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Drying experiments have been performed with potato cylinders and slices using a laboratory scale designed natural convection mixed-mode solar dryer. The drying data were fitted to eight different mathematical models to predict the drying kinetics, and the validity of these models were evaluated statistically through coefficient of determination (R(2)), root mean square error (RMSE) and reduced chi-square (χ (2)). The present investigation showed that amongst all the mathematical models studied, the Modified Page model was in good agreement with the experimental drying data for both potato cylinders and slices. A mathematical framework has been proposed to estimate the performance of the food dryer in terms of net CO2 emissions mitigation potential along with unit cost of CO2 mitigation arising because of replacement of different fossil fuels by renewable solar energy. For each fossil fuel replaced, the gross annual amount of CO2 as well as net amount of annual CO2 emissions mitigation potential considering CO2 emissions embodied in the manufacture of mixed-mode solar dryer has been estimated. The CO2 mitigation potential and amount of fossil fuels saved while drying potato samples were found to be the maximum for coal followed by light diesel oil and natural gas. It was inferred from the present study that by the year 2020, 23 % of CO2 emissions can be mitigated by the use of mixed-mode solar dryer for drying of agricultural products.

Drying experiments have been performed with potato cylinders and slices using a laboratory scale designed natural convection mixed-mode solar dryer. The drying data were fitted to eight different mathematical models to predict the drying kinetics, and the validity of these models were evaluated statistically through coefficient of determination (R(2)), root mean square error (RMSE) and reduced chi-square (χ (2)). The present investigation showed that amongst all the mathematical models studied, the Modified Page model was in good agreement with the experimental drying data for both potato cylinders and slices. A mathematical framework has been proposed to estimate the performance of the food dryer in terms of net CO2 emissions mitigation potential along with unit cost of CO2 mitigation arising because of replacement of different fossil fuels by renewable solar energy. For each fossil fuel replaced, the gross annual amount of CO2 as well as net amount of annual CO2 emissions mitigation potential considering CO2 emissions embodied in the manufacture of mixed-mode solar dryer has been estimated. The CO2 mitigation potential and amount of fossil fuels saved while drying potato samples were found to be the maximum for coal followed by light diesel oil and natural gas. It was inferred from the present study that by the year 2020, 23 % of CO2 emissions can be mitigated by the use of mixed-mode solar dryer for drying of agricultural products.

AbstractContamination of agricultural soil with heavy metals has become a serious concern worldwide. In the present study, Cr6+ resistant plant growth promoting Pseudomonas sp. (strain CPSB21) was isolated from the tannery effluent contaminated agricultural soils and evaluated for the plant growth promoting activities, oxidative stress tolerance, and Cr6+ bioremediation. Assessment of different plant growth promotion traits, such as phosphate solubilization, indole-3-acetic acid production, siderophores, ammonia and hydrogen cyanide production, revealed that the strain CPSB21 served as an efficient plant growth promoter under laboratory conditions. A pot experiment was performed using sunflower (Helianthus annuus L.) and tomato (Solanum lycopersicum L.) as a test crop. Cr6+ toxicity reduced plant growth, pigment content, N and P uptake, and Fe accumulation. However, inoculation of strain CPSB21 alleviated the Cr6+ toxicity and enhanced the plant growth parameters and nutrient uptake. Moreover, Cr toxicity had varied response on oxidative stress tolerance at graded Cr6+ concentration on both plants. An increase in superoxide dismutase (SOD) and catalase (CAT) activity and reduction in malonialdehyde (MDA) was observed on inoculation of strain CPSB21. Additionally, inoculation of CPSB21 enhanced the uptake of Cr6+ in sunflower plant, while no substantial enhancement was observed on inoculation in tomato plant.

