The Solar Water Heater, Collector Thermal Performance Test System Design And Application

GB26969-2011is the first mandatory national standards for solar thermal industry, and it is about to be implemented. Manufacturers of solar water heater need to establish a laboratory, which is accredited by CNAS. To test the coefficient of thermal performance of solar water heater.The solar collectors are the most important part of solar water heating systems. Its thermal performance has a direct impact on the entire solar water heating systems. So, thermal performance testing and evaluation of solar collectors, is the basis for research of solar water heating systems.In this thesis, testing principle and method of the thermal performance of domestic solar water heating systems and the thermal performance of solar collectors are analyzed. Based on national standards for domestic solar water heating systems and solar collectors, we designed the hardware and software of the testing system for the thermal performance of domestic solar water heating systems and the thermal performance of solar collectors. The main research works are as follows:The requirements of the testing device for the thermal performance of solar water heating systems are detailed analyzed. The system consists of two loops, the water supply (return) loop and water circulating loop. The components of the testing device and connections of water pipe can meet the testing requirements of different standards.Use Agilent Data Acquisition Instrument to collect analog signals, which are output of temperature sensor, first class pyranometer, anemoscope and flowmeter. After A/D converter, signals are transmitted to the computer via an RS232serial port. After data processing by the computer, we get the test data. A/D Conversion accuracy of the data acquisition instrument and accuracy of sensor conform to the requirements of GB.A two-stage control system of temperature is designed. The primary temperature is controlled by a large-capacity air-source heat pump water heater. The secondary heater is controlled by an integral separation PID controller. When there is a comparatively large deviation between the temperature of measured point and set value, using the PD control. Else, use PID control to reduce the static error. The temperature drift of inlet of the storage tank is controlled within±0.2℃.The test software of the thermal performance of solar water heater and the thermal performance of solar collectors is designed. Meantime, the methods how to think and the function per department are described in details. Design thought of the test software and the function of per department is introduced. The test method of daily useful energy per contour aperture area of domestic solar water heating system, average heat loss factor of domestic solar water heating system, single-day thermal performance, the steady state efficiency and the collector time constant test are introduced in detail. Moreover, the craftwork process for each test and the realization of software are shown chiefly. The test software can collect, store, analyze and process data automatically, also generate the test report. The software has friendly man-machine interface. Improve the level of automation of the testing process.Have Debugged modules of drainage method, the steady state efficiency and the collector time constant. Also, have done daily useful energy experiment, average heat loss factor experiment and single-day thermal performance experiment, under the test conditions that meet the requirements of GB. Moreover, the method of calculating the coefficient of thermal performance of solar water heater is described in detail. Experimental data of the thermal performance can be used as the basis for design of domestic solar water heating systems and solar collectors, and show direction to improve the quality of domestic solar water heating systems and solar collectors.