A rapid screening method for heat storage materials used in packed bed sensible heat storage devices

Abstract

A method for rapid screening of heat storage materials for packed bed sensible heat storage is proposed. Based on the principle of enhancing the heat storage rate of the heat storage device, reducing flow resistance, and improving economy, the average heat storage rate per unit volume and unit temperature difference is proposed as an evaluation index. Through four main steps, namely, clear heat storage scenario requirements, heat transfer fluid flow rate design, heat storage material type screening, and heat storage material size confirmation, the method can achieve rapid and efficient screening of heat storage materials for packed bed sensible heat storage devices. The screened heat storage materials can achieve higher heat storage rates and lower heat storage investment costs while meeting the requirements of heat storage device pressure loss and heat storage power. This method has important guiding significance and engineering application value for the design of packed bed sensible heat storage devices.

Description

Technical Field

[0001] The invention relates to a thermal energy storage technology, and in particular to a method for screening heat storage materials for a packed bed sensible heat storage device. Background Art

[0002] Thermal energy storage technology has the advantages of long service life and low cost. In the field of renewable energy and industrial applications, surplus energy can be stored in the form of thermal energy, which is safer and more reliable than electrical energy storage and has the potential for promotion. The packed bed heat storage formed by the accumulation of heat storage ball fillers has a large contact area between the heat storage material and the heat transfer medium, a high heat storage rate, and solid sensible heat storage materials are generally inexpensive. Therefore, packed bed sensible heat storage with good heat storage performance and low heat storage cost has received more and more attention.

[0003] Selecting appropriate heat storage materials according to the needs of the heat storage scenario is a key link in the design of packed bed sensible heat storage devices. In actual engineering applications, on the one hand, there are thousands of types of heat storage materials, and there are many factors affecting the heat storage materials. On the other hand, the heat storage process of the packed bed sensible heat storage device is a transient model, which requires a large amount of calculation. Therefore, for a specific heat storage application scenario, the final screening of heat storage materials often requires detailed calculations of the thermal and economic performance of the heat storage device. This cumbersome screening process is not conducive to the design of heat storage devices in actual engineering. It can be seen that it is urgent to develop a solid sensible heat storage material screening method with a certain degree of universality to guide the rapid screening of heat storage materials for packed bed sensible heat storage devices.

[0004] In view of the difficulty in screening heat storage materials in packed bed sensible heat storage devices, the present invention aims to improve the heat storage rate of the heat storage device, while considering flow resistance and economy, and proposes a method for screening heat storage materials in packed bed sensible heat storage devices that can be applied to actual engineering projects. Summary of the invention

[0005] The purpose of the present invention is to propose a method for rapid screening of heat storage materials for packed bed sensible heat storage devices that can be used in engineering practice to meet the design goals of high heat storage rate, low flow pressure loss and low heat storage cost of the heat storage device.

[0006] The screening method of the present invention mainly includes three key points: (1) design of heat transfer fluid flow rate based on heat storage scenario parameter requirements; (2) screening of heat storage material types based on heat storage rate; and (3) confirmation of heat storage material size based on heat storage device pressure loss.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for quickly screening heat storage materials for a packed bed sensible heat storage device comprises the following steps:

[0009] Step 1: Determine the heat storage demand and operating conditions of the heat storage device according to the engineering heat storage application scenario; the heat storage demand includes: the heat storage power requirement P of the heat storage scenario TES The maximum per unit flow pressure loss ΔP allowed by the heat storage device design,max The operating conditions include: the type and thermal properties of the heat transfer fluid, and the minimum operating temperature T of the heat storage scenario. L With the maximum operating temperature T H , and the site area A where the heat storage structure is placed min ~A max ; The thermal properties of the heat transfer fluid include its density ρ HTF Specific heat capacity c p,HTF , kinematic viscosity ν HTF and thermal conductivity λ HTF ;

[0010] Step 2, select candidate heat storage materials; after determining the type of heat transfer fluid, select solid sensible heat storage materials that are chemically stable in the heat transfer fluid as candidate materials, and obtain the thermal properties and cost parameters of the candidate materials. The thermal properties of the candidate materials include their density ρ s , constant pressure specific heat capacity c p,s and thermal conductivity λ s , the cost parameters include the material price per unit volume C s ;

