AC-2346 -- A Study of the Effect of Surface Treatment on Pool Boiling Heat Transfer in Refrigerant 12 PDF

Many investigators have shown that pool boiling heat transfer is dependent upon the fluid-surface combination. The surface condition (e.g., surface finish) effects the cavity size distribution for bubble nucleation. Berenson demonstrated the effect of surface finish on pool boiling from a copper flat plate with pentane as the working fluid. Using progressively finer emery cloth to finish the test surface, he demonstrated that surface finish has a profound effect on heat transfer.

The published data for pool boiling in refrigerants are mainly restricted to smooth surfaces. Stephan presented nomographs, based on experimental data, for twelve different refrigerants. His test surfaces were smooth cooper horizontal plates and cylinders. Furse has presented data on pool boiling of R-ll and R-12 from a smooth horizontal cooper surface. Blatt and Adt have published pool boiling data for R-ll and R-113 in horizontal stainless steel and copper tubes. An extensive study of the effect of oil content on pool boiling for R-12 and R-22 has been reported by Stephan.

This paper presents pool boiling heat transfer data for four surface treatments applied to a flat copper surface. Each treatment was tested in the vertical position in oil-free R-12. The heat transfer performance of these four surface treatments brackets the possible performance which can be expected. The data demonstrate the magnitude of the effect of surface treatment on heat transfer.

The results of the experimental investigation are presented in the form of plots of heat transfer coefficient and heat flux versus temperature difference for boiling at various pool temperatures. A correlation is then presented for each surface which can be used to estimate heat transfer performance at any pool temperature.