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In 21th century demand for energy is rapidly increasing as the population is increased. To provide desirable living conditions and satisfy the food needs of overpopulated humanity getting harder and harder due to the limited energy and nutrient resources. Nutrient sources pass through many stages such as heating, cooling, drying and freezing which includes thermal and electrical energy needs before being presented to the consumer in the food industry. In the current situation, these two main energy requirements are largely met by fossil fuels which are not efficient, unsustainable and not user friendly in terms of resource management. In this context, the possibilities of usage Photovoltaic-Thermal (PV/T) solar energy systems which will be able to eliminate these disadvantages, use solar energy as a source and can meet the thermal and electrical requirements of the facility continuously has been investigated and, a system was designed which can meet the energy needs according to different scenarios for different processes. It is aimed to produce food in low carbon-emission facilities by meeting both electrical and thermal energy from the solar energy which is a renewable and clean energy source. [ABSTRACT FROM AUTHOR]

The purpose of this research was to determine the drying characteristics of Uzun variety pistachios in a convectional dryer with air velocity of 1 m/s at 50, 55, 60, and 65°C. Through the end of drying, moisture transfer from in‐hull, and in‐shell pistachio samples was defined by using the diffusion model of Fick. The Arrhenius‐type relationship was used to establish the temperature dependence of the effective moisture diffusivity. The activation energy of in‐hull and in‐shell pistachios was determined to be 56.04 and 34.18 kJ/mol, respectively. Five well‐known models, that is, the logarithmic, page, two‐term, Midilli et al., and approximation of diffusion models were fit to data of moisture ratio. The Midilli et al., and the two‐term models were chosen to accurately describe the hot‐air drying behavior of in‐hull and shell pistachio samples. As shelf‐life criteria, the water activity (aw) values of fresh and dried pistachios were determined at different ambient air temperatures. The enthalpy (ΔH) and entropy (ΔS) values of the pistachio samples decreased with increasing the air temperature, while Gibbs‐free energy (ΔG) increased as the air temperature increased. Novelty impact statement: Pistachio kernel has rich nutritional significance for the human diet due to its 50%–60% fat content and unsaturated fatty acid and, the drying is the most important post‐harvest process in the pistachio industry. Pistachio kernels must be dried below aw of 0.82 and 0.70 for short‐ and long‐term storage and to avoid fungal development, respectively. This work evaluates the drying conditions and presents a mathematical model for hot‐air drying of pistachio nuts and, the results show that drying of pistachio can be carried out in industrial convective dryers. [ABSTRACT FROM AUTHOR]

In this study, grape pomace was dried in an infrared film dryer at 40, 45 and 50 °C surface temperatures to investigate the effects of heat transfer mechanism (natural and forced convection) and homogeneous drying on specific energy consumption, drying rate and drying time. Also, energy and exergy efficiencies were calculated. The average specific energy consumption values were calculated as 5.90, 4.49 and 4.07 kWh/kg in natural convection (Group 1) and 11.90, 11.32 and 11.81 kWh/kg in forced convection (Group 2), respectively. The maximum energy efficiency was observed as 54.71% at 45 °C in Group 1. Energy efficiencies at the experiments in Group 1 were found to be nearly 10% higher than Group 2. The maximum exergy efficiency was observed as 38.46% at 50 °C in Group 1, and the average exergy efficiency values for Group 1 and 2 were calculated as 34.84% and 33.76%, respectively. Group 2 experiments provided a faster drying process as expected. However, although forced convection was more effective in terms of drying time, natural convection was found more suitable considering all the performance parameters as a whole. This study offers a solution to dry grape pomace high quality, homogeneously and efficiently for industrial usage. Unlabelled Image • Heat and mass transfer analysis of infrared film dryer is performed. • A novel infrared film dryer is designed for homogeneous temperature distribution. • Infrared film dryer performance using energy-exergy methodology is analyzed. • Drying kinetics of grape pomace are investigated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Performance analysis of solar drying and solar-infrared drying of mint and apple slices. • The effect on drying performance of IR and solar energy in the extreme conditions. • IR energy is effective in reducing the drying time when solar energy is insufficient. • A design with a high rate of utilization of solar energy. • The maximum thermal efficiency has reached 83%. Abstract In this study, double-pass solar air dryer (DPSAD) and infrared assisted double-pass solar air dryer (DPSAIRD) were designed and tested. The effects of using infrared energy have been experimentally investigated to ensure continuity in climatic conditions (cloudy, etc.) where solar energy is insufficient. Comparative experiments were carried out in the summer and autumn. Energy and exergy analysis, mass and heat transfer, performance coefficient, specific energy consumption, drying efficiency, energy efficiency and error bars have been used as criteria for evaluating thermal and structural performance of solar dryer and to see the effects of infrared energy on dried products (apple slices and mint leaves). The highest thermal efficiency of the collector was obtained as 83.56%. For DPSAIRD and DPSAD, exergy efficiency values were calculated as 49.17%, 59.07%, 59.06% and 69.35%, respectively. Energy efficiencies varied between 1.15% and 8.59% for DPSAIRD, 2.20% and 26.46% for DPSAD. Despite the low radiation values in autumn and the lower ambient temperature, it was found that the drying times are almost the same as in the summer months, thanks to the use of infrared energy. The IR lamp significantly increased energy consumption; however, in cases where the collector was insufficient, it supported both the collector and protected the products against deterioration. [ABSTRACT FROM AUTHOR]

