System and method for cooling rocket engines

Abstract

A propulsion system for a rocket engine and a method of cooling a rocket engine includes a propellant tank fluidically coupled to the rocket engine to hold a pressurized propellant, a coolant tank to hold a coolant, a first heat exchanger thermally coupled to the rocket engine and fluidically coupled to the coolant tank, a second heat exchanger thermally coupled to the propellant tank and fluidically coupled to the first heat exchanger, and a third heat exchanger disposed inside the propellant tank to thermally couple a propellant withdrawn from the tank for combustion to a propellant disposed inside the tank. The coolant flows from the coolant tank to the first heat exchanger and through the first heat exchanger to cool the rocket engine. The propellant withdrawn from the propellant tank receives heat from the propellant disposed inside the tank through the third heat exchanger to convert to a gaseous propellant when withdrawn from the propellant tank as a liquid propellant. The coolant flows from the first heat exchanger to the second heat exchanger and through the second heat exchanger to heat the propellant disposed inside the propellant tank.

Description

FIELD OF THE DISCLOSURE[0001]The present disclosure generally relates to rocket engines, and more particularly, to a cooling system for rocket engines.BACKGROUND[0002]Rocket engines are used for missiles, for launching space bound vehicles, and control of spacecraft in space. Rocket engines that are used to control the attitude of a spacecraft in space are generally referred to as thrusters. Firing a thruster produces a propulsive force that is opposite to the direction of the combustion gases exiting the nozzle of the thruster. The duration of firing and the timing of firing of multiple thrusters can be adjusted to impart sufficient torque on the spacecraft to obtain the desired attitude of the spacecraft. Thus, multiple thrusters are rapidly and repeatedly fired for accurate control of spacecraft attitude.[0003]Thrusters typically use liquid monopropellants such as hydrogen peroxide (H2O2) or hydrazine (N2H4), or room temperature storable bipropellants such as nitrogen tetroxide (...

AI Technical Summary

Problems solved by technology

Nitrogen tetroxide and hydrazine are toxic and environmentally hazardous.

Other propellants, such as nitrous oxide (N2O) and liquid oxygen (O2) combined with a variety of fuels do not have these drawbacks, but there is no currently developed diaphragm tank technology for liquid oxygen and surface tension devices for nitrous oxide and liquid oxygen have not yet been demonstrated.

Furthermore, surface-tension devices only operate in extremely low gravity environments, and many vehicles require a propellant feed solution which works under a range of acceleration environments and directions.

Self-pressurized propellant by itself does not provide zero-gravity feed; however it is possible to consistently feed the gaseous form of the propellant out of the propellant tank by means of a heat exchanger between the withdrawn propellant and the tank contents.

However, as the propellant is fed out of the propellant tank, the pressure of the tank drops causing the liquid part of the propellant to boil.

Accordingly, in order to withdraw gaseous propellant consistently, the pressure of the tank drops significantly during use, to a degree which makes it impractical to use more than a small fraction of the tank contents in this way.

The use of certain propellants, such as liquid oxygen or nitrous oxide with most fuels prohibits radiation cooling because these propellants burn very hot and radiation cooling cannot provide sufficient cooling.

The latter cooling method, however, is not applicable to small thrusters because there is not enough cooling capacity in the propellant to cool the engine.

The problem with this type of system, however, is that continuation of the cooling cycle may excessively heat the coolant.

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