Tree shaped by bifurcation channels parallel and counter flow of heat exchanger heat transfer and flow investigation characteristics

In this study, a heat exchanger system capable of working on tree-shaped three-level parallel and opposite flow basis was designed and manufactured to improve the thermal characteristics in a single-phase flow, based on the branched Fractal like flow channel structure. A smiliar phylum of heat exchanger on discs that consists the plates of lower,middle and upper. 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. In this heat exchanger, as the fluid double, fluid liquid (cold and hot water) is used. On the both heat exchangers' both bottom and upper plates, in the input, 1 longitudinally; in the output 12 cylindirical radially channels are existing. 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. In this study, experimental and numerical analyzes were carried out using MATLAB R2013b and 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 decrasing in level of velocity. The result, requirement of designation as the bifurcation geometry divides the mass flow rate equally for each level ol branching, is obtained. The effects of the change in thermal capacity (Cr) on the test zone were investigated by the ε-NTU method. For different thermal capacities, ε =0,24-0,58 and NTU =0,3-0,81. The efficiency of the heat exchanger is also increased because the fluid flow rate in the heating section is gradually increased with respect to the fluid flow in the cooling section, which increases the average temperature in the heating section. As a result, it has been observed that increasing the number of channel levels in such flow channel geometries results in lower and more uniform velocity, increasing pressure drop and homogeneous temperature distributions when the existing maximum temperature is lowered. 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 is more efficient than the opposite flow conditions.