Question

Sequentially arrange the steps involved in a drying curve: A. Product reaches thermal equilibrium, evaporation rate rises as surface heats and free water mobilises. B. Surface dries, rate drop, moisture diffusion from interior limits. C. Linear moisture drop, but surface stay wet, evaporation rate will be constant until it reaches critical moisture constant. D. Rate approaches zero when EMC matching air humidity, bound water remains. E. Maximum drying rate achieved, unbound water evaporates steadily.

• A. D, B, E, C, A
• B. A, C, E, B, D
• C. A, E, C, B, D
• D. D, A, C, B, E

Hint:

Understanding the stages of a drying curve helps in optimizing drying processes for various materials.

Answer 1

The Correct Option is C

Step 1: Concept
A drying curve describes the process of moisture removal from a product as it dries. The steps in this process can be sequentially arranged to understand how the rate of evaporation changes over time.

Step 2: Meaning
The correct sequence should reflect the stages where the evaporation rate increases, stabilizes, and eventually decreases until no more water can be removed.

Step 3: Analysis
1. Step A: "Product reaches thermal equilibrium, evaporation rate rises as surface heats and free water mobilises." This is the initial stage where the product starts to dry due to increased temperature. 2. Step E: "Maximum drying rate achieved, unbound water evaporates steadily." After some time, the maximum rate of evaporation is reached when all easily accessible (unbound) water is being removed. 3. Step C: "Linear moisture drop, but surface stay wet, evaporation rate will be constant until it reaches critical moisture constant." As drying progresses, the rate becomes more consistent as the product's interior continues to release moisture. 4. Step B: "Surface dries, rate drop, moisture diffusion from interior limits." The surface of the product starts to dry out, and the rate drops because the remaining water is harder to access (bound). 5. Step D: "Rate approaches zero when EMC matching air humidity, bound water remains." Finally, as the equilibrium moisture content (EMC) is reached, no more evaporation occurs due to the air's humidity matching that of the product.

Step 4: Conclusion
The correct sequence aligns with these stages: A (initial heating and free water removal), E (maximum unbound water removal), C (consistent rate until critical moisture), B (surface drying limits further evaporation), D (final equilibrium). Final Answer: (C)