Numerical Analysis of LNG as a Coolant in Liquid Rocket Engines

Liquid Natural Gas (LNG) is a suitable propellant to be used, together with liquid oxygen as oxidizer, in a liquid rocket engine, because of possible advantages with respect to hydrogen in specific applications. Often approximated as pure methane, LNG is a mixture of methane, other heavier hydrocarbons and nitrogen. If LNG is to be used in a regeneratively cooled liquid rocket engine the knowledge of the thermodynamic and heat transfer characteristics when it flows in the cooling channels is of primary importance. This is especially true in the case of expander cycle engines for which the performance is strictly connected with the coolant heat transfer characteristics. The aim of the present work is to understand how the composition of LNG can influence the flow in the cooling channels. A parametric study is carried out considering different LNG compositions. Attention is devoted to the pressure drop and the heat transfer behavior, which are the aspects that have to be controlled in a regenerative cooling system.