AbstractContamination of agricultural soil with heavy metals has become a serious concern worldwide. In the present study, Cr6+ resistant plant growth promoting Pseudomonas sp. (strain CPSB21) was isolated from the tannery effluent contaminated agricultural soils and evaluated for the plant growth promoting activities, oxidative stress tolerance, and Cr6+ bioremediation. Assessment of different plant growth promotion traits, such as phosphate solubilization, indole-3-acetic acid production, siderophores, ammonia and hydrogen cyanide production, revealed that the strain CPSB21 served as an efficient plant growth promoter under laboratory conditions. A pot experiment was performed using sunflower (Helianthus annuus L.) and tomato (Solanum lycopersicum L.) as a test crop. Cr6+ toxicity reduced plant growth, pigment content, N and P uptake, and Fe accumulation. However, inoculation of strain CPSB21 alleviated the Cr6+ toxicity and enhanced the plant growth parameters and nutrient uptake. Moreover, Cr toxicity had varied response on oxidative stress tolerance at graded Cr6+ concentration on both plants. An increase in superoxide dismutase (SOD) and catalase (CAT) activity and reduction in malonialdehyde (MDA) was observed on inoculation of strain CPSB21. Additionally, inoculation of CPSB21 enhanced the uptake of Cr6+ in sunflower plant, while no substantial enhancement was observed on inoculation in tomato plant.

Abstract In the present study, a novel compact size convective batch-type solar-infrared assisted heat pump dryer is developed and experimentally investigated for closed air cycle drying of banana chips. Performances of four different operational modes of the system, simple heat pump drying, infrared-assisted heat pump drying, solar-assisted heat pump drying and solar-infrared-assisted heat pump drying are compared. Effects of drying time and product moisture content on various energetic and exergetic performance parameters are investigated. For all operational modes, the banana chips are dried to remove moisture from 83.8% to 11.5% at dryer inlet air velocity of 0.8 m/s. Both energy efficiency (58.5%) and exergy efficiency (24%) are found highest for solar-assisted heat pump dryer. The coefficient of performance is found highest for the simple heat pump dryer. The average moisture extraction rate is found highest (1.1618 kg/h) for solar-infrared-assisted heat pump dryer and lowest for the simple heat pump dryer. The specific moisture extraction rate is found highest for the solar-assisted heat pump drying and lowest in case of infrared-assisted heat pump drying. The present study shows the successful development of the combination of the different drying systems such as heat pump, solar and infrared in a single drying system for faster food chips drying.

Abstract In the present study, a novel compact size convective batch-type solar-infrared assisted heat pump dryer is developed and experimentally investigated for closed air cycle drying of banana chips. Performances of four different operational modes of the system, simple heat pump drying, infrared-assisted heat pump drying, solar-assisted heat pump drying and solar-infrared-assisted heat pump drying are compared. Effects of drying time and product moisture content on various energetic and exergetic performance parameters are investigated. For all operational modes, the banana chips are dried to remove moisture from 83.8% to 11.5% at dryer inlet air velocity of 0.8 m/s. Both energy efficiency (58.5%) and exergy efficiency (24%) are found highest for solar-assisted heat pump dryer. The coefficient of performance is found highest for the simple heat pump dryer. The average moisture extraction rate is found highest (1.1618 kg/h) for solar-infrared-assisted heat pump dryer and lowest for the simple heat pump dryer. The specific moisture extraction rate is found highest for the solar-assisted heat pump drying and lowest in case of infrared-assisted heat pump drying. The present study shows the successful development of the combination of the different drying systems such as heat pump, solar and infrared in a single drying system for faster food chips drying.

In this paper, a simulation study has been conducted for determination of the convective heat transfer coefficients of six crops, namely, green chillies, green peas, white gram, onion, potato and cauliflower under forced convection drying. Data obtained from experimentation under open and closed simulated conditions have been used to determine values of the coefficients C and n and, consequently, convective heat transfer coefficient. The data have also been analysed in terms of per cent uncertainty.

In this paper, a simulation study has been conducted for determination of the convective heat transfer coefficients of six crops, namely, green chillies, green peas, white gram, onion, potato and cauliflower under forced convection drying. Data obtained from experimentation under open and closed simulated conditions have been used to determine values of the coefficients C and n and, consequently, convective heat transfer coefficient. The data have also been analysed in terms of per cent uncertainty.