Browsing by Author "Perera, P.A.A."

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A Study of Wind Effects on Thermal Stability of Salt Pan Solar Ponds
(Annual Research Symposium, Faculty of Graduate Studies, University of Kelaniya, 2001) Punyasena, M.A.; Amarasekara, C.D.; Jayakody, J.R.P.; Perera, P.A.A.
An investigation of rain and wind effects on thermal stability of large-area saltpan solar ponds
(Solar Energy, 2003) Punyasena, M.A.; Amarasekara, C.D.; Jayakody, J.R.P.; Perera, P.A.A.; Ehamparam, P.
An investigation of the thermal stability of large area saltpan solar ponds under different climatic conditions is presented. The study focuses on time taken by the pond to reach its stable conditions with heavy rainfall and the effect of wind-mixing process for the stability of the pond. Investigations were carried out over a period of 60 days on a large-area solar pond of 90 cm deep. The temperature and density profiles obtained 34 days after filling showed that the pond had attained its stability with a bottom temperature of 63 �C. Results reveal that heavy rainfall is the prime cause for the pond to reach stability in a time period of about 30 days. Strong wind-induced mixing prevailed during the second half of the investigation, which contributed to the erosion of the nonconvecting zone is the cause for observed destabilization of the pond. The estimated critical wind speed for complete destruction of the nonconvecting zone is about 25 km/h.
Construction and commissioning of a large area solt gradient solar pond at Palatupana salterns in southern Sri Lanka
(2003) Punyasena, M.A.; Amarasekara, C.D.; Perera, P.A.A.
Solar ponds are large-scale solar energy collectors with integrated thermal energy storage. The concept of collecting and storing solar energy using non-convective salt gradient solar ponds has been known for some time. We report here the details of construction and commissioning of a large-area solar pond built at Palatupana salterns in Southern Sri Lanka. A rectangular pond with dimensions 70 m x 35 m could retain a maximum water capacity of ~ 5000 m3. The pond can be filled to a maximum height of 2 m. The initial controlled filling of the pond to a total depth of 60 cm with a 30 cm layer of high-density brine led to formation of the three-layer stability with a maximum bottom temperature of 52 oC. Destruction of the pond stability was observed with the increase of wind speed over the pond. About three months later with the monsoon rain, the pond bottom recorded a maximum temperature of 69 oC with the reestablishment of three-layer stability at a total depth of 110 cm. The observed salinity and temperature profiles show the usual three-layer configuration, but with relatively thick upper convective zone. This situation could arise due to wind mixing of layers to a depth of about 30 cm. It is remarkable to observe that the uncontrolled natural conditions raised the bottom temperature of the pond to a maximum of 69 oC. Our results indicate wind is the major cause for mixing of layers which prevents storing of solar energy at the bottom layers of the pond. The commissioned solar pond could be used for wind control mechanism studies and controlled filling mechanisms to optimize different layers of the pond to obtain maximum bottom temperatures.
Construction and Filling of a Large-area Deep-tank Solar Pond for Harnessing Solar Energy
(Annual Research Symposium, Faculty of Graduate Studies, University of Kelaniya, 2002) Jayakody, J.R.P.; Punyasena, M.A.; Perera, P.A.A.; Amarasekara, C.D.; Kumarasinghe, M.A.S.
Construction and Filling of a Large-area Deep-tank Solar Pond for Harnessing Solar Energy
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2002) Jayakody, J.R.P.; Punyasena, M.A.; Perera, P.A.A.; Amarasekara, C.D.; Kumarasinghe, M.A.S.
Daytime Variation of Temperature and Salinity Profiles in Large-Area Saltpan Solar Ponds at Palavi, Sri Lanka
(Proceedings of the 18th Technical Session of the Institute of Physics - Sri Lanka, 2002) Perera, P.A.A.; Amarasekara, C.D.; Jayakody, J.R.P.; Punyasena, M.A.
Optimization of Thermal Insulation of a Small-scale Experimental Solar Pond
(Sri Lankan Journal of Physics, 2012) Jayatissa, N.W.K.; Attalage, R.; Hewageegana, P.S.; Perera, P.A.A.; Punyasena, M.A.
A small-scale experimental salinity-gradient solar pond, which will be utilized for the research and development in harnessing solar energy for desalination of seawater and generation of electricity, has been constructed. The pond has effective length, width and depth of 3.0 m, 2.0 m and 2.0 m, respectively, covering a volume capacity of 12.0 m3. Thermal insulation plays a major role for the successful operation of a salinity-gradient solar pond, especially when the dimensions of the pond are relatively small. The construction details of the solar pond, with particular attention to the methodologies adapted for the thermal insulation, are reported in the present work. The expected total rate of heat loss due to conduction through the thermally insulated boundary walls, assuming a bottom temperature of 90�C, has been calculated and found to be 106.3 W. Contribution from the bottom convective zone itself to this total rate of heat loss is 69 W, which corresponds to 65% of the total value. Based on this rate, the estimated temperature drop during the period with no solar radiation present in a typical day is only 0.3�C. With such a small temperature drop, it is possible to extract the thermal energy stored in the bottom convective zone during the day time, continuously, while maintaining the stability of the solar pond.
Study of Daytime Variation of Convective and Non-Convective Zones in Salt Pan Solar Ponds
(Annual Research Symposium, Faculty of Graduate Studies, University of Kelaniya, 2002) Perera, P.A.A.; Amarasekara, C.D.; Jayakody, J.R.P.; Punyasena, M.A.