Flow boiling heat transfer and two-phase pressure drop of R134A in a microfinned helically coiled tube

摘要

The performance of evaporator is of importance in cryogenic and refrigeration systems. In this paper, evaporative heat transfer and pressure drop characteristics of refrigerant R134a boiling inside a new geometry microfinned helically coiled tube is experimentally studied. Compared with corresponding smooth helically coiled tube, the heat transfer enhancement factors of microfinned helically coiled tube are tip to 2.2 with the varieties of mass flux and heat flux. the frictional pressure drop values are obtained by subtracting acceleration pressure drop and gravitational pressure drop from the measured total pressure drop. The frictional pressure drop data can be well correlated using Lockhart-Martinelli method.