Abstract
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.
Highlights
R-22 is a non-fully halogenated refrigerant that is commonly found in residential refrigeration units and air conditioning (A/C) systems
R‐407C, the heat transfer in rate on flow pitch, R-407C, the heat transfer rate for the refrigerant depends on flow patterns, pitch, curvature, and void curvature, and void fraction
The pressure loss and heat transfer coefficient for refrigerant R-407C flowing in a helicoidal copper pipe have been investigated experimentally utilizing a purpose-built test rig
Summary
R-22 is a non-fully halogenated refrigerant that is commonly found in residential refrigeration units and air conditioning (A/C) systems. Environmental concerns are driving the replacement of R-22 with R-407C or other suitable refrigerants. The vapor pressure of R-407C is the same as that of R-22, so it can be installed in existing systems with no major modifications. Due to the zeotropic nature of the refrigerant R-407C, a 6 ◦ C temperature glide occurs through any heat transfer process [2]. This normally increases the thermal efficiency of refrigeration equipment
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