Thermal control design method suitable for liquefied gas cold gas propulsion products

Abstract

The invention discloses a thermal control design method suitable for liquefied gas type cold air propulsion products, and relates to the technical field of cold air propulsion systems. Three important parameters including the time t1 for heating the heating rod to reach the initial temperature, the time t2 for heating the working medium to 50 DEG C and the continuous working time t3 for maintaining the working medium at 50 DEG C or above after the heating power is given are obtained through simulation of heating of the heating rod on liquid ammonia in the heating channel, and multi-group simulation is further carried out by changing the structure size. And screening is carried out according to the result to obtain an optimal result. According to the method, required structure data can be accurately and quickly found, so that the structure design is accurately matched with the heat exchange efficiency and the heating power, and the problems of high test processing cost and long research and development period are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of cold air propulsion systems, and in particular relates to a thermal control design method suitable for liquefied gas cold air propulsion products. Background Art

[0002] Propulsion technology is the cornerstone of aerospace activities. Propulsion technology includes cold gas propulsion, chemical propulsion, electric propulsion, on-orbit refueling and other technologies. Among them, cold gas propulsion technology generates thrust by releasing high-pressure gas. With its advantages of simple and reliable system, low energy consumption, long life and low cost, it is widely used in satellite attitude control, orbit adjustment, space exploration and other fields. In order to improve the performance of the cold propulsion system, liquid ammonia with high specific heat capacity and specific impulse is used as propellant. Compared with the cold propulsion system with inert gas as propellant, the liquid ammonia needs to be heated to change from liquid to gas, and then ejected at high speed through the Laval nozzle to realize the conversion of thermal energy to kinetic energy. In this way, the specific impulse of the cold propulsion system is greatly improved.

[0003] The heating process of the existing technology is generally heated by the heating plate on the outer wall of the tank and the heating wire in the pipeline, which will heat the entire structure of the tank and all the liquid propellant inside. However, only a small part of the propellant is actually working each time, which will lead to low energy utilization and slow response speed, and will also put pressure on the overall energy consumption and reliability of the spacecraft. Therefore, it is urgent to propose a new design method for accurate structural design, reduce energy consumption and improve heat exchange efficiency under working conditions, and reduce the trial and error costs of testing and processing, and shorten the R&D cycle.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art that the structural design cannot accurately match the heating power, the heat exchange efficiency is low, the test processing cost is high and the R&D cycle is long, and to provide a thermal control design method suitable for liquefied gas cold air propulsion products, comprising the following steps:

[0006] S1. Determine the product's exterior envelope dimensions based on satellite thermal control technical index requirements and layout;

[0007] S2. Design an independent heating channel on the product according to the outer envelope size;

[0008] S3, drawing a three-dimensional model of the heating channel and the heating rod inside it;

[0009] S4. Calculate the total heat required for the working fluid to change from liquid to saturated vapor state based on the physical parameters and motion parameters of the working fluid;

[0010] S5, determine the target parameters: the time t1 for the heating rod to reach the initial temperature, the time t2 for the working fluid to be heated to 50°C, and the continuous working time t3 for the working fluid to maintain a temperature above 50°C after a given power consumption;

[0011] S6, performing heat exchange simulation based on the three-dimensional model; solving t1, t2 and t3 to obtain η=(t1+t2) / t3;

[0012] S7, modify the variable parameters in the simulation process, and execute step S6 again until all the modified conditions are calculated;

[0013] S8. Screening is performed based on the obtained several η, and corresponding variable parameters are selected, and the optimal result is found among the screened variable parameters.

[0014] In one embodiment of the present invention, the heating rod is provided with a plurality of heat exchange ribs.

[0015] In one embodiment of the present invention, the heat exchange fins are needle fins.

[0016] In one embodiment of the present invention, the variable parameters include: the diameter of the heating rod, the length of the heating rod, the power of the heating rod, the number of needle fins, the diameter of the needle fins, and the height of the needle fins.

[0017] In one embodiment of the present invention, the screening condition in step S8 is: take the first 30% of η in order from small to large, and retain their corresponding variable parameters, and remove the variable parameters corresponding to the last 70% of η.

[0018] In one embodiment of the present invention, after the variable parameter screening is completed, the heating rod is selected in order of priority according to weight, power, and cost.

[0019] In one embodiment of the present invention, in the process of selecting weight, power and cost, if the difference between a certain value and the lowest value of the corresponding type of data is within 5%, the two are deemed to have no difference.

[0020] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0021] 1. A dedicated heating channel is designed for the product structure, so there is no need to heat the entire working fluid. Only local heating can reduce power consumption, improve response speed and reduce energy waste.

