A heat engine operates with a power output of 10 kW. The engine rejects heat to the surroundings at a rate of 20 kW. What is the efficiency of the engine?

Core Concept

The efficiency of a heat engine is η = W/Q_h, where W is the work output and Q_h is the heat input. From conservation of energy, Q_h = W + Q_c, where Q_c is the heat rejected. Here, W = 10 kW and Q_c = 20 kW, so Q_h = 10 kW + 20 kW = 30 kW. Thus, η = 10 kW/30 kW = 1/3 ≈ 33%.