RP-45 -- Forced Convection Boiling of Refrigerants in Horizontal Tubes PDF

An experimental investigation was conducted to obtain local heat transfer coefficients and pressure drop for Refrigerant 12 evaporating in an electrically heated horizontal tube.

Type 304 stainless steel tubing, with an outside diameter of 0-500 inches, a wall thickness of 0.020 inches, and a heated length of 76 1/8 inches, served as the test section. Nine hypodermic-tube taps and 35 thermocouples measured the fluid saturation pressure and wall temperature distribution. Uniform wall heat fluxes from 2200 to 11,000 BTU/hr-sq ft were achieved by passing current of up to 200 amperes directly through the tube wall. The mass velocity was varied from 89,000 to 433,000 lb/hr-sq ft, with a constant inlet vapor quality of 20 percent.