Stratified Heating Solar Hot Water Storage Tank Optimal Design Base On CFD

Solar water heating system is one of the most widely used of clean energy hot water system. As the heat storage device, the design of hot water storage tank has a great impact on the efficiency of the heating systems. In the market, the amount of hot water supported by heating systems are often beyond people’s demand. So, a lot of hot water and energy is wasted. To solve this problem, this paper based on computational fluid dynamics (CFD) simulate and optimize a new stratified heating storage tank.This paper uses CFD to simulate the temperature field in the tank to optimize the best parameters. GAMBIT and ICEM are utilized to create the grids of the calculate zone. Investigate the temperature in the stratified heating tank by laminar unsteady numerical simulation model. The temperature of hot water(T), the heater power of electric auxiliary(P), the diameter(D) and height(H) of the pipe in the middle of the tank are the main factors that impacts the temperature and flow filed in the tank. According to the four factors, orthogonal computational simulations are set. There are total of16simulations. Define the utilization of the heat input (η) to determine the best results. Through simulations and analysis, it was found that:1. The new storage tank can realize stratified heating. And the water in the tank is heated on demand.2. The height of the middle pipe has a great influence on the efficiency of heat storage of the tank, it is a critical factor. When the height and diameter of the tank are1600mm,360mm respectively, the optimum height is1200mm;The velocity of the hot water from the heat exchange to the heat storage tank should be more than or equal to0.012m/s, otherwise it could easily lead to serious confusion; The best results is that: when available hot water (temperature not less than40℃) accounts for about one-third of the tank, the ratio of heat input utilization η is63%; When available hot water accounts for about two-thirds of the tank, η is77%. And at this simulation, His1200mm, D is32mm, T is333K, P is2.0kW.3. Compare the test results and simulation results, there is good agreement between the two. It has certain guiding significance simulating the flow field in the storage tank based on CFD.