Drying of Off-White Handmade Papers in Greenhouse Solar Dryer: An Experimental Study

An experimental study on a greenhouse solar dryer (GHSD) with a floor area of 1.82 × 1.52 m2 was conducted to dry handmade papers. The performance of GHSD was investigated under no-load and load conditions, and variation in drying time was compared with that of shade drying. Operating parameters like temperature and relative humidity (RH) of air outside and inside the dryer, solar intensity, weight of handmade papers dried in the shade and in the dryer, etc., have been recorded and analyzed during the experimentation. Handmade papers (75 in number) of 100 GSM (grams per square meter) thickness with a moisture content of 60.8% (w.b.) were dehydrated to 9.6% (w.b.) in 2.5–3 h inside the greenhouse solar dryer while traditionally drying, i.e., shade drying the same number of papers took 17–18 h. The maximum air temperature inside the dryer under no-load and load conditions was recorded to be 49.4 °C and 49.2 °C at solar intensity of 556 W/m2 and 594 W/m2, respectively, on the day of experimentation. The acquired findings demonstrate the variation of temperature, RH, relative humidity, moisture content, and drying rate, indicating that the developed dryer performed satisfactorily.