Oval finned tube condenser and design pressure limits

Finned tube heat exchangers presently used in the air-conditioning industry are made with round tubes (7.0-9.5 mm diameter) and plate fins of an enhan ced fin geometry. The air-side pressure drop is composed of friction on the fins and pressure drag on the tubes. This work investigates the use of ova l tubes to replace round tubes. This will result in higher heat transfer pe rformance and lower air pressure drop. Of particular interest is applicatio n of the oval tube design to refrigerant condensers, which are designed for operating pressures of 31 bar, or more. This paper compares the performanc e of a proposed oval tube design with that of a typical 9.5 mm finned tube design. Mechanical design and fabrication are also described. A key questio n addressed in this work is to determine the maximum allowable internal tub e pressure of the oval tube design. This question was addressed using 3-dim ensional finite element stress analysis.