Design of a compact mesh-based high-effectiveness counter-flow heat exchanger and its integration in remote cooling systems

Compact high-effectiveness Counter Flow Heat EXchangers (CFHEX) are crucial components of recuperative coolers, such as Joule-Thomson and Turbo-Brayton coolers and of remote cooling systems realised by a convective loop. This paper presents a design and analysis of a cryocooler-based remote cooling system that extends the cooling capabilities of a two-stage cryocooler. Increased heat exchange between high- and low-pressure channels is established by adding copper mesh material. A compact effective mesh-based CFHEX design covering the 4.5-290 K temperature and 1–10 bar pressure operation ranges is presented. The discretised numerical model of the CFHEX is also presented and covers a wide field of parameters, including axial conduction, variable material and fluid properties based on experimental and theoretical data and wall-mesh thermal contact conductance. In our design the latter has shown to have a significant influence on the effectiveness of the CFHEX based on the analysis of a range of inner tube materials. The sizing of a high-performance CFHEX with a predicted effectiveness of 96.5 % (number of transfer units (NTU)=27.6) and an accumulated pressure drop of 15 mbar using the model is demonstrated. The outlook for future work and experimental measurements of the parameters to complete the numerical model is presented.