Research Of The Energy Efficiency Evaluation System Of Domestic Solar Water Heating System In Service

Domestic solar water heating system is a new energy product that transforms solar radiation into heat energy,and its energy efficiency from factory to site has been the focus of attention of users.According to the current standards and test methods,The energy efficiency evaluation of the product before leaving the factory is usually based on the experimental data of four days and limits the experimental conditions during the test,The evaluation results ignore the influence of external factors and its own heat capacity attenuation on its thermal performance,and can not fully reflect the energy efficiency of products in long-term applications,and the accuracy of the inspection certificate of the product factory needs to be verified.In view of the above phenomena and problems,the following research work is carried out in this paper:1.In view of the problem that how to evaluate the energy efficiency of the domestic solar water heating system in service,summarizing the similarities and differences between the factory and the field evaluation,and building the household solar water heating system energy efficiency monitoring system to detect the product's actual energy efficiency.Energy efficiency monitoring system can realize the test function for mixing method,drainage method and real-time thermal performance parameters,and the upper computer interface based on Labview is compiled,which realizes the good human-computer interaction and data automatic collection,storage,analysis and processing.2.In view of the problem that the energy efficiency evaluation cycle of domestic solar water heating system is long,researching the test scheme to shorten the evaluation cycle.Using the measured mean values of five temperature sensors with equal spacing in hot water storage tank to replace the real time temperature in the water tank,and the eight hour heat collecting cycle is divided into several segments for data acquisition,the results showthat the average relative error of the temperature measurement by this method is 6.08%,verifying the feasibility and increasing the amount of data collection at the same time,thus the evaluation cycle is shortened.3.In view of the problem that how the heat gain of the domestic solar water heating system in service changes with the environment and the time it uses,researching the quantitative relationship between the heat gain of the system and the related external factors and the measurement method of its attenuation.Using BP neural network to establish the mathematical model of environmental temperature,wind speed,humidity,initial temperature of hot water system,sun exposure and effective heat,and the average relative error of the model is 11.81% by calculating the measured data,Verifying the feasibility of the model;the method for measuring the attenuation of heat in the system is based on the mathematical model established above,and using the method of quantitative comparison of parameters to ensure the reliability of the attenuation test results scientifically.