Development of a new type of solar dryer: Its mathematical modelling and experimental evaluation

Abstract

SUMMARYA solar dryer fitted with a novel design of absorber having inbuilt thermal storage capabilities was designed, fabricated, simulated and also tested at Rajiv Gandhi College of Engineering Research & Technology, Chandrapur (MS) India. Thermic oil was used as a storage material. The main objective of the study was to reduce the drying period and enhance the quality of dried product mainly chillies and fenugreek leaves. The products were laid in a single layer. The dimensions of the dryer were arrived at using the well-defined procedure available in literature. The mass of thermic oil needed in the absorber and mass of product to be dried in trays were optimized using simulation techniques. The maximum drying air temperature required for drying agricultural products was around 658C: The ambient conditions at the location were 25-408C; 16-43% RH and solar radiation 105-1024 W m À2 : Experimental studies based on temperature and humidity measurements were performed on the dryer. The research concluded that the desired drying air temperature was achieved and maintained for a longer period. The length of operation of the solar air heater and the efficiency of the dryer were increased, and better quality of agricultural products in terms of colour value were obtained compared with open sun drying.

A Granite Bed Storage for a Small Solar Dryer

“…Solid phase materials can be found, among others, in solar dryers with an oil tank [ 12 ], a battery made of concrete, as well as sand and rock bed [ 13 ]. The use of rocks as a material for filling a bed storage enables the construction of a simple drying installation that uses air as the working medium.…”

Experimental investigation of the performance of a solar dryer integrated with solid desiccant coloums using water based solar collector for medicinal herb

“…In developing countries solar dryer of hot air type is the dominant method that is used for drying medicinal herbs. Recently, various of types of medicinal herbs have been dried using the solar dryers of hor air type such as: black ginger [9], lemon verbeva leaves [10], curcuma [11], mint [12], [13], rosella [14], [15], Valeriana jatamansi [16], red pepper [17], wild ginger [18], Centella asiatica [19], thymus and mint [20], jerky [21], Andrographis paniculata [22], green tea [23], fenugreek leaves [24], and onion slice [25].…”

Performance evaluation of solar dryer system for optimal operation: mathematical modelling and experimental validation

“…For instance, Radajewski, Jolly, and Abawi (1987) proposed a computer model to reduce drying cost through optimisation of geometry and specific rate of air flow of solar assisted dryer system. In addition, dryer size optimisation studies of natural and forced convection solar dryer systems based on simulation models have been carried out to achieve minimum cost per unit moisture removal (Youcef-Ali and Desmons 2005;Potdukhe and Thombre 2008). Experimental investigations on open sun drying have also been carried out for determination of optimal surface area to volume ratio of breadfruit (Artocarpus altilis) for minimum drying time (George, McGruder, and Torgerson 2007).…”

“…Singh, Singh, and Dhaliwal (2006) obtained efficiency in the range of 5-28% during three successive drying days of natural circulation multi-shelf perforated tray solar dryer for solar intensity of 150-800 W/m 2 and ambient air temperature of 20 • C. Forson, Nazha, and Rajakaruna (2007) tested the mixed-mode natural convection solar dryer for solar irradiance of 350 W/m 2 for different load and concluded that efficiency increased to 3.5-12.5% for load variation of 49-162 kg. Potdukhe and Thombre (2008) determined the efficiency in the range of 8-21% for indirect natural convection solar dryer with chillies under the ambient conditions of 25-40 • C and solar radiation 173-934 W/m 2 . Ben Slama and Combarnous (2011) studied the dependence of temperature and air velocity on drying kinetics of orange peels using solar dryer with slightly oblique baffles.…”