Design Optimization Method for Adiabatic Compressed Air Energy Storage System

Abstract

The present invention belongs to the field of new energy storage technologies, and specifically discloses a design optimization method for an adiabatic compressed air energy storage system, including: Step 1, obtaining the inlet temperature and air flow rate of the expansion unit; Step 2, determining the heat storage temperature of the heat accumulator according to the inlet temperature; Step 3, determining the performance parameters of the compressor unit according to the heat storage temperature, and determining the hot water flow rate of the heat accumulator and the volume of the gas storage reservoir according to the air flow rate. The present invention determines the heat storage temperature of the heat accumulator according to the inlet temperature of the expansion unit, and further determines the performance parameters of the compressor according to the heat storage temperature of the heat accumulator; furthermore, the present invention also determines the hot water flow rate of the heat accumulator and the volume of the gas storage reservoir according to the air flow rate of the expansion unit, thereby realizing integrated design optimization and making it a standard process, so as to adapt to different design requirements, with simple and convenient operation and high calculation efficiency.

Description

Technical Field

[0001] The present invention discloses a design optimization method for an adiabatic compressed air energy storage system, belonging to the field of new energy storage technologies. Background Art

[0002] Compressed air energy storage can be classified into adiabatic compressed air energy storage (A-CAES), liquid air energy storage (LAES), supercritical compressed air energy storage (S-CAES), etc. according to the technical route. Among them, the adiabatic compressed air energy storage technology abandons the disadvantages of traditional compressed air consuming fossil energy to heat gas, improves the system efficiency, and is the mainstream technical route of compressed air energy storage at present.

[0003] The adiabatic compressed air energy storage system consists of an energy storage subsystem and an energy release subsystem. The two subsystems are connected as an overall system through devices such as gas storage and cold and heat storage. The energy storage subsystem uses the mechanical energy output by the motor of the compressor to inhale air from the atmosphere and do work on the gas, increasing the internal energy and pressure energy of the gas. After the high-temperature and high-pressure air leaves the compressor, it first enters the heat accumulator, transfers the heat of the gas to heat storage materials such as water and molten salt for storage, and then transports the cooled high-pressure air to gas storage devices such as rock caves and storage tanks for physical storage. The energy release process is the opposite. The high-pressure gas transmitted from the gas storage device first enters the heat exchanger for heating up, and then enters the expander for expansion work to drive the generator for power generation.

[0004] With the transformation of compressed air energy storage technology from technical demonstration to commercial application, the need for standardized design of the process system has become increasingly prominent. At present, the design of the process system of compressed air energy storage power stations is usually modified on the basis of a single scheme, lacking adaptability to different design requirements, which brings difficulties to engineering practice. In addition, in practice, it is necessary to conduct technical and economic comparison and selection of the selection of different system parameters, and it is difficult to select relevant determination targets. Summary of the Invention

[0005] The purpose of the present invention is to provide a design optimization method for an adiabatic compressed air energy storage system to solve the problem that the design of the compressed air energy storage system in the prior art lacks a standard process and thus cannot meet the adaptability to different design requirements.

[0006] The present invention provides a design optimization method for an adiabatic compressed air energy storage system, including:

[0007] Step 1: Obtain the inlet temperature and air flow rate of the expansion unit.

[0008] Step 2: Determine the heat storage temperature of the heat accumulator according to the inlet temperature.

[0009] Step 3: Determine the performance parameters of the compressor unit according to the heat storage temperature, and determine the hot water flow rate of the heat accumulator and the volume of the gas storage reservoir according to the air flow rate.

[0010] Preferably, the obtaining of the inlet temperature of the expansion unit specifically includes:

[0011] Step 1.1: Determine the initial inlet temperature of the expansion unit according to the designed outlet temperature, expansion ratio and initial adiabatic index of the last-stage expander in the expansion unit.

[0012] Step 1.2: Determine the transitional adiabatic index according to the initial inlet temperature of the expansion unit, and determine the final adiabatic index according to the error between the transitional adiabatic index and the initial adiabatic index.

[0013] Step 1.3: Determine the inlet temperature of the expansion unit according to the designed outlet temperature, expansion ratio and final adiabatic index of the last-stage expander in the expansion unit.

[0014] Preferably, Step 1.2 specifically includes:

[0015] Step 1.2.1: Determine the average temperature at the inlet and outlet of the last-stage expander according to the initial inlet temperature of the expansion unit.

