Ameliorating the Methodology to Chill Rocket Fuels for Launch Vehicle

Abstract

AbstractCurrent Launch vehicles of ISRO uses Earth storable propellant such as UH25/MMH and N2O4/MON3 as fuel and oxidizer respectively for their liquid engines. Chilling of these rocket fuels is necessary before loading them in Launch Vehicles to meet the liquid engine requirements so as to meet the desired net positive suction head for the turbo pumps of rocket engines (like VIKAS engines). Pressure fed engine is cooled using regenerative cooling technique. To compensate for the pressure drops in the piping when fuel flows, the chilled propellant makes it heavy in density and helps to maintain greater injection pressure. In ISRO spiral plate heat exchanger is used or chilling the propellants. The chilling activity requires around 10 to 12 hours to chill propellants from ambient to 10° C for given flow rate and effective reynolds number. Reducing this time will be very helpful in reducing the time required for overall system readiness for launch activities. Existing chilling process involves circulating propellant through one heat exchanger using a pump. The storage facility has two heat exchangers and two pumps and out of which only one heat exchanger and one pump is being used and the other act as standby. The paper aims to find possible alternate configurations using the idle heat exchanger and pump and also to study the effect of mass flow rate of propellant on chilling time. Study in this paper is done considering N2O4 propellant. A theoretical model is developed using basic heat transfer equations in MATLAB, it is evaluated by comparing the results with previous mission data. This is later applied on different configurations possible and chilling time for each configuration is calculated. The results obtained suggested that by operating two heat exchanger in parallel and one pump, time required for chilling of propellants can be reduced significantly.