University of Twente Student Theses


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.

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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 effectiveness of 99.8% and the final stage heat exchanger must deliver a cooling power of 0.4 W at 8 K. Different 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 µm 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 effectiveness of a counterflow heat exchanger. The effectiveness 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 effectiveness resulted in 93.05±1.10%. This agrees with the modeled effectiveness of 93.10%. At lower mass flow the effectiveness 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 effectiveness 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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