[0016] Step 1.2.2: Obtain the average pressure at the inlet and outlet of the last-stage expander, and determine the transitional adiabatic index according to the average temperature and the average pressure.

[0017] Step 1.2.3: If the error between the transitional adiabatic index and the initial adiabatic index is less than the preset threshold, record the transitional adiabatic index as the final adiabatic index; otherwise, record the transitional adiabatic index as the initial adiabatic index, and repeat Step 1.1 and Step 1.2.

[0018] Preferably, determining the heat storage temperature of the heat accumulator according to the inlet temperature specifically includes: obtaining the upper temperature difference of the heat exchanger corresponding to the expansion unit; determining the heat storage temperature of the heat accumulator according to the upper temperature difference of the heat exchanger and the inlet temperature.

[0019] Preferably, obtaining the air flow rate of the expansion unit specifically includes: obtaining the total enthalpy difference of each stage of expander in the expansion unit; determining the air flow rate of the expansion unit according to the preset energy release output power and the total enthalpy difference.

[0020] Preferably, determining the volume of the gas storage reservoir according to the air flow rate specifically includes: determining the volume of the gas storage reservoir according to the average density of the internal gas at the upper limit of the gas storage reservoir pressure, the average density of the internal gas at the lower limit of the gas storage reservoir pressure, the preset energy storage duration and the air flow rate.

[0021] Preferably, the hot water flow rate of the heat accumulator is determined according to the air flow rate, specifically including: determining the hot water flow rate of the heat accumulator during the energy storage stage according to the specific heat capacity at constant pressure of air, the specific heat capacity at constant pressure of water, and the air flow rate in the heat accumulator; determining the hot water flow rate of the heat accumulator during the energy release stage according to the hot water flow rate of the heat accumulator during the energy storage stage, the preset energy storage duration, and the energy release duration.

[0022] Preferably, the performance parameters of the compressor unit are determined according to the heat storage temperature, specifically including: determining the rated outlet temperature of the compressor unit according to the heat storage temperature and the upper temperature difference of the heat exchanger; determining the pressure ratio of the compressor according to the rated outlet temperature; determining the number of stages of the compressor in the compressor unit according to the pressure ratio of the first-stage compressor in the compressor unit.

[0023] Preferably, after determining the number of stages of the compressor in the compressor unit according to the pressure ratio of the first-stage compressor in the compressor unit, it further includes: obtaining the difference between the inlet enthalpy value and the outlet enthalpy value of each stage of the compressor.

[0024] Preferably, after step 3, it further includes:

[0025] Combined with the volume of the gas storage reservoir, determine the process of the pressure and temperature of the gas inside the gas storage reservoir changing with time.

[0026] The design optimization method of the adiabatic compressed air energy storage system of the present invention has the following beneficial effects compared with the prior art:

[0027] The present invention determines the heat storage temperature of the heat accumulator according to the inlet temperature of the expansion unit, and then determines the performance parameters of the compressor according to the heat storage temperature of the heat accumulator; further, the present invention also determines the hot water flow rate of the heat accumulator and the volume of the gas storage reservoir according to the air flow rate of the expansion unit, thereby realizing integrated design optimization and making it a standard process, so as to adapt to different design requirements, with simple and convenient operation and high calculation efficiency. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the adiabatic compressed air energy storage system in the embodiment of the present invention.

[0029] In the figure: 1 is a motor; 2 is a generator; 3 is a compressor unit; 4 is an expansion unit; 5 is a heat exchanger; 6 is a heat accumulator; 7 is a gas storage reservoir. Detailed Embodiments

[0030] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present invention.

[0031] Embodiments of the present invention provide a method for optimizing the design of an adiabatic compressed air energy storage system, which is applied to an adiabatic compressed air energy storage system with a capacity of 10 - 350 MW. The structure of the adiabatic compressed air energy storage system is as Figure 1 shown, and it includes an energy storage subsystem and an energy release subsystem. The energy storage subsystem includes a motor 1 that converts electrical energy into mechanical energy, a compressor unit 3 that increases the internal energy of the gas, and a heat exchanger 5 that exchanges heat between the gas and the heat transfer medium. The specific working principle of the energy storage subsystem is as follows: After receiving a start command, the motor 1 drives the compressor unit 3 to work, sucking in the atmosphere for compression. The compressor unit 3 consists of multiple-stage compressors. Between the stages of the compressor unit 3, the gas is passed into the heat exchanger 5 for cooling and then into the next-stage compressor, and the heat is stored in the regenerator 6.

