Air-side heat transfer characteristics of spiral-type circular fin-tube heat exchangers Mooyeon Lee, Taehyung Kang, Yongchan Kim* Department of Mechanical Engineering, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713, Republic of Korea article info Article history: Received 4 July 2009 Received in revised form 27 August 2009 Accepted 26 September 2009 Available online 6 October 2009 Keywords: Chiller Heat exchanger Finned tube Spiral Geometry Experiment Heat transfer abstract The objective of this study is to investigate the air-side heat transfer characteristics of spiral-type circular fin-tube heat exchangers used as evaporators in household refrigera- tors. The j-factors of the tested heat exchangers under non-frosting conditions were measured by varying the fin pitch, number of tube rows, and fin alignment. The j-factors of the spiral-type circular fin-tube heat exchangers were analyzed as a function of heat exchanger geometries and then compared with those of the flat plate fin-tube heat exchangers with discrete fins. Two empirical correlations of the j-factors were developed separately for the inline and the staggered fin alignment as a function of the Reynolds number, number of tube rows, and dimensionless fin pitch normalized by the hydraulic diameter. The mean deviation of the predictions using the present correlations from the measured data was 4.78% for the inline fin alignment and 6.02% for the staggered fin alignment. ª 2009 Elsevier Ltd and IIR. All rights reserved. Caracte ´ ristiques de transfert de chaleur co ˆ te ´ air des e ´ changeurs de chaleur circulaires he ´licoı¨daux a ` tubes ailete ´s Mots cle ´s : Refroidisseur ; E ´ changeur de chaleur ; Tube ailete ´ ; Serpentin ; Ge ´ome ´trie ; Expe ´rimentation ; Transfert de chaleur 1. Introduction Fin-tube heat exchangers have been widely used in various industries such as the air-conditioning, refrigerator, showcase, freezer, and process industries. The fin types of fin-tube heat exchangers are dependent on the controlling temperatures and the purpose of use of the heat exchanger. The fin type is an important factor affecting the air-side heat transfer characteristics of the fin-tube heat exchanger. Flat plate fin-tube heat exchangers are used as evaporators mostly in household refrigerators and freezers as well as in industrial applications such as intercoolers and showcases because of their ability to dispose of defrosting water easily. To improve the performance of the fin-tube heat exchangers, used in refrigerator and freezers under real operating conditions, heat transfer characteristics derived from advanced fin geometries need to be investigated. * Corresponding author. Tel.: þ82 2 3290 3366; fax: þ82 2 921 5439. E-mail address: yongckim@korea.ac.kr (Y. Kim). www.iifiir.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/ijrefrig 0140-7007/$ – see front matter ª 2009 Elsevier Ltd and IIR. All rights reserved. doi:10.1016/j.ijrefrig.2009.09.019 international journal of refrigeration 33 (2010) 313–320