SCIENTIFIC AND TECHNICAL SUBSTANTIATION OF THE PROCESS OF COOLING OF A LIQUID BY FROZEN SPHERES

The heat transfer in the single-phase fl ow of a liquid in an asymmetrically heated horizontal minichannel was investigated. Thermograms of the surface of a heater in the minichannel and the surface of its adiabatic part have been obtained with the use of an infrared camera, and they were used to construct temperature profi les for these surfaces. Stationary temperature distributions in the insulating foil, the heater surface, and the liquid fl ow in the minichannel have been obtained, respectively, with the use of the Laplace equation, the Poisson equation, and the energy equation involving the frictional heat losses. The solution of the system of these differential equations with special boundary conditions has culminated in the solution of three sequential inverse problems on the heat conduction in the indicated adjacent regions having different physical parameters. These problems were solved using the Trefftz method, and the temperature of the liquid fl ow in the minichannel was calculated by the Picard–Trefftz method. The temperature distributions obtained for the liquid fl ow and the heater surface were used to determine the heat transfer through the liquid–heater interface. The Trefftz and Picard–Trefftz methods yielded similar local heat transfer coeffi cients and temperature distributions. 
   
Author:  M. Grabowski, M. E. Poniewski, S. Hożejowska, and A. Pawińska
Keywords:  heat transfer, minichannel, single phase, inverse heat-transfer problem, Picard and Trefftz methods
Page:  355