Analytic Model of No-vent Filling (NVF) in Cryogenic Fluid Transfer

Abstract

Cryogenic propellant management is an essential technology for development of a space launch vehicle (SLV). Especially in space, it is difficult to supply cryogenic propellant with ventilation under micro-gravity condition due to fuzzy liquid-vapor interface and unwanted momentum generation. No-vent filling (NVF) is, therefore, suggested to solve the problems as method which is cryogenic propellant filling technology without ventilation. Numerical analysis model of NVF is required because significant cost is consumed to experiment NVF. There are two types of previous thermodynamic equilibrium NVF model, one is based on experimentally found heat transfer coefficients [1], and the other is only based on heat transfer theory [2]. The former model predicts NVF processes accurately with the experiments, however, its application is limited to specific experimental apparatus. The latter model which only used the heat transfer theory does not predict well experimental data. In this paper, therefore, the general applicable and high reliable model for NVF is suggested. Non-equilibrium thermodynamic phenomena are considered in the new model by using heat transfer correlations based on heat transfer theory. Receiver tank wall coordinate is constructed to calculate heat transfer, and it consists of top bulk, bottom bulk and n of grid in wall. According to the comparison results between numerical and experimental, the new model predicts various NVF processes pretty well. Reliability of conduction heat transfer calculations is verified by middle temperature tendency of receiver tank wall. The temperature tendency of analytic results fits well with experimental data. The bottom temperature is not accurately predicted initially but it fits well with experimental data later. The reason for inaccurate prediction of the bottom temperature is because the numerical model did not consider the non-uniform temperature distribution effect especially due to impinging jet cooling at the center. Pressure tendency is also well explained except for the very initial stage, but the maximum pressure value is well predicted with the maximum error of 15%. This paper presents physical characteristics of NVF processes in more detailed manner so that the developed non-equilibrium model can predict the feasibility of NVF more accurately.