constitute a limitation on the flow channel structure. Technicians can adjust the shapes and positions of the flow channels as needed to achieve sufficient heat exchange.

[0055] A cold storage medium flows through both the evaporator 5 and the condenser 6. The evaporator 5 and the condenser 6 are also connected to a cold storage medium hot tank 16 and a cold storage medium cold tank 15 for storing the cold storage medium. The evaporator 5, the cold storage medium cold tank 15, the condenser 6, and the cold storage medium hot tank 16 are sequentially connected to form a loop to circulate the cold storage medium. The cold storage medium releases heat in the evaporator 5 to evaporate the energy-charging medium, and absorbs heat in the condenser 6 to cool the energy-releasing medium.

[0056] Furthermore, the cold storage process is not limited to the common water storage, but also includes ice storage, hydrate storage, eutectic salt storage and other cold storage methods.

[0057] Furthermore, the charging medium and the discharging medium are both CO2, and both the charging cycle loop 100 and the discharging cycle loop 200 are transcritical cycles, and the high-pressure side pressure is greater than the critical pressure of CO2 (7.38MPa), and the low-pressure side pressure is lower than the critical pressure of CO2. At the same time, the charging cycle and the discharging cycle are not limited to single-stage compression and single-stage expansion modes, but also include multi-stage compression and multi-stage expansion modes.

[0058] The working process of the Carnot battery system based on multi-stream heat exchange in this embodiment is as follows:

[0059] During the charging cycle, CO2 gas is compressed into a high-temperature supercritical fluid by the compressor 1 and passed into the multi-stream air cooler 2. After the high-grade heat storage medium in the multi-stream air cooler 2 absorbs the high-grade heat energy in the CO2 fluid, the CO2 fluid continues to pass into the first multi-stream heat regenerator 3, and is divided and respectively passed into the first high-temperature side charging fluid flow channel and the second high-temperature side charging fluid flow channel. The low-grade heat storage medium absorbs low-grade heat energy by heat exchange with the first high-temperature side charging fluid flow channel. The CO2 fluid flowing out of the first high-temperature side charging fluid flow channel and the second high-temperature side charging fluid flow channel expands through the throttle valve 4 to become a low-temperature two-phase flow fluid and passes into the evaporator 5. The cold storage medium in the evaporator 5 releases heat to evaporate the CO2 fluid. After the CO2 reaches a saturated state at the working fluid outlet of the evaporator 5, it enters the low-temperature side charging working fluid flow channel 31 of the first multi-stream regenerator 3, and is heated to superheated gas after heat exchange with the CO2 fluid whose high-grade thermal energy has been absorbed in the second high-temperature side charging working fluid flow channel, and finally enters the compressor 1 to complete the charging cycle.

[0060] During the energy release cycle, the high-pressure working fluid pump 7 compresses CO2 to a high-pressure state and passes it into the second multi-stream heat exchanger 8. The high-pressure CO2 fluid enters the low-temperature side energy-charging working fluid flow channel 31 and is preheated by low-grade heat energy and the waste heat of the CO2 working fluid after expansion and work, and then enters the multi-stream heater 9 to be heated by high-grade heat energy. After being raised to a specified temperature, it enters the turbine 10 to expand and generate electricity. After the CO2 working fluid has expanded and done work, it flows into the high-temperature side energy-discharging working fluid flow channel 82 of the second multi-stream heat exchanger 8 to release waste heat, then enters the condenser 6 to be cooled to a liquid state by the cold storage medium, and finally enters the high-pressure working fluid pump 7 to complete the energy release cycle.

[0061] The high-grade heat storage medium is stored in the high-grade heat storage medium hot tank 11 and the high-grade heat storage medium cold tank 12 respectively before and after absorbing heat, and the high-grade heat storage medium circulates in the multi-stream air cooler 2, the high-grade heat storage medium hot tank 11, the multi-stream heater 9, and the high-grade heat storage medium cold tank 12. In the charging cycle, the high-grade heat storage medium absorbs the high-grade heat energy of the CO2 working medium compressed to high temperature and high pressure and stores it in the high-grade heat storage medium hot tank 11; in the discharging cycle, the high-grade heat storage medium releases the high-grade heat energy to heat the CO2 working medium to a high temperature state where it can expand and do work, and then stores it in the high-grade heat storage medium cold tank 12.

