Thermal-Hydraulic and Entropy Generation Optimization of Capsule-Type Plate Heat Exchangers With Spherical Dimples.

The capsule-type plate heat exchanger (PHE) is a new type of equipment with great potential, which is characterized by the concave and convex capsule-like surface. In this article, new structures consisting of capsules and spherical dimples of PHE were proposed. Flow through a periodic unit cell with four different geometries is simulated numerically to characterize the pressure drop, heat transfer coefficients, and entropy generation rate. The numerical results show good consistency with the existing experimental data. Results show that the flow in capsule-type plate can be divided into recirculation zone and high-velocity zone. The staggered capsule structure and the spherical dimple shape generate more secondary and impinging flows, which provide higher Nusselt number and friction factor. The maximum Nusselt number area changed from the upwind region of capsule to the vicinity of dimple region because of the downwash effect and the fluid impact effect. The Nusselt number is enhanced by 19%–46%, and the friction factor is 1.21–2.9 times to that of the primary capsule-type plate. In addition, Entropy analysis illustrates that the maximum reduction in the dimensionless entropy generation rate is 43.6%. [ABSTRACT FROM AUTHOR]