An investigation of the heat transfer coefficient odzenie during refrigerant evaporation
author:
KRZYSZTOF DUTKOWSKI, MARCIN KRUZEL, TADEUSZ BOHDAL
ORCID ID:
0000-0003-3945-9882, 0000-0001-8349-1375, 0000-0002-0621-2894
No:
10/2023 Instal p.15-20
DOI:
10.36119/15.2023.10.3
This study presents the experimental research data on the local heat transfer coefficient during refrigerant expansion
evaporation in horizontal pipe minichannel. Heat exchange took place between the heated channel wall and the
working fluid flowing inside (R134a and R404A). AISI 316 stainless steel pipe minichannels with an internal diameter
in the range of di = 0.64 – 2.30 mm were used. The so-called minichannels are widely used to build miniature heat
exchangers. Tests carried out in the range of mass flux density G = 350 – 1400 kg/(m2s) and heat flux density
reaching q = 90 kW/m2 allowed to observe the occurrence of the flashing phenomenon, not observed in
conventional channels. It has been shown that in the zone covered by the flashing phenomenon, the heat exchange
conditions deteriorate, and the value of the local heat transfer coefficient in this zone may drop by up to 50%.
Keywords:
About Authors:
dr hab. inż. Krzysztof Dutkowsk; krzysztof.dutkowski@tu.koszalin.pl; https://orcid.org/0000-0003-3945-9882,
dr inż. Marcin Kruzel; marcin.kruzel@tu.koszlin.pl; https://orcid.org/0000-0001-8349-1375,
prof. dr hab. Inż. Tadeusz Bohdal; tadeusz.bohdal@tu.koszalin.pl; https://orcid.org/0000-0002-0621-2894 – Koszalin University of
Technology, Faculty of Mechanical Engineering, Koszalin, Poland. Corresponding author: marcin.kruzel@tu.koszalin.pl