Following licentiate thesis is a summary of the advances made within the research project - Micro- and nano structured surfaces for enhanced boiling heat transfer – which is a collaboration effort between the Divi-sion of Applied Thermodynamics and Refrigeration and the Division of Materials Chemistry at the Royal Institute of Technology (KTH). The main objectives with this research project has been to: develop methods for producing highly efficient boiling surfaces with well defined micro- and nano-structured porous surfaces by the use of micro- and nano-manufacturing techniques. This objective has been achieved and the result is a novel micro-porous surface structure comprising dendritically ordered nano-particles of cop-per. The structure was fabricated by a high-current-density electrode-position process, in which the evolution of hydrogen bubbles serve as a dynamic masking template to the growth of the dendritic copper struc-ture. Important variables were identified that affect the production of the structure and its features, such as surface orientation during electrode-position, pressure and temperature of electrolyte, and a final heat treat-ment of the surface under reduced atmosphere, all of which have previ-ously not been reported on. Experimental tests have been conducted in a widely used refrigerant, R134a, where the micro-porous structure was shown to enhance the boiling performance of a copper surface over 15 times compared to a regular copper surface. The boiling characteristics of the structure were found to be dependent on controllable surface characteristics. The re-markably good boiling performance of the novel micro-porous en-hancement structure has been attributed to its high porosity ( ~94%), a dendritically formed and exceptionally large surface area, and to a high density of well suited vapor escape channels (>50 per mm2). A patent application, intended to protect the enhancement structure and its fabrication method, was submitted to the Swedish patent authorities (PRV) on March 1st, 2006. / QC 20101112
Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-4057 |
Date | January 2006 |
Creators | Furberg, Richard |
Publisher | KTH, Energiteknik, Stockholm : KTH |
Source Sets | DiVA Archive at Upsalla University |
Language | English |
Detected Language | English |
Type | Licentiate thesis, monograph, info:eu-repo/semantics/masterThesis, text |
Format | application/pdf |
Rights | info:eu-repo/semantics/openAccess |
Relation | Trita-REFR, 1102-0245 ; 06:51 |
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