Study On Ice-making Process And Convection Heat Transfer Coefficient In Tube By Fluidized Bed Method

Ice slurry has been used in air conditioning as a kind of cold storage medium with large cooling capacity,good flow characteristics and no pollution.The use of ice slurry storage and cooling can not only ease the peak-to-valley difference of the power grid but also can reduce the environmental pollution of traditional air conditioners.and air conditioning installed capacity,The use of ice slurry in food processing,medical and health care,physical rehabilitation of athletes,and cooling of deep wells in mines is also practiced abroad.Ice slurry refrigeration will be the main direction in the future development of refrigeration.The present ice slurry preparation method has its inevitable drawbacks.So ti is very necessary to find an ice slurry production method with simple operation and high heat exchange efficiency that can be applied in practical production.This paper has been theoretically calculated and set up on the test bench to study the process parameters and the heat transfer law of the fluidied method for making ice slurry.The main work is done as follow:(1)Study on flow characteristics of particlesThe initial and terminal fluidization velocities of eight solid particles with different diameters and materials were studied.The error between the calculated values and the experimental values of the five empirical formulas for these two speeds of liquid-solid fluidized solid particles was compared.The empirical formulae for calculating the initial and final fluidization rates of solid particles have been revised.The relationship between the initial fluidization velocity of cast iron particles and the particle diameter was summarized.(2)Study on the stable operation of liquid-solid fluidized bedthe stable cyclic operation characteristics of the external circulating fluidized bed in the cold state was studied.The relationship between the pressure loss and the liquid flow velocity for the inlet and outlet of the heat exchanger,the heat exchanger and the downcomer,the downcomer was mainly studied and fitted.The relationship between the height of the downcomer solids and the stable operation of the cold outside circulating fluidized bed was studied,and the stable operating curve of the external circulating fluidized bed heat exchanger was found.(3)Liquid-solid fluidized bed method for making ice slurry test benchOn the basis of literature research and analysis,the structural design of a liquid-solid fluidized bed method for ice slurry making equipment was carried out,including the pressure,temperature,and flow collection methods during work,the power unit and the refrigeration unit were selected,and the separator,the structure and dimensions of the mixer,lower fluidized tank and descending pipe parts was designed.According to the selected power unit and refrigerating device,suitable pipelines and control valves are selected for the test stand,and the construction of the ice slurry test stand for the fluidized bed method is completed.The cold stable operating parameters was measured for liquid-solid fluidized bed ice slurry test bench.(4)Study on process and parameters of fluidized bed ice slurry kakingBased on the newly constructed experimental platform,the process flow and heat transfer law of the fluidized bed method for making ice slurry were studied.he maximum degree of supercooling for avoiding ice blocking in the heat exchange pipeline was confirmed.The empirical formula of the convective heat transfer coefficient of ice slurry produced by fluidized bed method was obtained.