Phase change as secondary materials coolants
The pump ice slurry can be used instead of chilled water or in brine. The composition of these fluids is quite simple, consisting of water with ice crystals mixed with other liquids, such as ethylene glycol, ethanol, ammonia, NaCl. Only part of the water turns into a small crystals of ice (about 1 mm). It provides a uniform solution, while enhancing the cold transfer. Ice slurry can take advantage of the high latent heat of freezing, while retaining the ability to pump liquids for heat exchangers. Optimization is aimed at the search of the less viscous secondary refrigerant from within the available range, which has high energy efficiency.
Ice crystals can be produced by scratches the surface of the generators, which can be quite costly. Alternative methods of generation, which are being investigated. Various methods, products, and applications are given to Paul (1997, 2002).
Properties of carbon dioxide makes it very suitable for applications in the form of volatile secondary coolant. Liquid carbon dioxide of about 10C and 25-26 bar pressure can be pumped up coolers, where part evaporates.
Two-phase mixture is returned to the reservoir, where it is separated. In conventional refrigeration circuit maintains the pressure at the corresponding temperature of saturation.
Liquid carbon dioxide has a very low viscosity; and because of its high latent heat, the amount to be distributed is very small compared with any water-based solutions. Carbon dioxide exhibits a high boiling heat transfer coefficient, which contributes to the design of the coolers. Such a system is applied in supermarkets for medium temperature refrigeration. She also has significant potential in air conditioning systems (Pearson, 2004).
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Distributed Cooling, Thermal Storage