Thermodynamics is a branch of physics that deals with matter and conversion of energy. Engineering thermodynamics is a subject of mechanical engineering that involves applying the principles of thermodynamics to engineering design of processes, devices, and systems, which involve effective utilization of energy and matter. Conversion between heat and work is fundamental in engineering thermodynamics. Entropy refers to a measurable physical characteristic and a scientific concept that is connected to a state of uncertainty, unpredictability or disorder. It is utilized in a variety of fields, including the principles of information theory, classical thermodynamics, and the microscopic description of nature in statistical physics. Entropy is central to the second law of thermodynamics, which asserts that the entropy of isolated systems left to unstructured expansion cannot decrease over time. This is due to the isolated systems always reaching thermodynamic equilibrium with the highest entropy. Different scenarios involving entropy production such as optimizing power and waste heat reduction can be studied by taking the help of simulation tools. This book aims to shed light on some of the unexplored aspects of engineering thermodynamics and the latest researches on simulation with entropy. It will serve as a valuable source of reference for graduate and postgraduate students.