Parametric Optimization for Thermoacoustic Refrigerator Driven by Thermoacoustic Engine

Abstract

In this work, high fidelity numerical modelling is carried out to demonstrate the working of thermoacoustic refrigerator (TAR) coupled with thermoacoustic engine (TAE). The computational domain consists of two stacks, one for TAE and the other for TAR, in a long resonator tube which represent an actual physical model. The TAE stack’s horizontal walls are imposed with a temperature profile with decreasing gradient, whereas convective heat transfer coefficient is applied to the thin vertical walls. The numerical model solves unsteady Navier-Stokes equations in non-isothermal flow. Numerical simulations are done on Ansys/fluent. Air is used as the working gas. Pressure, velocity, and temperature fields are computed and recorded at various locations in the domain. The TAR stack is considered fully coupled and is conjugated with the flow. For the development of pressure wave, working gas is considered as compressible with the density varying according to the ideal gas law. The effect of varying heating source temperature and varying the lengths of both the stacks is investigated on the output parameters, specifically the temperature drop at the cold end of the TAR stack, and pressure & velocity of the developed acoustic wave. The most favourable results in terms of temperature drop were obtained with 1:2 stack ratio and with heating temperature of 700K. It was observed that the acoustic wave with high amplitude of pressure and velocity does not necessarily produce maximum cooling.