[0011] Step 3: Calculate the flow rate range u of the heat transfer fluid based on the thermal properties of the heat transfer fluid, the heat storage power, the heat storage temperature operating range, and the fluid flow cross-sectional area range. min ~u max ;

[0012] Step 4: Establish a flow heat transfer calculation model for a single heat storage ball unit in a packed bed sensible heat storage device, and obtain the average heat storage rate per unit volume and unit temperature difference of the heat storage ball unit based on the model. v,ave Calculation formula;

[0013] Step 5, preliminarily screening the types of heat storage materials based on the heat storage rate;

[0014] Step 6, selecting the final heat storage material type based on the operating temperature conditions and economic efficiency;

[0015] Step 7, determining the size of the heat storage material according to the pressure loss of the heat storage device.

[0016] Compared with the prior art, the effects of the present invention are embodied in:

[0017] 1) The present invention proposes a rapid screening method for heat storage materials, which includes four main steps: clarifying the heat storage scenario requirements, designing the flow rate of heat transfer fluid, screening the types of heat storage materials, and confirming the size of heat storage materials. The screened heat storage materials can achieve a higher heat storage rate and lower material investment cost while meeting the pressure loss and heat storage power requirements of the device. This method has important guiding significance and engineering application value for the design of packed bed sensible heat storage devices.

[0018] 2) The heat storage material screening method proposed in the present invention has wide applicability. The heat transfer fluid can be water, thermal oil, molten salt, metal fluid, steam, air, carbon dioxide, etc. The application scenarios can be building heating, industrial waste heat storage, solar thermal power generation heat storage, flexible peak regulation of thermal power plants, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of a packed bed sensible heat storage device.

[0020] Figure 2 Flow chart of the method for screening heat storage materials for packed bed sensible heat storage tanks.

[0021] Figure 3 This is a schematic diagram of the calculation results of preliminary screening of heat storage material types based on heat storage rate in an embodiment of the present invention.

[0022] Figure 4 The pressure loss per unit flow of the heat storage device at the minimum flow rate according to the embodiment of the present invention changes with the radius R of the solid heat storage material. s Schematic diagram of the changing rules. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0024] Figure 1 The structure of a packed bed sensible heat storage device is shown, comprising a tank body 1, a low-temperature heat transfer fluid inlet 2 is provided at the bottom of the tank body 1, a high-temperature heat transfer fluid outlet 3 is provided at the top, flow equalizers 4 are evenly distributed at the upper and lower parts of the tank body 1, solid sensible heat storage material 5 is filled between the upper flow equalizer 4 and the lower flow equalizer 4, and part of the solid sensible heat storage material 5 is in contact with the wall of the tank body 1.

[0025] See also Figure 2 The present invention provides a rapid screening method for heat storage materials used in a packed bed sensible heat storage device, which mainly comprises the following steps:

[0026] 1) Determine the heat storage requirements and operating conditions of the heat storage device based on the actual heat storage application scenario of the project.

[0027] Heat storage requirements include: heat storage power requirements P of heat storage scenarios TESThe maximum per unit flow pressure loss ΔP allowed by the heat storage device design,max .

[0028] Thermal storage operating conditions include: the type and thermal properties of the heat transfer fluid (thermal properties include its density ρ HTF , constant pressure specific heat capacity c p,HTF , kinematic viscosity ν HTF , thermal conductivity λ HTF ), the minimum operating temperature T of the heat storage scenario L With the maximum operating temperature T H , and the site area A where the heat storage structure is placed min ~A max , A min and A max are the minimum and maximum site areas for placing the thermal storage structure.

[0029] 2) Selection of alternative heat storage materials.

[0030] After determining the type of heat transfer fluid, a solid sensible heat storage material with chemical stability in the heat transfer fluid is selected as an alternative material, and the thermal properties and cost parameters of the alternative material are obtained, where the thermal properties of the alternative material include its density ρ s , constant pressure specific heat capacity c p,s and thermal conductivity λ s , the cost parameters include the material price per unit volume C s .

