Difference between conduction and convection – Table – Definition
We explain the difference between conduction and convection with table. The generation of heat is a process that involves the movement of particles. In simple words, heat can be explained by the work of molecules and the energy emitted by them creates heat or the energy emitted is converted into heat. conduction and convection
For example, when a person exercises or does any other activity, their body heats up and sweat is produced. Or during cooking when the food is heated or heated, it is simply the transfer of heat, by conduction or convection.
The reason behind heat transfer is scientific, it may seem easy and cliche to heat food, but it has scientific reasons behind it. Invisible or microscopic particles become charged and energy is created that is transferred in the form of heat.
The heat transfer process can be direct or indirect, there are also various materials in which heat can be transferred, and in some, it cannot be transferred, for example, not all types of plastic cannot withstand heat. conduction and convection
The difference between conduction and convection is that in conduction heat is transferred directly while heat by convection is transferred through the fluid. Both lead to the emission of heat, but there are differences in method.
Comparison table between conduction and convection conduction and convection
|Definition||Heat transfer between two objects by direct contact.||Heat transfer within the fluid.|
|State of matter||Solid||Liquid or gas|
|Electric current transfer||It allows||It does not allow|
|Particle density||High density||Low density|
|Heat transfer rate||Slow||Faster|
What is driving?
Conduction is the process of transferring heat or current. Conduction is the transfer of energy in the form of heat and current from one atom to another through direct contact.
Conduction can occur in all three states of matter; solid, liquid and gas. The best transfer can occur in the solid state because the atoms are compacted, allowing a faster transfer rate, the density of the molecules affects the rate of heat transfer, on the contrary, liquid and gases are less efficient in heat transfer due to low density of molecules. conduction and convection
There are two types of conduction: heat conduction and electricity conduction.
Heat conduction: when the temperature rises in the molecules, a vibration occurs and this causes heat in the molecules and then heat transfer occurs within the tight molecules. For example, when a heating pad is applied to the skin, it also causes heat in the muscles.
Conduction of electricity: occurs due to the movement of charged particles through any medium. This movement of charged particles causes a current that is carried by charged ions or electrons. For example, when current passes through wires, the wires are made of metal, which is a good conductor of electricity.
There are several factors that affect driving, those factors are; the difference in temperature, length, cross-sectional area, and material. Each material has a different conductivity, for example, aluminum, bronze, copper, water, etc., will have a different conductivity. Metals have the highest conductivity.
Conduction can be calculated through formulas in theory by various methods, for example, using Ohm’s law or Fourier’s law. The heat transfer rate is calculated by these formulas when the conductivity of the material is given. Conduction does not follow the law of reflection or refraction. conduction and convection
What is convection?
Convection is the process of heat transfer through the massive movement of molecules in any fluid. The initial heat transfer between the object and the fluid takes place due to conduction, but then the massive movement of fluid particles creates convection.
The convection process involves thermal expansion, that is, when a fluid is heated from below the surface, the lower layer of liquid heats up and thermally expands, the density of the molecule is higher compared to the liquid on the upper surface . Due to buoyancy, the less dense particles lift the warmer liquid up and the cooler liquid replaces it. conduction and convection
There are two types of convection, those are; natural convection and forced convection.
Natural convection: type of convection in which the difference in temperature causes a difference in densities, that is, where the buoyancy force plays an important role. for example, ocean winds.
Forced convection: a type of convection in which external forces induce convection, for example, fans, water heaters, geyser, etc.
The factors that affect convection are; medium (liquid or gas), temperature, a source that causes heat. One of the differences between conduction and convection is that convection does not support electrical current.
Some examples of convection are; a land breeze (occurs at night), or sea breeze (occurs during the day), fans used to cool the room, heaters used to heat water or steam, etc.
Natural convection cannot be easily calculated, but forced convection can be calculated theoretically using the formula given by Newton’s law of cooling. The formula is:
|P = dQ / dt = hA (T – T0)|
- P = dQ / dt- the rate at which heat is transferred
- h – heat transfer coefficient by convection
- A – exposed surface area
- T – the temperature of the submerged object
- T0 – the temperature of the fluid that is under convection
Main differences between conduction and convection
- Conduction takes place between objects through direct contact, on the other hand, convection takes place through fluid.
- Conduction takes place better in solids, on the contrary, convection occurs better in liquids or gases.
- In conduction, heat is transferred due to differences in temperature, while in convection it is transferred due to differences in density.
- Heat transfer in conduction is slow, on the other hand, heat transfer in convection is fast.
- Conduction is also compatible with electrical conduction, but convection is not compatible with electricity.
Both conduction and convection transfer energy in the form of heat.
Both can be produced naturally or artificially depending on their types.
Conduction and convection work in different states of matter (solid, liquid, and gas). The density of the particles mainly affects conduction and convection.