Counterflow heat exchanger design for the E-ELT METIS instrument cooler

Dollekamp, E. (2014) Counterflow heat exchanger design for the E-ELT METIS instrument cooler.

Abstract:This master thesis discusses the design of the final stage of the METIS detector instrument cooler for the European Extremely Large Telescope. The final stage is the lowest temperature part of the helium stage of the cooler. The final stage exists out of a counterflow heat exchanger, a Joule-Thomson throttle and a final stage heat exchanger. This final stage is the most critical part of the cooler. The counterflow heat exchanger needs to have an e�ectiveness of 99:8% and the final stage heat exchanger must deliver a cooling power of 0.4 W at 8 K. Di�erent types of counterflow heat exchangers are analyzed. Modeling indicates that long lengths of counterflow heat exchangers are required. A tube-in-tube counterflow heat exchanger needs a length of 17.16 m and a coiled finned tube counterflow heat exchanger needs a length of 9.85 m. The final stage heat exchanger can be relatively short with a length of 1 m and the Joule-Thomson throttle needs to be a small restriction in the �m range. The final stage experimental setup has been designed but due to the limited time span of the research the setup has not yet been manufactured. Instead a setup has been manufactured to measure the e�ectiveness of a counterflow heat exchanger. The e�ectiveness of a 3.02 m long tube-in-tube counterflow heat exchanger has been determined. At a mass flow of 99.62 mg/s the e�ectiveness resulted in 93.05�1.10%. This agrees with the modeled e�ectiveness of 93.10%. At lower mass flow the e�ectiveness increases but also the error in the measurement due an observed radiation heat inleak. A longer tube-in-tube CFHX and other type of counterflow heat exchangers still need to be manufactured and tested in an e�ectiveness characterization setup with lower radiation heat inleak.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics MSc (60436)
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