An experimental investigation of convection heat transfer during filling of a composite-fibre pressure vessel at low Reynolds number

The heat transfer process during filling of an evacuated vessel at low Reynolds number was investigated experimentally using air as the flow medium. The data was analysed using a thermodynamic model similar to one currently in use for the design of systems using commercial carbon fibre reinforced plastic vessels for storage of compressed hydrogen gas. Model assumptions included perfectly-stirred conditions within the vessel, one-dimensional unsteady heat conduction through the composite vessel wall, ideal gas and frictional adiabatic flow conditions through the inlet tube. A transition phenomenon from laminar to turbulent flow was observed by decreasing the inlet diameter while maintaining a similar mass flow rate. Based on the measurements, a new empirical correlation for the Nusselt number under low Reynolds number flow conditions is proposed.