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4126 (RP-630) — Heat Transfer Coefficients and Pressure Drops for R-134a and an Ester Lubricant Mixture in a Smooth Tube and a Micro-Fin Tube

$7.50

Conference Proceeding by ASHRAE, 1998

Category:

Description

This paper reports average heat transfer coefficients and pressure drops during the evaporation and condensation of mixtures of R-134a and a 150 SUS penta erythritol ester branched-acid lubricant. The smooth tube and micro-fin tube tested in this study had outer diameters of 9.52 mm (3/8 in.). The micro-fin tube had 60 fins, a fin height of 0.2 mm (0.008 in), and a spiral angle of 18°. The objective of this study is to evaluate the effectiveness of the micro-fin tube with R-134a and to determine the effect of circulating lubricant.

The experimental results show that the micro-fin tube has distinct performance advantages over the smooth tube. For example, the average heat transfer coefficients during evaporation and condensation in the micro-fin tube were 50% to 200% higher than those for the smooth tube, while the average pressure drops were on average only 10% to 50% higher. The experimental results indicate that the presence of a lubricant degrades the average heat transfer coefficients during both evaporation and condensation at high lubricant concentrations. Pressure drops during evaporation increased with the addition of a lubricant in both tubes. For condensation, pressure drops were unaffected by the addition of a lubricant.

Units: Dual

Citation: ASHRAE Transactions, 1998, Vol 104, pt. 1A, San Francisco

Product Details

Published:
1998
Number of Pages:
10
File Size:
1 file , 220 KB
Product Code(s):
D-7796