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DENDRITICALLY ORDERED NANO-PARTICLES IN A MICRO-POROUS STRUCTURE FOR ENHANCED BOILING

DOI: 10.1615/IHTC13.p8.70
10 pages

R. Furberg
Royal Institute of Technology, Stockholm, Sweden

Shanghua Li
Royal Institute of Technology, Stockholm, Sweden

Björn Palm
Royal Institute of Technology (KTH); Department of Energy Technology, Brinellvagen 60,100 44 Stockholm, Sweden

Muhammet S. Toprak
Royal Institute of Technology, Stockholm, Sweden

Mamoun Muhammed
Royal Institute of Technology, Stockholm, Sweden

Résumé

Presented research is an experimental study of the pool boiling performance of copper surfaces enhanced with a newly developed structure. The enhanced surfaces were fabricated with an electrodeposition method where metallic nano-particles are formed and dendritically connected into an ordered micro-porous structure. To further alter the grain size of the dendritic branches, some surfaces underwent an annealing treatment. The tests were conducted with the test objects horizontally oriented and submerged in a refrigerant: R134A, at saturated conditions and at an absolute pressure of 4 bar. The heat flux varied between 0.1 and 10 W/cm2. The boiling performance of the enhanced surfaces was found to be dependent on controllable surface characteristics such as thickness of the structure and the interconnectivity of the grains in the dendritic branches. Temperature differences less than 0.3 °C and 1.5 °C at heat fluxes of 1 and 10W/cm2 respectively have been recorded, corresponding to heat transfer coefficients up to 7.6 Wcm−2K−1. The micro-porous structure has been shown to facilitate high performance boiling, which is 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 − 470 per mm2).

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Measurement of fluid temperature with an arrangement of three thermocouples FLOW BOILING OF A HIGHLY VISCOUS POLYMER SOLUTION