Research On Heat Transfer Performance Between Gas And Liquid In The Direct Contact Ice Slurry Generator

Dynamic ice-making system which use ice slurry to storage cold energy can balance power load is one of the most important measures to improve the contradiction between power supply and demand. It overcomes the main shortcomings of traditional static ice-making system using solid ice to storage cold energy, and it has distinct advantages both in the economy and energy efficiency. There are many methods for dynamic ice-making system. Because it has high thermal efficiency and simple system design, and only small requires temperature differences for heat transfer, the direct contact heat transfer method shows a great application prospect. In the recent years, the dynamic ice-making system using gas as the refrigerant gets more attention gradually due to the low system initial investment, good benefits of environment and economy. Firstly, this paper introduced the principle of dynamic ice-making system, and reviewed the development process of it. Based on the differential equation of heat transfer and energy conservation equation, a heat transfer model between air bubbles and ice-making solution was built to calculate the height of the full heat transfer, from which the calculation values agreed well with the simulation values obtained by VOF with a relative error less than15%. So the equation of the height of the full heat transfer can be used to design ice generator in direct contact ice-making system. In this paper, the content is divided into three aspects:1. Based on the characteristic of rising bubble in the ice-making solution, an analytical model of heat transfer between the cooling bubbles and the ice-making solution has been developed from the differential equation of heat transfer and energy conservation equation to calculate the height of the full heat transfer.2. Based on the FLUENT14.5, the simulation of heat transfer between air bubbles and water solution was taken to observe the process of heat transfer and bubbles’deformation, and the equation of fully heat transfer height was validated since the calculation values agree with the simulation values well with a relative error less than15%. So the equation of the height of fully heat transfer can be used to design ice generator in direct contact ice-making system.3. According to the equation of fully heat transfer height obtained in the former, the influence of initial radius of bubble, inlet temperature, inlet velocity and ice-making solution temperature on fully heat transfer height was analyzed, while low temperature air bubbles and water were used as refrigerant and solution, respectively. The analytical results show that the higher the speed of the cooling bubbles, the bigger the radius of the initial bubbles, and the larger the temperature difference between the cooling bubbles and the ice-making solution, the higher the height of the full heat transfer. And the change of ice-making solution temperature doesn’t have an obvious impact on fully heat transfer height.