ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
EXPERIMENTAL STUDY ON REFRIGERANT GAS-LIQUID FLOW DISTRIBUTIONS IN MULTI-PASS CHANNELS WITH DISTRIBUTING INNER PIPE
Resumo
Parallel-flow type heat exchangers, which consist of dividing/combining headers and multiple branch tubes, have advantages of low thermal resistance and compactness. In applying them to evaporators, however, maldistributions of gas and liquid from the dividing header to branch tubes occur quite often and thermal performance is deteriorated. Therefore, improvement of the uniformity of gas-liquid distributions to branch tubes is a key issue to bring out the intrinsic performance of parallel-flow type evaporators. As one of the
methods to improve the distribution uniformity, the refrigerant-supplying method through a pipe with multiple outlet holes installed in the dividing header has been investigated. To the authors' knowledge, however, specifications of tested pipes are limited, and flow characteristics in the channel are not fully clarified yet. In this study, we examine experimentally the effect of the multi-hole distributing pipe on refrigerant (R-134a) gas-liquid distributions in the multi-pass channel. The test channel has a horizontal header and 10 vertical upward microchannel branch tubes. We have tested four distributing pipes with different outlet-hole specifications and installation orientations. We have observed visually the flow in the header and measured amounts of gas and liquid distributed to branch tubes. By comparing these results with those measured in the standard channel, we have evaluated the performance of multi-hole distributing pipes.