Cryogenic rocket engines use cryogenic fuels such as liquid hydrogen and liquid oxygen that are stored at very low temperatures. They provide several advantages including high energy density and producing only water exhaust, but also have challenges like boil off and leakage due to the extreme cold temperatures required. India's first unmanned lunar mission in 2008 failed when the indigenous cryogenic upper stage engine did not ignite as planned. Future rocket technologies being researched include ion engines, nuclear thermal engines, and other alternatives to further space exploration.

1. Cryogenic rocket engineBy :HimanshuChandMechEngg. VI semRoll No. 0709141014

3. IntroductionA cryogenic rocket engine is a rocket engine that uses a cryogenic fuel or oxidizer, that is, its fuel or oxidizer are gasses liquefied and stored at very low temperatures.rocket engines need high mass flow rate of both oxidizer and fuel to generate a sufficient thrust.the liquid oxygen (LOX) oxidizer and liquid hydrogen (LH2) fuel combination is one of the most widely used.

4. Brief historySpace travel was mainly developed by the Russians and the Americans.The Russians were the first to reach into space.Solid-fuel rocket engines were the first engines created by man.All the current Rockets run on Liquid-propellant rockets.The first operational cryogenic rocket engine was the 1961 NASA design the RL-10 LOX LH2 rocket engine, which was used in the Saturn 1 rocket employed in the early stages of the Apollo moon landing program.

5. The first operational cryogenic engine

6. constructionThe major components of a cryogenic rocket engine are:the thrust chamber or combustion chamber pyrotechnic igniterfuel injectorfuel turbo-pumpsgas turbinecryo valvesRegulatorsthe fuel tanksrocket engine nozzle

8. Position of various parts in shuttle

9. Cryogenic propellentIn a cryogenic propellant the fuel and the oxidizer are in the form of very cold, liquefied gases.super cooled gases used as liquid fuels are called cryogenic fuels as they stay in liquid form even though they are at a temperature lower than the freezing point.to store these propellants aboard a rocket is a very difficult task as they have very low densities.Thus by cooling and compressing them into liquids, we can vastly increase their density and make it possible to store them in large quantities in smaller tanks.

10. the propellant combination used is that of liquid oxygen and liquid hydrogen.Liquid oxygen being the oxidizer and liquid hydrogen being the fuel.Liquid oxygen boils at 297oF and liquid hydrogen boils at 423oF.

11. Working of Cryogenic Propellantsspecial insulated containers and vents are used to prevent gas from the evaporating liquids to escape.The liquid fuel and oxidizer are fed from the storage tank to an expansion chamber.Then it is injected into the combustion chamber.In this chamber, they are mixed and ignited by a flame or spark.The fuel expands as it burns and the hot exhaust gases are directed out of the nozzle to provide thrust.

12. Advantages :High Energy per unit mass:Propellants like oxygen and hydrogen in liquid form give very high amounts of energy per unit mass due to which the amount of fuel to be carried aboard the rockets decreases.Clean Fuels Hydrogen and oxygen are extremely clean fuels. When they combine, they give out only water. This water is thrown out of the nozzle in form of very hot vapor. Thus the rocket is nothing but a high burning steam engineEconomical Use of oxygen and hydrogen as fuels is very economical, as liquid oxygen costs less than gasoline.

13. Drawbacks:Boil off RateHighly reactive gasesLeakageHydrogen EmbrittlementZero Gravity conditions

14. Why didn't the cryogenic engine of India ignite?The GSLV D3, which lifted off well from Sriharikota on Thursday, April 15, 2010 later plunged into the sea as the indigenous cryogenic engine failed to ignite.The vehicle lifted off as planned at 4.27 p.m. and its performance was normal up to the end of its second stage till 293 seconds from the lift-off.An authoritative former ISRO official said: “It is very clear that the cryogenic engine did not ignite when you look at the curve [of the vehicle's trajectory]the vehicle developed problems when the cryogenic upper stage should have ignited 304 seconds after the lift-off, and it fell into the sea

15. The next generation of the Rocket EnginesAll rocket engines burn their fuel to generate thrust . If any other engine can generate enough thrust, that can also be used as a rocket engineThere are a lot of plans for new engines that the NASA scientists are still working with. One of them is the “ Xenon ion Engine”. This engine accelerate ions or atomic particles to extremely high speeds to create thrust more efficiently. NASA's Deep Space-1 spacecraft will be the first to use ion engines for propulsion. There are some alternative solutions like Nuclear thermal rocket engines, Solar thermal rockets, the electric rocket etc.We are looking forward that in the near future there will be some good technology to take us into space

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