Investigation of boiling hydrogen heat transfer characteristics under low-pressure conditions

Abstract

Understanding the heat transfer characteristics of boiling hydrogen is a critical issue in developing of liquid hydrogen system. However, there has been insufficient systematic research on boiling hydrogen flow characteristics. This report investigates the heat transfer characteristics of boiling hydrogen, following our previously reported gas-liquid mixing characteristics and flow regime transition characteristics. This study generated an arbitrary gas-liquid two-phase flow state in 15 mm tube by experimentally heating liquid hydrogen with an electric current. The experimental conditions were a pressure of 250 – 300 ▪, a mass flux of 50 – 110 ▪, and a heat flux of 0 – 12 ▪. Based on the experimentally obtained heat transfer coefficients, a heat transfer prediction model for boiling hydrogen was constructed, considering the change in the heat transfer process from liquid single-phase to saturated boiling. A one-dimensional flow simulator was also constructed that applies the proposed model and confirms that the model can be reduced the wall temperature error to about 1/10 against the conventional models.