Thermal engineering is the branch of mechanical engineering that undertakes the study of controlling the heating and cooling processes in an enclosed or open atmosphere. It is mostly used by chemical and mechanical engineers. Thermal engineering encompasses the concepts related to the design, development, and demonstration of components, devices, equipment, technologies, and systems involving thermal processes. These are applied to the production, storage, utilization, and conservation of energy. Thermal engineering borrows concepts from various areas of study such as thermodynamics, fluid dynamics, fluid statics and heat transfer. This book is a compilation of chapters that discuss the most vital concepts and emerging trends in the field of thermal engineering. It picks up individual branches and explains their need and contribution to a growing economy. This book will provide comprehensive knowledge to the readers.