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What is a Solar Dryer – Types, Applications & Construction

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The sun is the most important source of heat and light in the universe. During primitive times, the sun was solely used for its heat and light for all day to day activities, when there was no electricity. With increased usage of fossil fuel and thermal electricity, there is now a risk of global warming. It is being feared that if Earth progresses at the rate at which it is currently moving on, there will not be much of resources left for our future generations. All this has led the world incline towards alternative sources of power. While wind and hydro energy are also making progress, it is solar energy that has become the favoured one amongst masses, mainly due to its increased affordability.

Also Read about Solar Cookers

What is a Solar Dryer

A solar dryer is another application of solar energy, used immensely in the food and agriculture industry. Though sun is still used as the direct source for drying food items and clothes in certain parts of the world. An indirect source of solar power can also be used for the same purpose in the form of a solar dryer. The main disadvantage of drying directly under the sun is contamination – dirt, animals, insects etc. Also there is a fear of sudden change in weather conditions like wind or rain.

When using a solar dryer, you do not have to worry about all this!

solar-dryerA Solar Dryer for drying cocoa seeds

Types of Solar Dryer

A solar dryer can most conveniently be classified as direct or indirect.

Direct Solar Dryer – The item to be dried is exposed directly to solar radiation through a transparent material that covers the structure. The heat generated from the solar energy is used to dry the crops or food items and also heats up the surroundings. The main disadvantage of using the direct mode is that the heat that will be absorbed by the item cannot be controlled. Available in many sizes, ranging from kilograms to metric tons, the simplicity of the product and its affordability are its USP.

Read about Solar products in India

Indirect Solar Dryer – As the name suggests, this method does not expose the crop directly to the sunlight. The solar radiation is absorbed and converted into heat by another surface (like a black top) usually called the collector. Air that will be used for drying is passed over this surface and gets heated, which is then used to dry the food item inside the dryer. The main advantage of indirect mode of drying is that the temperatures can be controlled. The sizes can vary from kilograms to metric tons, but it is expensive and more complex to construct when compared to direct solar dryers.

solar-dryer-diyImage source

These are also commonly referred to as food, cloth or crop dryer, based on the items used for drying using the Solar Dryer. Many people can assemble/ construct a solar dryer with the help of DIY instructions available on the internet. The image shown above is self explanatory. Solar Dryer will find increased applications in the food, agriculture and plantation industries where food and crop items need to be dried before using. It helps in maintaining the quality of these items without contamination fears. In economies, where people hardly have power for their daily life, these devices will help a great deal in reducing the load on the main grid, and electricity from the grid can be used for other purposes.

PG

Sneha Shah

I am Sneha, the Editor-in-chief for the Blog. We would be glad to receive suggestions, inputs & comments on GWI from you guys to keep it going! You can contact me for consultancy/trade inquires by writing an email to greensneha@yahoo.in

2 Responses so far | Have Your Say!

  1. Al Nor

    Hello, I am Engr. Al Nor Limbo, A licensed Agricultural Engineer from the Philippines. I really like the concept of your design! such a brilliant idea. Also, it popped into my mind to modify your Greenhouse into a HYBRID GREENHOUSE SOLAR DRYER. Kindly see below my suggestions.

    First, I wish to suggest if you can make your roof as a half-circle shape so that you will be able to install it at the open field. It will help you to reduce the wind current during strong wind (or typhoon). In other words, your Greenhouse will be more flexible.

    Second, any seeds required a less than 43 Celsius temperature to maintain its vigor and seed germination. With that, I wish to suggest installing fans that based on the area of your GreenHouse to reduce the ambient temperature inside. The Ventilator fans also help to push vaporized gas (due to evaporation from the commodity) and high ambient RH during rainy days or night time. High ambient RH has a significant effect on the quality of your seeds or any commodities, particularly in microbial development.

    Third, install solar panels and deep cycle battery to run the ventilator fans so that you can use it in an off-grid place. The use of Solar Panel is to store energy in the Deep cycle battery. The deep cycle battery will be used to run the ventilator fans.
    or you can convert your solar panel to an electric type Greenhouse by using an inverter that changes direct current (DC) to alternating current (AC).

    my two cents.

  2. aashish

    please tell about flat type solar drier