Sukhmeet Singh

Regeneration of silica gel in multi-shelf regenerator

In the present paper an investigation on the regeneration of solid desiccant (silica gel) in a modified design of dehumidifier called “Multi-shelf Dehumidifier”, has been reported. A “Packed Bed Dehumidifier” was used as control. Both the dehumidifiers were fabricated and tested simultaneously. The effect of regeneration air temperature, bed-air velocity and number of shelves on regeneration of silica gel was investigated. The range of regeneration air temperature was 42–72°C, while bed-air velocity varied from 0.175-0.55 m/s and number of shelves from 2 to 4. The regeneration time decreased with the increase in regeneration air temperature, bed-air velocity as well as number of shelves. The values of regeneration air temperature and bed-air velocity for minimum energy input were found to be 52°C and 0.175 m/s irrespective of the number of shelves. The effect of the rest period was investigated for these optimum values of regeneration air temperature and air velocity for a number of shelves varying from 2 to 4. The rest periods used were 30, 60 and 180 mins. The regeneration time reduced with increase in rest period for all the values of number of shelves, but the reduction in regeneration time was not appreciable.

Solar Dryer for Powder Drying

A natural circulation solar dryer for drying products in the form of powder has been developed. It is of modular design and aperture area of one module is 3.34 m2. A new concept of moveable glazing has been introduced for ease in loading and unloading. Air entering the dryer moves in a zig-zag path as it flows over the product and under each tray before leaving from the top. There is a provision to dry the product under shade. Also, the dryer can be dismantled and stored in a room during off-season. The dryer was tested to dry Di-calcium phosphate (DCP) at Ludhiana (31°N). The average drying efficiency for a batch was found to be 54.0%. The cost of drying DCP using this solar dryer was 0.56 Rupees per kg of dried DCP as compared to 1.94 Rupees per kg of dried DCP for a wood-fueled industrial dryer. In comparison to a solar tunnel dryer for DCP drying, the initial investment per kilogram of the dried DCP, floor area per kilogram of wet DCP, and cost of drying per kilogram of dried DCP for this dryer was reduced by 7.1%, 67.2%, and 16.4% respectively.

Desiccant honey dehydrator

A desiccant honey dehydrator has been designed, developed and tested. It heats and dehumidifies air to dehydrate honey. Re-circulation has been employed to prolong use-period of the desiccant bed. The dehydration was done with dehumidified or ambient air at 35°C and 45°C. The honey was also dehydrated in open for reference purposes. The maximum moisture evaporation rates in the case of a desiccant honey dehydrator using dehumidified air, ambient air and open dehydrating at 45°C were 132, 78.7 and 52 g/h m2, respectively.

Desiccant seed dryer

SYNOPSIS A desiccant seed dryer operating in a closed loop was designed and fabricated to dry 1 kg of seed in about 6 hours. Silica-gel was used as the desiccant in the dryer, which was tested to dry onion seeds. The seeds were dried from initial moisture content of 8% to final equilibrium moisture content of 4.5% when drying air condition was maintained around 40°C and 20% relative humidity.

Honey moisture reduction and its quality

AbstractBeekeeping has been widely promoted in many countries as a major contributor to rural development. Honey is a sweet and viscous liquid which has sweetness due to the presence of monosaccharides. The major constituents of honey are sugars, water, proteins, enzymes, acids and minerals, while the major causes of quality deterioration include heating at high temperatures, high moisture content, adulteration, poor packaging and poor storage conditions. Heating not only eases the processing of bottling by reducing the viscosity of honey, but also reduces the water content in honey to prevent fermentation and delays the granulation by destroying large sugar nuclei. The paper discusses about the different honey moisture reduction systems designed by research workers as well as beekeepers at farm level and the different quality parameters affected by thermal treatment of honey.