Heat transfer ppt

The latent heat contained in steam is released in the instant the steam condenses into liquid phase. Most insulation is used to prevent the conduction of heat. This is the idea behind a styrofoam coolers, the air pockets between the styrofoam beads do not conduct heat very well.

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Thermal conductivities vary considerably, ranging from metals that have high values, through non-metallic solids and liquids, to gases that have the lowest values.

The metal molecules are conducting your body heat away from your hand quickly. Single- pass tubular heater Fixed-head heat exchanger Floating-head heat exchanger. My presentations Profile Feedback Log out. Within certain limits, the higher the number of the tubes in the bundle, the greater will be the total surface area offered for heat transfer.

It is used as a standard way of telling how good a material will insulate. The movement of the steam towards the outlet will carry these droplets away into the steam system.

In some cases radiation is a factor. Water being a better conductor of heat than dry steam, will act as a conductor between the steam and the metallic pipe, setting up active condensation and preventing economical working of boiler.

They support the long tubes and the tube sheets and prevent their weakening. That means the transfer of energy of one atom to the next is more effective.

So, for a given steam pressure, the heating medium ppr at a constant temperature.

This increase in energy can flow through materials and from one material to another. Convection is possible only in a fluid medium.

Auth with social network: This preserves a maximum temperature difference between the heating medium and process, which maximizes the heat transfer rate. This fraction is called reflectivity r Scattered Scattered light is deflected transter all directions, forward, backward, sideways.

The transfer of heat is caused by the process of condensing steam. The loss by radiation is a function of the fourth power of the absolute temperatures of ppt body and surroundings and will be small for low temperature differences but will increase rapidly as the temperature difference increases.

Shorter wavelengths carry more energy than longer wavelengths.

The conservation of heat and hence usually of steam is an economic necessity and some form of lagging should normally be applied to hot surfaces. The total heat of wet steam will be made up of h sensible heatf dryness fraction and L latent heat.

In an exchange, the shell-side and hheat transfer coefficients are of comparable importance, and both must be large if a satisfactory overall coefficient is to be obtained. An interesting fact is that poor conductors of electricity are also poor heat conductors.

That is why bundles of loosely trasnfer fiberglass strands are often used as insulation between the outer and inner walls of a house.

HEAT TRANSFER.

A hot storage vessel or a steam pipe will lose heat to the atmosphere by radiation, conduction and convection. Radiant energy is the energy that propagates through space or through material media in the form of electromagnetic radiation.

As they do their temperature increases and they begin to bump into the molecules next to them. The friction between the wall and the flowing fluid reduces its velocity to zero. These waves are called Electromagnetic Waves, because the energy travels in a combination of electric and magnetic waves. When saturated steam condenses, it condenses at the saturation temperature, and the saturated water condensate formed is of the same temperature as the saturated steam.

HEAT TRANSFER. - ppt download

We think you have liked this presentation. The Stefan-Boltzmann law tells us that as the temperature of an object increases, trznsfer radiation is emitted each second. Fiberglass is not a good conductor nor is air.

When the fluid motion arises artificially by an agitator or pump, and is known as forced convection.

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