Specialized in manufacturing T-shirts for 21 years

conduction, convection and radiation

by:Teesso     2019-09-10
Heat transfer through radiation can be transmitted through infrared radiation.
Different from conduction and convection
Need particles
Infrared radiation is a kind of radiation involving waves.
The light from the Sun reaches the Earth, because radiation can even work through a vacuum in space without the participation of particles.
This is why even if the sun is 0. 15 billion kilometers away from the Earth, we can still feel the heat of the sun.
Different surfaces are better than others in terms of reflection and absorption of infrared radiation.
This table summarizes some of the differences: The surface absorbs the emitted dim, matte, or rough light. You can see that the dim surface is a good absorber and transmitter for infrared radiation.
The glossy surface is a poor absorber and emitter (
But they are good mirrors for infrared radiation).
If two objects made of the same material have the same volume, then thin and flat objects radiate heat energy faster than fat objects.
This is one of the reasons why the home radiator is thin and flat.
The radiators are usually painted with glossy paint, but they heat better if they are painted with matte paint.
Also, despite their name, the radiator actually passes most of the heat to the room by convection rather than radiation.
Thermal radiation research can use a device called Leslie cube to study the transfer of infrared radiation from a hot object to a colder environment.
This is a metal cube prepared in four different ways: black, white, shiny or dim.
It can be filled with hot water, or it can be heated on the electric hot plate so that all sides are at the same temperature.
Methods a thermometer is used to measure the temperature at a fixed distance from both sides of the Leslie cube (
Or use a thermocouple, electrical equipment that generates a potential difference depending on the temperature).
Heat Leslie\'s Cube with boiling water or hot plates.
Within 5 minutes, continue to measure and record the temperature every 30 seconds, and then draw a graph of the temperature and time on each side.
Compare the four graphs obtained.
Keep in mind that the accuracy of the four thermometers may vary, so take this into account when analyzing the results.
Custom message
Chat Online 编辑模式下无法使用
Chat Online inputting...