Heat creation is a process that involves particle motion. Heat is explained in simple terms by the activity of molecules, and the energy emitted by them causes heat or is turned into heat.
When a person exercises or engages in any other activity, their body heats up and perspiration is created. It’s simply the transfer of heat, whether through conduction or convection, when food gets warm or heated during cooking.
The reason for heat transfer is scientific; it may appear simple and cliche to warm food, but there are scientific reasons for it. Energy is formed when invisible or tiny particles are charged, and this energy is transferred in the form of heat.
Heat transmission can be direct or indirect, and there are a variety of materials in which heat can be transferred and others in which it cannot, for example, not all forms of plastic can withstand heat.
Conduction Vs. Convection
The distinction between conduction and convection is that heat is transported directly in conduction, whereas heat is transferred through a fluid in convection. Both result in the emission of heat, but the methods are different.
What is Conduction?
The process of transferring heat or current is known as conduction. Conduction is the direct movement of energy from one atom to another in the form of heat and current.
Solid, liquid, and gaseous forms of matter can all conduct electricity. The best heat transfer occurs in the solid-state because the atoms are tightly packed, allowing for a higher rate of transmission. The density of molecules affects the rate of heat transfer, whereas liquids and gases, on the other hand, are less efficient in heat transfer due to low molecule density.
Conduction can be divided into two types: heat conduction and electrical conduction.
When the temperature of molecules is raised, a vibration is produced, which creates heat in the molecules, and then heat is transferred inside the densely packed molecules. When a heating pad is placed on the skin, it generates heat in the muscles as well.
The movement of charged particles through any medium causes conduction of electricity. A current is created by the movement of charged particles, which is carried by ions or charged electrons. When current runs via wires, for example, the wires are constructed of metal, which is an excellent conductor of electricity.
Conduction is influenced by a number of elements, including temperature differences, length, cross-sectional area, and the material. Every material has a varied conductivity, such as aluminium, bronze, copper, water, and so on. The highest conductivity is found in metals.
The conduction can be computed using a formula in theory using a variety of ways, such as Ohm’s law or Fourier’s law. When the material’s conductivity is known, these formulae can be used to compute the rate of heat transfer. The law of reflection or refraction does not apply to conduction.
What is Convection?
Convection is the transmission of heat from one fluid to another by the bulk movement of molecules. Conduction is responsible for the initial transfer of heat between the item and the fluid, but convection is responsible for the bulk movement of fluid particles.
The process of convection involves thermal expansion, which means that when a fluid is heated from below the surface, the lower layer of liquid is heated and thermally expanded, resulting in a higher molecular density than the liquid on the upper surface. Because of the buoyancy of the less dense particles, the hotter liquid rises and is replaced by a colder liquid.
Natural convection and forced convection are two different types of convection.
Natural convection is a type of convection in which a difference in temperature generates a difference in densities, and buoyant force is a big part of it. Take, for instance, marine winds.
Forced convection is a type of convection in which external forces, such as fans, water heaters, and geysers, generate convection.
Medium (liquid or gas), temperature, and a heat source are all factors that influence convection. Convection does not support electric current, which is one of the contrasts between conduction and convection.
A land wind (occurs at night) or a sea breeze (occurs during the day), fans used to cool the room, heaters used to heat water, or steamers, are all instances of convection.
Natural convection is difficult to calculate, however forced convection may be computed mathematically using Newton’s law of cooling’s formula. The formula is as follows:
|P =dQ /dt =hA(T−T0)|
P= dQ /dt- the rate at which heat is transferred
h – convection heat-transfer coefficient
A – exposed surface area
T – the temperature of the immersed object
T0 – the temperature of the fluid which is under convection
Difference Between Conduction and Convection
- Conduction occurs when two items come into direct touch; on the other hand, convection occurs when a fluid is present.
- Conduction is more efficient in solids, but convection is more efficient in liquids or gases.
- Heat is transferred via conduction due to temperature differences, whereas heat is carried by convection due to density differences.
- Heat transfer in conduction is sluggish; whereas, heat transfer in convection is rapid.
- Conduction and convection both support electric conduction, but convection does not.
Both conduction and convection transport energy in the form of heat. Depending on the type, they can be created naturally or artificially. In distinct states of matter, conduction and convection work ( solid, liquid and gas). Conduction and convection are heavily influenced by particle density.