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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

MEASUREMENT OF LOCAL HEAT TRANSFER COEFFICIENTS DURING CONDENSATION OF R134a INSIDE A SINGLE CIRCULAR MINICHANNEL

Get access (open in a dialog) DOI: 10.1615/IHTC13.p12.240
12 pages

Abstract

The measurement of the condensation heat transfer coefficient inside minichannels is still somewhat elusive due to the difficult task of getting accurate values of the heat transfer coefficients during the condensation process in minichannels.
The present authors show the first preliminary tests carried out on a new experimental apparatus for measurement of the local heat transfer coefficient inside a circular minichannel, lower than 1 mm in diameter. The heat transfer coefficient is measured during condensation of R134a and is obtained from the measurement of the heat flux and the direct measurement of the saturation and wall temperatures. The heat flux is derived from the water temperature profile along the channel, in order to get local values of the heat transfer coefficient. The test section has been designed so as to reduce thermal disturbances and experimental uncertainty.
A brief look into the design and the construction of the test rig is reported in the paper. The apparatus has been designed for experimental tests both in condensation and vaporization, in a wide range of operating conditions and for a wide selection of refrigerants.