Modelling in Transport Phenomena: A Conceptual Approach aims to show students how to translate the inventory rate equation into mathematical terms at both the macroscopic and microscopic levels. The emphasis is on obtaining the equation representing a physical phenomenon and its interpretation. The book begins with a discussion of basic concepts and their characteristics. It then explains the terms appearing in the inventory rate equation, including ""rate of input"" and ""rate of output."" The rate of generation in transport of mass, momentum, and energy is also described. Subsequent chapters detail the application of inventory rate equations at the macroscopic and microscopic levels. This book is intended as an undergraduate textbook for an introductory Transport Phenomena course in the junior year. It can also be used in unit operations courses in conjunction with standard textbooks. Although it is written for students majoring in chemical engineering, it can also serve as a reference or supplementary text in environmental, mechanical, petroleum, and civil engineering courses.