🔍 Key Concepts

• Heat transfer in shell-and-tube coolers (how heat moves from lube oil to cooling water) • Effect of restricted water flow or dirty cooling surfaces on oil operating conditions • Meaning of TBN number, viscosity, temperature, and foaming in lube oil analysis

💭 Think About

• If the water side of the cooler is partially blocked with scale and dirt, what happens to heat transfer from the oil to the water over time? • Which lube oil property would show a gradual, steady change during operation as the cooler becomes less effective, even if the oil itself has not chemically degraded? • Which of the listed properties is most directly and immediately affected by reduced cooling, rather than by contamination or aging of the oil?

✅ Before You Answer

• Be clear on what TBN (Total Base Number) actually measures and whether it would change due to poor cooling alone • Consider whether viscosity or foaming would necessarily change just because the cooler tubes are scaled, without any change in oil condition • Focus on the lube oil parameter that is most directly tied to the cooler’s ability to remove heat from the oil