At what pressure is forced circulation typically preferred?

Forced circulation is typically preferred at higher pressures, specifically in the range of above 12,400 - 14,000 kPa. This is because forced circulation improves the efficiency of heat transfer in high-pressure systems. At elevated pressures, the boiling point of water increases, which allows for more effective heat exchange in applications such as boilers, where maintaining proper flow and temperature distribution is crucial.

At these higher pressures, the use of pumps to create forced circulation helps maintain a consistent flow rate, which ensures that the heat generated is evenly distributed and transferred. This is essential in preventing localized overheating and ensuring the safety and efficiency of the system.

In lower pressure scenarios, such as below 5,000 kPa or equal to atmospheric pressure, natural circulation can often suffice as gravity can help drive fluid movement. However, as operating pressures increase, natural circulation may become inadequate due to the increased density of the fluid and potential for vapor formation, making forced circulation necessary to maintain system performance and safety.