ABSTRACT
This write up focuses attention on a detailed report and
account on the process of construction and formulation of plan for the actual
and physical realization of the construction of the project work captioned
fabrication and construction of a mobile cooling system. The report is therefore divided into chapters
and each chapter discussed extensively such that an illiterate refrigerator
mechanic who read and comprehends the report can easily carryout the
construction of refrigerator under little guidance and supervision.
Subsequently, the principles of
influencing the operation of a cooling system, choice of materials, various
methods used in the fabrication and recommendation for advancement were duely
treated.
Therefore, as the cooling system
composed of mechanical and electric all parts, a lot of effort were made to
break and discuss the various stages and sequences of assembly. Stating a quite number of safety rules which
must be adhered strictly to by and intended person or persons, who may embark
on the project in future to achieve a positive result.
Finally, this write up also
encompasses the maintenance of any cooling system irrespective of the size and
make without limiting it to only mobile refrigerator, with due consideration
that we are in the modern age of refrigeration due to the gradual destruction
of the ozone layer, so that any person who seized the opportunity of reading
through the report can maintain such equipment no matter the size and
complexity with ease and save himself from being overheated by the sun.
TABLE OF CONTENTS
Title page
Letter of
transmittal
Approval
page
Dedication
Acknowledgement
Abstract
Table of
contents
CHAPTER
ONE
1.0 Introduction
1.1
Purpose Of Construction
1.2
Importance And Specification Of Project
1.3
Scope And Limitations
1.4
Statement Of Problems
CHAPTER
TWO
LITERATURE REVIEW
2.0 The History Of Refrigeration
2.1
The Reversed Cannot Cycle
2.2
Condition At The Compressor Inlet
2.3
Sub Cooling Of The Condensed Vapour
2.4
Selection Of Material
CHAPTER
THREE
3.0 Construction Details
3.1
General Safety Rule
3.2
Construction Method And Procedure
3.3
Laying Of Evaporator Pipe (Piping)
3.4
Lagging
3.5
Electrical System In The Fridge
3.6
Description Of The Unit/Principle Of Operation
CHAPTER
FOUR
4.0 Construction Analysis
4.1
Heat Leakages Through The Boundaries
4.2
Refrigeration
4.3
The Evaporator
4.4
The Evaporator Capacity Size
4.5
The Condenser
4.6
The Capillary Tube Size
4.7
Co-Efficient Of Performance
CHAPTER
FIVE
Summary
Recommendation
Conclusion
References
CHAPTER
ONE
1.0 INTRODUCTION
A mobile refrigerator is not a different refrigerator
than a refrigerator that is portable (ie it can be moved fro one place to
another with little application of force).
Here, the
mechanical refrigeration has to do with the production of a machine that
controls a temperature lower than atmospheric temperature. This implies that it is t he process of
removing heat at a low temperature level
and rejecting it at a relatively higher temperature level.
By its
nature, heat flows from a body at a higher temperature to anot her at a lower
temperature but in the reverse case, it requires external energy to be
accomplished. T he carrier substance used to carry heat is called a
refrigerant. Therefore refrigerator is
the reversed heat engine cycle.
Refrigeration
is accomplished by various methods, such as the vapour compression system,
absorption system, and steam jet refrigeration cycle. In this project only vapour compression
system of refrigeration shall be discussed as it was the method adopted to
accomplished the refrigeration.
Refrigeration
contributes to the raising of living standard of people of all classes and
land. Although refrigeration is primarily
an of thermodynamics, but advances made refrigerant in recent years to grow
into so many phrase where we need technicians, craft persons, engineers,
scientists, and others from phases of engineering pool skills and knowledge in
the design, manufacturer application and operation of the refrigeration. Complete knowledge of thermodynamics and
properties of refrigerants must be known before the complete cycle analysis can
be made.
The
application of the refrigeration principle is limitless. The most common used and ones that is readily
recognized is the preservation of food and chilling of our drinks and water
during the time we are feeling hot and need our body to be chilled.
