Heat transfer is a branch of science that deals with the generation, transfer and conversion of thermal energy (or heat) between physical systems. It occurs between two systems that are at different temperatures, with the higher temperature system transmitting energy to the lower temperature one.

Heat transfer can take place in three ways: conduction, convection and radiation. Often, in real-world situations, heat is transferred by all the three modes simultaneously. HVAC systems, heat exchangers, and heat sinks in electronics are a few examples in which heat transfer plays a major role.

In this course, we reviewed some fundamental thermodynamics concepts and established how thermodynamics and heat transfer are complementary branches of thermal science. In simple terms, heat transfer is an extension of thermodynamics to nonequilibrium processes, i.e., the process of energy transfer during the system’s transition to equilibrium. Next, we reviewed the three modes of heat transfer and their mechanisms. Finally, we discussed some key concepts like 1D conduction, the electrical analogy, conduction in extended surfaces like fins of heat sinks and heat exchangers, and unsteady conduction.