[0032] The above-mentioned energy release subsystem includes a generator 2 that converts mechanical energy into electrical energy, an expansion unit 4 that converts the internal energy of the gas into mechanical energy, and a heat exchanger 5 that exchanges heat between the gas and the heat transfer medium. The specific working principle of the energy release subsystem is as follows: After receiving an energy release command, the outlet valve of the gas storage tank 7 is opened, and the high-pressure gas enters the heat exchanger 5 for heating and then passes into the expansion unit 4 for work, driving the generator 2 to generate electricity. The expansion unit 4 consists of multiple-stage expanders. The gas between the stages of the multiple-stage expanders is passed into the heat exchanger 5 for heating and then into the next-stage expander.

[0033] The energy storage subsystem and the energy release subsystem are decoupled from each other in time and are connected through the regenerator 6 and the gas storage tank 7 for storing high-pressure gas.

[0034] The method for optimizing the design of the adiabatic compressed air energy storage system provided by the embodiments of the present invention is based on the principle of the compressed air energy storage system and the characteristics of engineering thermodynamics. First, relevant parameters of the compressed air energy storage power station are set according to engineering needs to achieve the design optimization of different design requirements and optimization objects. The setting of relevant parameters specifically includes three categories: design target parameters, main engine performance parameters, and design optimization parameters. Among them, the design target parameters specifically include the energy release output power , the energy release duration , the energy storage duration , the ambient temperature , the ambient pressure ; the main engine performance parameters specifically include the isentropic efficiency of the compressor , Isentropic efficiency of the expander , Upper temperature difference of the heat exchanger , Lower temperature difference of the heat exchanger ; The design optimization parameters specifically include the upper limit of the gas storage chamber pressure , Fluctuation range of the gas storage chamber pressure range , Number of stages of the expander .

[0035] In the actual operation of the adiabatic compressed air energy storage system, the heat storage temperature is determined by the temperature of the gas at the outlet of the compressor during the energy storage process. , where is the heat storage temperature, is the temperature at the outlet of the -th stage compressor, is the total number of stages of the compressor, is the upper temperature difference of the heat exchanger. In engineering design, since the number of compressor stages and the pressure ratio distribution are unknowns, they cannot be derived forward. The present invention adopts reverse derivation: that is, first determine the inlet temperature of the expander, and then determine the heat storage temperature.

[0036] The design optimization method of the adiabatic compressed air energy storage system provided by the embodiment of the present invention specifically includes the following steps:

[0037] Step 1, Obtain the inlet temperature and air flow rate of the expander unit.

[0038] Among them, obtaining the inlet temperature of the expander unit specifically includes:

[0039] Step 1.1, Determine the initial inlet temperature of the expander unit according to the designed outlet temperature, expansion ratio and initial adiabatic index of the last-stage expander in the expander unit.

[0040] The method for determining the expansion ratio is as follows:

[0041] In the present invention, the expansion ratio of the multi-stage expander is distributed according to the average distribution principle, and the calculation formula is:

[0042] (1)

[0043] In the formula, is the initial value of the expander expansion ratio, is the rated intake pressure of the expander, is the ambient pressure, is the number of stages of the expander.

[0044] Since the gas between the stages of the expander needs to be heated by the heat exchanger, there will be pressure loss during the inter-stage heat exchange of the gas. Therefore, the actual expansion ratio needs to consider the influence of the inter-stage loss. Taking a three-stage expander as an example, taking As the initial value, substitute it into the non-linear equation of formula (2) below to solve the actual expansion ratio of each stage of the expander. .

[0045] (2)

[0046] In the formula, is the design pressure loss of the heat exchanger, is the rated inlet pressure of the expander, is the ambient pressure.

[0047] After obtaining the actual expansion ratio, determine the initial inlet temperature of the expansion unit according to the designed outlet temperature, expansion ratio and initial adiabatic index of the last-stage expander in the expansion unit, as follows:

[0048] (3)

[0049] In the formula, is the inlet temperature of the expansion unit, is the designed outlet temperature of the last-stage expander in the expansion unit, is the isentropic efficiency of the expander, is the actual expansion ratio of the expander, is the adiabatic index. It should be noted that in the existing design method of compressed air energy storage systems, the adiabatic index is generally a fixed value, taken as 1.4. However, since the adiabatic index is related to the thermodynamic process, the existing method causes a certain degree of calculation error to a certain extent. The design optimization method of the present invention adopts an error iteration method to reduce the error influence caused by the deviation of the adiabatic index. First, set the initial adiabatic index as 1.4, and calculate the initial inlet temperature of the expansion unit using formula (3).

