Performance study of mixed mode solar kiln with paraffin as storage medium

In this study, the performance of a mixed mode solar kiln was carried out. The kiln was incorporated with double glazed flat plate solar heat collector with built in paraffin as a heat storage medium. The off-load site study of the kiln during sun shine and no-sun shine periods of the day were carried out in Nsukka (Latitude 7o N), Nigeria. The range of ambient temperatures during the study period was between 18.3–33.2oC. Equally, the daily radiation ranged between 11.8–20.9 MJ m-2. The results obtained showed a maximum cumulative efficiency of 40.7% for the kiln. In addition to this, an average efficiency of 38.8% was obtained in the system. The result of a timber drying operation carried out with the kiln showed an improvement over a similar kiln but with pebble stone as storage medium in the literature. It is therefore recommended that for optimum thermal energy utilization while using mixed mode model during the sunset periods, the top glazing of the working section should be covered to reduce the top heat loss since it is no longer receiving any solar radiation during these periods. Equally, a development of a mathematical model to simulate the solar kiln is strongly recommended.