Tree Shaped in Channels Parallel and Counter Flow Through Heat Exchanger Heat Transfer and Flow Investigation of Characteristic

Abstract

I n this study, a heat exchanger system capable of working on tree-shaped three-level parallel and counter flow basis was designed and manufactured based on the branched Fractal like flow channel structure. A similar phylum of heat exchanger on discs onto one surface of the lower and upper plates and both surfaces of middle plate, 156 Branched-micro channels with cylindrical sections were opened in three levels symmetrically with each other at different levels and diameters. According to the parallel and counter flow type based open circuit and closed circuit principle, the fluid enters the system at equal thermal capacity ratios from the axial or radial connection points and discharges. In the open circuit operating conditions, the heating water is in the temperature range of 35-45°C and the flow rate is 2,0-4,0 lt / min. Similarly, in the closed circuit operating conditions, the heating water is in temperature range of 45-60°C and the flow rate is 2,0-4,0 lt/ min. During the experimental work, the temperature and hydrodynamic characteristics of the system are controlled through software written in the MATLAB R2013b package program. Experimental and numerical analyzes were carried out using ANSYS-Fluent ready packet programs. In the analysis, in the increasing flow rate, positions of some external and lateral channels are determined as cause of the decreasing in level of velocity. The result, requirement of designation as the bifurcation geometry divides the mass flow rate equally for each level of branching, is obtained. The results show that increase in level of branches is not important on the fluid channels which includes this kind fractal branch channel with tree-shaped. The results also show that, in the branched model heat exchanger, for opened and closed circuits, parallel flow increasing branching levels, heating unit and cooling unit is more efficient than the counter flow increasing branching levels heating unit and decreasing branching level cooling unit conditions.

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