[0050] Step 1.2: Determine the transitional adiabatic index according to the initial inlet temperature of the expansion unit, and determine the final adiabatic index according to the error between the transitional adiabatic index and the initial adiabatic index, specifically including:

[0051] Step 1.2.1: Determine the average temperature at the inlet and outlet of the last-stage expander according to the initial inlet temperature of the expansion unit .

[0052] In the embodiments of the present invention, since the inlet temperature of each stage of the expander is the same, the initial inlet temperature of the expansion unit here is the same as the inlet temperature of a single expander.

[0053] Step 1.2.2: Obtain the average pressure at the inlet and outlet of the last-stage expander , and determine the transitional adiabatic index according to the average temperature and the average pressure .

[0054] In the embodiment of the present invention, the outlet pressure of the last-stage expander is the atmospheric pressure, and the inlet pressure is the product of the outlet pressure and the expansion ratio. Then, according to the average temperature and the average pressure the transitional adiabatic index is determined. Specifically: using and as the characteristic values, the corresponding adiabatic index value is searched and recorded as the transitional adiabatic index .

[0055] Step 1.2.3: If the error between the transitional adiabatic index and the initial adiabatic index is less than the preset threshold, then record the transitional adiabatic index as the final adiabatic index; otherwise, record the transitional adiabatic index as the initial adiabatic index, and repeat Step 1.1 and Step 1.2.

[0056] where the error between the transitional adiabatic index and the initial adiabatic index is determined by formula (4):

[0057] (4)

[0058] In the formula, is the initial adiabatic index, is the transitional adiabatic index.

[0059] Step 1.3: Determine the inlet temperature of the expansion unit according to the designed outlet temperature, expansion ratio and final adiabatic index of the last-stage expander in the expansion unit. Specifically, substitute the designed outlet temperature, expansion ratio and final adiabatic index of the last-stage expander into formula (3) to determine the inlet temperature of the expansion unit.

[0060] Step 2: Determine the heat storage temperature of the heat accumulator according to the inlet temperature, which specifically includes: obtaining the upper-end difference of the corresponding heat exchanger of the expansion unit; determining the heat storage temperature of the heat accumulator according to the upper-end difference of the heat exchanger and the inlet temperature.

[0061] In the embodiment of the present invention, the upper-end differences on the compressor unit side and the expansion unit side are the same, so no distinction is made.

[0062] In the embodiment of the present invention, the heat storage temperature of the heat accumulator is determined according to the following formula (5) :[[]]

[0063] (5)

[0064] In the formula, is the upper-end difference of the heat exchanger, is the inlet temperature of the expansion unit.

[0065] Step 3: Determine the performance parameters of the compressor unit according to the heat storage temperature, and determine the hot water flow rate of the heat accumulator and the volume of the gas storage reservoir according to the air flow rate.

[0066] Since compressed air energy storage requires a relatively large compression ratio during the energy storage stage (usually >80), a single-stage compressor is difficult to meet the system requirements. Compressed air energy storage usually sets up a compressor unit 3 composed of multiple-stage compressors. To facilitate the design and calculation of multi-stage compressors with different numbers of stages, in the design optimization method of the present invention, the compressor types are divided into three categories according to different inlet and outlet condition parameters: (1) the first-stage compressor, with the inlet condition being the ambient condition; (2) the intermediate-stage compressor, with constant inlet and outlet temperatures; (3) the last-stage compressor, with the outlet condition set. It should be noted that this classification method is applicable to any multi-stage compressor type with the number of compressor stages >2. When the number of compressor stages = 2, the intermediate-stage compressor is the last-stage compressor.

[0067] The performance parameters of the compressor unit to be determined in the embodiment of the present invention include the rated outlet temperature of the compressor, the compression ratio, enthalpy value of each stage of the compressor, and the number of stages of the compressor unit.

