| Author | Komkrit Chuawittayawuth |
| Call Number | AIT Thesis no. ET-00-16 |
| Subject(s) | Solar water heaters
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Natural circulation solar water heating systems are the most widely used solar system in the world. Most domestic solar water heating systems (DSWH) in Thailand are of horizontal tank type. The aim of this study was to study a natural circulation DSWH with horizontal tank and its suitability in providing hot water in a tropical climate using TRNSYS and expe1iment. Experiments on DSWH system were conducted and temperature of absorber plate, glass, water in riser tubes, water in storage tank and flow rate through riser and connecting pipe were measured. Fourteen days of experimentation was done for clear and cloudy days. The profiles of the absorber plate temperature near the riser tubes (near the bottom and the top headers), the water temperature in riser tubes (near outlet), the mean plate and mean fluid temperature and the flow rate in connecting pipe during a day were compared with theoretical models. The temperature of water in the riser tubes and temperature of absorber plate near riser was found to be fairly unifonn for cloudy day and clear day with high fluctuation of radiation. But for clear day with little fluctuation of radiation, the temperature of water in riser tubes and absorber plate of riser no.1 and no.2 was found to be higher than that of riser no.3 to no.8. The high temperature of water near riser no. l and no.2 corresponds to the longer time taken by water to flow through these risers. The absorber plate temperature, measured mean plate and mean fluid temperature were close to the theoretical values. The flow rate of water in connecting pipe was compared with the theoretical studies and the difference was in the same range as in earlier studies. Based on six days of experiment, empirical equations to predict the mean plate and mean fluid temperature, and the collector water outlet temperature from the mean glass temperature were obtained with good agreement with theoretical models. An empirical equation to predict the useful energy stored in tank at the end of day based on the total global solar radiation on collector surface was obtained. TRNSYS simulation program was used to study the optimum configuration of a natural circulation DSWH. A time step of 6 min was used to investigate the optimal configurations for DSWH with horizontal tank. The input for simulation was taken from an actual DSWH and radiation data from AIT meteorological station of 1998. The optimum diameters of riser, header and connecting pipe were obtained at 9 mm, 17 mm and 17 mm, respectively. Increasing thy storage tank volume to 300-350 liters will provide the maximum number of days in a year that could give the mean storage tank temperature in the range of 40-50°C. The results of simulation compared well with the experiment for collector water outlet temperature and mean storage tank temperature. |
| Year | 2000 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Kumar, S |
| Examination Committee(s) | Bhattacharya, S. C.;Surapong Chirarattananon |
| Scholarship Donor(s) | H.M. the King of Thailand |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2000 |