| The aim of this work was to provide a composition of multicomponent refrigerant liquid which including ethanol, propylene glycol, sodium chloride and water in immersion chilling and freezing (ICF) based on the advantages and disadvantages of current refrigerant liquids. The effects of composition and freezing point on the properties of heat transfer were studied, selected the proper solution in -20℃, -30℃and -40℃. Under the new dynamic testing ICF equipment and dynamic situation, researched the regularity for change of the heat transfer coefficient between the solution and the foodstuffs under the condition of laminar and turbulent flow.The research showed that the content of ethanol, propylene glycol, sodium chloride had a significant influence on the properties of heat transfer. When the freezing temperature of -20℃, -30℃and -40℃, the solution with the best capacity of heat transfer as follows: ethanol 20%, propylene glycol 14%, sodium chloride solution 4% in -20℃;ethanol 20%, propylene glycol 21%, sodium chloride 4% solution in -30℃;and ethanol 20%, propylene glycol 30%, sodium chloride 4% in -40℃. Compared to the sodium chloride and ethanol, the quaternary solution can freeze between -20℃and -40℃, had some good heat properties and the amount of permeability and loss was very small. The new ICF equipment's rate of heat transfer was quicker and the amount of permeability was smaller.In this paper, the work and findings are as follows: analyzing the current refrigerant liquid used for ICF. The results showed that the refrigerant liquid which including ethanol, propylene glycol, sodium chloride and water had a better properties of heat transfer than the binary solution such as sucrose solution, the ternary solution such as NaCl / CaCl2(or KCl), ethanol / NaCl , glucose (or sugar) / NaCl, sucrose / fructose (or invert sugar). However, in these applications, some problems such as sodium chloride is easy to penetrate to the surface of food material to Corrode equipment and the loss of ethanol is heavy and so on, they all inhibit the development of ICF. Propylene glycol is non-toxic and low volatile, its concentration on the impact of freezing temperature is the same to ethanol and the ability of permeability is low, corrosiveness is also very little.So, Propylene glycol can replace ethanol and NaCl..A small amount of NaCl is added to the solution, it can decrease the freezing point largely, so it can reduce the content of ethanol and propylene glycol. Therefore, the quaternary refrigerant liquid which including ethanol, propylene glycol, sodium chloride and water can be used as an effective refrigerant in ICF. The relationship between the composition of solution and freezing point was studied..According to the composition of solution and the freezing point distribution of the binary and ternary solution, when the ethanol content reach to 20 ~ 30% (the total content of ethanol and propylene glycol which less than 55%), the freezing temperature of solution can meet the minimum value, thus the optimum value of ethanol can be 20%.Selecting the quaternary refrigerant liquid composed of ethanol, propylene glycol, salts (NaCl, CaCl2, KCl, MgCl2) and water, then studied the relationship between the composition of refrigerant liquid and the point of freezing temperature. The results showed that the solution added to the NaCl or CaCl2 can reduce its freezing point significantly, and the solution added NaCl had a much greater decreasing rate than CaCl2. The quaternary solution's distribution of freezing point was studied at different concentration and formulations, results showed that, compared to the aqueous with the same concentration such as ethanol aqueous, propylene glycol aqueous and the ternary solution including ethanol, propylene glycol and water, the quaternary solution's freezing point was lower significantly.For the quaternary solution including ethanol, propylene glycol, sodium chloride and water, the relationship between the composition and the properties of heat transfer was studied.First of all, study the effect of the composition and temperature on different density, concentration, viscosity and thermal diffusivity. Results indicated that the effect of ethanol, propylene glycol, sodium chloride on density was very little (can ignore) while had a significant influence on viscosity and thermal diffusion coefficient. The viscosity was found to increase as the contents of ethanol, propylene glycol, sodium chloride increasing, in which sodium chloride had the greatest impact. The viscosity and the increasing rate improved with the decreasing temperature. Thermal diffusion coefficient increased at first and decreased later with the increase of content of ethanol, propylene glycol, or sodium chloride.Then according to the viscosity and thermal diffusion coefficient of refrigerant liquid, thus Prandtl number (Pr) was measured, and the heat transfer was evaluated by Pr..With the content of ethanol, propylene glycol, sodium chloride increasing and the tendency of viscosity and thermal diffusion coefficient, Pr increased at first and decreased later. Pr was small when the content of ethanol and propylene glycol was small. Especially, Pr was smallest when the content of NaCl was small.When the freezing temperature of -20℃, -30℃and -40℃, response to the relationship between the composition, freezing point and Pr, the formulation of solution as follows: ethanol 20%, propylene glycol 14%, sodium chloride solution 4% in -20℃, ethanol 20%, propylene glycol 21%, sodium chloride 4% solution in -30℃and ethanol 20%, propylene glycol 30%, sodium chloride 4%.To the three kinds of quaternary refrigerant liquids from the above, the heat transfer coefficient under the condition of laminar and turbulent flow was studied..The heat transfer coefficient and thermal conductivity was studied in the section of straight circular tube under the situation of the laminar flow. Results indicated that the heat transfer coefficient and thermal conductivity were influenced significantly by the composition of solution, while little by the temperature.The new structure of ICF equipment with spiral type was designed and produced. The heat transfer coefficient of solution to spherical food model under the situation of turbulent flow was studied, and then established the dimensionless criterion equation of convection heat transfer. Results showed that the Reynold number (Re) was 0.697, Pr was 0.36, and constant was 2.012·10-4.
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