Construction of a Model Shell and Tube Heat Exchanger
Chapter One
AIMS OF THE STUDY
The study is being carried out in order to:
- Make appropriate thermal control in the chemical industries since the most important aim in the chemical engineering sector of any plant is to control the flow of thermal energy between two thermal.
- Enable us to predict the amount of energy required to change a system from one equilibrium state to another
- Examine some of the techniques through which heat is transferred from one fluid stream to another.
- Know the rate at which the exchange of heat take place.
CHAPTER TWO
LITERATURE REVIEW
HISTORICAL BACKGROUND OF HEAT EXCHANGER
The first commercially successful plate-and frame heat exchanger in the world was introduced in 1923 by Dr. Richard Sehigman, the founder of Aluminum plate and vessel company ltd, commonly known today as APV, the very first paraflow was constructed of cast gumetal plates and enclosed within a frame that set the standard for today’s computer-designed thin metal plate heat exchanger known around the world.
A heat exchanger equipment, otherwise called a heat exchanger is a device used primarily for transferring heat energy between the fluids which are at different temperature (Owen 1985).
TYPES OF HEAT EXCHANGER
There are various types of heat exchanger equipment generally defined by the function it performs in a chemical industry, they are:
- REGENERATORS
- OPEN-TYPE HEAT EXCHANGER AND
- CLOSED-TYPE HEAT EXCHANGER OR RECUPERATOR
A) REGENERATORS
These are heat exchangers in which the hot and cold fluid through the same space alternatively with a little physical mixing as possible occurring between the two streams. The amount of heat transferred depends on the fluid and flow properties of the fluid streams as well as the geometry and thermal properties of the surface.
b) OPEN-TYPE HEAT EXCHANGERS
These are devices where by fluid stream flow into an open chamber and there the complete mixing occurs. Hot and cold fluid enter the exchanger separately and will at the other end leave as single fluid stream.
CHAPTER THREE
METHODOLOGY
Construction of a shell and tube heat exchanger (Portable type).
COMPONENTS:
- Small pipes of a known dimension (i.e tube bundle with straight tubes).
DIMENSIONS:
- Length of the small pipes è500mm
- Diameter of the small pipes è20mm
- Flanges (i.e. tube a sheet)
DIMENSIONS:
- Diameter è160mm
- Diameter of the holes in flanges (i.e. for nut and bolts) è8mm
- Big pipe of a k when dimension (i.e. shell or housing)
DIMENSIONS:
- Length è650mm
- Diameter è120mm
- Nut and bolts
INTRODUCTION: SHELL AND TUBE HEAT EXCHANGER
Shell and tube heat exchangers are a type of heat exchanger that have a bundle of tubes inside or shell or housing. Fluids at different temperatures run through the shell and the tubes. As the fluid pass through the respective chambers, heat exchange take place between them.
Heat exchangers are devices that help in efficient heat exchange from ne medium to another. the media are separated from each other with solid material so that they newer mix with each other. These devices are widely used in refrigeration, air conditioning, different types of power plants and natural gas processing units.
CHAPTER FOUR
DISCUSSION
The purpose of this project is to construct a model shell and tube heat exchanger.
Heat exchanger as stated earlier is a device used for the cooling and heating of fluid. The construction type a model shell and tube exchanger whole parts which include- shell, tubes flanges bonnets baffles, bolts and net etc are normal fixed together to effect efficiency in operation.
There is a standard for the dimension of the tubes for heat exchangers. Any derivation from this standard will effect the performance of the equipments. The constructed heat exchanger was not of the standard dimensions due to minor errors encountered during the fabrication.
The shell side of the tubular heat exchanger is the external part of the exchanger. It is always desired to be made of any material with low thermal conductivity, high resistance to wear and corrosion. From the research findings from text and other research centres, I was shown that heat exchanger (tubular) shell are thick with a minimum thickness of about 9-5mm and length of about 16ft and above. It was also found from research that the shell side is often made of stainless steel. The constructed one was made with a carbon steel instead of the stainless steelens discussed the earlier due to cost.
The tube bundle are the most important part of the tubular heat exchanger. It consists of tubes, tube plates and floating heat. From research work, the tubes are made of materials that posses high thermal conductivity and high resistance to corrosion and wear. Cooper has been found to be the material that posses these qualities which is a factor needed by the tube for effective transfer of heat energy from fluid in the tube to that in the shell side.
Baffles are means through which the direction of the flow of the shell fluid is made possible across the tube bundle in order to obtain’ high heat transfer co-efficient. They are usually arranged perpendicular to the shell axis to increase the velocity of the fluid over the tube, baffles are properly fitted across the tube bundle.
To effect good and easy cleaning of the outside of the bundle, proper choice of pitch arrangement was made. A square pitch while permit cleaning easily of tubes was used. There is also an alternative which services of functions when a very clean fluid is used ie triangular pitch.
CONCLUSION
To successfully construct a model shell and tube heat exchanger which can be used industrially, thermal considerations, general design considerations pressure drop, flow pattern and most expediently cost of materials and economic factors should be strictly adhered to because the sole aim of any engineering construction is to produce an equipment with high performance or efficiency at the least cost.
RECOMMENDATION
The production of this equipment though complex was not supposed to be as tedious as it was. This is as a result of the production site inadequacies which is the IMT industrial centre. Effort should be intensified to make sure that the “centre” workers are always available to attend to students in order to remove this hitches.
The equipment is recommended for use in the students laboratory demonstration so that students can well visualize how a model shell and tube heat exchanger looks like and how it works.
REFERENCES
- Louis Gary Lamit “Piping systems, drafing and design” 2nd edition, 1972.
- Engr. Abalu B. N. Heat Transfer 1st Edition 2006
- L. Earle Unit operation in food processing 1983 pages 23-30, 64-68
- McCabe and Smith Unit operation of chemical engineering 6th edition (2001).
- P. Holman Heat Transfer 5thEdition(1981).