Heat exchanger performance modeling using ice slurry as secondary refrigerant

Ice slurry is well known as a biphasic secondary refrigerant that presents several potential advantages compared to single phase secondary refrigerants. These potential advantages can be summarized in the ability to use the thermal storage and the high cooling capacity given by the latent heat. Theoretically, these features should allow important energy savings in secondary refrigerant distribution loop. However, an accurate evaluation of these energy savings requires the knowledge of the thermal and rheological performance of the refrigerant studied. Based on the experimental model developed by the authors for brine based ice slurry, a theoretical analysis of heat exchangers performance is presented in this work in order to calculate the potential energy savings associated to its use. The influence of ice concentration, mass flow rate, heat exchanger length and cooled fluid temperature over pumping power and heat transfer rate is studied. The ratio between heat transfer rate and pumping power is used as the evaluation parameter, which allows us to find the most favourable operation conditions for ice slurry flow. In order to assess the improvement obtained using ice slurry, results for ice slurry are compared to those obtained for carrier fluid at same inlet temperature.This research has been partially financed by the project DPI2007-66551-C02-01 grant from the “Dirección General de Industria, Mº de Ciencia y Tecnología”, the project 2I05SU0029 grant of the “Secretaría General de la Consejería de Educación y Cultura de la C.A. de la Región de Murcia” and the HRS Spiratube Company, Murcia (Spain)