Performance evaluation of ducts with non-circular shapes: Laminar fully developed flow and constant wall temperature

• The performance characteristics of the tube bundles with non-circular ducts have been evaluated.
• As a common constraint, the hydraulic diameter of the non-circular duct has been specified.
• The bundles with rectangular, trapezoidal or hexagonal ducts can compete with those with circular tube.
• The choice of the tube shape depends on the constraints imposed and the objectives pursued.

Extended performance evaluation criteria (ExPEC) have been used to assess the performance characteristics of single-phase fully developed laminar flow through bundle of ducts with non-circular shape – rectangular, isosceles triangular, elliptical, trapezoidal and hexagonal. The bundle of circular tubes has been used as a reference heat transfer unit. Constant wall temperature has been selected as the thermal boundary condition. The performance characteristics of the bundles with non-circular ducts have been evaluated and compared to those of the reference unit for different objectives and constraints imposed. As a common constraint, the hydraulic diameter of the duct has been specified.The results clearly show that the rectangular, trapezoidal or hexagonal duct configuration can compete, in some cases, with the circular tube configuration. The choice of the tube shape and geometrical details depends on the constraints imposed and the objectives pursued. The results obtained from the present study revealed that they differed from those obtained with a common constraint of specified cross sectional area.