Present day technology is vibrant and changing rapidly. But the essential characteristics remain the same; when a fuel is burnt, the aim will always be to completely burn it and derive maximum heat out of it. A furnace and its refractory linings are must to utilize the fuel. When the fuel is burnt and some process(s) are performed in the furnace, it becomes a consequential necessity to measure the temperature in the furnace, to have a proper control over the operations. An effort is made to give the students a deep insight into the utilization of fuels, with some fundamentals, essential to have a grasp of the subject. This book thus tries to encompass the fuel utilization to a satisfactory level. Salient features · Units are converted to S.I. Units from CGS or FPS systems · More material is added in Nuclear and Solar Energy topics