The Theoretical And Experimental Study On The Dynamic Ice-making System Using Supercooling Water Based On The Nano-fluorocarbon Coating Material

There is a vast potential for the application of ice slurry in the energy saving due to reducing usage of the refrigerant with destruction of environment and improving the performance of the refrigeration system. At present, the energy becoming less and less and the requirement of environmental protection is daily increasing urgency. Therefore, as an environment-friendly medium of ice thermal storage, ice slurry can improve energy efficiency and reduce building energy consumption thanks to the latent heat of ice crystals and its good fluidity. Supercooling water is used as a superior method to generate ice slurry for its high efficiency and energy conservation. However, the ice blockage occurred in the supercooling heat exchanger is a prominent problem that reduces the efficiency of the ice generation system. In this study, in order to avoid or retard ice blockage, a fluorocarbon coating with super-hydrophobicity was applied onto the surface of the supercooling heat exchanger to continuously make ice slurry without any additive.In this paper, n the basis of summarizing the research fruits of dynamic ice-making using supercooled water worldwide, a nano-fluorocarbon coating was first applied in ice-making system. The surface characteristics of the nano-fluorocarbon coating were investigated, the results showed that the surface wettability of water was significantly improved by this nano-fluorocarbon coating material, and the freezing time was delayed effectively. A nano-fluorocarbon coating and a disturbing device were respectively used for the improvement of the supercooling heat exchanger, and a series experiments were carried out accordingly.The average thickness of the nano-fluorocarbon coated on the solid surface was only9.7nm. It was the very thin film made the solid surface superhydrophobicity with the contact angle of163.01°. This film not only has a good property in anti-icing but also anti-scale. Compared with the uncoated surface, the process of water freezing on the coated surface with nano-fluorocarbon was slower which demonstrated that the icing on the coated surface was restrained in the experiment. The experiments were conducted by the self-established ice-making system, and the experimental results were analyzed. It was found that the supercooling degree in the coated supercooling heat exchanger was higher, the supercooling state was longer, and the time of ice blockage was delayed. Thus, more ice production can be obtained accordingly and the efficiency of the whole ice-making system was enhanced. Though the heat transfer coefficient was increased using the supercooling heat exchanger with a disturbing device, it was more often blocked in the supercooling heat exchanger due to a more favorable condition for icing offering by the added disturbing device.In this paper, based on the principles of minium entropy production and minium entansy dissipation with the experimental data and the results, the heat exchanging performance supercooling heat exchanger was evaluated comprehensively providing a ground-work for the improvement and perfection in ice-making test system. The analytical results revealed that, the heat exchanging conditions were optimized in the coated supercooling heat exchanger with nano-fluorocarbon coating compared with the uncoated one, the performance of heat exchanger was increased as well, as a result, the efficiency of the whole ice-making system was higher and the purpose of energy saving is also attained.