22 May 2008

USE OF A NOVEL NANO- AND MICRO-POROUS STRUCTURE FOR ENHANCED BOILING IN A PLATE HEAT EXCHANGER


Presented research is an experimental study of the performance of a standard
plate heat exchanger evaporator with a novel nano- and micro-porous copper structure, used
to enhance the boiling heat transfer mechanism in the refrigerant channel. The enhancement
structure had a porosity of 95%, a pore density of 75 pores/mm2 and a thickness of about
250 µm. Flow boiling tests were conducted at heat fluxes ranging between 4.5 and 17 kW/m2
with R134A as refrigerant. Based on water-to-water experiments to determine the water side
heat transfer coefficient, the plate heat exchanger with the enhancement structure displayed
up to 10 times improved heat transfer coefficient in the refrigerant channel. The overall
performance of the heat exchanger was improved by over 100%. This significant boiling
enhancement is in agreement with previous pool boiling experiments and confirms that the
enhancement structure may be used to enhance the performance of plate heat exchangers.