[0068] The embodiment of the present invention determines the rated outlet temperature of the compressor unit according to the heat storage temperature and the upper temperature difference of the heat exchanger, as shown in formula (6):

[0069] (6)

[0070] In the formula, is the rated outlet temperature of the compressor, is the heat storage temperature of the heat accumulator, is the upper temperature difference of the heat exchanger. In the embodiment of the present invention, the heat storage temperature is equal to the temperature of the heat storage medium of the heat exchanger during the energy storage stage.

[0071] Furthermore, the compression ratio of the compressor is determined according to the rated outlet temperature, as shown in formula (7):

[0072] (7)

[0073] In the formula, is the compression ratio, is the isentropic efficiency of the compressor, is the rated outlet temperature of the compressor, is the inlet temperature of the compressor, is the final adiabatic index, and its determination method is the same as that of above, and will not be elaborated here.

[0074] Even further, the number of stages of the compressor in the compressor unit is determined according to the compression ratio of the first-stage compressor in the compressor unit , as shown in formula (8):

[0075] (8)

[0076] In the formula, is the environmental pressure, is the pressure ratio of the first-stage compressor, is the outlet pressure of the last-stage compressor, is the floor function.

[0077] In the embodiment of the present invention, the enthalpy difference of the compressor is determined according to formula (9):

[0078] (9)

[0079] wherein, is the enthalpy difference of the -stage compressor, is the outlet enthalpy of the -stage compressor, is the inlet enthalpy of the -stage compressor.

[0080] In the embodiment of the present invention, the compressor performance calculation module determines the rated outlet temperature of the compressor according to the heat storage temperature, calculates the pressure ratio and the inlet and outlet enthalpy differences of each stage of the compressor respectively according to the classification method of the three types of compressors, and obtains the performance of the overall multi-stage compressor. Since the last-stage compressor usually undertakes the task of adapting to the changes of different back-pressure conditions and has a smaller pressure ratio compared with the other two types of compressors, the number of compressor stages is determined by the number of intermediate-stage compressors plus the first-stage and the last-stage compressors.

[0081] Step 3 of the embodiment of the present invention also needs to determine the hot water flow of the heat storage and the volume of the gas storage according to the air flow of the expansion unit. The specific method for obtaining the air flow of the expansion unit is as follows: obtain the total enthalpy difference of each stage of the expander in the expansion unit; determine the air flow of the expansion unit according to the preset energy release output power and the total enthalpy difference.

[0082] The total enthalpy difference of the above-mentioned stages of expanders is determined according to formula (10):

[0083] (10)

[0084] wherein, is the inlet enthalpy of the -stage expander, is the outlet enthalpy of the -stage expander, is the total enthalpy difference.

[0085] The embodiment of the present invention determines the air flow of the expansion unit in the energy release stage according to formula (11) :

[0086] (11)

[0087] wherein, is the preset energy release output power, is the total enthalpy difference.

[0088] After obtaining the air flow rate of the expansion unit during the energy release stage the embodiment of the present invention determines the volume of the gas storage reservoir according to the air flow rate. The calculation of the volume of the gas storage reservoir is determined by the initial and final states of the gas storage reservoir and the total gas consumption, and it is necessary to assume the initial and final temperatures of the gas storage reservoir at the beginning of the design, and then correct this parameter through the dynamic performance calculation module.

[0089] The embodiment of the present invention determines the volume of the gas storage reservoir specifically as follows: determine the volume of the gas storage reservoir according to the average density of the internal gas when the pressure of the gas storage reservoir reaches the upper limit, the average density of the internal gas when the pressure of the gas storage reservoir reaches the lower limit, the preset energy storage duration, and the air flow rate as shown in formula (12):

[0090] (12)

[0091] In the formula, is the average density of the internal gas when the pressure of the gas storage reservoir reaches the upper limit, is the average density of the internal gas when the pressure of the gas storage reservoir reaches the lower limit, , obtained by looking up values, is the air flow rate of the expansion unit during the energy release stage, is the energy storage duration.

[0092] The embodiment of the present invention can also determine the hot water flow rate of the regenerator according to the air flow rate of the expansion unit during the energy release stage The type of the heat storage and heat exchange device is related to the compressed air energy storage stage route. Generally, water or heat transfer oil is used as the heat exchange medium for medium-temperature and medium-high-temperature compressed air energy storage technologies, and a packed bed is used as the heat exchange device for high-temperature compressed air energy storage technologies, which needs to be selected according to the heat storage temperature.

