Loading...
Thesis
Browse
1 results
Search Results
ThesisItem Open Access Design, development and performance evaluation of LHAassisted hybrid solar dryer for onion (Allium Cepa L.)(Punjab Agricultural University, Ludhiana, 2018) Attkan, Arun Kumar; Alam, M.S.The study was conducted to design, develop and evaluate LHA-assisted hybrid solar drying system. The 3D-CAD model of the hybrid dryer was designed and prepared in NX-8 CAD drawing software on the basis of design calculations. Experiments were conducted to test the developed low humidity air (LHA) system for its regeneration capacity using silica gel for regeneration temperature (60-100ºC), air velocity (3-5 m/s) and loading weight (1-3 kg) using three factors, three levels Box-Behnken design. The optimized regeneration process parameters obtained were 100°C regeneration temperature, 4.77 m/s air velocity and 1.73 kg loading weight resulting in 0.255 kg/hr of regeneration rate, 160 minutes regeneration time, 0.83 kWh power consumed by blower and 0.75 kWh power consumed by heater. In order to evaluate the developed dryer, drying experiments were conducted on onion slices by varying the drying air temperatures (50, 60 and 70°C), KMS pre-treatment (0.1, 0.3 and 0.5%) and loading weight (10, 20 and 30 kg). RSM was employed for optimizing the drying process parameters of onion slices for the developed hybrid solar dryer and found the optimized drying process parameters were 64.98°C drying air temperature, 10 kg loading weight and 0.5% KMS pre-treatment resulting in maximum pyruvate content, rehydration ratio, color L-value, overall acceptability and minimum drying time, color change and power consumed by blower and heater. Mathematical model was developed by writing the heat and mass balance equations for developed dryer. Eight thin layer drying models (Newton, Page, Modified Page, Exponential, Asympotic, Two-term exponential Wang and Singh and Logistic) were fitted to mass transfer data and their adequacy of fit was investigated. Page equation accurately describes the drying behavior of onion slices Six EMC models (Modified Exponential, Modified Halsey, Modified Oswin, Modified Chung-Pfost, Guggenheim-Andersonde Boer (GAB) and BET) were fitted to the EMC data to investigate the sorption behavior of onion slices. Modified exponential equation was found superior for explaining the sorption behavior of onion slices with in the selected temperature and relative humidity range. A computer program was written in VISUAL BASIC language to develop the model. The developed computer model showed close agreement between the measured and predicted values and was quite effective in predicting the drying behavior of treated onion slices with average % error of 9.31, 11.43% and 2.93% for moisture content, moisture ratio and product temperature respectively. The cost economics of the developed hybrid solar dryer was evaluated on the basis of benefit cost ratio (Rs. 1.49), breakeven point (101.96 kg) and payback period (0.092 year) of dried onion powder at selling price of Rs. 400/- per unit respectively. Overall, the developed hybrid solar dryer was found quite energy efficient, economically viable and capable in maintaining the quality of dried onion slices.