[0062] The low-grade heat storage medium is stored in the low-grade heat storage medium hot tank 13 and the low-grade heat storage medium cold tank 14 before and after absorbing heat, and the low-grade heat storage medium circulates in the first multi-stream heat regenerator 3, the low-grade heat storage medium hot tank 13, the second multi-stream heat regenerator 8, and the low-grade heat storage medium cold tank 14. In the charging cycle, the low-grade heat storage medium absorbs the low-grade heat energy of the CO2 working medium and stores it in the low-grade heat storage medium hot tank 13; in the discharging cycle, the low-grade heat storage medium releases the low-grade heat energy to preheat the CO2 working medium and stores it in the low-grade heat storage medium cold tank 14.

[0063] The cold storage medium is stored in the cold storage medium hot tank 16 and the cold storage medium cold tank 15 respectively before and after absorbing cold energy, and the cold storage medium circulates in the evaporator 5, the cold storage medium cold tank 15, the condenser 6, and the cold storage medium hot tank 16. In the charging cycle, the cold storage medium releases heat to heat and evaporate the CO2 working medium and then stores it in the cold storage medium cold tank 15; in the discharging cycle, the cold storage medium absorbs heat to cool the CO2 working medium into a liquid state and then stores it in the cold storage medium hot tank 16.

[0064] It should be noted that the high grade and low grade in the embodiments of the present invention are relative concepts, high grade is relative to low grade, and low grade is relative to high grade.

[0065] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Carnot battery system based on multi-stream heat exchange, characterized in that: include: An energy charging circulation loop comprises a compressor, a multi-stream air cooler, a first multi-stream heat regenerator, a throttle valve and an evaporator which are connected in sequence, wherein the evaporator is connected to the compressor through the first multi-stream heat regenerator to form a loop, and an energy charging working medium circulates in the energy charging circulation loop; The energy releasing circulation loop comprises a condenser, a high-pressure working medium pump, a second multi-stream heat exchanger, a multi-stream heater and a turbine connected in sequence, wherein the turbine is connected to the condenser through the second multi-stream heat exchanger to form a loop, and an energy releasing working medium circulates in the energy releasing circulation loop. Wherein, a high-quality heat storage medium also flows in the multi-stream air cooler, and the high-quality heat storage medium absorbs and stores the high-quality heat energy in the charging medium compressed by the compressor. A low-grade heat storage medium also flows through the first multi-stream heat regenerator, and the low-grade heat storage medium absorbs and stores the low-grade heat energy in the charging medium after absorbing heat through the multi-stream air cooler. The second multi-stream heat regenerator receives the low-grade heat storage medium having low-grade thermal energy, and preheats the exothermic working medium by using the low-grade thermal energy. The multi-stream heater receives the high-grade heat storage medium with high-grade thermal energy, and heats the exothermic working fluid to a high-temperature state through the high-grade thermal energy so that the working fluid can enter the turbine to expand and perform work.

2. The Carnot battery system based on multi-stream heat exchange according to claim 1, characterized in that: The multi-stream air cooler is provided with a high-grade heat absorption channel, the multi-stream heater is provided with a high-grade heating channel, and the high-grade heat absorption channel and the high-grade heating channel are both circulated with the high-grade heat storage medium. The high-grade heat absorption flow channel is also connected to a high-grade heat storage medium hot tank to store the high-grade heat storage medium with high-grade thermal energy, and the high-grade heat storage medium hot tank is connected to the high-grade heating flow channel. The high-grade heating flow channel is also connected to a high-grade heat storage medium cold tank to store the high-grade heat storage medium before absorbing heat and storing energy or after releasing high-grade heat energy, and the high-grade heat storage medium cold tank is connected to the high-grade heat absorption flow channel. The high-grade heat storage medium circulates among the high-grade heat absorption flow channel, the high-grade heat storage medium hot tank, the high-grade heating flow channel, and the high-grade heat storage medium cold tank, absorbs the high-grade thermal energy of the charging medium in the multi-stream air cooler, and releases the high-grade thermal energy to the releasing medium in the multi-stream heater.

3. The Carnot battery system based on multi-stream heat exchange according to claim 2, characterized in that: The number of the high-grade heat absorption flow channels is multiple, and the number of the high-grade heat storage medium hot tank, the high-grade heating flow channel and the high-grade heat storage medium cold tank matches the number of the high-grade heat absorption flow channels and are connected one by one.

4. The Carnot battery system based on multi-stream heat exchange according to claim 3, characterized in that: Different types of high-grade heat storage media flow through each of the high-grade heat absorption channels to collect, store and circulate high-grade thermal energy at different temperatures.

