An Experimental Investigation of Pressure Drop and Heat Transfer in an In-Tube Condensation System of Pure Ammonia

Pressure drop and heat transfer measurements were taken for smooth and internally enhanced aluminum test sections using pure R22 and ammonia. Two-phase condensation tests were conducted in the horizontally-oriented test sections. Inside diameters for the two test sections were measured at 7.52 mm (0.3 "). The test conditions included mass fluxes from 20 to 270 kg/m 2-s (15 to 199 klbm/ft 2-hr), inlet qualities of 0 to 95%, and test section heat fluxes from 2.0 to 10.0 kW/m 2 (635 to 3175 Btu/ft 2-hr). The majority of the two-phase experiments were run at an inlet temperature of 35 °C (95 °F) with a few points taken at saturation temperatures of 40 – 53 ºC (104 – 127 °F). The data is compared to pressure drop and heat transfer correlations to help explain the characteristics of the two test sections. Experimental data showed an average increase of pressure drop by a factor of 1.4 for the enhanced test section regardless of mass flux or quality. Heat transfer data showed a decreased heat transfer coefficient in the enhanced test section. When coupled with the area enhancement, the enhanced test section performed much worse when compared to the basic or smooth test section.

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