Heat transfer characteristics of a spirally coiled, finned-tube heat exchanger under dry-surface conditions

Abstract

In the present study, the experimental and theoretical results of the heat transfer characteristics and performance of a spirally coiled, finned-tube heat exchanger under sensible cooling conditions are investigated. The test section is a spiral-coil heat exchanger, which consists of a steel shell and a spirally coiled finned-tube unit. The spiral-coil unit consists of six layers of concentric, spirally coiled, finned tubes. Each tube is fabricated by bending a 9.6 mm-diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium annular fins with a thickness of 0.6 mm and outer diameter of 28.4 mm are placed helically around the tube. The edge of each fin at its inner diameter is corrugated. Air and water are used as working fluids in the shell side and tube side, respectively. A mathematical model based on mass and energy conservation is developed to simulate the heat transfer characteristics and performance of the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data.