Condensation Heat Transfer of R-134A in Horizontal Straight and Helically Coiled Tube-in-Tube Heat Exchangers
Tóm tắt
This article presents an experimental investigation on condensation heat transfer of R-134a in horizontal straight and helically coiled tube-in-tube heat exchangers. The experiments were carried out at three saturation temperatures(35°, 40° and 45°) with the refrigerant mass flux varying from 100 kg/m2 s to 400 kg/m2 s and the vapor quality ranging from 0.1 to 0.8. The effects of vapor quality and mass flux of R-134a on the condensation heat transfer coefficient were investigated. The results indicate that the condensation heat transfer coefficients of the helical section are 4%–13.8% higher than that of the straight section. The experimental results were compared with the data available in literature for helical and straight pipes.
Tài liệu tham khảo
ECKEKS S. J., PATE M. Evaporation and condensation of R134a and CFC-12 in a smooth tube and a micro-fin tube [J]. Transactions ASHRAE, 1991, 97: 71–81.
DONGSOO Jung, YOUNGMOK Cho and KIHO Park. Flow condensation heat transfer coefficients of R22, R134a, R407C, and R410A inside plain and micro-fin tubes [J]. International Journal of Refrigeration, 2004, 27(5): 25–32.
CAVALLINI A.G., CENSI D Del Col. Experimental investigation on condensation heat transfer and pressure drop of new HFC refrigerants (R134a, R125, R32, R410A, R236ea) in a horizontal smooth tube[J]. International Journal of Refrigeration, 2001, 24(1): 73–87.
DOBSON M. K., CHATO J. C. Condensation in smooth horizontal tubes[J]. Journal of Heat Transfer, 1998, 120(1): 193–213.
LIU Xin. Condensing and evaporating heat transfer and pressure drop characteristics of HFC-134a and HFC-22[J]. Journal of Heat Transfer, 1997, 119(1): 158–163.
JEAN-PIERRE M. Bukasa, LEON Liebenberg and JOSUA Meyer. Influence of spiral angle on heat transfer during condensation inside spiraled micro-fin tubes[J]. Heat Transfer Engineering, 2005, 26(7): 11–21.
UDDIN M., PATRICK J. and NEWLIN A. Variation of local condensation heat transfer coefficient for R134a in helically coiled tubes[C]. International Mechanical Engineering Congress and Exhibition of Winter Meeting. Chicago, Illinois, USA, 1994, 103–110.
KANG Han-jun, LIN Cheng-Xian and EBADIAN M. A. Condensation of R134a flowing inside helicoidal pipe[J]. International Journal of Heat Transfer, 2000, 43: 2553–2564.
HAN Ji-tian, LIN Cheng-xian, EBADIAN M. A. Condensation heat transfer and pressure drop characteristics of R-134a in an annular helical pipe[J]. International Communications in Heat and Mass Transfer, 2005, 32(10): 1307–1316.
ZAKI M., LIU Y. Z. and DONG Z. F. et al. Condensation heat transfer of R134a in helical pipe[C]. Proceedings of the ASME Heat Transfer Division. Baltimore, Maryland, USA, 1997, 141–148.
HAN Ji-tian, LIN Cheng-xian and EBADIAN M. A. Condensation heat transfer of R-134a in a helical pipe [J]. Journal of Hydrodynamics, Ser. B, 2004, 16(2): 144–150.
BRIGGS D. E., YOUNG E. H. Modified Wilson plot techniques for obtaining heat transfer correlations for shell and tube heat exchangers[J]. Chemical Engineering Program Symposium, 1969, 92(65): 35–45.
NIST. Refproe, Version6.01 [M]. US Department of Commerce, 1999.
MOFFAT R. J. Describing uncertainties in experimental results [J]. Experimental Thermal Fluid Science, 1988, 1(1): 3–7.