[0093] Taking water as the heat exchange medium as an example in the embodiment of the present invention, the method for determining the hot water flow rate of the regenerator during the energy release stage and the energy storage stage is as follows: determine the hot water flow rate of the regenerator during the energy storage stage according to the specific heat capacity at constant pressure of the air in the regenerator, the specific heat capacity at constant pressure of water, and the air flow rate of the expansion unit during the energy release stage

[0094] ; determine the hot water flow rate of the regenerator during the energy release stage according to the hot water flow rate of the regenerator during the energy storage stage, the preset energy storage duration, and the energy release duration ; .

[0095] Among them is determined according to formula (13):

[0096] ​(13)

[0097] In the formula, is the specific heat capacity of air at constant pressure, is the specific heat capacity of water at constant pressure.

[0098] It is determined according to formula (14):

[0099] (14)

[0100] In the formula, is the hot water flow rate of the heat accumulator during the energy storage stage, is the energy release duration, is the energy storage duration.

[0101] After step 3 in the embodiment of the present invention, it further includes:

[0102] Step 4: Combine the volume of the gas storage cavern to determine the process of the pressure and temperature of the gas inside the gas storage cavern changing with time.

[0103] The current design of the adiabatic compressed air energy storage system uses the steady-state calculation method. However, the actual energy storage and release process is a non-steady-state and variable operating condition process, and the steady-state calculation method will produce a large error. The present invention realizes the non-steady-state calculation of the entire operation period of the compressed air energy storage system by embedding the dynamic performance calculation process, improving the calculation accuracy.

[0104] The dynamic performance calculation supplements the relevant equations of the gas state inside the gas storage chamber and the time iteration steps on the basis of the steady-state performance calculation. The material and energy relationship between the gas storage chamber and the compressor / expander belongs to the problem of an unsteady thermodynamic open system. The relevant mass conservation and energy conservation formulas are as follows:

[0105] (15)

[0106] In the formula, is the mass of the gas in the gas storage cavern, are the gas mass flow rates flowing into and out of the gas storage cavern respectively, is time.

[0107] (16)

[0108] In the formula, is the mass of the gas in the gas storage cavern, are the gas mass flow rates flowing into and out of the gas storage cavern respectively, is time, are the enthalpy values of the gas flowing into and out of, is the temperature of the gas in the gas storage cavern, is the heat transfer coefficient between the gas storage cavern and the outside world, is the surface area of the gas storage chamber. When the shape of the gas storage chamber is determined, , is the ambient temperature, is the gas velocity.

[0109] The differential equations for the pressure and temperature of the gas inside the gas storage reservoir in the embodiments of the present invention changing with time are as follows:

[0110] (17)

[0111] In the formula, is the specific heat capacity at constant pressure of the gas in the gas storage chamber, is the specific heat capacity at constant volume of the gas in the gas storage chamber.

[0112] (18)

[0113] In the formula is the gas pressure in the gas storage reservoir, is the ideal gas constant, taking .

[0114] Furthermore, the main performance evaluation indicators of the adiabatic compressed air energy storage system in the embodiments of the present invention are: system efficiency and energy density , which are respectively as follows:

[0115] (19)

[0116] (20)

[0117] In the formula is the volume of the gas storage reservoir, the system output energy and the system input energy are respectively calculated through the dynamic energy release program and the dynamic energy storage program, and are calculated through the following formula:

[0118] (21)

[0119] (22)

[0120] In the formula are respectively the time iteration steps of energy release and energy storage, is the total enthalpy difference of each stage of the expander, is the total enthalpy difference of each stage of the compressor.

[0121] The present invention has established a complete set of design optimization methods for adiabatic compressed air energy storage systems, realizing iterative optimization of key parameters such as the upper and lower limits of the gas storage chamber pressure and the heat storage temperature in the design stage, and improving the performance and economy of the overall system.

[0122] The current adiabatic compressed air energy storage system design uses a steady-state calculation method. However, the actual energy storage and release process is a non-steady-state and variable operating condition process, and the steady-state calculation method will produce relatively large errors. Through the embedding of dynamic performance calculation, the present invention realizes the non-steady-state calculation of the entire time period of the operation of the compressed air energy storage system, improving the calculation accuracy.

