🔍 Key Concepts

• Heat transfer in a shell-and-tube heat exchanger (which side has the scale, and how that affects heat flow and temperatures) • Relationship between reduced heat transfer area and the temperature change (ΔT) on each side of the exchanger • How the engine jacket water (fresh water) temperature and raw water outlet temperature respond when cooling becomes less effective while flow rates stay about the same

💭 Think About

• If scale builds up inside the tubes, does heat move more easily or less easily from the fresh water to the raw water? Think about whether the engine’s fresh water will be cooled more or less than before. • With poorer heat transfer but roughly the same raw water flow, will the raw water coming out of the exchanger be hotter, cooler, or about the same as before? How does that affect its temperature rise? • If the engine is making the same amount of heat but the cooler is less effective, what happens to the temperature drop of the fresh water as it passes through the exchanger?

✅ Before You Answer

• Be clear which side is raw water and which side is fresh (jacket) water in the illustration before you decide. • Think about whether excessive scale acts more like an insulator or a conductor for heat between the two fluids. • Check that your choice matches a situation where overall cooling is less effective, not more effective, while the engine is still under load.