A hot air dryer has been developed for achieving uniform temperature distribution throughout the drying trays with the use of an air disperser. Comparative experiments were conducted with and without the use of the disperser. Then, 1 mm thick potato slices were dried at 50, 55, and 60°C and 1.5 m/s air velocity at different locales of the tray. Validation of drying rate uniformity was done by studying the temperature distribution on the drying tray using thermal imaging and measuring the chromatic, textural, and morphological properties of dried potato slices. Without the air disperser, the average temperature and average initial drying rate measured after 30 min at five different points on the bottom tray varied from 42.5 to 52.2°C and 0.086 to 0.185 g water/min, respectively, whereas the variation was only in the range of 49.0–49.6°C and 0.182 and 0.206 g water/min when the air disperser was used at a set dryer temperature of 50°C. Similarly, drying rates at all the positions in different trays were observed to be in close proximity throughout the drying period with the presence of air disperser; however, without it, the drying rate was found to be higher at the center of the tray than other four points. Similar observations were also made for all the qualitative parameters of potato slices at all drying temperatures. Practical Applications The dryer has provision for placement of different types of imaging devices and sensors for online monitoring of process parameters and the product being dried. It has been designed for nondestructive study of the drying progression using machine vision system. Such a dryer will be especially useful for controlled drying experiments and laboratory simulation of different hot air drying processes.

No abstract

Узагальнений підхід до аналізУ режимів сУчасних систем теплопостачання Purpose. Solving analysis problems and improvement of modern physically inhomogeneous heat supply and heating systems. Developing the mathematical models that are suitable for applying all the features of the theory of energy circuits. Methodology. The study was conducted through applying fundamental laws of physics, fundamental principles of the theory of energy circuits and sectoral theories of hydraulic and electrical circuits, formalized methods for analysis of utility networks, methods of mathematical modeling. Findings. Contour and nodal mathematical models were improved as an instrument of a generalized approach to the modes analysis of heat supply and heating systems. It has been shown that the mathematical models can adequately reproduce modes of studied systems. The models take into account the nature of the power and features of the two forms of mechanical energy-kinetic and potential. It is important for the analysis of mine heating modes, as there are considerable differences in height and emergency modes, due to leakages of heat-transfer agent to the environment. Originality. The generalized approach complies with all the requirements by principles of the metrical and energy analogies. It allows applying previously unavailable tools for the modes analysis of heating systems, in particular, power balance. The important advantage of this approach is the observance of unified system variables, which allows describing the phenomenon in circuits of different physical nature. Practical value. The developed mathematical models provide an effective tool for analysis of the planned and existing modern heat supply systems and their optimization in terms of minimizing energy costs.

Potato is the fourth most important crop in the world after rice, wheat, and corn. Considered a healthy, low-fat, economical food, it is the only noncereal crop that has the potential to eliminate malnutrition and hunger while ensuring food security. In most of the unorganized sectors of India, potatoes are sliced, blanched, dried, stored, and consumed as a snack food throughout the year. Hot air drying is the most popular method after open sun drying. During drying, the dynamics of moisture and temperature gradient have opposite effects. The strength of these gradients determine the product quality. A stronger moisture gradient produces a good quality product; otherwise, there can be issues like case-hardening and crusting of the surface and the edges (Zhao & Gao, 2016), leading to poor product quality and early spoilage.The product moisture is the indicator of the drying condition of the product. Conventionally, the weight measurement method determines the sample moisture content during drying. This method is very accurate but requires human intervention, which poses a higher chance of contamination of the product and is not very practicable in the case of continuous dryers. Additionally, in hot air drying, using a continuous weight-measuring system like a load cell is not feasible, as the incoming hot air creates vibrations that interfere with the performance of a sensor-based weight measurement system. Change in chromatic properties of the products is one of the primary visual