🔍 Key Concepts

• Evaporator operation in freshwater generators or distillation plants • Effect of scale (mineral deposits) on heat-exchanger performance • Relationship between heat transfer surfaces and system efficiency

💭 Think About

• What physical effect does a layer of scale have between the hot medium and the water being evaporated? • If heat transfer becomes more or less efficient, how would that impact evaporation rate and overall system performance? • Consider whether scale acts more like an insulator or a conductor, and how that would change the behavior of the evaporator.

✅ Before You Answer

• Identify whether scale improves or worsens heat transfer across metal surfaces • Think about how insulating layers generally affect temperature differences and energy flow • Eliminate any options that describe a beneficial effect that doesn’t logically follow from adding a crusty, non-metal layer to a heat-exchange surface