Analysis of the heat dissipation enhancement with finned surfaces in pool boiling of dielectric fluid

Abstract

This paper summarises the main results of a research work about the heat transfer enhancement and its theoretical estimation, in the two-phase thermal control with dielectric refrigerant fluids. The authors consider pool boiling applications at atmospheric conditions and without supplementary energy. Two methods are considered to enhance the heat transfer: the use of the finned surfaces and the natural re-circulation of the condensed fluid, pool boiling with controlled return (PBCR). First of all the purpose is to evaluate the possibility of a thermal dissipation comparable with the one obtainable by means of the boiling water at atmospheric pressure, about 1 MW/m2; secondly, to increase the knowledge about the burn-out incipience. A detailed experimental analysis of the burn-out incipience is performed using a single fin. Moreover the objective is to propose theoretical methods to estimate the critical heat flux related to finned surfaces as well as a possible approach to perform a 'nearly optimum' design of fins and fin arrays in pool boiling

Heat transfer enhancement in pool boiling of a refrigerant fluid with wire nets structures

“…Only to give an example, this value is close to the one considered as minimum interfin spacing, resulting in high effect of extended surface in pool boiling of a refrigerant fluid. This was revealed in [18] for R113 and experimentally confirmed in [19] for HCFC141b. For a smaller mesh aperture, though it is possible to increase a nucleation sites density, the problem arises with stable vapor escape at rather high heat fluxes.…”

“…12 and 13. Really, a finned surface also can be considered as a good mean to reduce the negative effect of boiling crisis due to a possibility of coexistence of different boiling regimes along the fins [19]. But, as clearly appears in Fig.…”