Intensive parameter analysis of adiabatic capillary tube using approximate analytic solution

Parameter analysis is helpful to have an insight into the flow characteristics of capillary tubes. Based on the approximate analytic solutions developed by the author, influences of geometrical parameters (inner diameter and length) and inlet operating parameters (pressure, subcooling or quality) on the mass flow rate through an adiabatic capillary tube have been intensively studied in this work. Some simple theoretical relations have been developed. The relations show that the mass flow rate is the power function of the geometries. For the subcooled inlet, good generic linearity between (2−C₂) power of the mass flow rate and the inlet operating parameters was deduced. With further approximation, some well-known linear trends could be theoretically interpreted. For the low quality inlet, good linearity between (C₂−2) power of the mass flow rate and the inlet quality was proposed. Approximately, the reciprocal of the mass flow rate is linear with the inlet quality. Experimental data supplemented by numerical data for R22, R410A and R407C are employed to verify the relations.