Speaker
Description
Compact efficient Counter Flow Heat EXchangers (CFHEX) or recuperators are crucial components of recuperative coolers, such as Joule-Thomson and Turbo-Brayton coolers. Also in cryogenic systems that apply a convective cooling loop, in which a working fluid is circulated by a warm pump and cooled by a cryocooler, high-effectiveness recuperators are essential. In a collaboration project of ESA, University of Twente and CERN, a new innovative mesh-based recuperator design covering the 4.5-290 K temperature and 1-10 bar pressure operation ranges is developed and presented. A system level analysis of a convective cooling loop circuit with helium as the working fluid has been accomplished defining the performance characteristics of the CFHEXs, while matching the available cooling powers of a two-stage cryocooler. A discretized numerical model including the flow and material parameters, based on experimental and theoretical data, was developed to size the first recuperator prototype, which was tested between 40 K and 290 K. The schematic test stand is presented for measuring the effectiveness and the pressure drop of both fluid streams at variable mass flow and pressure levels. An average effectiveness of ≈ 94.8 % with a pressure drop of ≈ 30 mbar was achieved in the first design iteration. The numerical model was correlated with the experimental results showing good agreement for the set mass flow and inlet pressure dependencies. The deviations from the model were investigated and design improvements are proposed for a recuperator construction for Reverse Turbo-Brayton cooler application.
