Experimental investigation on pressure drop and friction factor of slush nitrogen turbulent flow in helically corrugated pipes

Experiments were performed to investigate the pressure drop and friction factor for turbulent slush nitrogen in helically corrugated pipes. Comparison of pressure drops of slush nitrogen and subcooled liquid nitrogen shows no significant difference between the solid-liquid fluids and single phase turbulent flows in the corrugated pipes and the influence of particle concentration on pressure loss of slush nitrogen pipe flow is negligible. An improved experimental empirical correlation for the friction factor of slush nitrogen in corrugated pipes with the slush Reynolds number in the range of 2×104⩽Resl⩽1.7×105 has been obtained, which takes the structural parameters (i.e., inner diameter and pitch) of the corrugated pipes as well as the fluid flow conditions into consideration. With the increasing slush Reynolds numbers, the friction factor of slush nitrogen in corrugated pipes increases, while the trend for the smooth pipe shows a contrary dependence. Moreover, the friction factor increases very slightly with the solid fraction. It can be concluded that the slush nitrogen with a solid fraction up to 20% still has comparable fluidity performance with the subcooled liquid nitrogen in the helically corrugated pipes.