5. The Carnot battery system based on multi-stream heat exchange according to claim 1, characterized in that: The first multi-stream heat regenerator is provided with a first low-grade flow channel, the second multi-stream heat regenerator is provided with a second low-grade flow channel, and the low-grade heat storage medium flows through both the first low-grade flow channel and the second low-grade flow channel. The first low-grade flow channel is also connected to a low-grade heat storage medium hot tank for storing the low-grade heat storage medium with low-grade thermal energy, and the low-grade heat storage medium hot tank is in communication with the second low-grade flow channel. The second low-grade flow channel is also connected to a low-grade heat storage medium cold tank to store the low-grade heat storage medium before absorbing heat and storing energy or after releasing low-grade heat energy, and the low-grade heat storage medium cold tank is connected to the first low-grade flow channel. The low-grade heat storage medium circulates among the first low-grade flow channel, the low-grade heat storage medium hot tank, the second low-grade flow channel, and the low-grade heat storage medium cold tank, absorbs the low-grade thermal energy of the charging medium in the first multi-stream heat regenerator, and releases the low-grade thermal energy to the releasing medium in the second multi-stream heat regenerator.

6. The Carnot battery system based on multi-stream heat exchange according to claim 5, characterized in that: The first multi-stream heat regenerator is provided with a first high-temperature side energetic medium flow channel, a second high-temperature side energetic medium flow channel and a low-temperature side energetic medium flow channel. The inlets of the first high-temperature-side energetic working medium flow channel and the second high-temperature-side energetic working medium flow channel are both connected to the working medium outlet of the multi-stream air cooler, and the outlets of the first high-temperature-side energetic working medium flow channel and the second high-temperature-side energetic working medium flow channel are both connected to the working medium inlet of the throttle valve. The energetic medium after high-grade thermal energy is absorbed flows through the first high-temperature-side energetic working medium flow channel and the second high-temperature-side energetic working medium flow channel, and heat is exchanged with the first low-grade flow channel through the first high-temperature-side energetic working medium flow channel. The inlet of the low-temperature side energizing working fluid flow channel is connected to the working fluid outlet of the evaporator, and the outlet of the low-temperature side energizing working fluid flow channel is connected to the working fluid inlet of the compressor. The energizing working fluid that has successively expanded through the throttle valve and evaporated through the evaporator flows in the low-temperature side energizing working fluid flow channel. The energizing working fluid in the low-temperature side energizing working fluid flow channel is reheated through the second high-temperature side energizing working fluid flow channel and passed into the compressor.

7. The Carnot battery system based on multi-stream heat exchange according to claim 5, characterized in that: The second multi-stream heat regenerator is provided with a high-temperature side exothermic working medium flow channel and a low-temperature side exothermic working medium flow channel. The inlet of the high-temperature side energy-releasing working medium flow passage is connected to the working medium outlet of the turbine, and the outlet of the high-temperature side energy-releasing working medium flow passage is connected to the working medium inlet of the condenser. The energy-releasing working medium after expansion and work in the turbine flows in the high-temperature side energy-releasing working medium flow passage, and is passed into the condenser after releasing the residual heat. The inlet of the low-temperature side energy-releasing working fluid flow channel is communicated with the working fluid outlet of the high-pressure working fluid pump, and the outlet of the low-temperature side energy-releasing working fluid flow channel is communicated with the working fluid inlet of the multi-stream heater. The energy-releasing working fluid pressurized by the high-pressure working fluid pump flows in the low-temperature side energy-releasing working fluid flow channel, and is preheated by the low-grade thermal energy of the low-grade heat storage medium and the waste heat released by the energy-releasing working fluid in the high-temperature side energy-releasing working fluid flow channel.

8. The Carnot battery system based on multi-stream heat exchange according to claim 1, characterized in that: A cold storage medium flows through the evaporator and the condenser, and the evaporator and the condenser are also connected to a cold storage medium hot tank and a cold storage medium cold tank to store the cold storage medium. The evaporator, the cold storage medium cold tank, the condenser, and the cold storage medium hot tank are connected in sequence to form a loop to circulate the cold storage medium. The cold storage medium releases heat in the evaporator to evaporate the energy-charging working fluid, and absorbs heat in the condenser to cool the energy-releasing working fluid.

9. The Carnot battery system based on multi-stream heat exchange according to claim 1, characterized in that: The charging working fluid and the discharging working fluid are both CO2, the charging cycle loop and the discharging cycle loop are both transcritical cycles, and the pressure on the high-pressure side is greater than the critical pressure of CO2, and the pressure on the low-pressure side is lower than the critical pressure of CO2.

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