Rankine cycle rocket engine system
阅读说明：本技术 一种朗肯循环火箭发动机系统 (Rankine cycle rocket engine system ) 是由 侯辉 刘恒娟 于 2019-09-29 设计创作，主要内容包括：本发明涉及一种朗肯循环火箭发动机系统,该系统包括推力室(1)、冷凝器(5)、推进剂增压单元、膨胀机(4)、朗肯循环增压泵(6)和电机,所述推进剂增压单元与推力室(1)连接并供给燃料,所述推力室(1)、膨胀机(4)、冷凝器(5)和朗肯循环增压泵(6)串联形成朗肯循环子系统,所述膨胀机(4)传动连接推进剂增压单元,或者同时传动连接推进剂增压单元与朗肯循环增压泵(6)；所述推进剂增压单元和/或朗肯循环增压泵(6)连接提供额外动力的电机。与现有技术相比,本发明电池重量大大降低,且简单可靠,易于控制,价格低廉。(The invention relates to a Rankine cycle rocket engine system, which comprises a thrust chamber (1), a condenser (5), a propellant pressurization unit, an expansion machine (4), a Rankine cycle booster pump (6) and a motor, wherein the propellant pressurization unit is connected with the thrust chamber (1) and supplies fuel, the thrust chamber (1), the expansion machine (4), the condenser (5) and the Rankine cycle booster pump (6) are connected in series to form a Rankine cycle subsystem, and the expansion machine (4) is in transmission connection with the propellant pressurization unit or is simultaneously in transmission connection with the Rankine cycle booster pump (6); the propellant booster unit and/or the Rankine cycle booster pump (6) is connected to an electric motor providing additional power. Compared with the prior art, the battery has the advantages of greatly reduced weight, simplicity, reliability, easy control and low price.)
1. A rankine cycle rocket engine system, characterized in that the system comprises a thrust chamber (1), a condenser (5), a propellant pressurizing unit, an expander (4), a rankine cycle booster pump (6) and a motor, wherein the propellant pressurizing unit is connected with the thrust chamber (1) and supplies propellant, and the thrust chamber (1), the expander (4), the condenser (5) and the rankine cycle booster pump (6) are connected in series to form a rankine cycle subsystem;
The expansion machine (4) is in transmission connection with the propellant pressurization unit or is simultaneously in transmission connection with the propellant pressurization unit and the Rankine cycle booster pump (6);
The propellant booster unit and/or the Rankine cycle booster pump (6) is connected to an electric motor providing additional power.
2. Rankine cycle rocket engine system according to claim 1, wherein the propellant pressurization unit is connected to the condenser (5) before the thrust chamber (1).
3. Rankine cycle rocket engine system according to claim 2, wherein the propellant booster unit comprises a fuel booster pump (3) and an oxidant booster pump (2), the fuel booster pump (3) being connected to the expander (4) and/or the electric machine, the oxidant booster pump (2) being connected to the expander (4) and/or the electric machine.
4. Rankine cycle rocket engine system according to claim 3, wherein the fuel booster pump (3) is used for boosting propellant, the oxidizer booster pump (2) is used for boosting oxidizer, and the condenser (5) uses pressurized fuel and/or pressurized oxidizer as cooling medium.
5. The Rankine cycle rocket engine system according to claim 1, wherein a regenerator (8) is further provided in the Rankine cycle subsystem.
6. Rankine cycle rocket engine system according to claim 5, wherein the condenser (5) and regenerator (8) are plate heat exchangers or tube heat exchangers.
7. The Rankine cycle rocket engine system according to claim 1, wherein the electric motor and expander (4) are powered by a shafting and/or transmission comprising gears, belt drives and couplings in mating connection with each other.
8. Rankine cycle rocket engine system according to claim 1, wherein the expander (4) is a turbine or a screw expander.
9. Rankine cycle rocket engine system according to claim 3, wherein the oxidant booster pump (2), fuel booster pump (3), Rankine cycle booster pump (6) are centrifugal pumps or plunger pumps.
