How does scale-up affect heat management?

• A. Heat removal becomes easier
• B. Temperature remains constant regardless
• C. No need to consider heat at larger scales
• D. Heat removal becomes more challenging, increasing risk of heat buildup and runaway

Answer: (D)

Scale-up challenges heat management: as you increase the amount of material, the total heat that can be generated grows, but the cooling surface area grows much more slowly. This lowers the surface area-to-volume ratio, making it harder for the system to transfer heat to the surroundings. Changes in geometry and mixing can further reduce effective heat transfer coefficients, and cooling systems often have fixed capacity. The combination means heat can accumulate faster than it can be removed, raising the risk of hot spots and runaway reactions. So, heat removal becomes more challenging, increasing the chance of heat buildup and runaway.