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Microchannels (diameter of 1 mm or less) have received significant research attention nowadays due to their high heat transfer and space saving capability compared to the conventional sized tubes for a given heat duty. Use of microchannel core can make an automotive heat exchanger further light-weighted and down-sized while keeping the heat duty similar or even higher as compared to the traditional compact heat exchangers. Automotive engine generally uses heat exchange process in air-glycol crossflow orientation for its cooling system. Research and thermo-hydrodynamic design correlations and sufficient experimental data on single-phase pressure drop and heat transfer using multi-port microchannel slab in air-to-glycol crossflow orientation is rare in the open literature. The availability of a well instrumented dynamic test facility, i.e. both fluids are in motion, for such research is also limited.

Airside heat transfer and fluid flow characteristics of a single array cross flow heat exchanger, made of elliptical tubes, were studied. The heat exchanger, consists of 18 tubes each of 30 cm long with 0.30 minor to major outside axis ratio and equally spaced by 0.61 cm gap, was oriented in a 30 cm by 30 cm test section of a wind tunnel with the major axis parallel to the air flow. Tests were performed with hot water flowing inside the tubes, while cold air flowing across them externally. The mean temperature difference between the approaching air and the surface of the tubes was maintained at roughly 14±2°C. Reynolds number based on the mean free stream air velocity and hydraulic diameter of the elliptical tube was varied from 4500 to 15000, while that based on the mean water velocity inside the tube was altered from 1400 to 7400.