This book provides a practical study of modern heat pipe engineering, discussing how it can be optimized for use on a wider scale. An introduction to operational and design principles, this book offers a review of heat and mass transfer theory relevant to performance, leading into and exploration of the use of heat pipes, particularly in high-heat flux applications and in situations in which there is any combination of non-uniform heat loading, limited airflow over the heat generating components, and space or weight constraints. Key implementation challenges are tackled, including load-balancing, materials characteristics, operating temperature ranges, thermal resistance, and operating orientation. With its presentation of mathematical models to calculate heat transfer limitations and temperature gradient of both high- and low-temperature heat pipes, the book compares calculated results with the available experimental data. It also includes a series of computer programs developed by the author to support presented data, aid design, and predict performance.