A novel design of a mini heat exchanger utilizing forced convection heat transfer enhancement with electrohydro-dynamic (EHD) technique has been numerically investigated. When a high voltage is applied to a metal wire, air in its vicinity will be ionized and the injected ions will travel towards electrically grounded heat exchanger surfaces, leading to the corona wind. As a result, the corona wind disturbs the heat exchanger boundary layer and thus enhances heat transfer between the heat exchanger surface and its ambient air. A three dimensional numerical model has been developed to evaluate the heat transfer coefficient (HTC) and air side pressure drop of this EHD enhanced mini heat exchanger. Influences of position and size of the wire are evaluated in order to achieve the highest enhancement. In addition, the swirling flow pattern induced by EHD has been studied due to its important role in heat transfer enhancement. The results show a three times increase of HTC enhanced by EHD effect in present design comparing to the one without EHD effect. The most promising result shows an overall heat transfer coefficient equal to 318 W/(m2·K) for a bare tube in cross flow configuration with airside pressure drop of 2.8 Pa.

Volume Subject Area:
Computational Heat Transfer
Topics:
Electric fields, Flow (Dynamics), Heat exchangers, Numerical analysis, Design, Heat transfer, Heat transfer coefficients, Pressure drop, Wind, Wire, Boundary layers, Computer simulation, Cross-flow, Forced convection, Grounding (Electricity), Ions, Metals, Swirling flow
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