The Problemof Refrigerant Return Line Calculations in Pump Recirculation Systems

This chapter illustrates the problem of refrigerant return line calculations in pump recirculation systems. The chapter also outlines that small heat quantities penetrating into the insulated line don't affect the flow conditions. The flow of each phase at a given mass output under single-phase flow conditions would be a turbulent one. It is also highlighted in the chapter that Lockhard and Martinelli maintain that an increase in flow resistance as measured during two-phase flow as compared with flow resistance values for the flow of the gaseous phase only, at a given mass output, expressed as a ratio of both resistance values, depends solely upon the mass rates of flow, of both phases their viscosity and specific volume. The results also show that the boundary layer existing at the pipe surface effectively reduces its roughness. Experiments also suggest that the application of the coefficient binding for smooth piping is fully reasonable in the case of usual piping applied for refrigerating installations.