Experimental investigation of highly effective plate-fin heat exchanger surfaces

Abstract

Results are presented of an experimental investigation of a new convective rational heat transfer augmentation law in plate-fin heat exchanger surfaces. This law is characterized by Nu/Nu sm ≥ ξ/ξ sm by comparing channels (heat transfer surfaces) with vortex promoters with similar smooth channels at equal Reynolds numbers. For experimental confirmation and investigation of this law, heat exchanger cores having three different plate-fin surfaces were developed and manufactured. Two surfaces are formed by short offset channels (interrupted surfaces) of equilateral triangular and rectangular cross sections. The third surface has channels of isosceles triangular cross sections, with transverse projections and grooves along the channel length direction. The experimental results and correlations are reported for the three surfaces. The experiments were conducted in a wind tunnel with specially developed precise instrumentation that ensured experimental uncertainties of δξ = ± 2.3% and δRe = 1.7% at a 0.997 confidence level. Analysis of the results indicated that the fundamental character and causes limiting rational heat transfer augmentation to Nu/Nu sm ≥ ξ/ξ sm depend upon the heat transfer surface configuration. This paper consolidates the author's research on the subject reported in the Russian language over the last 25 years.