Two-phase flow visualization of R134A in a multiport microchannel tube

Results are presented from a flow visualization investigation of a multiport microchannel tube using R134a, a medium pressure refrigerant. The study covers mass fluxes from 50-300 kg/s.m(2) and qualities ranging from 10-90%, with a 6-port microchannel tube with a hydraulic diameter of 1.5 mm under adiabatic conditions, The results from the flow visualization studies indicate that several flow configurations may exist in multiport microchannel tubes at the same time while constant mass flux and quality flow conditions are maintained, Based on these observations, development of a typical flow regime map does not appear to be an appropriate manner for describing the flow field if the flow conditions for each port are not known. Flow mapping of the fluid regimes in this multiport microchannel is accomplished by developing functions that describe the fraction of time or the probability, that the fluid exists in an observed flow configuration. An application of the alternative method of flow description for pressure drop predictions in multiport channels is included.