Parametric Analysis of Cooling Properties of Candidate Expander-Cycle Fuels

Flow evolution and heat transfer capability in the cooling system of liquid rocket engines heavily depend on propellant thermophysical properties. Coolant thermophysical property analysis and modeling is therefore important to study the possibility of relying on a regenerative cooling system, whose performance is crucial to determine feasibility and convenience of pump-fed liquid rocket cycles of the expander type. The aim of the present study is to compare the behavior of different liquid fuels for expander-cycle engines. They are light hydrocarbons, binary mixtures of them, and liquefied natural gas, which is a mixture made basically of methane and minor fractions of other light hydrocarbons and nitrogen. A parametric analysis is carried out by a validated numerical solver to compare temperature increase, pressure loss, and heat transfer evolution for the different fuels along the same straight tube and subjected to assigned heat fluxes. Results show that similar engine performance can be obtained by the different candidate expander-cycle fuels, but significant differences can be seen in the flow evolution through the cooling channels.