Objectives:-

The drying process is used to remove moisture from a substance, typically a solid material, by exposing it to heat, air or other means of dehumidification. The objectives of the drying process can vary depending on the application, but some of the most common objectives include:


(1) Preservation: Drying is often used as a method of preserving perishable materials such as food, herbs, and flowers, by removing moisture which can lead to spoilage.

(2) Increased Shelf-Life: By removing moisture, the shelf-life of products such as foods, pharmaceuticals, and chemicals can be extended, which can reduce waste and improve profitability.

(3) Improved Product Quality: Drying can improve the quality of materials such as paper, textiles, and wood by reducing their moisture content and increasing their strength, durability, and appearance.

(4) Reduced Weight and Volume: Drying can also reduce the weight and volume of materials, making them easier to transport, store and handle.

(5) Energy Efficiency: Drying can also be used to improve energy efficiency by removing moisture from materials such as biomass and sewage sludge, making them easier to burn or convert into other forms of energy.

   Overall, the objectives of the drying process are to remove moisture from materials to achieve a desired level of dryness that meets specific requirements, and to do so in a way that is cost-effective, energy-efficient, and environmentally sustainable.


 

Application:-

(1)  Food industry: Drying is used to preserve and extend the shelf life of food products like fruits, vegetables, meat, fish, and grains.

(2)  Pharmaceutical industry: Drying is used to remove moisture from drugs and medicines, ensuring their stability and preventing microbial growth.

(3)  Textile industry: Drying is used to remove moisture from fabric after washing and dyeing.

(4)  Chemical industry: Drying is used to remove water content from chemical products to improve their quality and shelf life.

(5)  Paper Industry: Drying is used in the paper industry to remove moisture from paper pulp and coated paper, ensuring the proper formation and finishing of the paper.

(6)  Wood Industry: Drying is used in the wood industry to remove moisture from timber, reducing its weight and improving its strength.

(7)  Paint Industry: Drying is used in the paint industry to remove solvents from paint and coatings, improving their adhesion and durability.

(8)  Electronics Industry: Drying is used in the electronics industry to remove moisture from electronic components and circuit boards, ensuring their proper functioning.


Mechanism:-

The drying process is a mechanism of removing moisture or water content from a material or product through evaporation or sublimation. The mechanism of the drying process depends on the properties of the material being dried and the drying method being used. Here are the two most common mechanisms of the drying process:

(1)  Convective Drying: In this mechanism, hot air is blown over the surface of the material or product. The heat from the air causes the moisture to evaporate, and the resulting water vapor is carried away by the air. The air can be either forced or natural convection.

(2)  Contact Drying: In this mechanism, the material or product is placed in direct contact with a hot surface. The heat from the surface causes the moisture to evaporate, and the resulting water vapor is removed either by natural convection or through a forced air flow. This method is commonly used for materials with high thermal conductivity, such as metals.

In addition to these two mechanisms, some materials can undergo sublimation, where the moisture is removed directly from the solid state to a gas state, without passing through the liquid state. This occurs in materials such as freeze-dried foods and certain chemicals.

The choice of drying mechanism and process parameters, such as temperature, humidity, and airflow, depends on the properties of the material or product being dried, the desired final moisture content, and the production requirements. Proper control of these parameters is critical to achieving an efficient and effective drying process.