Question

Majority of fermentation medium are pseudoplastic. Therefore, heat transfer and mass transfer rates are poor away from the impeller because:

• A. Density decreases
• B. Viscosity decreases
• C. Density increases
• D. Viscosity increases

Hint:

In pseudoplastic fluids, high viscosity away from the impeller limits heat and mass transfer efficiency.

Answer 1

The Correct Option is D

Step 1: Understanding Pseudoplastic Fluids 
Pseudoplastic fluids (shear-thinning fluids) have viscosity that decreases with increasing shear rate, but can exhibit high viscosity away from the impeller. 
Step 2: Impact on Heat and Mass Transfer 
- Density: Does not significantly affect the heat and mass transfer in this context. 
- Viscosity: Increases away from the impeller, reducing the flow and limiting mass and heat transfer. 
- Conclusion: The primary cause of poor heat and mass transfer is the increase in viscosity, which slows down the flow.