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International Heat Transfer Conference 15

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

Parameter Comparison of Condensation Heat Transfer of R134a Outside Horizontal Low-Finned Tubes

Ding-cai Zhang
Zhongyuan University of Technology

Wentao Ji
Key Laboratory of Thermo-Fluid Science and Engineering of MOE, Xi'an Jiaotong University, 28 Xian Ning West Road, Xi'an 710049, China

Jiadi Du
Zhongyuan University of Technology

Zhen Zhang
Zhongyuan University of Technology

Xiaowei Fan
Zhongyuan University of Technology

Ya-Ling He
Key Laboratory of Thermo-fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China

Wen-Quan Tao
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, Shanghai 200092, China; Key Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy and Power Engineering, Xian Jiaotong University, Xian 710049, China

DOI: 10.1615/IHTC15.cds.008916
pages 907-916


KEY WORDS: Condensation, Heat transfer enhancement, R134a refrigerant, Low-finned tubes

Abstract

Experimental studies of film condensation of R134a on single horizontal smooth tube and five low-finned tubes have been conducted. The fin number per meter varies from 736 to 2156. The objective is to enrich the basic data for film condensation of R134a on enhanced tubes and to obtain optimum fin density for the condensation of R134a on low-finned tubes, and to obtain deeper understanding of the effect of surface geometries on condensation heat transfer performance. Wilson plot technique was used to obtain the vapor side heat transfer coefficients. The results indicate that the predicted condensation heat transfer coefficients of R134a on smooth tube from Nusselt theory agree with the experimental data within 10 percent. It is found that the condensation heat transfer coefficient increases with the increase of fin density, so the optimum fin density is about 2156fpm for R134a condensing outside low-finned tubes. Compared with the smooth tube, at a saturated temperature of 40? and for the identical temperature difference, the enhancement factors of the five enhanced tubes(2156fpm, 1720fpm,1475fpm, 1020fpm, 736fpm) are 6.6-9.4?6.8-8.7?6.9-7.6?5.1-5.6?4.1-4.5, respectively. Compared with five commonly prediction models, the deviations mostly agree within ±25%. The Honda model gave relatively accurate predictions compared with experimental results.

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