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Condensation Pressure Drop Characteristics of Propane in Helically Coiled Tube-In-Tube Heat Exchanger

This paper presents an experimental study on condensation pressure drop characteristics of propane (R290) flowing through an annular passage of helically coiled tube-in-tube heat exchanger. Experimental rig is compression refrigerant cycle that consists of compressor, condenser, expansion valve and evaporator. Compression cycle is equipped with internal heat exchanger that can be bypassed to see the effect of the component on the pressure drop in condenser. The test section (condenser) is made of two copper tubes that are coaxially oriented. Inner tube of the condenser is grooved on its outside surface. Diameter of inner tube is 19.7 mm and the nominal outer diameter is 22.2 mm. Inner diameter of outer tube is 30.0 mm. The coil diameter is 280 mm and the coil pitch is 35 mm. The coil axis is oriented vertically, so the pressure drop is affected by gravitational force. Pressure drop values are determined at different saturation temperatures 30 oC, 35 oC, 40 oC and 45 oC, and at different heat fluxes 21 kW/m2, 26 kW/m2 and 35 kW/m2. Mass flux rates were in the range between 37 and 70 kg/(m2s). Experimental pressure drop results are compared to the existing Lockhart-Martinelli correlation. The pressure drop results show a satisfactory agreement between correlation and experimental data at lower heat flux. It is also noticed that the internal heat exchanger in compression cycle has significant effect on pressure drop due to its effect on thermo-physical properties of refrigerant.

Pressure drop, propane (R290), condensation, coaxial tube, helically coiled tube, heat exchanger

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