Energy, Entropy and Engines: An Introduction to Thermodynamics is an introductory textbook on thermodynamics for engineering students. Its most important objective is to help students grasp the meaning of concepts such as energy, entropy, equilibrium and reversibility, which form the foundation of engineering science. It uses simple, direct language and relies on physical rather than mathematical definitions. Each new concept is explained starting from first principles, and only after explaining why it is necessary. This book introduces entropy and the second law of thermodynamics using both microscopic and macroscopic viewpoints, and makes the links between them clear. Simple analogies are used to explain the concept of entropy at a molecular level and why the second law is a consequence of the laws of probability, without requiring expertise in statistics. Once students are comfortable with the idea of entropy, learning thermodynamics becomes much easier. Starting with four fundamental concepts (mass, volume, energy, entropy) and four postulates (state postulate and the first, second and third laws) thermodynamic definitions of temperature and pressure are derived. An analysis of liquid-vapour phase equilibrium is used to derive the relation between saturation temperature and pressure and introduce saturation property tables.