Preface

Throughout the years, new applications for heat pipes have been discovered. Heat pipes are considered as an effective thermal solution, particularly in high heat flux applications and in situations where there is a combination of nonuniform heat loading, limited airflow over the heat-generating components, and space or weight constraints.

This book is intended to explore some of the recent developments and advances in heat pipes and their applications in thermal systems. The book starts with experimental and numerical thermosyphon heat pipe technology, and then looks at heat pipes and loop heat pipes.

The book should be of interest to engineers and those who intend to do research in this exciting field.

> **Wael I.A. Aly** Professor of Mechanical Engineering, Department of Refrigeration and Air Conditioning Technology, Faculty of Industrial Education, Helwan University, Egypt

**1**

**Figure 1.**

*Number of published documents on heat pipes each year.*

**Chapter 1**

*Wael I.A. Aly*

**1. Introduction**

Introductory Chapter: Recent

Heat pipe is a two-phase flow passive and reliable heat transfer device widely used in thermal systems [1]. It is known that the thermal conductance of heat pipes is higher than any solid conductor due to the accompanying latent heat during the closed two-phase cycle. Moreover, heat pipes have many advantages compared to other heat exchangers: higher amounts of heat transferred over long distance, faster thermal response time, easier design and manufacturing, lower temperature difference, broad temperature range for applications, and easier control which allow transporting high rates of heat at various temperature levels. Also, as a passive device, no external power is required for its operation, and heat pipe is highly reliable and almost requires no maintenance. Because of the mentioned advantages, heat pipes are ideal for many applications. Heat pipe is considered as an effective thermal solution, particularly in high heat flux applications and in situations where there is a combination of nonuniform heat loading, limited airflow over the heat-

After the introduction of heat pipes with the paper *Structures of Very High Thermal Conductance* by the authors Grover et al. [2] in 1964, the interest in the applications of heat pipes has increased remarkably. Currently, a huge amount of documents (research articles, review articles, and books) concerning heat pipes

Advances in Heat Pipes

generating components, and space or weight constraints.

### **Chapter 1**