[0022] 2. Results can be obtained quickly through simulation, and it has the advantages of low cost and high speed when facing more variable parameters.

[0023] 3. The η value is a comprehensive analysis of the heat exchange condition based on three time data. Screening based on the η value can quickly eliminate unqualified variable parameters, and then determine the optimal result based on the indicators of the three dimensions of weight, power, and cost, so as to quickly and accurately guide product design work and enable the product to have the advantages of low power consumption, high heat exchange efficiency, and fast response speed.

[0024] 4. Although there are many structural data such as heating rods and needle ribs in the variable parameters, it is not necessary to analyze these structural data directly. Instead, they are compared with the weight, power and cost of the heating rods, which significantly simplifies the complexity of the analysis work. When the optimal result is determined, production can be carried out according to the corresponding variable parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flow chart of a thermal control design method according to an embodiment of the present invention;

[0026] Figure 2 It is a structural schematic diagram of a three-dimensional model of a heating channel and a heating rod inside the heating channel applicable to a liquefied gas cold air propulsion product according to an embodiment of the present invention.

[0027] Figure 3 It is a schematic structural diagram of a liquefied gas cold air propulsion product according to one embodiment of the present invention.

[0028] Description of main reference numerals:

[0029] 1. Heating channel; 2. Heating rod; 3. Needle fin; 4. Storage tank; 5. Solenoid valve; 6. Pressure reducing valve; 7. Nozzle. DETAILED DESCRIPTION

[0030] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0031] The technical solution of the present invention is described below by specific embodiments. It should be understood that one or more steps mentioned in the present invention do not exclude the existence of other methods and steps before and after the combination step, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and does not limit the order of arrangement of each method or limit the scope of implementation of the present invention. The change or adjustment of the relative relationship thereof can also be regarded as the scope of implementation of the present invention without substantial changes in the technical content.

[0032] The sources of the raw materials and instruments used in the examples are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0033] like Figure 1 As shown, a thermal control design method for liquefied gas cold air propulsion products according to a preferred embodiment of the present invention includes the following steps:

[0034] S1. Determine the product's exterior envelope dimensions based on satellite thermal control technical specifications and layout.

[0035] The outer envelope size strictly limits the rectangular space occupied by the product.

[0036] S2. Design an independent heating channel 1 on the product according to the outer envelope size.

[0037] The structure of the product is adjusted, and a heating channel 1 is set within the range of the outer envelope size to heat the working medium. The setting of the heating channel 1 should not be limited to a specific product structure form, but should have wide adaptability.

[0038] See also Figure 3 An example of a liquefied gas cold air propulsion product is: it includes a storage tank 4, a solenoid valve 5, a pressure reducing valve 6 and a nozzle 7. The space inside the storage tank 4 is provided with mutually independent chambers and heating channels 1. Figure 3The hidden heating channel 1 structure is indicated by dotted lines, and the hidden heating rod 2 is indicated by a cross section. The solenoid valve 5 is arranged on the outer wall of the tank 4, the inlet of the solenoid valve 5 is connected to the chamber in the tank 4, and the outlet of the solenoid valve 5 is connected to one end of the heating channel 1. The inlet of the pressure reducing valve 6 is connected to the other end of the heating channel 1, and the outlet of the pressure reducing valve 6 is installed with a nozzle 7. The heating rod 2 is arranged in the heating channel 1. The solenoid valve 5 is used to control the liquid ammonia in the tank 4 to enter the heating channel 1. In the heating channel 1, the heating rod 2 is used to heat the liquid ammonia to change it from liquid phase to gas phase. The pressure reducing valve 6 is used to control the pipeline pressure and flow stability in front of the nozzle 7, and the ammonia gas is ejected at high speed through the nozzle 7 to generate thrust. The entire heating process is completely confined in the heating channel 1, which is equivalent to only locally heating the liquid ammonia in the heating channel 1, thereby reducing power consumption, improving response speed, and reducing energy waste.

[0039] S3. Draw a three-dimensional model of the heating channel 1 and the heating rod 2 therein.

[0040] The style of the 3D model is as Figure 2 In order to improve the heat exchange efficiency, a plurality of heat exchange ribs are provided on the heating rod 2, and the heat exchange ribs are preferably needle ribs 3 in consideration of the space size and heat exchange performance.

[0041] S4. Calculate the total heat required for the working fluid to change from liquid to saturated vapor based on its physical parameters and motion parameters.

[0042] The total calories are calculated as:

[0043] Q=C×q m ×Δt

[0044] Where: Q is the amount of heat absorbed, in W; c is the constant pressure specific heat capacity of the propellant, in J / (g·K); q m is the working fluid flow rate, in g / s; Δt is the change in temperature of the working fluid after being heated, in K.

