Development of empirical correlations for non-adiabatic capillary tube based on mechanistic model Debasish Sarker, Ji Hwan Jeong* School of Mechanical Engineering, Pusan National University, Busan 609 735, Republic of Korea article info Article history: Received 25 August 2011 Received in revised form 29 December 2011 Accepted 30 January 2012 Available online 7 February 2012 Keywords: Capillary Heat exchanger Refrigerating system Simulation abstract Capillary tubes play a vital role in the refrigeration cycle, as they reduce the temperature of the refrigerant. The non-adiabatic capillary tube (capillary tube-suction line heat exchanger: CT-SLHX) is widely incorporated into small refrigeration systems to enhance the cooling performance and ensure that only the refrigerant vapor enters the compressor. It is necessary to develop an accurate and fast-running non-adiabatic capillary tube model, as the performance of the refrigeration cycle simulation tool is largely dependent on the accuracy and run-time its component models. In the present study, a reliable mechanistic model was used to generate reference data. An empirical model was developed based on the data produced by this mechanistic model. This new empirical model was validated against experimental measurements available in the literature for R-134a and R-600a. The new model is fast-running and its performance metrics are in good agreement with experimentally measured data. ª 2012 Elsevier Ltd and IIR. All rights reserved. De ´ veloppement de corre ´ lations fonde ´es sur un mode `le me ´ canique pour un tube capillaire non adiabatique Mots cle ´s : Tube capillaire ; E ´ changeur de chaleur ; Syste ` me frigorifique ; Simulation 1. Introduction Capillary tubes are widely used as a refrigerant expansion device in small-capacity vapor-compression refrigeration systems. This type of tube connects the exit of the condenser to the inlet of the evaporator. It is a long and narrow copper tube with a constant cross-sectional area inside. They are typically between 2 m and 6 m in length with a diameter ranging from 0.33 mm to 2.00 mm (Yang and Wang, 2008). The capillary tube reduces the pressure of the refrigerant when the refrigerant flows through it. It plays a very important role in vapor-compression refrigeration systems and contributes to reducing the cost of these systems as well. In addition, capil- lary tubes have “self-compensating” features that help them perform under off-design conditions. A capillary tube can either be adiabatic or a non-adiabatic, as shown in Fig. 1. An adiabatic capillary tube is thermally insulated. Additionally, the heat exchange with the ambient environment is negligible as a non-adiabatic capillary tube is soldered onto the suction line to form a capillary tube-suction line heat exchanger. * Corresponding author. Tel.: þ82 51 510 3050; fax: þ82 51 512 5236. E-mail address: jihwan@pusan.ac.kr (J.H. Jeong). www.iifiir.org Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/ijrefrig international journal of refrigeration 35 (2012) 974 e983 0140-7007/$ e see front matter ª 2012 Elsevier Ltd and IIR. All rights reserved. doi:10.1016/j.ijrefrig.2012.01.021