ABSTRACT
This project
is on the design and fabrication of deep freezer for the preservation of
items/products and making the items to cool. The project is able to develop a
simple efficient economical and environmental friendly refrigeration system (A
freezer) towards better technological advancement in Nigeria. This project
modifies the existing refrigeration system with the use of R-600a which is
ozone friendly, and non-contaminant like previous refrigerant of the
hydrofluoric-carbon, HFC and CFC like R-12, and R22 which has been phased out
according to the general convection at Britain in 1996. The cooling load
obtained was 10682KW, and co-efficient of performance be minimized. The
material used were mild steel and the inner pipe of the cabinet i.e. evaporator
in order to minimize corrosion. For the better improvement of this work, low
power consumption of the compressor refrigeration was used so as to maintain
the rate of cooling and freezing of large items/products. And the outer
dimensions are: length-1245mm, breadth-895mm-0. 895m, Height-906mm-0.96m and
the inner dimensions are Iength-1225mm-1.225m; Breadth-895mm-0.895m,
Height-886mm- 0.886m.
TABLE OF CONTENTS
Abstract
Table of content
CHAPTER ONE: REFRIGERATION
1.0 Introduction 1
1.1 Literature Review 2
1.2 General Definition and
Development 3
1.3 Purpose and Scope of
Refrigerator 4
1.4 Aim and Objectives 7
CHAPTER TWO: TYPES OF REFRIGERATOR SYSTEM
2.0 Types of Refrigerator
System 8
2.1 The Vapor Compression
Refrigeration System 8
2.2 The Vapor Absorption
Refrigeration System 9
CHAPTER THREE: DESCRIPTION OF THE COMPONENTS PARTS
3.0 Description of the
Components Parts 13
3.1 Compressor 13
3.2 The Condenser 16
3.3 The Evaporator 17
3.4 Pressure Gauges and
Thermometers 19
3.5 Strainer/Drier 19
3.6 The Capillary Tube 20
CHAPTER FOUR: DESIGN CRITERIA, CALCULATION AND ELECTION
OF EQUIPMENT
4.0 Design Criteria,
Calculation and Selection of Equipment 21
4.1 The Evaporator Cabinet
21
4.2 Design Condition 22
4.3 Evaporator for Cabinet
Casing 23
4.4 Conducted Heat 27
4.5 Refrigerant Piping
Design 28
4.6 Calculations of
Component Parts 32
4.7 Refrigerator Load
Estimation 40
4.8 Refrigerant Used 41
4.9 Determination of the
Flow Rate 47
4.10 Heat Balance for the
System 48
4.11 Co-efficient of
Performance 50
CHAPTER FIVE: FABRICATION DETAILS
5.1 The External Cabinet
and Material Select 53
5.2 Insulation 53
5.3 Compressor Base 55
5.4 Condenser 55
5.5 Assembly of Part 55
5.6 Lubricants in
Refrigeration System 56
5.7 Trouble Shooting in
Domestic Refrigerator 57
5.8 Bill of Engineering Materials
and Evaluation (BEME) 59
CHAPTER SIX: CONCLUSION AND RECOMMENDATION
6.0 Conclusion 60
6.1 Recommendation 60
References 62
CHAPTER ONE
REFRIGERATION
1.0 INTRODUCTION
The ice
cream being sold at the corner stores, the frozen vegetable for dinner, the
refreshing water for drinking at the office, water cooler are all dependent on
the science of refrigeration. Refrigeration in its specialized forms in a
comparative modern development which has been in practice for generations, and
its application in controlling environmental condition has made possible some
outer space programs and many other scientific and commercial activities as it
can be obtained in our houses and on the farm which is considered as an example
of a natural refrigeration techniques, the porous clay jugs used in hot desert countries
for cooling water, the ice box, for food preservation etc. (Raymond, C.G.
(1973).
This
write up presents the principle of mechanical refrigeration in vapor
compression refrigeration system and it application which gives a clear
understanding about the design and operation of the unit.
1.1 LITERATURE
REVIEW
Refrigeration
is branch of engineering that is concerned with the science of producing and
maintaining temperature below that of the surrounding atmosphere [Raymond, C.G.
(1973)]. It also the process of removing heat from the substance.
Before
the advent of mechanical refrigeration, water was kept cool by storing in
semi-porous pots, so that the water could seep through and evaporate. The
evaporation carried away heat and cooled the water [Raymond, C.G. (1 973)].
The
first development took place in 1834 when Perkins proposed a hand operated
compressor working machine. In 1851 came Gorries and in 1856 Lind developed a
machine working on ammonia [Andrew, D. & Alfred, (1970)]. The development
was considered quickened in the forties when Dupent put in the market, a family
of new working substances, the floro chloro derivate of methane,1 ethane etc.
under the name of ferons; then followed the liquefaction of other permanent
gases included helium in 1908. [Andrew, D. & Alfred, F.B. (1970)].
