Numerical investigation on the performance of a new type of perforated-serrated fins for plate-fin heat exchangers in cryogenic helium systems

Abstract

Plate-fin heat exchangers (PFHEs) with serrated fins are commonly employed in cryogenic helium systems. To further improve the heat transfer performance and compactness of PFHEs, traditional serrated fins structure is optimized and a new type of perforated-serrated fins is proposed with each serrated fin perforated. Numerical simulations considering the influence of cryogenic conditions, using well-validated 3D models, are carried out. The results show that the heat transfer performance of optimized fins is improved. Compared with traditional serrated fins, Colburn j factor of perforated-serrated fins increases by 30.61–12.61 % at 20 K and by 16.71–2.9 % at 77 K. Although the flow performance of perforated-serrated fins is somewhat inferior, overall thermo-hydraulic performance is superior, particularly at low Reynolds numbers. The JF factor of perforated-serrated fins increases by 23.75–9.34 % at 20 K and by 11.04–3.3 % at 77 K. In addition, the effects of perforated position and fin porosity on thermo-hydraulic characteristics of perforated-serrated fins are obtained. For the design below 80 K PFHEs used in cryogenic helium systems, replacing traditional serrated fins with perforated-serrated fins may be worth considering to further improve overall thermo-hydraulic performance.