1.1 Introduction
A heat exchanger is a thermal device that enables the exchange of heat between a solid and a fluid or between two or more different fluids. Heat exchangers are used in car radiators, air conditioners, refrigerators, chemical industries for processes involving distillation, fractionation, etc. Heat exchangers are also used in pulp and paper, power generation, pharmaceuticals and food and beverages processing industries. A shell and tube heat exchanger is one of the most popular types of exchangers due to its flexibility. In this type, there are two fluids with different temperatures, one of them flow through tubes and another flow-through shell. Heat is transferred from one fluid to another through the tube walls, either from the tube side to the shell side or vice versa. This system handles fluids at different pressures; higher pressure fluid is typically directed through tubes, and lower pressure fluid is circulated through a shell side.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Heat exchanger is a device in which heat is transferred from one fluid stream to another normally by the combined process of conduction and convention. Heat exchangers are the most important item in many thermal systems (Abalu 2006). Heat exchangers are widely used in manufacturing and process industries for several applications. The choice of heat exchanger for a given application is dependent on several factors. In a highly competitive environment, it is essential that the heat exchanger must deliver the required heat transfer, occupy less space, weigh less, and yet be priced competitively.
A shell and tube heat exchanger is made up of a tube bundle mounted in a shell. The tube bundle contains fluid that could be either heated or cooled, while the fluid flowing over the tube bundles contains fluid that could either be cooled or heated. Usually, two fluids of different starting temperature flow through the heat exchanger; these fluids could either be liquid or gas. Heat is transferred from one fluid to the other through the tube walls. Besides the shell and tube bundle, other parts that make up the heat exchanger include: tube sheet, baffles, tie rods and spacers, and headers.
Since our major concern is construction of model shell and tube heat exchanger, which is a type of recuperates or closed-type heat exchanger, model shell and tube heat exchangers constitute the bulk of unfired heat transfer equipment used in chemical process plants. They are found in different forms as fixed - tube-sheet heat exchanger, u-tube heat exchanger, floating heat exchanger, and internal floating heat exchanger. They can be inform of; double-pipe heat exchangers. Plate-type heat exchangers, air-cooled heat exchangers and graphite block heat exchangers (Harriot 1985).
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to design and construct a Model Shell and Tube Heat Exchanger.
1.3 Statement of Problems
There are some problems associated with the study of heat exchanger:
- Time: Due to lectures and other school activities like practical's and assignments we do not normally have enough time to visit the library and cyber cafe for the study of modern shell and tube heat exchanger.
- Browsing Problem: When browsing, sometimes there is network problem in the sense that the result will not come out easily, sometimes it will not be easy to fish-out the main thought in the outcome.
- Cost: There is high cost of construction of a modern shell and tube heat exchanger and browsing for the study.
1.4 Aim and Objectives of Study
The aim of the study is to Design and Construct of a Model Shell and Tube Heat Exchanger. In achieving this aim, the following specific objectives were laid out as follows:
- To predict the amount of energy required to change a system from one equilibrium state to another
- To know the rate at which the exchange of heat take place.
- To examine some of the techniques through which heat is transferred from one fluid stream to another.
- 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.
1.5 Significance of Study
The future developments in the aerospace industries will hinge mainly upon the case with which structures and engines can be cooled; modern electrical and electronic plants require efficient dissipation of losses converted to thermal energy; the design of chemical engineering plant is usually governed by heat transfer and the analogues mass transfer processes and even civil engineers must take account of thermal effects in buildings and structures.
This study will be of immense benefit to academic students and other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The scope of the research is focused on the Design and Construction of a Model Shell and Tube Heat Exchanger.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection.
1.8 Methods of Research
Since the major concern is the construction of model shell and tube heat exchanger, the research method used was mainly constructional method of model shell and tube heat exchanger.
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