An experimental study of thermo-syphon solar water heater in Thailand

Main Article Content

N. Sritong
K. Krajangkul
S. Chungpaibulpatana
B. Limmeechokchai


The thermo-sysphon solar water heater (TSSWH) is probably the most widespread application of solar thermal energy during the past years. This paper presents the experimental study and the mathematical models for prediction of hot water temperature produced from the TSSWH. Results are presented of collector temperature, storage temperature and thermal efficiency of the TSSWH. From the experimental study, it is found that the average TSSWH thermal efficiency was about 56% during the test days. The characteristics of this TSSWH are then used in simulation to predict its annual performance in Thailand using the three-year weather data during 2006-2008. Results from the simulation showed that the average year-round thermal efficiency is about 48%, average collector temperature is 51°C, and average hot water in the storage tank is 46°C. Finally, the technical and economic parameters of the TSSWH are used to assess its cost effectiveness under conditions in Thailand. Results from economic analysis revealed that TSSWH is competitive to the conventional electric heaters, especially when electricity price is higher, utilization factor is higher and the first cost of the TSSWH is lower.

Article Details

How to Cite
Sritong, N., Krajangkul, K., Chungpaibulpatana, S., & Limmeechokchai, B. (2018). An experimental study of thermo-syphon solar water heater in Thailand. Journal of Research and Applications in Mechanical Engineering, 1(2), 15–18. Retrieved from


[1] Runsheng T, Yuqin Y, Wenfeng G. (2011). Comparative studies on thermal performance of water-inglass evacuated tube solar water heaters with different collector tilt-angles, Solar Energy, vol.85, April 2011, pp. 1381-1389.

[2] M.S. Hossain, R. Saidur, N.A. Rahim, M.R. Islam, J.U. Ahamed, M.M. Rahman. (2011). Review on solar water heater collector and thermal energy performance of circulating pipe, Renewable and Sustainable Energy Reviews, vol.15, June 2011, pp. 3801-3812.

[3] Wikipedia The Free Encyclopedia, (2011) Passive and active systems, URL:

[4] Sirindhorn International Institute of Technology Thammasat University, Mechanical Engineering Faculty (2009), Mechanical Engineering Laboratory II Solar Water

[5] Solar Direct, Florida, USA (2010), Compare Solar to Conventional Water Heater, URL: http://www.

[6] Digital Focus, Thailand (2009), Price of Solar Water heater, URL:

[7] Thaigoodview, Thailand (2011), Calculation of Electricity cost, URL:

[8] Wikipedia The Free Encyclopedia, (2011), Time value of money, Present value of future sum, URL: