ASSIGNMENT HELP ON HEAT EXCHANGER PROJECT REPORT

ABSTRACT

Heat transfer plays a major role in industries. In this we had explained about how the heat exchange takes place between two surfaces and various types adopted to heat exchangers to heat exchangers that are using by many industries.

Generally heat exchanger is used to estimate the amount heat exchange between the surfaces or two substances. In this we use tabular and shell type heat exchangers. The other type of heat exchanger which is rarely used is spiral heat exchanger.  

INTRODUCTION:

A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact.[1] They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment. One common example of a heat exchanger is the radiator in a car, in which the heat source, being a hot engine-cooling fluid, water, transfers heat to air flowing through the radiator (i.e. the heat transfer medium).The process of heat exchanger between two fluids that are at different temperatures and separated by a solid wall occurs in many engineering applications. In this we consider the principals of heat transfer needed to design and or evaluate the performance of a heat exchanger. 

Flow arrangement:

There are two primary classifications of heat exchangers according to their flow arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side. In counter-flow heat exchangers the fluids enter the exchanger from opposite ends. The counter current design is most efficient, in that it can transfer the most heat from the heat (transfer) medium. See countercurrent exchange. In a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger.

For efficiency, heat exchangers are designed to maximize the surface area of the wall between the two fluids, while minimizing resistance to fluid flow through the exchanger. The exchanger's performance can also be affected by the addition of fins or corrugations in one or both directions, which increase surface area and may channel fluid flow or induce turbulence.

The driving temperature across the heat transfer surface varies with position, but an appropriate mean temperature can be defined. In most simple systems this is the "log mean temperature difference" (LMTD). Sometimes direct knowledge of the LMTD is not available and the NTU method is used.