IIT Guwahati Solar dryers use solar power to dry food items especially agricultural products & spices to preserve them.
In a bid to assist the spice market of Northeast india, a team of IIT-Guwahati led by Professor P Muthukumar have developed a reasonable solar dryer that increases the shelf-life of spices.
Prof Muthukumar said “Northeast india is known for its spices,Several high-value agricultural products, such as cardamom & high-quality ginger & chilli are produced here.But currently, the technology used for preserving these spices are very simple like open-sun drying and sometimes large-scale farmers choose smoke-drying method. Both these technologies are having their inherent demerits & you cannot preserve the actual quality of the product because of the long drying time,” he said.
Explaining why, the Professor said, “Sometimes due to the long drying time, you’ll see the formation of fungal growth over the merchandise . And more than twenty to thirty percent of the product gets spoiled during the drying period. This is an enormous loss for the farmers.If farmers lose One kilogram of cardamom, the loss will be about ₹10,000.” To solve this issue of produce getting spoiled, the IIT-Guwahati team has worked on a low-cost solar dryer, mainly for farmers from the Northeast india.
Prof Muthukumar said, “The dryer we developed has capacity to dry thirty to fourty kilograms of any product at a time. Compared to the open sun drying method, if you employ our dryer, you’ll dry your product within a maximum of two days.And at an equivalent time. So you can preserve the colour as well. Also, we’ve done all the standard checks, like antioxidant quality, protein, and every one other properties. Whatever product has been tried by the team on this solar dryer by IIT Guwahati, the first quality was preserved.”
On the expenditure and materials required to make the machine, the professor said, “This is an indigenously developed technology & can be manufactured locally. Maybe we’d like to possess some plywood then some glass, but these are all locally available. The cost will be approximately ₹20,000 – 25,000.”
He added that the solar dryer are often used for drying any agricultural product. The Team is hoping that their device will increase the income of farmers. They also plan on fabricating such dryers & deploying them in various parts of the Northeast & provide training to farmers so that they can use the device efficiently.
How IIT Guwahati Solar dryer works:
The solar dryer has an absorbing surface which will absorb radiation and gain heat from it. The thermal energy is then wont to remove the moisture content from the products, hence, dehydration the merchandise within the process.
There are three general types of solar dryers: Direct, Indirect & Mixed mode. In the direct solar drying method, the substance is exposed to be dehydrated in direct sunlight. Here, the product directly gains heat from sunlight & to be dried. In this case, there are often chances for contamination of the merchandise by dust from wind, birds, insects, or animals.
In the case of the indirect solar drying method, the air is heated separately by employing a solar air heater and therefore the hot dry air with a coffee percentage of relative humidity (RH) is passed to the dryer chamber where the product is placed. Here, direct sunlight isn’t allowed on the merchandise because the direct sun can chemically alter the contents of the merchandise , making them less appetizing.
In the mixed mode of drying, solar radiation is allowed to enter the drying chamber to heat the products inside & hot air is also supplied to the drying chamber from a separately connected solar air heater. In this case, the dryer receives heat from both solar radiation & hot air, due to which the drying rate is much faster.