Author(s)

A. Cavallini, S. Bortolin, D. Del Col, M. Matkovic & L. Rossetto

Abstract

The present authors have designed and built a test apparatus for heat transfer and pressure drop measurements during forced convective single phase flow, condensation and flow boiling in one single minichannel. The performance of the test apparatus for investigation of heat transfer and fluid flow is described in this paper. Some construction issues with important effects on the experimental technique are also reported in the paper. The adiabatic and diabatic two phase pressure drop, the local heat transfer coefficient and the dry-out phenomenon, as well as the single phase heat transfer coefficient measurements, are all discussed herein. The experimental apparatus has turned out to be highly effective in terms of low experimental uncertainty, local measurement capabilities and rather fast data acquisition rate over a wide range of test conditions. Vast, reliable experimental data have a key role in semi-empirical modelling. Indeed, these experimental results, together with data associated to minichannels from different authors, have been used for the development of new heat transfer and pressure drop models able to accurately predict experimental data for low, medium and high pressure fluids. Keywords: heat transfer, pressure drop, minichannels, condensation, flow boiling, dry-out. 1 Introduction In the field of heat transfer mini-, micro- and nanochannels have gained a great deal of attention in engineered systems. A number of advantages associated with minichannels, with an inner diameter in the range of 0.2-3 mm [1], have pushed their use far ahead of the actual understanding of the microscale process and how the scaling down alters the governing physical processes. First compact heat

Keywords

heat transfer, pressure drop, minichannels, condensation, flow boiling, dry-out.