In 1926,
Ginque and Diebye independently proposed adiabatic demagnetization of a
paramagnetic salt. In 19th century application of mechanical refrigeration in
fields other than ice making including direct cooling and freezing of
perishables foods, air conditioning for industry and human comfort [[Andrew, D.
& Alfred, F. B. (1970)].
1.2 GENERAL
DEFINITION AND DEVELOPMENT
Refrigeration
may be defined as the process of removing heat from a substance. The American
society of Engineers defines refrigeration as “the science of producing and
maintaining temperature below that of the surrounding atmosphere”. This implies
the development of temperature differential rather than the establishment of a
given temperature level.
Therefore
refrigeration is accomplished by establishing temperatures differentials and
evaporation of liquids or combination of both methods for removing heat from a
substances in a refrigeration i.e. heat is put into the working substance at
lower pressure and temperature and provide the latent heat to make it boil and
change to vapor. The vapor is then compressed to a high pressure and
temperature at which the superheated gas can be removed and the fluid is turn
to liquid. The total cooling effect will be the heat transferred to the working
fluid in the evaporator [Raymond, C. G. (1973)].
In any refrigeration process, three basic
factors are involved which are: Heat change, pressure control and liquid gas
relationship, therefore a working system will require a connection between the
condenser and the inlet to the evaporator to complete the circuit.
1.3 PURPOSE
AND SCOPE OF REFRIGERATOR PROJECT
The
purpose of refrigerator deals with the use of refrigerator which is in three
forms.
i. To produce the temperature of a substance (Act of cooling).
ii. To change a substance from one state to another (as water to
ice)
iii. To maintain substance in a desired temperature state (food
preservation or ice storage) [Raymond, C. C. 1973].
All the
above purpose is personal comfort in both temperature and hot climatic regions.
It importance to the society can also be grouped under the following sub
headings:
1. DOMESTIC: Refrigerators are commonly used in the house
for domestic purpose. They are usually in all sizes having a compressor rating
between (1/2) half and (1) one-horse power and are hermetically sealed type.
They are commonly employed for cooling drinks and as food preservation [Andrew,
D.
&
Alfred, F. B, (1970)].
2. COMMERCIAL: Commercial
refrigerators is concerned with designing, installation and maintenance of
refrigeration fixture of the type used in retail store, restaurant, hotels and
institution for storing, processing and dispensing of perishable goods [Andrew
& Alfred, F. B. (1970)].
3. INDUSTRIAL: Industrial refrigerator are larger in size
than commercial application and have the distinguishable features requiring an
attendant on duty, usually of licensed operating engineer Example are ice
plant, large food packaging plant, breweries, ceramics and in industrial plant
such as oil refineries, chemical plant and rubber plant [Andrew, D. &
Alfred, F. B. (1970)].
4. MARINE AND
TRANSPORTATION: Refrigeration are needed for
fishing boats and for marine vessels transporting perishable goods This is also
applied in modern passenger train and trunks for carrying chilled fish, meat
and other refrigerated fixture through a long distance [Raymond, C. 0.(1973)].
5. AIR CONDITION: It deals with the control of temperatures and
humidity of the air, moisture filtering and cleaning of air within some
designated areaor space. They are of two types, the comfort air application or
industrial air- conditioning, it could be formed in the control of moisture
content of hygroscopic material governing the rate of chemical and biochemical
reaction, limiting variation in the size of precision and manufactures articles
due to thermal expansion and contraction, filtered is often essential to trouble
free the operation and to give production of good product. [Raymond. C. O.
(1973)].
6. HOSPITAL: Refrigerators are used in hospital for
preservation of bones, blood tissue and some drugs that are kept under a
particular temperature; it also play an important role in the act of keeping
dead Bodies in mortuaries from being decayed [Raymond, C. G. 1973)].
1.4 AIM
AND OBJECTIVES
v
This
project is to educate students of engineering and refrigeration technology
lovers on how to achieve maximum cooling during refrigeration by increasing the
coefficient of performance (COP)
v
This
project will help in the aspect of teaching the users of refrigerator the
necessity of taking good care of their refrigerator, the danger of using sharp
point object which could eventually damaged the evaporator.
v
This
project work is aim at designing a domestics refrigerator for food
preservation.
v
Its also
demonstrate practically how the various components of a refrigeration
functions.
v
It is
meant to Educates and encourages students who may like to embark on similar
project in future, using the available raw materials
This project will
help in the aspect of teaching the users of refrigerator, the dangers of using
sharp and pointed object in removing products from the evaporator compartment
which may lead to puncturing of evaporator cool.