Study Of Improving The Thermal Efficiency Of A Domestic Solar Water-heating System

In order to reduce energy consumption in domestic hot water,our country is vigorously promoting the application of renewable energy in hot water production.Solar water heatering is the most mature and most widely used renewable energy technology in the production of hot water.However,in order to ensure that solar water heater can be used in daily life,the present methods still need to consume great deal of additional auxiliary energy.Especially in winter and rainy days,solar energy is far from meeting the needs and amount of electrical energy,gas and other energy must be used to heat hot water.One hand,heating a tank of water needs to consume a large of energy sources.The other hand,keeping the temperature of hot water at a certain level also need to consume a large of energy,which lead to the thermal efficiency of solar energy heater has been greatly reduced.In view of this,aiming at the low thermal efficiency of solar water heater in winter and rainy days,this study proposed a method to improve the thermal efficiency of solar water-heating systems.Installed in a smart control system in the solar water heater,users only need to determine the day weather level from the Weather Forecast,the control system will automatically calculate the amount of hot water for the day,and intelligently controls the water level,so that hot water up to the expected temperature.Users would adjust the amount of water and heat water by electricity when the amount of hot water is not enough only from solar energy.In addition,an intelligent control program was prepared,and an intelligent controller was produced based on the program.This study also analyzed the feasibility and prediction accuracy of the method in the application of solar water heaters through the experiment.The experimental results show that the proposed system is applicable and the hot water temperature can be estimated at an accuracy of 5 ℃.According to analysis results for the application in a residential building,it was found that the optimized electric-assisted solar water heater has obvious economic,energy saving and environmental benefits comparing with convenitional solar water heaters,and the benefits are more great for the location where solar radiation is scarce.Therefore,the proposed method for improving the thermal efficiency of a domestic solar water-heating system has a high potential of application in residential buildings.