HEAT PIPE

HEAT PIPE

ABSTRACT:

The transfer of the heat energy by conduction using solid material is essentially limited by thermal conductivity of that material. As the thermal conductivity increases cost of the material also increases hence it become costly. Because of the thermal energy is being transported by evaporation–condensation process rather than conduction. The heat pipe can transfer the heat much more effectively than the solid conductor of the same cross-section in practice conduction of heat by heat pipe may be several hundred (500) times that the best available metal conductor such as copper.

Heat pipe system provides the maximum effective heat sink surface area with the minimum volume demand. A heat pipe heat sink is a passive cooling device that requires no moving parts, and operates silently and reliably. Additionally, heat pipe technology is emerging as a cost-effective thermal design solution. This paper explains the operation of heat pipes and its various applications.

Introduction:

What is a Heat Pipe?

A heat pipe is a simple device that can quickly transfer heat from one Point to another. By means of evaporation & condensation of fluid in a sealed system they are often referred to as the "superconductors" of heat as they possess an extra ordinary heat transfer capacity & rate with almost no heat loss.

It consists of a sealed aluminum or copper container whose inner surface have a capillary wicking material. The working fluid is placed inside it &it is highly evacuated. Because of that the working fluid is virtually in a state of liquid-vapour equilibrium. consequently, a slight increase in temperature will cause it to boil &evaporate The central portion of it is heavily insulated on the outside. One end of pipe is known as heating end (evaporator) where heat is absorbed & the other end is known as cooling end (condenser) where heat is given out.

A heat pipe is similar to a thermosyphon. It differs from a thermosyphon by Virtue obits ability to transport heat against gravity by an evaporation –condensation cycle with the help of porous capillaries that form the wick. The wick provides the capillary driving force to return the condensate to the evaporator. The quality and type of wick usually determines the performance of the heat pipe, for this is the heart of the product. different types of wicks are used depending on the application for which the heat pipes being used


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