How does increasing the number of effects in a Multi-Effect Distillation (MED) system primarily improve its performance?

Increasing the number of effects in a Multi-Effect Distillation (MED) system primarily improves its performance by increasing its thermal efficiency. In MED, seawater is evaporated in a series of vessels called effects, each operating at progressively lower pressures and temperatures. The steam generated in one effect is then used as the heating medium for the next effect. By reusing the heat in this way, MED systems significantly reduce the amount of energy required to produce a given amount of desalin....