TED-AJ03-588 CONDENSATION HEAT TRANSFER AND PRESSURE DROP OF REFRIGERANT R-134A IN A HORIZONTAL ANNULAR HELICOIDAL PIPE :
Article
Yu, B, Han, JT, Lin, CX et al. TED-AJ03-588 CONDENSATION HEAT TRANSFER AND PRESSURE DROP OF REFRIGERANT R-134A IN A HORIZONTAL ANNULAR HELICOIDAL PIPE :
. 2003(6), 264-264.
Yu, B, Han, JT, Lin, CX et al. TED-AJ03-588 CONDENSATION HEAT TRANSFER AND PRESSURE DROP OF REFRIGERANT R-134A IN A HORIZONTAL ANNULAR HELICOIDAL PIPE :
. 2003(6), 264-264.
Condensation of environmentally friendly refrigerant R-134a is of significant importance to the effective design of helicoidal pipe heat exchangers for refrigeration, air conditioning, thermal pumps, and many other practical applications. While extensive investigations have been conducted both experimentally and numerically of condensation heat transfer and flow characteristics of R-134a in smooth and a variety of enhanced surface tubes, very little publication has been presented on condensation heat transfer and pressure drop of R-134a flowing through annular helicoidal pipes. The advantages of helicoidal pipes over straight tubes make them a practical option to use as helicoidal heat exchangers in air conditioning and refrigeration systems with R-134a. Experimental investigation was conducted into condensation heat transfer and pressure drop characteristics of R-134a in an annular helical coil with its axis at horizontal. The experiment was performed at two different saturated temperatures (35 and 40℃) with the mass flux ranging from 100 to 420kg/(m^<2s>). The results were compared with a previous work, which conducted an experimental investigation on the annular helical coil with its axis at vertical. It was shown that the average overall and refrigerant side condensation heat transfer coefficients and pressure drops of R-134a for the horizontal coil increase with mass flux of R-134a as do the behaviors for the vertical coil. However, the horizontal coil shows worse heat transfer characteristics than the vertical coil. Furthermore, the pressure drop of the horizontal coil for the R-134a side is larger than that of the vertical coil. The thermal behaviors of the annular helical coil are totally different from those of the circular helical coil, in which a horizontal coil presents much better heat transfer rates.
