Nucleate Pool Boiling Heat Transfer from High-Flux Tube with Dielectric Fluid HFE-7200

Abstract

In the present experimental study, nucleate pool boiling heat transfer measurements of two high-flux tubes (sample A and sample B) were conducted at atmospheric pressure with HFE-7200 as the working fluid. Both high-flux tubes were made from a sintered Cu-Ni (high-flux) alloy powder. The porous high-flux surface was coated inside the test tube and it is tested within the heat flux ranging from 2.6 to 86 kW/m2. The major difference between sample A and sample B was the coating thickness, where sample B (0.6 mm) was much larger than that of sample A (0.07 mm). Both tubes showed about three times enhancement in heat transfer coefficient (HTC) when compared to plain tube. Even though sample B contained a higher HTC than sample A, it also revealed a faster level-off phenomenon regarding the HTC vs. wall superheat. The major parameter which characterizes the boiling performance of high-flux tube was the ratio of coating thickness to pore diameter which also yielded different trends upon HTC vs. wall superheat amid sample A and B. It was found that the porous based Nishikawa correlation can well predict the performance of sample A but not sample B. This is because the ratio of coating thickness to pore diameter is far outside the applicable range of the Nishikawa correlation. Hence, a modified Nishikawa correlation is proposed. The predicted capability of the proposed modified Nishikawa correlation against sample A and sample for HTC was within ±28% deviation. The standard mean deviation of the Nishikawa correlation with experimental data for sample A and sample B was 0.302 (12.48%) and 5.64 (73%), respectively.

Heat Transfer Performance of R-1234ze(E) with the Effect of High-Viscosity POE Oil on Enhanced GEWA-B5H Tube

“…The error associated with the HTC and heat flux for the refrigerant and refrigerant oil mixtures has been briefly reported by the authors of [13,16,17]. The smallest wall superheats (∆T w ) for the pure refrigerant and refrigerant-oil mixture at the heat flux of 10 kW/m 2 was 0.76 • C and 0.88 • C respectively.…”

Recent Advances in the Critical Heat Flux Amelioration of Pool Boiling Surfaces Using Metal Oxide Nanoparticle Deposition

“…Pool boiling is proposed as a beneficial method for the transfer of high thermal energy in various applications of industry, such as refrigeration, cooling electronic chips as well as nuclear reactor cooling, the generation of thermal power and the conversion of energy. Regarding to the widespread use of this process in different fields, understanding the origin, process and existing developments in this field is of valuable importance [1,2]. In the pool boiling process, the heating surface is submerged in a pool with a great amount of stagnant liquid.…”