[0123] As described above, only several embodiments of the present invention are given, and no any form of limitation is imposed on the present invention. Although the present invention is disclosed by the preferred embodiments as above, it is not intended to limit the present invention. Any person skilled in the relevant art can make some changes or modifications by using the disclosed technical content within the scope of the technical solution of the present invention, which are all equivalent to the equivalent embodiments and all fall within the scope of the technical solution.

Claims

1. A design optimization method for an adiabatic compressed air energy storage system, characterized by Including: Step 1: Obtain the inlet temperature and air flow rate of the expansion unit; Step 2: Determine the heat storage temperature of the heat accumulator according to the inlet temperature, specifically including: Obtain the upper end difference of the heat exchanger corresponding to the expansion unit; Determine the heat storage temperature of the heat accumulator according to the upper end difference of the heat exchanger and the inlet temperature; Step 3: Determine the performance parameters of the compression unit according to the heat storage temperature, and determine the hot water flow rate of the heat accumulator and the volume of the gas storage tank according to the air flow rate; Among them, determining the volume of the gas storage tank according to the air flow rate specifically includes: Determine the volume of the gas storage tank according to the average density of the internal gas at the upper limit of the gas storage tank pressure, the average density of the internal gas at the lower limit of the gas storage tank pressure, the preset energy storage duration, and the air flow rate; Among them, determining the hot water flow rate of the heat accumulator according to the air flow rate specifically includes: Determine the hot water flow rate of the heat accumulator during the energy storage stage according to the specific heat capacity at constant pressure of air in the heat accumulator, the specific heat capacity at constant pressure of water, and the air flow rate; Determine the hot water flow rate of the heat accumulator during the energy release stage according to the hot water flow rate of the heat accumulator during the energy storage stage, the preset energy storage duration, and the energy release duration.

2. The design optimization method of the adiabatic compressed air energy storage system according to claim 1, wherein The obtaining of the inlet temperature of the expansion unit specifically includes: Step 1.1: Determine the initial inlet temperature of the expansion unit according to the designed outlet temperature, expansion ratio, and initial adiabatic index of the last-stage expander in the expansion unit; Step 1.2: Determine the transitional adiabatic index according to the initial inlet temperature of the expansion unit, and determine the final adiabatic index according to the error between the transitional adiabatic index and the initial adiabatic index; Step 1.3: Determine the inlet temperature of the expansion unit according to the designed outlet temperature, expansion ratio, and final adiabatic index of the last-stage expander in the expansion unit.

3. The design optimization method of the adiabatic compressed air energy storage system according to claim 2, wherein The specific content of Step 1.2 includes: Step 1.2.1: Determine the average inlet and outlet temperature of the last-stage expander according to the initial inlet temperature of the expansion unit; Step 1.2.2: Obtain the average inlet and outlet pressure of the last-stage expander, and determine the transitional adiabatic index according to the average temperature and the average pressure; Step 1.2.3: If the error between the transitional adiabatic index and the initial adiabatic index is less than the preset threshold, record the transitional adiabatic index as the final adiabatic index; otherwise, record the transitional adiabatic index as the initial adiabatic index, and repeat Step 1.1 and Step 1.

2.

4. The design optimization method of the adiabatic compressed air energy storage system according to claim 1, characterized in that The obtaining of the air flow rate of the expansion unit specifically includes: Obtain the total enthalpy difference of each stage of expander in the expansion unit; Determine the air flow rate of the expansion unit according to the preset energy release output power and the total enthalpy difference.

5. The design optimization method of the adiabatic compressed air energy storage system according to claim 1, wherein Determining the performance parameters of the compression unit according to the heat storage temperature specifically includes: Determine the rated outlet temperature of the compression unit according to the heat storage temperature and the upper end difference of the heat exchanger; Determine the compression ratio of the compressor according to the rated outlet temperature; Determine the number of stages of the compressor in the compression unit according to the compression ratio of the first-stage compressor in the compression unit.

6. The design optimization method of the adiabatic compressed air energy storage system according to claim 5, wherein After determining the number of stages of the compressor in the compression unit according to the compression ratio of the first-stage compressor in the compression unit, it further includes: Obtain the difference between the inlet enthalpy value and the outlet enthalpy value of each stage of compressor.

7. The design optimization method of the adiabatic compressed air energy storage system according to claim 1, wherein After the said Step 3, it further includes: Based on the volume of the gas storage reservoir, determine the process of the change of the pressure and temperature of the gas inside the gas storage reservoir over time.

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