HEAT TRANSFER

INTRODUCTION 

Heat move is the course of the development of energy because of a temperature distinction. The energy that causes molecules to move is heat. Molecules that have more heat energy move faster than those that have less heat energy. Heat will always move toward the cooler object or substance from the warmer one. Until the two things are the same temperature, this heat transfer will continue.

MODES OF HEAT TRANSFER 

Conduction, convection, and radiation are the three modes of heat transfer. All modes of heat transfer involve moving from a high-temperature medium to a lower-temperature one, requiring a temperature difference.

Conduction:-

Conduction is the process of moving through stationary fluids or solids. Conduction is the process by which heat is transferred through the skin when you touch a hot object. The conduction of heat is explained by two mechanisms: particle collision and lattice vibration. A combination of the two mechanisms results in the passage of heat through solids: heat is directed through writing material liquids essentially by atomic crashes.

Similar to springs, atoms in solids are linked to one another by a series of bonds. Atomic movements are more pronounced on the hot side of a solid when there is a temperature difference. Through the springs, the vibrations travel to the solid's cooler side. All of the atoms are vibrating at the same energy when they reach equilibrium.

Free electrons are present in all solids, particularly metals. These electrons are not attached to any particular atom and can freely move around the solid. On the hot side of the solid, electrons move more quickly than on the cooler side. During a series of collisions between the electrons, the faster ones give the slower ones some of their energy. Through a series of random collisions, equilibrium is reached, where the average velocity of the electrons is the same.

Electron collision is more efficient than lattice vibration for conductivity; Metals are generally better heat conductors than ceramics, which have fewer free electrons, because of this. The thermal conductivity, or k, of a material is used to measure how effectively heat is transferred through it. For instance, a deep fryer uses conduction heating because the hot oil cooks the food when it comes into direct contact with it.

Convection:-

CONVECTION Heat transfer between a surface and a moving fluid at different temperatures is referred to as convection. Heat is transferred through convection by the motion of fluids. In a commonplace convective intensity move, a hot surface warms the encompassing liquid, which is then moved by smooth motion like breeze.

For instance, when a pot of water is brought to a boil on the stove, conduction heat warms the pot, heating the water molecules within. Convection moves these molecules away from the pot's interior as they are replaced by cooler molecules as they heat. Convection heat transfer occurs within the water as a result of this constant current.

Radiation:-

Radiative heat transfer does not necessitate the passage of a medium; Consequently, it is the only method of heat transfer found in a vacuum. It makes use of electromagnetic radiation (photons), which are emitted by anything with a temperature above -273 degrees Celsius and travel at the speed of light.

The electromagnetic range characterizes radiation as indicated by frequencies of the radiation. From short to long wavelengths, the most common types of radiation are: ultraviolet (UV), visible light, infrared (IR), microwaves, and radio waves are all examples of gamma rays. Shorter wavelength radiation is more energetic and contains more heat. While visible light, which has wavelengths of 10-7 m, contains less energy and has little effect on life, X-rays, which have wavelengths of 10-9 m, are extremely energetic and can be harmful to humans.  

Take, for instance, making dinner in the microwave.