Thermal and hydraulic analysis of aluminium oblique-tube condenser coils with plain fins manufactured by controlled atmosphere brazing

Abstract

This paper presents new development of aluminium oblique-tube condenser coils with plain fins manufactured by controlled atmospheric brazing (CAB) for air-conditioning applications. The CAB technique provides good quality joints and thermal contact between oblique tubes and fins for more effective heat transfer. Performances of seven oblique-tube coils with different numbers of tubes per pass (i.e. 1, 2, 3, 4, 5, 7 and 14) were assessed against those of a commercial circular-tube coil with corrugated fins. The contribution of the slender oblique tubes with plain fins reduced air pressure drop penalties by 20.9–30.9% for 1–3 m/s air velocity. Thermal performance of the 1-tube-per-pass coil surpassed that of the commercial coil albeit not energy-saving. On the other hand, the 4-tube pass coil when matching with the heat transfer performance of the 3- and 2-tube-per-pass coils and the circular-tube coil saved water-side pump energy as high as 27.9%, 36.3% and 38.7%, respectively.