Heat transfer is the movement of thermal energy from one object or system to another due to a temperature difference. This can occur through conduction, convection, or radiation.
Heat transfer is caused by the natural tendency of heat to flow from a warmer object to a cooler object until both reach the same temperature. This process is driven by the second law of thermodynamics.
The rate of heat transfer is measured in units of power, such as watts, and is typically denoted by the symbol Q. The specific heat transfer rate, or heat flux, is measured in units of power per area, such as watts per square meter.
The three types of heat transfer are conduction, convection, and radiation. Conduction is the transfer of heat through a solid material. Convection is the transfer of heat through a fluid, either through the movement of the fluid itself or through forced convection, such as a fan. Radiation is the transfer of heat through electromagnetic waves.
Heat transfer problems can be solved using mathematical equations and principles, such as Fourier's law for conduction, Newton's law of cooling for convection, and the Stefan-Boltzmann law for radiation. These equations can be used to calculate the heat transfer rate and temperature distribution within a system.