Heat transfer analysis is needed to optimally design heat exchangers and determine equipment sizes. It is essential for sizing nuclear reactor cores, aircraft performance, refrigeration applications, and solar equipment. Thermodynamic analysis determines the heat required for a state change, while heat transfer analysis evaluates the rate of heat transfer. The three methods of heat transfer are conduction through solids, convection through fluid movement, and radiation through electromagnetic waves. Extended surfaces like fins increase heat transfer area and rates.