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CuPGS Laminate Core for a Matrix Microchannel Heat Exchanger
Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
2019 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Cryocooling is a continuously developing field of engineering, applied in the fieldsof aerospace, military, and medical sciences among others. There is a demand forsmaller and more efficient cryocoolers for spaceborne low-light observation missions,with many custom cooling systems having completed successful missions. The Stir-ling cycle is the most prevalent refrigeration technique used for space applications,with the pulse-tube, Joule-Thomson or reverse Brayton cycles being used in somespecial cases.A matrix heat exchanger is designed with 3D-printed 17-4 PH stainless steel end capsstreamlined for computer numerical control (CNC) production.

The heat exchanger (HX) core consists of 1mm thick stainless steel spacers and 250μm thick copperchips that are tolerance-matched for photo etching, as well as pyrolytic graphitesheets (PGS) of 25μm, the thickest commercially available PGS without addedadhesive film material.The experiments of joining PGS and copper chips with Epo-Tek 301-2 epoxy tocreate a solid core structure for the heat exchanger did not result in a pressure-resistant laminate material. The graphite surface proved difficult to adhere to usingthis epoxy, creating voids, and easily delaminated into separate layers of PGS. Bond-ing the stack together using indium, testing epoxy with a higher ability to permeatethe PGS or diffusion-bonding through other means are presented as options forfurthering the HX development.Pressure testing of a copper-only laminated heat exchanger core showed that theend cap recess adhesion capability is a potential point of failure, as the designedstructure makes it impossible to inspect the results of the bond without curingthe epoxy and pressurising the system. The difficulty in establishing a tight seambetween the main counter-flow channels of the HX is also demonstrated here, asleakage between the channels occurred at pressures in the vicinity of 2

Place, publisher, year, edition, pages
2019. , p. 48
Keywords [en]
cryogenics, counter-flow, matrix heat exchanger, microchannel, PGS
National Category
Aerospace Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-76914OAI: oai:DiVA.org:ltu-76914DiVA, id: diva2:1373902
External cooperation
APR Technologies AB
Subject / course
Student thesis, at least 30 credits
Educational program
Space Engineering, master's level
Examiners
Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2019-11-28Bibliographically approved

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Department of Computer Science, Electrical and Space Engineering
Aerospace Engineering

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5678910118 of 78
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Citation style
  • apa
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Output format
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