INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. 2006; 30:1013–1021 Published online 16 May 2006 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/er.1204 SHORT COMMUNICATION Melting of ice slurry in a tube-in-tube heat exchanger Dong Won Lee z and Atul Sharma n,y New & Renewable Energy Research Department, Korea Institute of Energy Research, 71-2, Jnag-dong, Yusong-gu, Daejon 305-343, Korea SUMMARY One of the main components of a closed ice slurry system is the heat exchanger in which ice slurry absorbs heat resulting in the melting ice crystals. Design calculations of heat exchangers are mainly based on heat transfer coefficient and pressure drop data. But experiments presented in this paper show the effect of ice slurry mass flux on heat transfer rate and heat transfer coefficient during melting. For the experiments, ice slurry was made from 6.5% ethylene glycol–water solution, flowing through a 16.91 mm internal diameter, 1500 mm long horizontal copper tube. The ice slurry was heated by hot water circulated at the annulus gap of the heat exchanger. Experiments of the melting process were conducted with changing the ice slurry mass flux and the ice fraction from 800 to 3500 kg m À2 s À1 and 0 to 25%, respectively. During the ex- periment, it was found that the measured heat transfer rates increase with the mass flow rate and ice fraction; however, the effect of ice fraction appears not to be significant at high mass flow rate. At the region of low mass flow rates, a sharp increase in the heat transfer coefficient was observed when the ice fraction was more than a certain value. Experiments were also conducted to investigate the effect of hot water temperature on the heat transfer coefficient. Copyright # 2006 John Wiley & Sons, Ltd. KEY WORDS: ice slurry; direct transportation; melting heat transfer; ethylene glycol 1. INTRODUCTION The ice slurry is useful for the future of refrigeration with a context of ozone depletion and global warming. As a result of the planned reduction of HFCs by the Kyoto protocol and the increased use of natural refrigerants such as ammonia, the number of indirect refrigeration systems has grown steadily in the last decade. The drive for energy conservation and reduction of CO 2 emissions to the environment in many industrial and commercial sectors has promoted Received 15 May 2005 Revised 2 January 2006 Accepted 5 January 2006 Copyright # 2006 John Wiley & Sons, Ltd. y E-mail: atul sharma2@yahoo.com z E-mail: dwlee@kier.re.kr Contract/grant sponsor: Korea Energy Management Corporation n Correspondence to: Atul Sharma, New & Renewable Energy Research Department, Korea Institute of Energy Research, 71-2, Jnag-dong, Yusong-gu, Daejon 305-343, Korea.