DRYERS FOR AGRICULTURAL PRODUCTS USING SOLAR ENERGY

VINASAY, Vietnam is a pioneer and market leader in commercializing solar dryer technology for a variety of agricultural products. Our Poly Carbonate Solar Dryers are available in a variety of capacities, ranging from small household applications to large commercial applications.

We present a brief overview of Solar Drying Technology and its general characteristics in order to make the subject more understandable.

Drying is the process of removing moisture from food in order to prevent biochemical reactions and microbial growth. Drying extends the shelf life of the product, allowing it to be sold during the off-season.

Drying is one of the earliest methods of agricultural product preservation. The drying process requires approximately 2.4 MJ of energy to evaporate one litre of water. Most of our food crops are 80–90% water, and the majority of this water must be removed prior to long-term storage. In practice, the majority of dryers used are less than 50% efficient, indicating that significant amounts of energy are consumed during this post-harvest activity.

Sun drying agricultural products in the open air is a traditional method used in the majority of developing countries. The term "sun drying" refers to the process of exposing a commodity to direct solar radiation and the convective force of natural wind. Drying is the most cost-effective and widely used method of preserving and storing agricultural products.

Certain new techniques for efficient drying processes, such as hot air drying or dielectric heating, have been introduced. However, these processes consume a great deal of energy, which is typically derived from conventional energy sources such as fossil fuels. Due to the depletion of fossil fuels and the subsequent increase in energy prices, an increasing emphasis is being placed on the use of renewable energy sources for drying.

Drying the product at an optimal temperature is critical, but other factors such as contamination with foreign bodies, chemicals, dust, and bacteria are also critical.

The following criteria must be met in order to classify a solar dryer:

- Mode of air movement

- Exposure to insulation

- Direction of airflow

- Arrangement of the dryer

- Solar contribution

- Type of fruit to be dried

Solar drying systems have been developed as a viable and cost-effective method of agricultural product drying. Solar drying is accomplished through direct sunlight and the greenhouse effect. Solar energy received by the drying chamber is dependent on the amount of sunshine, the climate, the weather, the clarity of the atmosphere, and the location.

On a clear day, the amount of solar radiation available to any location is determined by the sun's angle relative to the horizon. Solar energy is a zero-cost, renewable, abundant, and environmentally friendly source of energy.

Solar dryers face two fundamental limitations: sunlight hours and weather change.

Polycarbonate Solar Dryers: These are solar dryers that are directly irradiated, meaning the products absorb solar energy directly through the polycarbonate sheet. Direct solar radiation heats and dries the upper layer, while conduction heats and dries the subsequent layers. Solar natural dryers include polyhouse or greenhouse drying. Due to the fact that the drying process is weather and sunlight dependent, a constant drying temperature cannot be maintained. Solar dryers thrive in conditions of high outdoor temperature, low humidity, and clear skies. The inside air temperature of the polyhouse is approximately 20–30 °C warmer than the outside air temperature, which accelerates drying in comparison to conventional drying, thereby reducing drying time.

THE BENEFITS OF SOLAR DRYERS

Several advantages of solar dryers include the following:

- Solar dryers can help you save money on fuel and electricity, and the drying time is significantly shorter than with open drying.

- Solar-dried fruits and vegetables are higher in quality and more hygienic than those dried in the open.

- Products are protected from flies, rain, and dust; products can be left in the dryer overnight during inclement weather due to the waterproof nature of the dryer.

- It minimizes losses and provides a more competitive market price for the products.

- Materials required to construct a solar dryer are readily available locally.

- Solar dryers pose no risk of fire.

- The dryers can be connected in series to increase capacity as needed, and they can be easily dismantled for easy transportation from one location to another.

- Achieved Product Quality

CONCLUSION: Solar drying systems, particularly for agricultural and marine products, are particularly viable in developing countries where labor costs are low but fossil fuel energy costs are extremely high.