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ARTICLE:
Alberto Cavallini
Dipartimento di Fisica Tecnica, Universita di Padova, via Venezia 1,I-35131 Padova, Italy Davide Del Col
Dipartimento di Fisica Tecnica, Università di Padova, Padova, Italy M. Matkovic
Dipartimento di Fisica Tecnica, University of Padova, Padova, Italy Luisa Rossetto
Dipartimento di Fisica Tecnica, Universita di Padova, via Venezia 1,I-35131 Padova, Italy
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.
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MPH-24 pages
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