[0031] 3) According to the thermal properties of the heat transfer fluid (ρ HTF 、c p,HTF ), heat storage power (P TES ), heat storage temperature operating range (T L ~T H ) and fluid cross-sectional area range (A min ~A max ), calculate the flow rate operating range u of the heat transfer fluid according to formula (1) min ~u max .

[0032]

[0033] 4) Establish a flow heat transfer calculation model for a single heat storage ball unit in a packed bed sensible heat storage device, and based on the constructed model, obtain the average heat storage rate per unit volume and unit temperature difference of the heat storage ball unit q v,ave Calculation formula.

[0034] 4-1) Physical model

[0035] The structure of the packed bed sensible heat storage device involved in the present invention is as follows: Figure 1As shown in the figure, the heat release process of a single heat storage ball in the heat storage device is taken as the research object, and the radius of the solid sensible heat storage material is R s , unit m, the heat transfer fluid flow rate is u during the heat storage process, and its temperature (T L ) is lower than the initial temperature of the heat storage ball (T H ), the heat storage ball releases heat and the temperature decreases. When the temperature inside the heat storage ball is uniform and drops to T L When , the heat storage ball reaches the ideal heat release state. The heat storage process is the opposite.

[0036] 4-2) Mathematical model

[0037] The heat storage process of the sensible heat storage ball is a one-dimensional non-steady-state heat conduction process, and its control equation is shown in formula (2).

[0038]

[0039] Where T is temperature, °C; t is time, s; r is radial coordinate, m; λ is thermal conductivity, W·m -1 ·K -1 ; ρ is density, kg·m -3 ;c p is the specific heat capacity, J·kg -1 ·K -1 ; Subscript s refers to solid sensible heat storage sphere.

[0040] At the initial moment, the temperature inside the heat storage ball is uniform, and the initial conditions are shown in formula (3).

[0041] 0≤r≤R s ,t=0:T s (r,t)=T H (3)

[0042] The center of the heat storage sphere has an adiabatic boundary condition, as shown in equation (4), and the outer boundary has a third-type boundary condition, as shown in equation (5).

[0043]

[0044]

[0045] Where h is the convective heat transfer coefficient between the solid sensible heat storage material and the heat transfer fluid, in W·m -2 ·K -1 .

[0046] Introducing dimensionless temperature θ(r,t) = T s (r,t)-T L , substituting into equations (2)-(5) we can get:

[0047]

[0048] 0≤r≤R s ,t=0:θ(r,0)=θ 0 (7)

[0049]

[0050]

[0051] In the formula, a s is the thermal diffusivity of the solid sensible heat storage material, m 2 ·s -1 , a s =λ s / (ρ s ·c p,s ).

[0052] 4-4) Model solution

[0053] The separation of variables method is used to solve equations (6)-(9), and the analytical solution of the dimensionless temperature θ(r, t) inside the sensible heat storage sphere is obtained as an infinite series as shown in equation (10).

[0054]

[0055] Where η is the dimensionless radius, η = r / R s ; Fo——Fourier number, Fo=a s t / R s 2 ;μ n is the root of the transcendental equation (11).

[0056] 1-μ n cot(μ n )=Bi(n=1,2,...) (11)

[0057] Where Bi is the Biot number, Bi = hR s / λ s .

[0058] It is known that when Fo>0.2, the deviation between the result obtained by ignoring the second and subsequent terms of the infinite series and the result calculated according to the complete series is less than 1%, that is, n≥2, C n It can be approximated to 0. Its physical meaning is that when Fo>0.2, the influence of the initial conditions has disappeared, and the heat storage ball is in a "normal state" afterwards. Therefore, the analytical solution of the dimensionless temperature of the heat storage ball in the normal state stage can be simplified to:

[0059]

[0060] From the initial moment to the process of thermal equilibrium (the ideal state of complete heat storage), the heat transferred by the heat storage ball is Q0 for:

[0061]

[0062] The heat Q(t) transferred from the initial moment to a certain moment t is:

[0063]

[0064] According to equations (12) and (14), the dimensionless temperature and heat storage capacity of the heat storage ball in the normal state can be uniformly expressed as follows:

[0065]

[0066]

[0067] In the formula, M, N and f(μ 1 The expression of η) is shown in formula (17).

