Numerical Investigation of a Heat Exchanger with Annular Fins for Cryocooler Application

In this paper, the heat transfer characteristics of a typical hot heat exchanger used in pulse tube cryocooler have been numerically investigated. The numerical simulation is performed with the help of the commercial tool Ansys Fluent® to study the effect of different shapes and sizes of fins on the rate of heat transfer. The major parameters of the analysis include the diameter and pitch of the fins, the oscillating temperature at the inlet and outlet of the heat exchanger, and its operating frequency. A numerical investigation is conducted for the annular fin to illustrate its effect on the rate of heat transfer by calculating its Nusselt number and heat transfer coefficient. The effect of with fin and without fin on temperature and pressure variations has been studied for different angles in a cycle. The vortex development mechanisms within the gap between fins have been analyzed and compared with the vortex development mechanisms without fin. Results will be helpful for better design of heat exchangers for cryocoolers.