Performance of solar hot-water installations from roof-constructed solar collectors integrated with a central heating supply for tobacco curing

In view of the abundant solar energy available during the tobacco curing season, a solar hot-water installation to provide auxiliary heating for bulk tobacco-curing operations was developed, based on the original concept of a boiler-driven central heating supply that transported hot water over short distances by pipeline, using solar collectors connected in parallel and installed on the unoccupied flat roofs of 20 curing barns. The results showed that daily solar conversion efficiency ranged from 65% to 67%. During the tobacco curing period from 10:00 hours to 14:00 hours each day, in sunny or partly cloudy weather, heating water temperatures exceeding 75°C were automatically derived for use in the bulk curing barns needed. Use of solar energy as a substitute for coal fuel in tobacco curing, in conjunction with precise automatic control, enabled solar energy to account for 18.4% of the total curing energy consumption in this study. Through comparative analysis, the use of solar hot-water installations can help the local tobacco industry to reduce absolute carbon emissions by more than 10% at the experimental location in the pay-back period.