1.1 PURPOSE
OF CONSTRUCTION
The main
objectives of the this project is to achieve the following purpose viz:
a.
To construct and fabricate a portable domestic cooling
equipment that would be easy to be moved to any convenient position.
b.
To construct a cooling/freezing system that is
efficient with little or no complexity in maintenance.
c.
To construct cooling system that will be mobile,
economic and cost effective that even a common man can afford.
d.
To produce a machine that will make life easier and
more comfortable to live, even in a hot environment, and season.
e.
To construct a portable cooling system equipment with
a reduced weight.
1.2 IMPORTANCE AND SPECIFICATION OF PROJECT
The importance attached to this construct is the
accomplishment of a fast freezing
system without breaking of bottles at very low temperature and without adverse
effects on the food tissues, the flavour, freshness and natural nutrients of
food materials. The construction
intention is based on reduced weight and cost, longer life span, fast freezing
techniques, compactness, portability and so on, while constructing this project
we put into consideration the Nigeria
factor and possibility of expanding and marketability and its adverse effects
on our environment, that is why we used refrigerant that has no effect on our
ozone layer.
While
taking the specification on the size we put into consideration the item that
are to be cooled or preserved. Also the
cabinet dimensions and compressor capacity were put into consideration as well.
The
essential design parameters for the mobile refrigerator are as follows:
i.
Compressor
ii.
Capillary tube
iii.
Condenser
iv.
Evaporator
v.
Thermostat
vi.
Refrigerant
vii.
Rubber seal
viii.
Drier
ix.
Relay and overload
x.
Rollers
xi.
Lagging materials
xii.
Lubricating oil
xiii.
Mild steel metal sheet
xiv.
Aluminum sheet
xv.
Valve
1.3 SCOPE AND
LIMITATION
Refrigeration can be divided into three main categories
namely:
i.
Industrial refrigeration
ii.
Commercial refrigeration
iii.
Domestic refrigeration
The design
“mobile Refrigerator†as it’s name entails is for domestic application and to
some extent for commercial purpose due to its fast freezing nature and mobility.
Well the
limitation of this mobile cooling system is basically on its specification in
terms of size, capacity and area of need in terms of power source. Based on the specification, the equipment is
not congruent for industrial use, where large refrigerator unit are more ideal
and readily available.
1.4 STATEMENT
OF PROBLEMS
The use of
low temperature refrigeration to obtain expansion fits has substituted shrunk
fitting of metal parts, in the chilling of aluminum rivets to control age
hardening, the stimulation of straphere conditions in the laboratory for the
testing of all types of air craft equipment, including the engine themselves
requires refrigeration at - 670F,
in the process industries refrigeration is used to carry out such operation a s
the separation of crystals from solutions.
Application
of refrigeration in the medical profession is increasing daily, not only in the
preservation of certain products, but also in the actual treatment of some
physical ailments. The use of cold
“anesthesia†has shown great promise in the field of surgery. The manufacture of penicillin requires
refrigeration and removal of moisture under high vacuum. The same process is required in the drying of
blood plasma, and the preservation of blood which requires refrigeration before
the dry is accomplished.
In
the refrigerated food industry, developments are occurring so rapidly that it
is difficult to keep abreast of
them. In case application of domestic
refrigerators have been supplemented by the entire new field of domestic low –
temperature cabinets for the preparation and storage of frozen foods, both inc
cooked and pre cooked. Lower plants for
the storage of frozen food are becoming common thing both in our rural and
urban areas.
The
movement of our foodstuff has been a matter of concern over years, but with the
new development in
the refrigeration of ships, rail road, cars and trucks. These are but a few of the widespread
applications of refrigeration. In
serving some of the function and considering the area and situation of need
such as resort centers, picnic, school etc.
Hence the need arises more than even prior to design of mobile cooling
system of acceptable standard that will meet certain essential requirement such
as portability and cost effectiveness.
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