[0068]

[0069] In order to measure the heat storage performance of the sensible heat storage ball unit, the average heat storage rate per unit volume and unit temperature difference (q v,ave , W·m -3 ·K -1 ) is the evaluation index, and its definition is shown in formula (18).

[0070]

[0071] In the formula, κ is the ratio of actual heat storage to theoretical heat storage, and κ = 1 means that heat storage or heat release is complete, that is, the heat storage ball reaches a balanced state; t κ The actual heat storage capacity reaches κQ 0 Time required, s; ​​ΔT = T H -T L .

[0072] From the root formula (16), we know that when Q / Q 0 = κ when Fo κ for:

[0073]

[0074] Thus, the actual heat storage capacity reaches κQ 0 The time required t κ for:

[0075]

[0076] Substituting formula (20) into formula (18), we can obtain:

[0077]

[0078] When the method of the present invention is used to screen heat storage materials, the recommended value of κ is 0.95.

[0079] 5) Preliminary screening of heat storage material types based on heat storage rate.

[0080] 5-1) Thermal conductivity λ of heat storage material s Preliminary value, the density of the heat storage material ρ s , constant pressure specific heat capacity c p,s , radius R s Set to the default value. For example, set λ s The initial value is 0.1W·m -1 ·K -1 , ρ s 、c p,s , R s Set to 3000kg·m -3 、1000kJ·kg -1 ·K -1 、0.03m.

[0081] 5-2) Based on the minimum heat storage operation temperature T determined in step 1) L With the maximum temperature T H , Type and properties of heat transfer materials (ρ HTF 、c p,HTF , ν HTF , HTF ), and the minimum design flow rate u of the heat transfer fluid obtained according to formula (1) min , calculate q v,ave .

[0082] 5-3) For q v,ave With λ s The growth rate δ(δ=|q v,ave (λ s +Δλ s )-q v,ave (λ s )| / q v,ave (λ s )) to judge, if δ<ε δ , then proceed to step 6; if δ≥ε δ , then update the thermal conductivity λ of the heat storage material s ←λ s +Δλ s , recalculate q v,ave , until δ<ε is satisfied δ Judging conditions, so as to obtain the minimum recommended value λ of thermal conductivity of heat storage materials s,th In this embodiment, ε δ =10-3 , Δλ s =0.1

[0083] 5-4) Determine the thermal conductivity λ of the candidate solid sensible heat storage materials s Is it higher than λ? s,th If it is not satisfied, the candidate material is eliminated, thereby preliminarily obtaining a series of heat storage material types that can meet the high heat storage rate target.

[0084] 6) Optimize the final type of heat storage material based on operating temperature conditions and economic efficiency.

[0085] 6-1) Determine the applicable temperature range (T s,min ~T s,max ) can meet the operating temperature range of the thermal storage scenario (T L ~T H ), if not satisfied, then T L <T s,min or T H >T s,max , then eliminate this alternative material.

[0086] 6-2) Calculate the unit volume heat storage density cost C of the remaining candidate heat storage materials according to formula (25): TES , select C from the remaining candidate materials TES The lowest material type, thus ultimately obtaining a solid sensible heat storage material type with better economy.

[0087] 7) Determine the size of the heat storage material based on the pressure loss of the heat storage device.

[0088] 7-1) The minimum radius R of the thermal storage material that can actually be purchased or processed s,L .

[0089] 7-2) According to the maximum pressure loss per unit flow allowed by the heat storage device ΔP design,max , heat storage power requirement P TES , and the minimum flow rate u determined in step 3 min , calculated by formula (23) when the system pressure loss is equal to ΔP design,max When the minimum flow rate u min The minimum allowable radius R of the lower heat storage material s,min .

[0090] 7-3) Based on the premise of meeting the heat storage power requirement and the goal of maximizing the heat storage rate, the minimum diameter that meets the actual processing conditions and pressure loss requirements is selected, that is, when R s,min <R s,L The radius of the heat storage material R s Select R s,L , otherwise Rs Select R s,min . This determines the final size R of the heat storage material s .

