The external, nucleate pool-boiling heat-transfer coefficient in R-114 with up to 10% oil (by mass) was measured on a smooth copper tube and on a porous-coated copper-nickel tube. The heat flux was varied from 160 to 30,000 Btu/hr•ft2 (0.5 to 95 kW/m2) at boiling temperatures of 28 F and 44 F (-2.2 °C and 6.7 °C).
The porous-coated surface was found to improve the heat-transfer coefficient over the smooth surface by a factor of 7 to 10 in oil-free R-114. The presence of up to 3% oil caused about a 35% reduction in the heat-transfer coefficient of the porous-coated surface at all heat fluxes. With 6% or more oil, the boiling performance of this surface declined drastically at heat fluxes in excess of 9500 Btu/hr•ft2 (30 kW/m2). Some plausible mechanisms to explain the observed behavior are described.
Units: Dual
Citation: Symposium, ASHRAE Transactions, 1986, vol. 92, pt. 2B, Portland, OR
Product Details
- Published:
- 1986
- Number of Pages:
- 14
- File Size:
- 1 file , 1.3 MB
- Product Code(s):
- D-PO-86-11-4
