🔍 Key Concepts

• natural circulation boiler operation (no circulation pump) • how density changes in water/steam mixtures cause movement • role of heating surfaces vs. fluid properties in creating flow

💭 Think About

• In a natural circulation boiler, what actually pushes the water to move if there is no pump? • When water is heated and turns partly to steam, what happens to the density of that mixture compared to the cooler water elsewhere in the boiler? • Which option describes a property that can create a continuous driving force (like a buoyancy effect) rather than just a way of adding heat?

✅ Before You Answer

• Identify which choice describes a fluid property (not just a heat transfer mechanism). • Ask: which mechanism can create a pressure/density difference between risers and downcomers? • Confirm that your choice would still work even if the flame pattern changed slightly, as long as hot and cold regions exist in the boiler.