10. A rankine cycle rocket engine system according to any one of claims 1-9 wherein the rankine cycle subsystem is for the cycle of rankine cycle fluid selected from the group consisting of water, liquid ammonia, ammonia mixture, R41, R125, R218, R143a, R32, RE125, R1270, R290, R134a, R227ea, R161, R152a, RC270, R236fa, RE170, R600a, R236ea, R600, R245fa, Neo-C5H12One or more of R601a, R601 or n-hexane.
Technical Field
The invention relates to the field of engine systems, in particular to a Rankine cycle rocket engine system.
Background
Traditional pump-type rocket engine systems are divided into open-type cycles and closed-type cycles according to the engine cycle, the open-type cycles mainly comprise gas generator cycles, and the closed-type cycles mainly comprise staged combustion cycles and expansion cycles. In both open and closed cycles, the system is complex and the control involves complex feedback because it involves the use of partial propellant combustion or gasification to drive the turbine. Especially, in the closed cycle, the feedback degree is very deep, and the complexity and control difficulty of the system are the best of those of industrial products. In addition to the characteristics such as high temperature and high pressure of a thrust chamber, the pumping pressure type rocket engine system builds a high and unsmooth technical threshold for the rocket engine system, and only a few aerospace strong countries can control the rocket engine system.
And with the successful launching of the carrier rocket of the electronic number of 1 month and 21 days in 2018, the looseness appears in the field. The 'electronic number' carrier rocket indicates a brand-new way for the design of future rocket engines by the brand-new cycle of the electric rocket engine: the power source for pressurizing the propellant is not from the turbine, but is provided by the motor. The circulation mode enables the system to have the characteristics of simple design and debugging, high engine performance, easy maintenance and use, easy expansion and the like. The combination of the inexpensive launch price of the rocket company makes this technology known in the industry as "it is possible to significantly reduce the difficulty of designing and manufacturing small rocket engines".
However, the electric rocket engine cycle has a fatal weakness that the weight of the battery is too high. From analysis, even with the highest state of the art lithium batteries, the battery weight required to provide pump boost power for the rocket stage must reach 2t, while the total weight of the rocket body is no more than 10 t. Therefore, even if various weight-reducing methods are adopted, the nominal emission mass of the 500km solar synchronous orbit is only 150kg, and the mass of the payload actually carried in the first emission is only 39 kg. Too high weight of the battery has been the biggest obstacle to the development thereof.
Disclosure of Invention
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a rankine cycle engine system, particularly for a rocket, which can greatly reduce the weight of a battery, is easy to control, is simple and reliable, and is inexpensive.
The purpose of the invention is realized by the following technical scheme:
a Rankine cycle rocket engine system comprises a thrust chamber, a condenser, a propellant pressurizing unit, an expander, a Rankine cycle booster pump and a motor, wherein the propellant pressurizing unit is connected with the thrust chamber and supplies fuel, the thrust chamber, the expander, the condenser and the Rankine cycle booster pump are connected in series to form a Rankine cycle subsystem, and the expander is in transmission connection with the propellant pressurizing unit or is in transmission connection with the Rankine cycle booster pump; the propellant booster unit and/or the rankine cycle booster pump are connected to an electric motor providing additional power.
When the system works, fuel and oxidant are mixed and combusted in the thrust chamber to release heat, the heat is transferred to liquid Rankine cycle working medium through the chamber wall, the Rankine cycle working medium changes from liquid to superheated steam after absorbing heat, does work outwards through an expansion machine (mechanical energy is transferred to a propellant pressurization unit and/or a Rankine cycle booster pump), changes into low-temperature low-pressure steam and then changes into supercooled liquid through a condenser, then the supercooled liquid is pressurized through the Rankine cycle booster pump to become high-pressure low-temperature liquid, and finally the high-pressure low-temperature liquid enters a Rankine cycle fluid channel of the thrust chamber to form Rankine cycle.
The system can adopt a control mode that the motor provides additional power, and when the motor is used as main power, the Rankine cycle subsystem only provides partial power; the system can also adopt a control mode that the motor only provides partial power and the main power is provided by the Rankine cycle subsystem; the control mode that a motor is not arranged in the system, the initial power is provided by the pressure of the fuel storage tank, and the subsequent power is provided by the Rankine cycle subsystem can be adopted.
