Flow Distribution in U- and Z-Type Manifolds: Experimental and Numerical Investigation

Abstract

Heat exchangers are used to transfer energy from one medium to another and increase contact area for higher efficiency. In case of fluids, higher flow area would lead to high/low flow zones that severely affect the fluid dynamics and thermal performance. Channels are used to distribute the flow uniformly to fully utilize the whole heat exchanger area. The flow uniformity in a flow distribution manifold is dependent on several factors such as flow rate, inlet and exit locations, and the manifold and channel geometrical configuration. In the current work, flow distribution measurements were performed using a particle image velocimetry (PIV) technique in two types of rectangular manifolds. The experimental results are further verified against the results obtained from numerical modeling with similar trends. The flow distribution in U- and Z-type arrangements are evaluated and compared with ten channels incorporated in the design. It was found that the flow is more in the channels near the inlet for U-type design, while more near the outlet for the Z-type. An increase in the inlet flow rate enhances the flow distribution for the U-type while results in more maldistribution for the Z-type. For the U-type, the normalized velocity varies from 1.34 to 0.52 in a wide manifold, and between 2.82 and 0.18 for a narrow manifold. A U-type wider manifold is recommended for all conditions examined in this work since at lower flow rates, both have similar mirrored distribution, while at higher flow rates, U-type manifold has better flow distribution.