| Author | Pisit Pannigul |
| Call Number | AIT Thesis no.ET-99-20 |
| Subject(s) | Solar water heaters
|
| Note | A thesis submitted in partial fulfillment of the requirements
for the degree of Master of Engineering. School of Environment Resources and Development
|
| Publisher | Asian Institute of Technology |
| Abstract | Domestic solar water heaters (DSWH) with horizontal tank are commonly available in
Thailand. The aim of this study was to conduct experimental studies on two commercial
systems, to study the temperature and flow distribution in the collector, riser, piping and
storage tank in order to compare their performances and identify parameters influencing the
performance of the system.
Two different DSWH systems were used in the study. In the old DSWH system, two
methods of connecting the return pipe to storage tank (at the top and at the middle) were used,
while in the new system, the return pipe was connected to the middle. For all three modes (of
the two systems), temperature of absorber plate, water and flow rate through riser and
connecting pipe were experimental measured. Twelve days of experimentation was done (four
for each mode of connection), while for analysis, days with similar radiation were used. The
temperature and flow distribution curves have been drawn for each of the modes and
comparative studies with theory done. The model for temperature distribution based on energy
balance was compared to experimental data, while Close's model was used to compare the
flow rate. The experimental observations indicate that the water flow rate through each riser at
a given time can be considered to be fairly uniform (of about 0.8 to 2.0 cm3
/sec). The riser and
connecting pipe dimensions seem to influence the flow rate through the risers. Lower flow rate
in a riser is found to increase the water temperature. The model of Close was found to predict
the flow rate within reasonable limits for horizontal storage tanks as well. The temperature of
absorber plate across risers follows closely the theoretical prediction, except where the flow
rate is not uniform. Experiments indicate that it takes about 5 hours for all water in storage
tank to circulate through the new system. This leads to an increase in the water temperature at
the storage tank bottom much more than if the circulation takes more time. In the old system,
the time taken for the water to circulate was much longer (about 8 hours) and this reduced the
highest temperature attained and the efficiency. This is also influenced by the pipe dimensions
and location of the pipe at the storage tank.
The results of the study indicates that uniform flow through the riser and the
appropriate dimensions of pipe (connecting and risers) influence strongly the rate of water
circulation and therefore the efficiency of heating water. |
| Year | 1999 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| 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, Sivanappan; |
| Examination Committee(s) | Pham, Hoang Luong;Surapong Chirarattananon; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1999 |