An experimental evaluation of copper, steel and polypropylene tubes in solar water heaters with thermosyphonic flow
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- Riazi, M.R., Razavi, J., Sadeghi, A. et al. Appl. Sol. Energy (2009) 45: 65. doi:10.3103/S0003701X09010174
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In this paper we report experimental results for the performance and rate of heat transfer in copper tubes in solar water heaters with thermosyphonic flow in continuation of experimental data reported in previous publications (Solar Energy, 2003, vol. 74, pp. 441–445, and Energy Sources, 1997, vol. 19, pp. 147–152). We also show a comparison between performances of three kinds of tubes: copper, polypropylene and steel under similar conditions. An analytical relation for calculation of rate of heat transfer in copper tubes is also presented in terms of Nusselt versus Reynolds and Prantdl numbers. A comparison of experimental data showed that performance of copper tubes is slightly better than polypropylene tubes while both of these tubes are significantly better than steel tubes.