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Condensation heat transfer and pressure drop of R410A and R32 inside horizontal small-diameter tubes.

Number: pap. n. TP-063

Author(s) : ICHINOSE J., INOUE N.

Summary

Experiments have been conducted to obtain the condensation heat transfer and pressure-drop characteristics using internally helical-grooved and smooth small-diameter tubes with a 4.00-mm outside diameter and using R410A and R32 refrigerants. The experimental apparatus was a vapor-compression heat pump system. In the experiments, the condensation temperatures were kept at 35 or 40°C, and the refrigerant mass flux was 215–1290 kg/(m2•s). The results are as follows: (1) For the same vapor quality and R410A, the pressure drop of the 4.00-mm internally helical-grooved tube was about 1.6–1.8 times higher than that of the smooth tube. Further, the pressure drops with R32 were almost the same as those with R410A in the low mass-flux region, and larger than those with R410A in the high mass-flux region. (2) For R410A, the local heat transfer coefficients of the internally helical-grooved small-diameter tube were about 1.2–2.0 times larger than those of a smooth tube. Moreover, the local heat transfer coefficients of R32 were about 1.7–2.3 times larger than those of R410A when the vapor quality was about 0.8. (3) In the internally helical-grooved small-diameter tube with a 4.00-mm outside diameter, the internal grooves are effective in enhancing heat transfer in the low mass flux region for both R410A and R32. (4) The estimation formulas of the condensation heat-transfer coefficient and the pressure drop for R410A and R32 that could be applied to internally helical-grooved and smooth small-diameter tubes with a 4.00-mm outside diameter were proposed.

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Pages: 8 p.

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Details

  • Original title: Condensation heat transfer and pressure drop of R410A and R32 inside horizontal small-diameter tubes.
  • Record ID : 30008293
  • Languages: English
  • Source: 4th IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants
  • Publication date: 2013/06/17

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