Heat exchange is the process of transferring thermal energy between two or more substances at different temperatures. This transfer can occur through conduction, convection, or radiation. In everyday life, heat exchange is commonly observed when a hot cup of coffee cools down in a cooler room or when ice melts in a warm drink. In various applications, such as in HVAC systems or industrial processes, heat exchangers are used to efficiently transfer heat without mixing the fluids involved. These devices help in maintaining desired temperatures, improving energy efficiency, and reducing costs in heating and cooling systems.