Interest in fuel cells and thermally activated (heat pipe heat exchangers) adsorption systems using natural refrigerants and/or alternatives to HFC-based refrigerants has increased significantly. During the last few decades, research aimed at the development of thermally powered adsorption cooling technologies has also intensified. This book covers state-of-the-art adsorption research and technologies for relevant applications based on the use of efficient heat-transfer devices-heat pipes and two-phase thermosyphons-with the objectives of energy efficiency and sustainability. It explores a range of topics, including the heat pipe thermal control of spacecraft.