Optimal design of a novel non-isometric helically coiled recuperator for Joule-Thomson cryocoolers

A novel non-isometric helically coiled heat exchanger, with first-dense-then-sparse type structure, was proposed to improve the performance of Joule-Thomson (J-T) cryocoolers. The physical model and analysis model of exergy destruction of this new non-isometric helically coiled heat exchanger were developed. The influence of three key geometrical parameters (the separation position i, the fin pitch of the dense part f(p1), the fin pitch of the sparse part f(p2)) on the performance of heat exchanger were investigated, and the structure of recuperator was further optimized using response surface methodology (RSM). The results show that the total exergy destruction of the optimum recuperator decreased by 8% and the material consumption reduced by 4%. Furthermore, the refrigeration capacity increased by 9%, which proves the potential of this novel non-isometric helically coiled heat exchanger in heat transfer performance and material consumption. This study provides helpful guidance for geometrical optimization of the recuperator for J-T cryocoolers.