Experimental investigation of drying characteristics of lima beans with passive and active mode greenhouse solar dryers

Abstract

In the study, the thermal performance of the even span and parabolic roof type solar greenhouse dryers is investigated under the active and passive modes under the same operating conditions. Dryers were covered with the 200‐μm UV stabilized polyethylene sheets to enhance the solar insolation effect. The performance of these dryers is evaluated for drying lima beans (Phaseolus lunatus). The moisture content of Lima beans was reduced from 75% (w.b.) to 11% (w.b). For both of active and passive mode conditions, the parabolic dryer could dry in 28 and 32 hr, respectively and that for the even span dryer, it could achieve the same state in 32 and 36 hr, respectively. The open sun drying took as high as 40 hr to dry time for the lima beans. The highest thermal efficiency of the dryers was estimated to be 14.7% for the active mode parabolic dryer and the minimum as 12.03% in the passive mode even span dryers. The nutrition retainment was the highest for parabolic active mode dryer with the payback period as 2.15 years, as against 10 years of expected solid life span and strong suggestion is made for the use of the small scale needful farmers. Practical Applications Drying is an energy consuming processes, and industries require more amount of energy for drying a food grain. In the current scenario, more attention is toward for usage of the Solar based dryers for the abundance of availability of solar energy which makes cost effective. However, the popularly available conventional method of open Sun drying of lima beans resulted in contamination of product from external dirt, degradation due to direct heating, existence of uncontrolled dry rate and additional dry time. To solve the above constraints, in open sun drying and to improve the dried product quality, the author constructed a simple, compact and economically modified greenhouse solar dryer. The quality of dried lima beans under active mode convection parabolic roof was superior. The much needed carbohydrate and protein values, of dried lima beans of 100 g sample for forced convection parabolic roof greenhouse solar dryer had shown the increase of 2 and 10% than open sun dry sample. Among various seeds used to making food stuff, the lima beans are one of the choices for people.

A review of solar and solar‐assisted drying of fresh produce: state of the art, drying kinetics, and product qualities

“…Several works of literature have demonstrated the effectiveness of glasshouse drying on food products. Mani and Thirumalai 30 studied the drying characteristics of lima beans with glasshouse solar dryers (passive and active mode). The authors reported that the product dried using glasshouse solar drying took less time to complete the drying than all other dryers with less MC.…”

Dataset on the optimization by response surface methodology for dried banana products using greenhouse solar drying in Thailand

“…The fiber and potassium content remains relatively unaffected by greenhouse solar drying [ 8 , 9 ]. Perspective in term of energy, the comparative energy consumption of greenhouse solar dryer and conventional drying (open sun, hot air, freeze, and microwave) can vary depending on several factors, including the specific drying technologies employed, the scale of drying operations, and the local climate conditions [ 10 , 11 ].…”

A review on environmental effect of various designs and types of drying methods

“…Greenhouse solar active and passive mode dryer for drying lima beans Investigated experimentally active and passive modes of drying Greenhouse SD and also researched the thermal performance of span and parabolic roof kind of GHSD under the passive and active mode of drying (Mani & Natesan, 2021a) this kind, the maximum efficiency obtained in an active mode of drying was 14.7% in a parabolic dryer and the minimum efficiency obtained in a passive mode of drying was 12.03% in a span dryer. Finally, they conclude that the GHSD of forced convection parabolic drying gives much better results than other kinds of drying and noted that parabolic forced dryer gives 16.39 kcal/100 g more drying energy than OSD.…”

“…Investigated experimentally active and passive modes of drying Greenhouse SD and also researched the thermal performance of span and parabolic roof kind of GHSD under the passive and active mode of drying (Mani & Natesan, 2021a) as shown in Exhibit 11. Dryer model is fabricated and covered with a polyethylene sheet to enhance the solar energy effects.…”