Open Access

ARTICLE

Heat Transfer Enhancement Using R1234yf Refrigerants in Micro-Ribbed Tubes in a Two-Phase Flow Regime

Daoming Shen^1,*, Xia Zhang¹, Wei He¹, Jinhong Xia¹, Songtao Xue²

1 School of Civil Engineering & Architecture, Xinxiang University, Xinxiang, China
2 Department of Architecture, Tohoku Institute of Technology, Sendai, 982-8577, Japan

* Corresponding Author: Daoming Shen. Email:

Fluid Dynamics & Materials Processing 2020, 16(6), 1259-1272. https://doi.org/10.32604/fdmp.2020.010951

Received 09 April 2020; Accepted 24 October 2020; Issue published 17 December 2020

Abstract

Experiments about heat transfer in the presence of a two-phase flow due to the condensation of a R1234yf refrigerant have been performed considering a smooth tube and two micro-fin tubes. The following experimental conditions have been considered: Condensation temperatures of 40°C, 43°C and 45°C, mass fluxes of 500–900 kg/(m² ·s), vapor qualities at the inlet and outlet of the heat transfer tube in the ranges 0.8–0.9 and 0.2–0.3, respectively. These tests have shown that: (1) The heat transfer coefficient increases with decreasing the condensation temperature and on increasing the mass flux; (2) The heat transfer coeffi- cient inside the micro-fin tube is larger than that for the smooth tube; (3) The heat transfer enhancement factors for the micro-fin tube with a fin helical angle of 8° and 15° are 2.51–2.89 and 3.11–3.57, respectively; both are higher than the area increase ratio. These experimental results have been compared with correlations available in the literature: the Cavallini et al. correlation has the highest accuracy in predicting the heat transfer coefficient inside the smooth tube, the related percentage error and the average prediction error are ±8% and 0.56%, respectively; for the micro-fin tube these become ±25% and 6%, respectively.

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Keywords

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