This paper reports experimental investigation of condensation heat transfer and pressure drop of an ozone friendly refrigerant, R-134a, inside a helical pipe for climatic conditioning of hot regions. This study concerns the condensation of R-134a flowing through annular helical pipes with different conditions of operating refrigerant-saturated temperatures. The average pressure drop was measured and compared with data from relevant literature. The measurements R-134a were performed on mass flow flux ranges from 50 to 680 kg/m2 s. The study provides experimental and analytical data which could be used for the design and development of more efficient condensers for refrigeration and air conditioning (A/C) systems working with the same refrigerant.
The results of an experimental study to evaluate the characteristics of R-407C thermofluid during condensation in a helically coiled copper tube heat exchanger are presented. The effects of saturation temperature (Tsat), and mass and heat fluxes of refrigerant R-407C on thermal performance and pressure drop were determined. The relationship between the refrigerant wall subcooling and heat transfer coefficients was also investigated. This paper reports the effect of the temperature of the water used as cooling medium on the heat transfer rate of condensing R-407C. The study was conducted with mass flux of R-407C in the range of 100–450 kg/m2s, mass flux of the coolant water in the range of 500–5000 kg/m2s and Tsat of 31 °C, 35 °C, and 39 °C. Compared with a straight smooth tube, the use of the helical coiled (helicoidal) tube increased the condensation rate with a corresponding pressure drop that depended on the value of Tsat of the refrigerant and temperature of the coolant.
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