Frost formation on fin-and-tube heat exchangers. Part I—Modeling of frost formation on fin-and-tube heat exchangers Deniz Seker a, *, Hakan Karatas a , Nilufer Egrican b a Arcelik A.S. ATGM 34950, Tuzla, Istanbul, Turkey b Yeditepe University, Umraniye, Istanbul, Turkey Received 29 November 2002; received in revised form 10 November 2003; accepted 9 December 2003 Abstract In this study, the heat and mass transfer characteristics of heat exchangers during frost formation process are analyzed numerically. Unsteady heat and mass transfer coefficients of the air side, heat transfer coefficient of the refrigerant side, air-frost layer interface temperature, the surface efficiency of the heat exchanger and the mass flow rate of the frost accumulated on the heat exchanger surface are calculated. The total conductivity (UA) and pressure drop of the heat exchanger are reported for different air inlet temperature, relative humidity, air mass flow rate and the refrigerant temperature. # 2003 Elsevier Ltd and IIR. All rights reserved. Keywords: Modelling; Frost formation; Finned tube; Mass transfer; Heat transfer; Parameter Formation de givre sur les e´changeurs de chaleur a` tubes ailete´s. Partie I—Mode´lisation de la formation de givre sur les e´changeurs de chaleur a` tubes ailete´s Mots cle ´s : Mode´lisation ; Givrage ; Tube ailete´ ; Transfert de masse ; Transfert de chaleur ; Parame`tre 1. Introduction The frost formation on a cold surface below 0  C acts not only as a thermal insulator between the surface and the humid ambient air, but also significantly reduces the performance of the heat exchanger, since the air passages become narrower and pressure drop generated becomes higher. Therefore, an efficient physical understanding of frost formation is essential. Literature survey show that a relatively large amount of work has been done on understanding of frost formation. The design and thermal selection of the heat exchangers have been extensively studied by Kakac et al. [1,2]. Hayashi [3], characterized the frost formation in 3 stages; a) crystal growth period, b) frost layer growth period and c) frost layer full growth period. On these stages, ice columns occur 1-dimensional and become 3- dimensional with time and cause the frost layer to be porous. Yonko et al. [4], examined frost formation on flat plates and reported that the thermal conductivity of frost varies with its density. Jones et al. [5] studied frost formation on flat plates and found that increase of 0140-7007/$35.00 # 2003 Elsevier Ltd and IIR. All rights reserved. doi:10.1016/j.ijrefrig.2003.12.003 International Journal of Refrigeration 27 (2004) 367–374 www.elsevier.com/locate/ijrefrig * Corresponding author. Fax: +90-216-423-30-45. E-mail addresses: deniz.seker@arcelik.com (D. Seker), hakan.karatas@arcelik.com (H. Karatas), egrican@yeditepe. edu.tr (N. Egrican).