Research And Development Of Automatic Test System For Thermal Performance Of Domestic Sun Hot Water System

Thermal performance represents the capacity of a household solar water heating system to convert the available solar radiation into heat which actually heats the water. It is an important parameter to quantify the quality of household solar water heating products. In this thesis, an automatic thermal performance measuring system for household solar water heating systems was designed and the following aspects were studied and analyzed.This thesis conducted a study on the thermal performance testing standards for household solar water heating systems, and examined the various important parameters to represent the thermal performance, including the amount of obtained hot water in the storage tank, the daily heat gain per area of the system’s aperture, the daily useful heat gain per area of the system’s aperture and the water temperature in the storage tank at the end of testing with the daily accumulated solar radiation of 17 MJ. The required data and the way to collector such data for processing were also analyzed.The required data for thermal performance testing were analyzed, along with the standards and flowcharts for the thermal performance testing. The overall design of the thermal performance testing system was conducted, including the setup of the platform for the thermal performance testing system and the software to monitor the collection of the testing data.The thesis analyzed the temperature probes used for the data acquisition of the thermal performance testing system and the principles and characteristics of data logger and the relevant electronic parameters, as well as the circuit structures of the testing. The characteristics and the electronic parameters of the water valves, pilot relay and other control equipment used in the thermal performance testing were also examined. The circuits for the hardware part of the testing system was designed and set up and the features of RS232 serial port used in the communication interface and the connection of RS232 serial port to the upper monitor terminal, data acquisition instrument and pilot relay were also analyzed and designed. A benchmark testing was carried out to debug the developed monitor program using the serial debugging assistant software.Based on the designed platform for thermal performance testing system and the thermal performance testing procedures, this thesis developed programs to monitor the data acquisition using the Visual Studio 2005 software and computer programming language C#. The programs incorporated the concepts of serial initialization module, data read module and other subroutine modules which can be called by the main monitor program.The developed data acquisition monitor program for thermal performance testing system was used to conduct experimental measurements of the household solar water heating system and the obtained data were analyzed. During the experimental study, two similar household solar water heating systems with similar configurations, collector aperture areas and storage tanks were selected to do the comparative experiments simultaneously. One system was used to conduct the thermal performance testing using the data acquisition monitor program developed by this thesis and another system was used to conduct the thermal performance testing using the existing data acquisition instrument. The obtained measurement results were compared and analyzed.