Study On Characteristic For Direct Contact Ice Slurry Making Process

Ice slurry, the mixture of water and ice particle, takes the form of mud suspend liquid, and has higher unit volume heat capacity than chilled water, since has good mobility characteristic, it can be pumped. In some developed countries, ice sulrry had been used in many practical projects, it is a kind of cooling medium with bright future. Compare with traditional methods, ice making by the means of directly contact heat transfer have such characteristics as high-efficient, energy-conservation ,etc.Direct contact heat transfer has low thermal resistance and no scaling and corrosion, comparing with traditional spiral tube type. Direct contact ice thermal storage is recent hot problem in home and abroad which casts off such problems as ice layer thickness increasing, additional thermal resistance increasing and increases the COP of the refrigerators. It has very important instructive significance for research on direct contact ice thermal storage system especially its mixed heat transfer characteristic to design and optimum in direct contact ice thermal storage system.The research works in this paper focus mainly on the following aspects:A physical model for drop sensible heat transfer was put forwarded and obtain the general form of the solution, get the equation of a drop surface heat transfer coefficient, and point out how to obtain the value of λ by minimizing the error-square-sum between the measured and predicted temperatures. Have set up the heat transfer model based on a dorp fall in water, get the terminal velocity, and the drop Reynolds number based on it. The value of thevolumetric heat transfer coefficient α_v is obtained by solving for h_d using e^-λ_eq,and the error-suqare-root within 10% by comparing with the experimental value.In order to carry out the research on direct contact thermal storage technology and its heat transfer characteristic, a direct contact ice thermal storage system research apparatus has been designed and developed, which having cool storage, cool relieving and measure parts. It has following functions: (1) Research on the law of ice crystal producing in the ice-making tank; (2) The experimental research on heat transfer law in the tank; (3) Research on ice thermal storage system efficiency; (4) The experimental research on cool relieving law; (5) The selective reseach of direct contact thermal storage medium; (6) The research on resistance characteristic of ice slurry.Investigations were carried out experimentally on heat transfer research ofdirect contact ice-making tank, which takes volumetric heat transfer coefficient as a research subject. Some effects such as velocity of HCFC123 spray in the tank, pattern and arrangement of injectors, concentration of glycol, turn on/off the stirrer on volumetric heat transfer coefficient and the temperature distribution in the tank were investigated.Investigations were carried out experimentally on which volumetric heat transfer coefficient in tank increases with HCFC123 spray velocity and injectors in the tank. As to effect by stirrer, it was found that stir can help to increase the volumetric heat transfer coefficient. It can also be found that volumetric heat transfer coefficient in the tank decreases with concentration of glycol. By means of experimental investigation, we found that the ice-making efficiency increases with volumetric heat transfer coefficient.By means of experimental, it was found that the power of stirrer can reflect ice density in the tank, and it is hopeful to become a kind of method to measure ice density online actually.Analysed the problem presented in the course of experiment, and proposed the advices for improvement.This project is financially supported by Shuangliang Air Conditioning Equipment Co., Ltd and Shanghai Main Subject Foundation.