It is approximately 10 years since the Third Edition of Heat Pipes was published and the text is now established as the standard work on the subject. This new edition has been extensively updated, with revisions to most chapters. The introduction of new working fluids and extended life test data have been taken into account in chapter 3. A number of new types of heat pipes have become popular, and others have proved less effective. This is reflected in the contents of chapter 5. Heat pipes are employed in a wide range of applications, including electronics cooling, diecasting and injection moulding, heat recovery and energy conservation, de-icing and manufacturing process temperature control, and chapter 7 discusses some of the latest uses, while retaining full data on those established for many years. Appendices have been updated, as appropriate.