The heat transfer coefficient determination with the use of the Beck-Trefftz method in flow boiling in a minichannel

Abstract

Abstract. In this paper, the solution of the two-dimensional inverse heat transfer problem with the use of the Beck method coupled with the Trefftz method is proposed. This method was applied for solving an inverse heat conduction problem. The aim of the calculation was to determine the boiling heat transfer coefficient on the basis of temperature measurements taken by infrared thermography. The experimental data of flow boiling heat transfer in a single vertical minichannel of 1.7 mm depth, heated asymmetrically, were used in calculations. The heating element for two refrigerants (FC-72 and HFE-7100, 3M) flowing in the minichannel was the plate enhanced on the side contacting with the fluid. The analysis of the results was performed on the basis of experimental series obtained for the same heat flux and two different mass flow velocities. The results were presented as infrared thermographs, heated wall temperature and heat transfer coefficient as a function of the distance from the minichannel inlet. The results was discussed for the subcooled and saturated boiling regions separately.

Impact of selected thermal and flow parameters on flow boiling heat transfer in a minichannel

“…4c,d) in the outlet section of the minichannel. Similar dependencies were observed by Strąk et al in [5], where markedly higher local heat transfer coefficients were also observed at lower mass flux in the saturated boiling region. The boiling curves in Figs.…”

“…Previous studies of the authors examined other methods for determining the local heat transfer coefficient in two-dimensional approaches, using the Trefftz or Beck methods obtained from solving the inverse problem [4,5,9,12,[34][35][36][37][38].…”

“…The Kielce University of Technology has conducted a series of studies of flow boiling heat transfer with different refrigerants [4][5][6] flowing along minichannels with enhanced heated plates [4,[7][8][9][10][11][12][13][14] at various orientations [4,15,16]. The use of enhanced surfaces produced in thermal processes is known to intensify the heat transfer process as shown in [7,[17][18][19][20][21] Such surfaces are applied also in pool boiling heat transfer [22][23][24][25][26].…”