[0045] S5. Determine the target parameters: the time t1 for the heating rod to reach the initial temperature, the time t2 for the working fluid to be heated to 50°C, and the continuous working time t3 for the working fluid to be maintained above 50°C after a given power consumption.

[0046] S6. Perform heat exchange simulation based on the three-dimensional model; solve t1, t2 and t3 to obtain η=(t1+t2) / t3.

[0047] Fluent can be used as simulation software.

[0048] S7, modify the variable parameters in the simulation process, and execute step S6 again until all the modified conditions are calculated.

[0049] The variable parameters include: the diameter of the heating rod, the length of the heating rod, the power of the heating rod, the height of the needle fin, the diameter of the needle fin, and the number of the needle fins. Each variable parameter has its variation range, and multiple η can be calculated by selecting values ​​with equal differences within the variation range.

[0050] S8. Screening is performed based on the obtained several η, and corresponding variable parameters are selected, and the optimal result is found among the screened variable parameters.

[0051] The screening conditions are: take the first 30% of η in order from small to large, and keep the corresponding variable parameters, and remove the variable parameters corresponding to the last 70% of η. The value of t1+t2 is required to be as small as possible, and the value of t3 is required to be as large as possible.

[0052] After the screening is completed, there will still be multiple sets of variable parameters left. Then, the priority of the weight, power, and cost of the heating rod is selected in sequence, that is, the weight is measured first, the lower the weight, the better; the power is measured secondly, the lower the power of the heating rod, the better; and the cost is measured lastly, the lower the cost, the better. During the measurement process, if a certain value is within 5% of the minimum value of the corresponding type of data, the two are deemed to have no difference. Please refer to the exemplary data in Table 1 below for details, which is intended to illustrate the selection process.

[0053] Serial number weight power cost 1 10g 20W 20 Yuan 2 10.3g 15W 30 Yuan 3 12g 10W 10 Yuan

[0054] Table 1 Parameter variable table

[0055] See the data in Table 1. First, compare the weight data. The minimum value of the weight is 10g. The weight difference between the second group of data and the first group of data is 3%, which is considered indifferent. The weight difference between the third group of data and the first group of data is 20%, so the third group of data is no longer considered. Then compare the power data of the first and second groups. The power data of the second group is lower than that of the first group, so the variable parameters corresponding to the second group of data are finally determined to be the optimal result.

[0056] Once the optimal result is determined, production can be carried out according to the corresponding variable parameters.

[0057] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A thermal control design method for liquefied gas cold air propulsion products, characterized in that: The following steps are involved: S1. Determine the product's exterior envelope dimensions based on satellite thermal control technical index requirements and layout; S2. Design an independent heating channel on the product according to the outer envelope size; S3, drawing a three-dimensional model of the heating channel and the heating rod inside it; S4. Calculate the total heat required for the working fluid to change from liquid to saturated vapor state based on the physical parameters and motion parameters of the working fluid; S5, determine the target parameters: the time t1 for the heating rod to reach the initial temperature, the time t2 for the working fluid to be heated to 50°C, and the continuous working time t3 for the working fluid to maintain above 50°C after a given power consumption; S6, performing heat exchange simulation based on the three-dimensional model; solving t1, t2 and t3 to obtain η=(t1+t2) / t3; S7, modify the variable parameters in the simulation process, and execute step S6 again until all the modified conditions are calculated; S8. Screening is performed based on the obtained several η, and corresponding variable parameters are selected, and the optimal result is found among the screened variable parameters.

2. The thermal control design method for liquefied gas cold air propulsion products according to claim 1, characterized in that: The heating rod is provided with a plurality of heat exchange ribs.

3. The thermal control design method for liquefied gas cold air propulsion products according to claim 2 is characterized in that: The heat exchange fins are needle fins.

4. The thermal control design method for liquefied gas cold air propulsion products according to claim 3, characterized in that: The variable parameters include: the diameter of the heating rod, the length of the heating rod, the power of the heating rod, the number of needle fins, the diameter of the needle fins, and the height of the needle fins.

5. The thermal control design method for liquefied gas cold air propulsion products according to claim 1, characterized in that: The screening condition in step S8 is: take the first 30% of η in order from small to large, and retain the variable parameters corresponding to them, and remove the variable parameters corresponding to the last 70% of η.

6. The thermal control design method for liquefied gas cold air propulsion products according to claim 1, characterized in that: After the variable parameter screening is completed, the heating rod is selected in order of priority according to the weight, power and cost.

7. The thermal control design method for liquefied gas cold air propulsion products according to claim 6, characterized in that: In the process of selecting weight, power and cost, if the difference between a certain value and the lowest value of the corresponding type of data is within 5%, the two are deemed to have no difference.

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