Constructal wavy-fin channels of a compact heat exchanger with heat transfer rate maximization and pressure losses minimization

• A type of wavy-fin of compact heat exchangers is designed by constructal theory.
• Both pressure drop minimization and heat transfer maximization are considered.
• The optimal geometrical parameters of wavy-fin channels are found.
• The optimal configuration has a decrease of 54% in pressure drop.
• The heat transfer rate of the optimal configuration is enhanced by around 26%.

In this paper a new generation of wavy-fin channels of a compact heat exchanger is investigated based on the Constructal Theory with maximizing the heat transfer rate and minimizing the pressure losses. Three dimensionless variables such as the channel space, the wavelength ratio and the amplitude ratio of two wavy walls are considered to find the optimal configuration of wavy-fin channels for the compact heat exchanger applied in a heat recovery system of a microturbine. Two dimensional numerical simulations are conducted to obtain the steady laminar heat transfer and pressure drop characteristics by using Computational Fluid Dynamics (CFD). All of the CFD simulations are carried out for a sufficiently long time so that the initial conditions are completely convected out of the channels and have no effects on simulated results. The results show that the new generation of wavy-fin channel can help to reduce the pressure drop by more than 54% and to enhance the heat transfer rate by around 26%. The optimal design regions of the three dimensionless parameters are also provided so as to help design wavy-fin heat exchangers.