Heat transfer in nature allows the universe to exist in the form to which we are all accustomed to.It's hard to say how the world would look like, disappear heat transfer for a moment.Let's take a closer look at what are the different types of heat transfer, and what is meant by the term.
generally accepted definition, the heat transfer is a physical process in which heat energy is one way or another is shared between several bodies with varying degrees of heat.The process is stopped during the alignment temperature or, in other words, upon reaching thermodynamic equilibrium.
enumerate what are the basic types of heat transfer: convection, heat conduction, radiation.All other possible variations are a combination of two or several basic ways.This point must always be taken into account.
Convection is familiar to everyone since childhood.Needless Latin word «convectio» means the transfer.Consequently, in the case of convection heat transfer flow of material.It is typical for gases and liquids, but sometimes occurs in some bulk materials.Imagine a hot summer day above the heated ground noticeably slight haze - this distortion is due to rising air currents.At nightfall, when the heating effect of sunlight stops, begins the process of leveling the surface temperature of the earth and air: According to soil heat the lower layers of the atmosphere (it's a mixed mechanism of heat transfer) that rise up and replaced by colder air masses.Here's another example: put a heater in a container with water and turn it into the net.A careful observation of visible moving streams of water.Hot mass displaced from the heat source, and in their place come the colder.
What could be better than an interesting chat over a cup of hot tea on a cold winter night?It is sufficient to momentarily distract and take up peeking edge metal spoon to quickly draw back the hand to avoid burns.The reason is simple - some types of heat very quickly heated to a temperature of a metal spoon in a cup of water.It is a thermal conductivity.Situations in which you can meet with this type of heat transfer, a huge amount.We give the definition: the thermal conductivity - is the transfer of heat from a warmer part of the body to a colder body components through particles (electrons, atoms, molecules).A special case - the transfer of heat between different objects in contact.Different materials have different thermal conductivity.So, if the heat one end of a piece of wood, the second will be cold.But if you do this experiment with a metal rod, the result is the opposite.This difference is due to differences in the internal structure of materials.
Considering the types of heat transfer, not to mention the transfer of heat by radiation.The heat source generates electromagnetic waves with a wavelength of up to 1000 microns (infrared part of the spectrum).The intensity of radiant flux and the temperature of the heated body are directly related.To understand how the radiation heat transfer is sufficient to conduct a little experiment - to light a fire and put between himself and the fire transparent glass.Although the barrier, heat will still be transmitted.Or look at a cat that winter is on the window sill in the sun soaking.It's simple - in these examples, the thermal energy is transferred by radiation.One feature of this method of heat transfer - independence from the intermediate media.If transfer occurs by convection of the substance (gas), while the thermal conductivity - particles, the radiation does not need a "mediator".So, the sun passes its heat through a vacuum is through radiation.
