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强化传热期刊
影响因子: 0.562 5年影响因子: 0.605 SJR: 0.175 SNIP: 0.361 CiteScore™: 0.33

ISSN 打印: 1065-5131
ISSN 在线: 1026-5511

强化传热期刊

DOI: 10.1615/JEnhHeatTransf.v12.i4.60
pages 373-384

Augmentation of Forced Convection Condensation Heat Transfer Inside a Horizontal Tube Using Spiral Spring Inserts

M. A. Akhavan-Behabadi
University of Roorkee, Roorkee-247 667, India; Center of Excellence in Design and Optimization of Energy Systems, School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
M. R. Salimpoor
Department of Mechanical Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran
Ravi Kumar
Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, India
K. N. Agrawal
Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee-247667, India

ABSTRACT

An experimental investigation has been carried out to study the augmentation of the heat-transfer coefficient during condensation of R-134a vapor inside a horizontal tube with different spiral spring inserts. The test condenser was a double-pipe counter-flow heat exchanger of 1040-mm length; the refrigerant flowed inside the inner tube and the cooling water flowed in the annulus. Four spiral springs of 1.0-mm diameter and different pitches of 5, 8, 10, and 13 mm were inserted, one by one, on the refrigerant side of a test-condenser tube. For each spiral spring insert, the data were acquired for the mass flow rates of 87, 105, 122, and 144 kg/m2·s. The spiral spring of 10-mm pitch gave the highest enhancement in the heat-transfer coefficient, h, in a range of 65 to 75% in comparison to that for a plain tube. Subsequently, three more spiral spring inserts of 10-mm pitch and 0.5-, 0,7-, and 1.5-mm coil-wire diameter were also tested. The spiral spring with 1.5-mm wire diameter outperformed the other spiral spring inserts and increased the condensing side heat-transfer coefficient, h, in a range of 75 to 80% in comparison to that for a plain tube. In addition, the influence of vapor quality on the heat-transfer coefficient, h, is also investigated. An empirical correlation has been developed to predict the heat-transfer coefficient, h, during condensation inside a horizontal tube in the presence of a spiral spring insert.