This study aims to analyze the performance of a novel design of the double pass solar air collector (DPSAC)-assisted drying system and investigate the drying kinetics of grape pomace which is an agricultural by-product. The samples were dried to a moisture content of 0.01 g water/g dry matter between 100 and 250 min depending on the weather conditions. The average thermal efficiencies of DPSAC were calculated as 79.77, 79.85, and 69.46%. Average values of the coefficient of performance of DPSAC were determined as 5.32, 5.13, and 4.32. The highest specific moisture extraction rate value was achieved as 617.18 g water/kWh. Whereas the mass transfer coefficient (hm) values ranged from 9.15E−11 to 1.04E−7 m/s, the effective moisture diffusivity (De) values were obtained between 3.04E−13 and 1.02E−10 m2/s. The qualitative analysis showed that the drying using DPSAC may be an alternative for drying applications in terms of short drying time and energy usage. Nevertheless, these results clearly suggest a complex and effective interplay between thermal performance and drying kinetics. [ABSTRACT FROM AUTHOR]

In this study, energy and exergy analyses of the closed‐cycle infrared (IR) convective walnut drying were performed. The effects of the combined heat transfer, product–source distance, and temperature–relative humidity (RH) control on the food quality of walnuts and performance were investigated. Experiments were conducted with and without an IR lamp. The temperature and RH of the drying air were set at 40°C and 20%, respectively. The distance between the product and the IR source was changed to 20 cm and 30 cm. The coefficient of performance values of the whole system changed between 1.56 and 2.34. Exergy efficiencies varied between 60.81% and 88.19% without IR and 72.73%–78.54% with IR. Energy and time savings increased by 14.7% and 26.1%, respectively, with using IR at a 20 cm distance compared with the convective system. The fatty acid composition of walnut samples and chemical properties of walnut samples such as total phenolic content, oil, ash, color, antioxidant activity, peroxide values, free fatty acid, conjugated trienes, conjugated dienes, saponification value, and iodine number parameters were analyzed. Food analysis results of all dried walnuts were in the acceptable range. As a result, energy and time savings were achieved with the desired food quality. Novelty impact statement: This application makes it possible to achieve the desired conditions with less energy. In this study, the effects of heat transfer mechanisms, the effect of using two mechanisms together, and the effects of the variables within each mechanism on the drying of walnuts were investigated. It has been observed that the addition of an infrared heat source with the right and suitable application shortens the drying time as well as saves energy. As a result of the food quality analysis, it was determined that all products dried without deteriorating the food quality. The closed‐cycle intermittent infrared convective drying system is recommended for industrial use. [ABSTRACT FROM AUTHOR]

Walnut drying is a time-consuming and an energy-intensive process. To decrease energy consumption a new type drying system was designed. Effect of heat transfer mechanism and bi-directional penetration of the heat to the product were investigated according to energy-exergy analysis. In this study, walnuts were dried with a heat pump dryer with heat recovery (HP) and an infrared assisted heat pump dryer with heat recovery (IRAHP). Energy efficiencies varied between 0.29-7.94% and 0.28–6.54% in IRAHP and HP, respectively. Exergy efficiencies varied between 59.54 and 68.39% in IRAHP and 54.76–59.92% in HP. The average COP values of the heat pump were calculated as 4.10 in IRAHP and 3.97 in HP. The average COP values of the whole system were determined as 3.14 for IRAHP and 3.34 for HP. It was seen that IRAHP provides 10% energy saving and 20% time saving compared to HP. • Walnut was dried with convection and combined radiation & convection. • A vertical tray was used for bi-directional penetration of the heat to the product. • Energy and exergy analyses were performed for two heat transfer mechanism. • Drying time was reduced by 20% and energy consumption was reduced by 10%. • Drying kinetics of walnut and performance analysis of system were investigated. [ABSTRACT FROM AUTHOR]

Grape is one of the most popular fruits and various types of grape have been cultivated by more than 100 countries around the World. The wine and juice industry produces large quantities of by-product, called grape pomace (GP) as an industrial waste and it consists of skins, seeds, and stems. Various processes such as separation, pressing, drying, and milling are applied to benefit from its health effects. In this study, the seeded black GP Kalecik karası (Vitis vinifera) was dried in an assisted closed cycle heat pump dryer (HPD) designed for high-moisture products to investigate the drying behaviors of GP. The effects of drying air temperature on bioactive properties and the drying characteristics of GP, and performance of system have discussed. Experiments were carried out at two different temperatures (45 and 50°C) and air velocity of 1.0 m/s. It was seen that increasing temperature decreased the drying time, coefficient of performance of whole system (COPws), and specific energy consumption (SEC). The average values of COPws for temperatures 45°C and 50°C were calculated as 3.28 and 3.10, respectively. The drying efficiencies (DE) at drying air temperature of 45°C and 50°C ranged from 2 to 12% and from 2 to 15%, respectively. Additionally, result of analysis has indicated that using a HPD at lower temperatures increases performance of system despite of higher energy input. Bioactive properties of dried samples at drying air temperature of 45°C are better than 50°C. The results show that drying the GP at low temperature is more suitable for product quality. For this reason, heat pump may be preferred. It shows that this drying system with higher capacities in the future can be recommended as an alternative technique in terms of energy usage, drying time, and performance of system. [ABSTRACT FROM AUTHOR]