[0091] This determines the type and size of the heat storage material and the flow rate range of the heat transfer fluid in the packed bed sensible heat storage device.

[0092] Parameter definition in the design process of the present invention:

[0093] 1) Thermal storage power requirements for thermal storage scenarios (P TES , kW)

[0094] P TES =q m,HTF c p,HTF (T H -T L ) (22)In the formula, q m,HTF is the flow rate of heat transfer fluid, kg·s -1 ;c p,HTF is the constant pressure specific heat capacity of the heat transfer fluid, kJ·kg -1 ·K -1 ;

[0095] 2) Unit process pressure loss of heat storage device (ΔP, Pa·m -1 )

[0096]

[0097] Where A is the cross-sectional area of ​​the heat storage channel, m 2 ; Δp is the pressure loss of the packed bed per unit cross-sectional area per unit process, Pa·m -3 , calculated using the Ergun formula, as shown in formula (24).

[0098]

[0099] In the formula, R s is the radius of the solid heat storage material, m; ν HTF is the kinematic viscosity of the heat transfer fluid, m 2 ·s -1 ; u is the flow rate of the heat transfer fluid in the packed bed heat storage, m·s -1 ; ε is the porosity of the packed bed heat storage, ε=0.368+0.383R s A -0.5 .

[0100] 3) Unit heat storage density cost of heat storage materials (C TES , yuan·kWh -1 )

[0101]

[0102] In the formula, C s is the price of heat storage material per unit volume, RMB·m -3 ρ s is the density of the solid heat storage material, kg·m -3 ;c p,s is the constant pressure specific heat capacity of the solid heat storage material, kJ·kg -1 ·K -1 .

[0103] In one embodiment of the present invention, a specific heat storage application scenario is to use a packed bed sensible heat storage device to store heat. According to the method described in this patent, the following steps are used to quickly screen heat storage materials.

[0104] Step 1: Determine the heat storage requirements and operating conditions of the heat storage device according to the project heat storage application scenario. TES The maximum per unit flow pressure loss ΔP allowed by the heat storage device is 100kW. design,max The heat transfer fluid used is air, and the minimum operating temperature is T L The maximum operating temperature is 100°C. H The area of ​​the heat storage structure is 300℃. min ~A max ) is 1m 2 ~5m 2 The thermal properties of air are: density ρ HTF =0.611kg·m -3 , constant pressure specific heat capacity c p,HTF =1044.9J·kg -1 ·K -1 , kinematic viscosity ν HTF =4.77×10 -5 m 2 ·s -1 , thermal conductivity λ HTF =0.045W·m -1 ·K -1 ;

[0105] Step 2: Selection of candidate heat storage materials. Eleven solid sensible heat storage materials with chemical stability in air were selected as candidate materials, and their thermophysical property parameters are shown in Table 1.

[0106] Step 3: According to the thermal properties of the heat transfer fluid, the heat storage power, the heat storage temperature operating range and the fluid cross-sectional area range, the flow rate operating range (u min ~u max ) are 0.16m / s and 0.78m / s.

[0107] Step 4: Based on the established flow heat transfer calculation model of a single heat storage ball unit in the packed bed sensible heat storage device, the average heat storage rate per unit volume and unit temperature difference of the heat storage ball unit q is obtained. v,ave The calculation formula is shown in formula (21).

[0108] Step 5: Preliminary screening of heat storage material types based on heat storage rate. First, set the thermal conductivity λ of the heat storage material s The initial value is 0.1W·m -1 ·K -1 , the density, specific heat capacity, radius (ρ s 、c p,s , R s ) are set to 3000kg·m -3 、1000kJ·kg -1 ·K -1 , 0.03m. Secondly, based on the determined heat storage operating temperature range, air thermal properties, and the minimum design air flow rate, q is obtained according to formula (21): v,ave and q v,ave Growth rate δ(δ=|q v,ave (λ s +Δλ s )-q v,ave (λ s )| / q v,ave (λ s ))With λ s The calculation results are as follows: Figure 3 Next, take ε δ =10 -3 , when λ s 2.5W·m -1 ·K -1 When δ is 9.69×10 -4 , satisfying "δ<ε δ ", so 2.5W·m -1 ·K -1 is the minimum recommended value of thermal conductivity of heat storage materials λ sth Finally, the thermal conductivity λ of 11 candidate solid sensible heat storage materials was determined. s Is it higher than λ? s,th There are five materials that meet the requirements, namely aluminum, 12% aluminum-88% silicon, cast steel, mullite, and magnesia bricks.

