ABSTRACT
This write up is a defeat of the process and formulation of plans for the physical realization of the construction of a mobile deep freezer. It is divided in chapters which discussed extensively on the practical refrigeration system with full attention given design factors, working principle and choice of material. It is strongly believed that this will make and interesting study for inquisitive minds and collection of facts further related work.
NOMENCLATURE
M = Mass
A = Area
S = Enthropy
V = Volume
M = mass flow rate
D = Diameter
Gr = Gravity
P = (rho) Density
t = Temperature Different
h = Enthalpy
Q = Heat Quantity
hl = Latent heat of fusion
Gr = Equivalent load
L = Length
P = Pressure
T = Temperature
U = Internal energy
K = Thermal conductivity
X = Material thickness
COP = Coefficient of performance
Q = Heat transfer per area
H.P = Horse power
Vs = Swept vol.
A.C = Alternating current
C = Specific heat.
TABLE OF CONTENTS
CHAPTER ONE
1.0 Introduction
CHAPTER TWO
The Relation of Refrigeration System to Thermodynamics Principle
CHAPTER THREE
3.0 The Basic Component of Deep Foreign
CHAPTER FOUR
4.0 Analysis and Calculation as it Relates to Deep Freezer or Ref. System
CHAPTER FIVE
5.0 Choice of Refrigeration
CHAPTER SIX
6.0 Mode of Operation
CHAPTER ONE
1.0 INTRODUCTION
The most significant contribution to the development and maintenance of our modern technological society has been our ability to extract large amount of energy from natural resources. These extractions of energy allow us to control or use work, power and heat to meet society needs. The science that explains and predict how much energy we may extract and how efficiently we may do it for a particular situation is called thermodynamics. It is a science that studies energy in its various form and explains why some type of energy are easier to use than others. Because of this subject matter, the science of thermodynamics is used often by engineers and technologists in practical design problem and in problems of the operation of large or complicated system.
However, industrial revolution has been exponential growth of population and material wealth of any developing nation. These growths have been associated with the use of energy and machinery. This revolution began with the use of coal and progressively narrowed down to petroleum, which were and are still our primary source of energy employed in every day to day activities. The concepts of preservation hence enables us to study quantitatively and qualitatively the analysis of how machines convert the chemical of nuclear energy into useful work. For decades ago the idea of preservation was very primitive but despite that, the early men had the initiatives that something could be done to preserve perishable (food) items for instance, tribes living close to the ice berg region observed that animals (fish) hunted during the winter period were preserved better than those of the summer. This was simply preserved because of the temperature variation.
Moreover, in African the insulative properties of sand used in moulding clay pot for preserving water was observed to offer a cooling effect on its content. Also wet leaves were used to wrap on some fruits such as colanuts, this offers considerable preservation for a given period of time when the leaves get dried up. During these years, there was no extensive record or any constructive attempt to modernize any system that could serve the purpose.
How - be – it, William Gullen made the first attempt in 1948. he investigated the effect of evaporation of ethyl – either into a particular vacuum. He was here faced with the problem of arranging a food vacuum system progressively, in latter years, Ferdinard made use of a reciprocating compressor to compress ammonia gas as a refrigerant, which improves both its reliability and efficiency. However, many gas were used but some were poisonous and explosive. Others functioned at very high pressure, which required the construction of a compressor and other system components. Having posed much problem on the choice of refrigerant, an American Vice President Research of general motors which frigdine (An American Company that built fridge) be came convince in 1928 that refrigeration system will not be successful except a new refrigerant is found. Thomal midgely and his associates Herme and Menay thought of florine compound. Hence Dichlorofloura (CCL1F2) offered better performance. Other gases that were reserved were air, Co2, No2 etc.
The discovery of feron 12 (CCL2) enables the manufacturer to think of a smaller compressor together with other system component. In 1937; the Engineers though of the design and manufacturing techniques, these ideals were unveiled by Tecumsh product company who discovered the first range fo welded hermetic compressors. By the mid of 1960s, there were about 7.5 million refrigerators and food freezer on use in USA and most European Countries. The boom in domestic appliance revolutionizes the refrigeration industries and its commercial outlet. The lot awareness created by refrigeration industries actracted the masses on the use and advantages of preserving with refrigeration rather than using those crude means. These demands lead to the manufacture of different types of suit particular purpose(s); thus refrigeration plant were produced to freeze fish on the traveler; freeze pre – cooked meats; poultry freezing factor, ice cream, movable refrigeration etc.
Our point of interest is on the design and fabrication of a mobile deep freezer. The mobility factors units the size and moreover, due to high manufacturing cost, the size is made moderate. The design objective is to produce an efficient, mobile deep freezer that could be used both for indoor and outdoor services to preserve drinks, food item, and other similar products. The limitation of change is only for smaller units of item since the size will not accommodate large quantities or units of item.
1.1 THE PURPOSE OF THE DESIGN
The project is meant to achieve the following purposes.
1.2 THE IMPORTANCE AND SPECIFICATION OF THE DESIGN
The importance of this design is to achieve cooling at a very low temperature without adverse effect on its content such as poisoning of food tissues. More so, it expected that this design would enable us to get acquainted with the application of thermodynamics principle to a particularly realistic state. The design intention in based on reduced cost. Long life span, fast freezing capacity to improve an existing design compactness portability ease of mobility etc.
The design specification is to meet a volume capacity of about 2m3 but due to cost consideration of the components involved, it is desirable to limit the volume capacity to a moderate size provided its functionality is perfect or ensured.
The essential design parameters for this design are
Others are
Fish - Chamber
Over - Load
Accumulator etc
1.3 SCOPE AND LIMITATION
Refrigeration system can be divided into (3) three main categories viz
The industrial refrigerators/cooled room is a very large system, which can contain even up to a fruiter load of any perishable item. Its mainly need in the food industries, such as ice fish, breweries etc.
The commercial type includes those ones used in business premises such as super markets min-cooled room, restaurant etc. while the domestic type are those ones used in our various homes for domestic purposes such as preservation of food stuffs etc. precisely, due to its fast cooling effect it may also be used for commercial purpose. However, based on the design specification it may not be suitable for industriable usage where large refrigeration units are most ideal.
However, the design may not e as perfect as the ones manufactured in refrigeration companies / industries due to some lapsed in techniques and practicability.
1.4 STATEMENT OF THE PROBLEM
The main problem to be tackled in this project is to produce a mobile deep freezer that will be used to effect cooling on food stuffs and drinks thus preserving them.
However, this project may cover other sub – problems such as determining the efficiency performance of the system viz; COP of the system.
The dryness fraction of the drier strainer
The maintenance of the system.
How to operate the system.
1.5 ASSUMPTION
In power plants, heat is received by the working fluid at high temperature and rejected at a lower temperature. But in refrigeration cycle in particular, we assume that the reverse is
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