Drying characteristics and quality evaluation in convective drying of Cissus quadrangularis Linn.

This study aimed to investigate the effect of drying temperature (40, 60, 80, and 100°C) on drying characteristics of Cissus quadrangularis Linn. (CQ) undergoing convective drying. Physical properties and phytochemicals of the dried CQ were also evaluated. CQ with the thickness of 5 mm was dried from about 10 to 0.1 g water/g dry matter. The results showed that increasing drying temperature increased drying rate (DR) and effective moisture diffusivity (Deff) and consequently decreased drying time. The drying time, maximum DR, and Deff were in the ranges of 85-1920 min, 0.0059-0.0248 g water/g dry matter·min, and 0.7302-9.1281×10-9 m2/s, respectively. Lower drying temperature could preserve quality of the dried CQ. Decreasing drying temperature resulted in greener and lower bulk density and shrinkage. The greatest total phenolic content (TPC) and quercetin content were obtained by drying the CQ at 60°C

Experimental investigation of air characteristics during dehumidification in the multilayer desiccant bed column system

The gold of this research is to investigate air characteristics during dehumidification process using the multilayer desiccant bed. Silica gel packing in the multilayer column was used as a desiccant material. Airflow direction in the column was designed in a zigzag path passing each desiccant layer. The changes in temperature and relative humidity of exit air were recorded after dehumidification at different airflow rates of 18, 36, and 72 m3/h. In the desiccant regeneration process, moisture in silica gel was removed by 85°C of hot air at varied airflow rates. The characteristics of exit air after regeneration were also monitored. The result revealed that air humidity ratio was significantly decreased using multilayer desiccant bed column. The highest rates of air dehumidification and desiccant regeneration were observed in the first 5 min operation. The highest air dehumidification rate was 12.82 g/min at the airflow rate of 72 m3/h and the highest regeneration rate of desiccant was 6.70 g/min at the airflow rate of 72 m3/h. In addition, the dual column of multilayer desiccant bed can be successfully applied to cyclic operation of dehumidification and regeneration when the cycle time were 5 min and airflow rate 36 and 72 m3/h

Evaluation of cyclic efficiency of multilayer desiccant bed column

The main objective was to evaluate cyclic efficiency of a multilayer desiccant bed column. The experimental setup consisted of an air humidifier unit, a heating unit for regeneration, and the desiccant bed column with 15 layers. An airflow rate of 2.4 m3/min with the humidity ratio of 20 g water/kg dry air was used in this study. The results showed that the highest dehumidification rate of 21 g water/min was found at the beginning of the dehumidification process. During the regeneration process, the highest regeneration rate was 39 g water/min when regenerating the desiccant at a temperature of 90°C. For cyclic operation process, the cyclic efficiencies were 11% and 7% at the regeneration temperatures of 70°C and 90°C, respectively. The cyclic efficiency was dependent on the regeneration temperature

Experimental investigation of air characteristics during dehumidification in the multilayer desiccant bed column system

The gold of this research is to investigate air characteristics during dehumidification process using the multilayer desiccant bed. Silica gel packing in the multilayer column was used as a desiccant material. Airflow direction in the column was designed in a zigzag path passing each desiccant layer. The changes in temperature and relative humidity of exit air were recorded after dehumidification at different airflow rates of 18, 36, and 72 m3/h. In the desiccant regeneration process, moisture in silica gel was removed by 85°C of hot air at varied airflow rates. The characteristics of exit air after regeneration were also monitored. The result revealed that air humidity ratio was significantly decreased using multilayer desiccant bed column. The highest rates of air dehumidification and desiccant regeneration were observed in the first 5 min operation. The highest air dehumidification rate was 12.82 g/min at the airflow rate of 72 m3/h and the highest regeneration rate of desiccant was 6.70 g/min at the airflow rate of 72 m3/h. In addition, the dual column of multilayer desiccant bed can be successfully applied to cyclic operation of dehumidification and regeneration when the cycle time were 5 min and airflow rate 36 and 72 m3/h

Effect of different desiccant bed designs in a desiccant column on their dehumidification performance

A design with multilayers of solid desiccant and air ducts in a desiccant container was developed to allow good air flow in a zigzag pattern. The desiccant material was silica gel stacked as multiple layers in a column with different numbers of layers and with or without air holes on the upper cover of the container that penetrated through all layers. Air dehumidification characteristics and psychrometric properties of air of various desiccant bed designs were investigated. Dehumidification rate, percentage adsorbed water, desiccant column effectiveness of each design were evaluated at an air flow rate of 1.2 m3/min, where the control was a single layer packed bed design. Both kinds of multilayer bed designs (with and without air ducts) exhibited a significantly better dehumidification rate, percentage adsorbed water, and desiccant column effectiveness than the control. The experimental dehumidification psychrometric process was consistent with the theoretical adiabatic dehumidification process. The percentage dehumidification rate as time passed for every multilayer bed design was better than that of the control. The 15-layer bed design with air holes exhibited the highest values of about 16 g water/min dehumidification rate, 52% adsorbed water, and 0.998 desiccant column effectiveness

Image analysis based validation and kinetic parameter estimation of rice cooking

© 2017 Wiley Periodicals, Inc. The thermal efficiency of currently employed cooking methods ranges between 10 and 25%. Cooking accounts for ~40% of total energy consumed in developing world indicating toward huge scope for improvement. To develop the cooking methods of better efficiency, bringing down the energy consumption, it is necessary to understand the kinetics of cooking. As rice is a staple food for nearly 50% of the world's population, an attempt is made to scientifically explore the kinetics of rice cooking process. It is a well-known fact that presoaking of the rice reduces the cooking time and thus reduces energy consumption, to support this numerically, different parametric measurements such as moisture absorption, change in dimensions (length and width) of rice grain while cooking, are utilized for estimating the cooking kinetics. In addition, the technique of image analysis was also used for easy and quick estimation of the extent of cooking. Experiments were performed with both un-soaked and presoaked rice at three different temperatures (80, 90, and 97 °C) to evaluate the kinetics of rice cooking process. The activation energies for cooking of un-soaked and presoaked rice were found to be ~ 75 kJ/mol and ~ 70 kJ/mol, respectively, which is in good agreement with the values reported in literature. Regime of operation for cooking of rice is found to be diffusion controlled based on swelling particle model. Practical applications: Around 40 % of the total energy consumed in the developing world (population more than 496 billion) goes in cooking processes (Joshi et al.,). This huge energy consumption can be attributed to the inefficiencies related to cooking methods and/or devices. There is an urgent need to employ an energy efficient engineering solution for preparing hygienic, nutritious meals, which also has advantages of energy efficiency, ease of operation and efficient resource utilization. In order to design any efficient cooking device, kinetics of cooking for particular food material must be studied. Shinde et al. (), Joshi et al. () have designed the energy efficient batch and continuous cookers. Presented work utilizes simple method for determining kinetics of rice cooking, which can be easily extended to obtain kinetics of any other food material