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Abstract
The distribution of air flow approaching a finned-tube heat exchanger is one of the predominant factors influencing the heat exchanger's performance. This article describes a method for measuring and predicting the inlet air flow distribution using particle image velocimetry (PIV) and a computational fluid dynamics (CFD) model, highlighting the source and magnitude of air side maldistribution. The studied case was a single-slab, four-depth-row, louvered-fin heat exchanger installed vertically in a horizontal duct. The measured data showed that the air approaching this very simple test case generally maintained velocities of 1.25 ms−1 (4.1 fts−1) to 1.35 ms−1 (4.4 fts−1), but certain portions of the coil were completely obstructed, resulting in no air flow, and other portions realized velocities of over 1.7 ms−1 (5.6 fts−1). A CFD model of the air flow through this heat exchanger was developed based on a momentum resistance modeling approach. The CFD results agreed well with the PIV measurements, predicting the local velocities within 3% over most of the domain and within 10% in areas with the largest velocity gradients.
Acknowledgments
This article not subjuect to U.S. Copyright law.
David A. Yashar, PhD, Associate Member ASHRAE, is a Mechannical Engineer. Piotr A. Domanski, PhD, Fellow ASHRAE, is a Group Leader. Hong Hyun Cho, PhD, is a Lecturer.