[0109] Step 6: Select the final thermal storage material type based on the operating temperature conditions and economic optimization. First, the operating temperature range of the five materials currently selected all meet the operating temperature range requirements of the thermal storage scenario of 100-300°C, and no materials are eliminated. Secondly, by querying the current market sales costs of the five materials, the unit thermal storage density cost C of the thermal storage material is obtained. TES , where C of mullite TES The lowest is 43.2 yuan per kWh -1 , the heat storage economy is the best, so mullite is selected as the final heat storage material.

[0110] Step 7: Determine the size of the heat storage material according to the pressure loss of the heat storage device. According to equations (23) and (24), calculate the pressure loss per unit flow of the heat storage device ΔP as a function of the radius R of the solid heat storage material at the minimum flow rate. s The changing rules, such as Figure 4 As shown, when ΔP is equal to ΔP design,max At this time, R s It is 0.014m, which is the minimum allowable radius R of the heat storage material under the pressure loss requirement. s,min The research shows that the minimum radius R that mullite can actually process is s,L is 0.005m. s,min >R s,L , which meets the processing requirements of mullite. Therefore, in this heat storage scenario, the radius of the heat storage material can be selected as 0.014m.

[0111] Through the above steps 1-7, for the heat storage scenario, the final type of heat storage material screened is mullite, the radius of the heat storage material is 0.014m, and the flow rate range of the heat transfer fluid (u min ~u max ) are 0.16m / s and 0.78m / s. Under the given heat storage scenario conditions, the selection of the above heat storage materials not only meets the requirements of heat storage pressure loss and heat storage power, but also the average heat storage rate per unit volume and unit temperature difference can be as high as 235.5W·m -3 ·K -1 The unit heat storage density cost is only 43.2 yuan per kWh. -1 , which can achieve higher heat storage rate and lower heat storage investment cost.

[0112] Table 1 Thermophysical properties of candidate heat storage materials

[0113]

[0114]

Claims

1. A method for rapid screening of heat storage materials for packed bed sensible heat storage, characterized in that: The following steps are involved: Step 1: Determine the heat storage requirements and operating conditions of the heat storage device according to the engineering heat storage application scenario; The heat storage demand includes: the heat storage power requirement P of the heat storage scenario TES The maximum per unit flow pressure loss ΔP allowed by the heat storage device design,max The operating conditions include: the type and thermal properties of the heat transfer fluid, and the minimum operating temperature T of the heat storage scenario. L With the maximum operating temperature T H , and the site area A where the heat storage structure is placed min ~A max ; The thermal properties of the heat transfer fluid include its density ρ HTF , constant pressure specific heat capacity c p,HTF , kinematic viscosity ν HTF and thermal conductivity λ HTF ; Step 2, select candidate heat storage materials; after determining the type of heat transfer fluid, select solid sensible heat storage materials that are chemically stable in the heat transfer fluid as candidate materials, and obtain the thermal properties and cost parameters of the candidate materials. The thermal properties of the candidate materials include their density ρ s , constant pressure specific heat capacity c p,s and thermal conductivity λ s , the cost parameters include the material price per unit volume C s ; Step 3: Calculate the flow rate range u of the heat transfer fluid based on the thermal properties of the heat transfer fluid, the heat storage power, the heat storage temperature operating range, and the fluid flow cross-sectional area range. min ~u max ; Step 4: Establish a flow heat transfer calculation model for a single heat storage ball unit in a packed bed sensible heat storage device, and obtain the average heat storage rate per unit volume and unit temperature difference of the heat storage ball unit based on the model. v,ave The calculation formula is as follows: In the formula, κ is the ratio of actual heat storage to theoretical heat storage; R s is the radius of the solid sensible heat storage material; The calculation formulas for M and N are as follows: μ1 is the root of the following transcendental equation: 1-μ1cot(μ1)=Bi Where Bi is the Biot number, Bi = hR s / λ s ; h is the convective heat transfer coefficient between the solid sensible heat storage material and the heat transfer fluid; Step 5, preliminarily screening the types of heat storage materials based on the heat storage rate; Step 6, selecting the final heat storage material type based on the operating temperature conditions and economic efficiency; Step 7, determining the size of the heat storage material according to the pressure loss of the heat storage device.