When the scheme that the motor provides partial power is adopted, the required motor power is smaller, so that the required amount of the battery serving as a power source of the motor is smaller, the weight of the battery can be greatly reduced, and the control is easy; the super capacitor and the battery are reasonably matched to use, so that the weight of the battery is greatly reduced while the control is convenient.
Further, the electric motor comprises a first electric motor connected with the propellant booster unit and/or a second electric motor separately connected with the rankine cycle booster pump. The same motor is adopted to simultaneously provide power for the propellant pressurization unit and the Rankine cycle pressurization pump, so that the efficiency is higher in energy utilization, but the structural layout has larger limitation. The degree of freedom that the second motor provides power for the Rankine cycle booster pump alone is more in the control, can be convenient realize adjusting Rankine cycle operating pressure through adjusting the second motor rotational speed, and realize adjusting Rankine cycle operating flow through adjusting the first motor rotational speed, and then realize the purpose of adjusting whole engine system operating mode. At this time, the rankine cycle booster pump is not connected to the propellant booster unit.
furthermore, the propellant pressurizing unit is connected with the condenser firstly and then connected with the thrust chamber, the propellant can be used as a cold source, the energy exchange principle is better applied, and the energy utilization efficiency of the Rankine cycle subsystem is higher.
Further, the propellant pressurizing unit comprises a fuel pressurizing pump and an oxidant pressurizing pump, the fuel pressurizing pump is connected with the expander and/or the motor, and the oxidant pressurizing pump is connected with the expander and/or the motor.
Further, the fuel booster pump is used for boosting fuel, the oxidant booster pump is used for boosting oxidant, and the condenser adopts the boosted fuel and/or the boosted oxidant as cooling media. The cooling scheme is determined according to the heat absorbed by the cooling medium required by the system, wherein the fuel alone is safer to use as the cooling medium.
Furthermore, a heat regenerator is further arranged in the Rankine cycle subsystem, namely the heat regenerator is further arranged between the expansion machine and the condenser and used for transferring the heat of the low-temperature low-pressure working medium steam in front of the inlet of the condenser to the low-temperature high-pressure working medium liquid in front of the inlet of the fluid channel of the thrust chamber. Generally, the temperature of low-temperature low-pressure steam before the inlet of the condenser is higher than that of low-temperature high-pressure liquid before the inlet of a Rankine cycle fluid channel of the thrust chamber; the heat regenerator is arranged, so that the cooling load of the propellant and/or the oxidant can be effectively reduced, and the heat absorption capacity of the isobaric heat absorption process of the system is increased.
Further, the condenser and the heat regenerator are plate heat exchangers or tubular heat exchangers, and are all common heat exchanger types.
Further, the motor and the expansion machine provide power through a shaft system and/or a transmission device, and the transmission device comprises a gear, a belt transmission mechanism and a coupler which are mutually matched and connected and is a common transmission device.
Further, the expander is a turbine or screw expander, which are two types of expanders commonly used in rankine cycles.
Further, the oxidant booster pump, the fuel booster pump and the rankine cycle booster pump are centrifugal pumps or plunger pumps, and are all commonly used pump types.
Further, the Rankine cycle subsystem is used for circulation of a Rankine cycle working fluid selected from water, liquid ammonia, an ammonia mixture, R41, R125, R218, R143a, R32, RE125, R1270, R290, R134a, R227ea, R161, R152a, RC270, R236fa, RE170, R600a, R236ea, R600, R245fa, Neo-C5H12One or more of R601a, R601 or n-hexane.
The thrust chamber of the pump-type rocket engine generally achieves the purpose of cooling the wall of the thrust chamber through regenerative cooling, and in the process, Rankine cycle working media in a Rankine cycle fluid channel of the thrust chamber cool the wall of the thrust chamber through absorbing combustion heat transmitted by the wall of the chamber; the process belongs to spontaneous transfer of heat from high temperature to low temperature, and the second law of thermodynamics shows that the process belongs to an irreversible process and can bring loss of system working capacity.
The invention mainly adopts Rankine cycle technology to absorb heat generated by combustion of the thrust chamber and convert the heat into mechanical energy for pressurizing fuel and/or oxidant in the expander, thereby achieving the purpose of greatly reducing the weight of the battery.
