DEVELOPMENT OF AN INNOVATIVE MICROWAVE SOLAR DRYER FOR SEAFOODS

Abstract

Drying is an ancient fish preservation method, involving a combination of heat and mass transfer to extend the life of fish materials. It is, however, an energy-intensive process that consumes approximately 20 to 25% of the energy used by the food processing sector. Developing innovative drying systems such as Microwave Solar Drying (MSD) and utilizing renewable energy such as solar energy in drying can be a potential solution for reducing conventional energy consumption in the drying process. An innovative solar energy-focused MS dryer system is developed and implemented in this Thesis. Microwave solar dryer optimization is necessary to create an efficient system that can influence drying conditions (e.g., relative humidity, flow rate, air temperature, MW power) to reach better efficiency and better-quality dried fish. An air duct is designed and connected to this microwave setup to accurately measure the velocity of additional controlled air (0.1 m/s, 0.11 m/s, and 0.12 m/s) supplied to the microwave from outside. The solar-assisted microwave dryer is carried out at different air velocities (0.1 m/s, 0.11 m/s, and 0.12 m/s) of 200 watts and 400 watts. This thesis also determines and compares the drying time and quality of some dried Bombay duck, silver belly, and silver Jewfish from both (MSD) and (TSD). Three marine fish samples obtained from sun and microwave drying were tested for Proximate composition and bacterial loads at the department of marine fisher’s lab and poultry research lab training centre at Chittagong Veterinary and Animal Sciences University. All the fish samples were analyzed moisture, protein, crude fiber, crude fat, ash, calcium, and phosphorus according to AOAC (AOAC, 2016) methods. Microwave solar dryer (200-watt, 400 watt) drying yielded the best food content of Bombay duck, silver belly, Silver Jew fish compared to natural sun drying. Bacteriological study was conducted according to FDA BAM method. The bacterial loads of the solar-assisted microwave drying and traditional sun drying in Bombay duck, silver belly, and Silver Jewfish were 5.89×106cfu/g, 8.9×105cfu/g, & 4.96×105cfu/g (MSD) and 8.6×107cfu/g 5.6×108cfu/g, & 8.0×106cfu/g (TSD) respectively. In comparison to convective natural air drying, microwave solar drying produced fish with better product quality while using significantly less power. According to the study's findings, Microwave solar drying at 50°C with a pulse ratio of 3.0 reduced considerably drying time when compared to convective natural air drying, and it should be the preferred approach for drying to vi produce high-quality dry fish products with better physical (color and texture) attributes. This analysis found that the PMS drying time was approximately 5.20 hours, whereas traditional sun drying required an average drying time of 3-4 days (for Jewfish), 4-5 days (for silver belly), and 3-4 days (for squid) (for Bombay duck fish). The payback calculation in this study was based on the results of the HOMER simulation. The optimization produced a total Net Project Cost (NPC) of $2961 and an energy cost of 0.160 $/KWh or 16 BDT/KWh. And the payback is roughly one year and twenty days. In comparison to natural convective drying, the developed pulsed microwave sun drying significantly reduced drying time, increased product quality and color, and reduced energy consumption. mvims‡ÿc