2. The rapid screening method for heat storage materials used in packed bed sensible heat storage according to claim 1 is characterized in that: In step 3, the flow rate operating range of the heat transfer fluid is u min ~u max The calculation formula is as follows:

3. The rapid screening method for heat storage materials used in packed bed sensible heat storage according to claim 1 is characterized in that: In step 5, the preliminary screening method of the types of heat storage materials is as follows: First, for λ s Initial value, ρ s 、c p,s , R s Set to default value; Secondly, based on the T determined in step 1 L , T H , HTF 、c p,HTF , ν HTF , HTF , and u obtained in step 3 min , calculate q v,ave ; Next, for q v,ave With λ s The growth rate δ is used to judge, if δ<ε δ , then proceed to step 6; if δ≥ε δ , then update λ s ←λ s +Δλ s , recalculate q v,ave , until δ<ε is satisfied δ , thus obtaining the minimum recommended value λ of the thermal conductivity of the heat storage material s,th ; where ε δ is the set value; Finally, determine whether the thermal conductivity of the candidate material proposed in step 2 is higher than λ s,th If it is not satisfied, the candidate material is eliminated, thereby preliminarily obtaining a series of heat storage material types that can meet the high heat storage rate target.

4. The rapid screening method for heat storage materials used in packed bed sensible heat storage according to claim 1 is characterized in that: In step 5, s 、c p,s , R s The default values ​​are 3000kg·m -3 、1000kJ·kg -1 ·K -1 , 0.03m; s The initial value is 0.1W·m -1 ·K -1 , Δλ s 0.1W·m -1 ·K -1 , ε δ For 10 -3 .

5. The rapid screening method for heat storage materials used in packed bed sensible heat storage according to claim 1 is characterized in that: In step 6, the method for screening the types of the final heat storage materials is as follows: First, determine the applicable temperature range T of the candidate heat storage materials after preliminary screening. s,min ~T s,max Whether it can meet the operating temperature range T of the thermal storage scenario L ~T H If the requirements are not met, the candidate material will be eliminated; Secondly, calculate the unit volume heat storage density cost C of the remaining candidate heat storage materials TES , select C from the remaining candidate materials TES The lowest material type, ultimately obtaining an economical solid sensible heat storage material type.

6. The rapid screening method for heat storage materials used in packed bed sensible heat storage according to claim 1 is characterized in that: In step 7, the method for determining the size of the heat storage material is as follows: First, investigate the minimum radius R of the selected thermal storage material that can actually be purchased or processed. s,L ; Secondly, according to ΔP design,max , P TES , calculate when the system pressure loss ΔP is equal to ΔP design,max When the minimum flow rate u min The minimum allowable radius R of the lower heat storage material s,min ; Finally, with the requirement of heat storage power as the premise and the maximum heat storage rate as the goal, the minimum diameter that meets the actual processing conditions and pressure loss requirements is selected, that is, when R s,min <R s,L When the radius of the heat storage material R s Select R s,L , otherwise R s Select R s,min , thereby determining the final size of the heat storage material.

7. The rapid screening method for heat storage materials used in packed bed sensible heat storage according to claim 1, characterized in that: In step 7, the unit process pressure loss ΔP of the heat storage device is calculated according to the following formula: Where A is the cross-sectional area of ​​the heat storage flow channel; Δp is the pressure loss of the packed bed per unit cross-sectional area per unit flow.

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