The Rankine cycle technology is adopted, heat generated by combustion of a propellant in the thrust chamber is used as a heat source, pressurized fuel and/or pressurized oxidant are used as a cold source, work is applied to the outside through the expansion machine, and power can be provided for the oxidant booster pump, the fuel booster pump and the Rankine cycle booster pump, so that the load of a motor is reduced, the power consumption is reduced, and the purpose of greatly reducing the weight of a battery is achieved.
Different from the traditional engine system, the Rankine cycle subsystem only has a heat exchange relation with the main engine system except for driving the pump, so that the Rankine cycle subsystem is low in coupling degree and easy to control. The characteristic also makes the invention and the electric circulating system can be compared in the aspects of simplicity, reliability, low price and the like.
In addition, the temperature of the cold source has great influence on the Rankine cycle efficiency, and the lower the temperature of the cold source is, the higher the Rankine cycle efficiency is; meanwhile, because the cold source has low temperature and enough cooling capacity, the temperature of the heat source can be increased, and the work capacity of the system is further enhanced; for a thrust chamber with extremely high combustion temperature, the temperature of the Rankine cycle working medium can be easily increased through design.
Taking a liquid hydrogen liquid oxygen engine as an example, when the system works, the high temperature of the Rankine cycle working medium can reach more than 500 ℃, and the low temperature can reach below-150 ℃, compared with the efficiency of the Rankine cycle working medium adopting the method in the embodiment 2, the high temperature of the Rankine cycle working medium and the low temperature of 50 ℃ can not be in the same day. Therefore, for the liquid rocket engine widely using the low-temperature propellant, the Rankine cycle mode has the unique advantage of reducing rocket quotation.
The invention can be applied to the carrier rocket, and the carrying capacity can be greatly improved on the basis of simplicity, reliability and low cost, thereby greatly improving the competitiveness. More significantly, after the Rankine efficiency is greatly improved by adopting the low-temperature propellant and/or the low-temperature oxidant as a cold source at the condenser, the thrust and the specific impulse of the system are basically the same as those of a closed cycle, and the weight of the battery is basically negligible compared with the total weight of the rocket body. At the moment, the rocket can utilize the characteristic of more flexible control to complete tasks with higher control difficulty, such as the recovery of a first-stage rocket.
By applying the scheme in the satellite and deep space detector, the electric power of the solar cell panel can be effectively utilized, and the performance of the engine is further improved on the existing basis. The method has important significance for prolonging the on-orbit working time of the high-orbit satellite and saving the propellant of the deep space controller.
Compared with the prior art, the invention has the following advantages:
1. The motor and the expander are adopted to cooperate to provide power for the oxidant booster pump, the fuel booster pump and the Rankine cycle booster pump, so that the weight of a matched battery can be greatly reduced and even reduced to be close to zero, and the expansion type booster pump is suitable for rockets and the like with strict requirements on weight.
2. The pressurized propellant and the oxidant firstly pass through the condenser and then enter the thrust chamber, so that the characteristic of low temperature of the fuel and the oxidant can be effectively utilized, and the heat of the Rankine cycle working medium is transferred out.
3. The heat regenerator is arranged to reduce the cooling load of the pressurized fuel and oxidant.
4. the system has few components, simple circulation loop, greatly reduced control difficulty and low price.
Drawings
FIG. 1 is a schematic view of a Rankine cycle rocket engine system according to embodiment 1;
FIG. 2 is a schematic view of a Rankine cycle rocket engine system according to embodiment 2;
FIG. 3 is a schematic structural view of a Rankine cycle rocket engine system according to embodiment 3;
FIG. 4 is a schematic structural view of a Rankine cycle rocket engine system according to embodiment 4;
FIG. 5 is a schematic structural diagram of a Rankine cycle rocket engine system according to embodiment 5.
In the figure: 1-a thrust chamber; 2-oxidant booster pump; 3-fuel booster pump; 4-an expander; 5-a condenser; 6-Rankine cycle booster pump; 7-a first motor; 8-a heat regenerator; 9-a second motor.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.