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Fabrication Of Domestic Deep Freezer
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 CHAPTER THREE
ANALYSIS OF REFRIGERATION SYSTEM AND CHOICE OF PROJECT AS BEST.
3.0 THE CYCLE OPERATION OF VAPOR COMPRESSION.
The cycle operation of vapor compression is as follow:
- The liquid refrigerant (e.g R12) enter the evaporator
- As liquid refrigerant and absorbs heat in the evaporator, the vapor is drawn through the suction line to the compressor.
- From the compression, the refrigerant is compressed at supper heated temperature and high pressure to the condenser
- All the condenser the refrigerant is considered at high pressure and heat is disputed.
- The liquid refrigerant is then passed through throttling device to the evaporator at low temperature as a contribution of vapor and liquid.
- At the evaporator, the refrigerant absorb the latent heat to become complete vapor before being passed to the suction side of the compressor.
3.1 TYPES OF GAS COMPRESSOR.
The most common compressor used in chiller are reciprocating, rotary screw centrifugal and scroll compressors, each applitrapping refrigerant vapor and reducing the volume of the refrigerant along the rotors to the discharge point (Myers Richard, (2003)).
ï¶ Centrifugal Compressors: centrifugal compressors are dynamic they compress refrigerant by imparting velocity or dynamic energy, using a rotary impeller and converting it to pressure energy.
ï¶ Scroll Compressor: scroll compressor are also positive displacement compressors. The refrigerant is compressed when one spiral or bit around a second stationary spiral, creating smaller and smaller pocket and higher pressures by the time the refrigerant is discharged it is fully pressurized.
3.2 THERMODYNAMIC ANALYSIS OF THE SYSTEM.
The thermodynamic of the vapor compression cycle can be analyzed on a temperature versus entropy diagram as depicted in figure. The circulating refrigerant enters the compressor as a saturation vapor which is entropically compressed (i.e. compressed at constant entropy) and exits the compressor as a super heated vapor. (Paunken mike, (1999))
From point 2 and 3, the super heated vapor travel through the part of the condenser which remove the super heat by cooling the vapor between point 3 and 4. The vapor travel through the remainder of the condenser and is condensed into a saturated liquid. The condensation process occurs at essentially constant pressure.
Between point 4 and 5, the saturated liquid refrigerant passes through the expansion value and under goes on abrupt decreases of pressure. The process results in adiabatic flash evaporation and auto refrigeration of the liquid (typically; less; than half of the liquid flashes), the adiabatic flash evaporation process is isenthalpic (i.e occurs at a constant enthalpy).
Between 5 and 1, the cold are partially vaporized refrigerant through the coil or tubes in the evaporation where it is totally vaporized by the warm air (form the space being refrigerated) that fan circulate across the coil or tube in evaporator. The evaporator operates at essentially constant pressure, the resulting saturated refrigerant vapor returns to the Compressor inlet at point 1 to complete the thermodynamic cycles.
It should be noted that the above discussion is based on the ideal vapor compression refrigeration cycle which does not take account in real world items like frictional pressure drop in the system, slight internal irreversibility during the compression of the refrigerant vapor, or non-ideal gas behavior.
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ABSRACT - [ Total Page(s): 1 ]ABSTRACTRefrigeration is term used to denote the maintenance of a body at a temperature lower than that of its surroundings. The applications of refrigeration are many and varied. In addition to the common applications of refrigerationin the manufacture of ice, in the preservation of foods, in air-conditioning filed, and in the creation of skating rinks, the refrigeration effect is also used in the presentation of blood plasma, in the low-temperature treatment of metals and in the liquefaction o ... Continue reading---
APPENDIX A - [ Total Page(s): 1 ] ... Continue reading---
LIST OF TABLES - [ Total Page(s): 1 ]LIST OF TABLE4.1 Material Selection, Fabrication Details and Assembly 4.3 Bill of Engineering Materials and Evaluation 4.4 Trouble Shooting and Service Chart ... Continue reading---
LIST OF FIGURES - [ Total Page(s): 1 ]LIST OF FIGURERefrigeration Cycle Isometric View of Fabrication of Domestic Deep Freezer Orthographic Projection of Fabrication of Domestic Deep Freezer Explode View of Fabrication of Domestic Deep Freezer ... Continue reading---
TABLE OF CONTENTS - [ Total Page(s): 1 ]TABLE OF CONTENTTitle page Approval page Dedication Acknowledgement Abstract Table of Content List of Tables List of Figure CHAPTER ONE: Introduction1.1 History of Refrigeration 1.2 Important of Refrigeration Application 1.3 Freezer 1.4 Impact of Life Cycle 1.5 Aims and Objectives CHAPTER TWO: LITERATURE REVIEW2.1 Absorption System of Refrigeration 2.2 Mechanism of Absorption system Process 2.3 Vapor Compression System CHAPTER THREE: ... Continue reading---
CHAPTER ONE - [ Total Page(s): 2 ]CHAPTER ONEINTRODUCTION1.1 HISTORY OF REFRIGERATIONBefore the invention of mechanical and thermal refrigeration system, ice houses were used to provide cool storage for most of the year placed near fresh water lakes or packed with snow and ice during the winter, they were once very common (Pauken mike 1999). Natural means are still used to cool, also mountain sides run-off from melting snow is a convenient way to cool drinks, and during the winter, one can keep milk fresh much longer just ... Continue reading---
CHAPTER TWO - [ Total Page(s): 2 ]CHAPTER TWOLITERATURE REVIEW2.1 ABSORPTION SYSTEM OF REFRIGERATION The absorption system is difficult from the compression system. It used heat energy directly instead of mechanical system. It uses heat energy directly instead of mechanical to make change in the deduction necessary to complete as refrigeration cycle. The system may use element as source of heat (Paunken Mike, (1999) ). The system has fewer moving parts and operates relatively quietly. Such systems are used in commerc ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 3 ]CHAPTER FOUR4.2 ASSEMBLY AND INSTALLATION The first stage of the assembly is the laggings materials and its facing the aluminum sheet.4.2.1 LAGGING MATERIAL AND FACING ALUMINUM SHEET The polystyrene is cut to thickness of 25mm. this is used to cover the internal of the cabinet. Then, the laying of evaporators through the polystyrene, one end of the evaporator is welded to the compressor to serve as inlet. The chemical sheet is used to face the polystyrene with the use of gum (e ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 1 ]CHAPTER FIVERECOMMENDATION AND CONCLUSION5.1 RECOMMENDATION- The use of electric voltage regulator (stablizer0 recommended when using the freezer. - It is also recommended that the freezer should be used for domestic purposes.- Preventive maintenance should be carried out as at when due.- The project is unable to modification.- The project is a very good size, it improves students knowledge of thermodynamic engineering therefore it is recommended that this typ ... Continue reading---
REFRENCES - [ Total Page(s): 1 ]REFERENCES 1. Pauken Mike (1999), freezer (www. En.wikipedia.org (2010)).2. Adams Cecil *(2005), important of refrigeration (www. En. Wikipedia. Org, (2010))3. Albert Einsten (1999). Impact on life (www. En. Wikipedia. org).4. Pauken Mike (2001) Thermodynamic analysis (www. En. Wikiopedia. org ).5. Albert Einsten (2001) Refrigerant *(www. En. Wikipedia org ).6. Myers Richard (2003) types of compressor (www. Wikipedia. org). 7. Pauken Mike (1999) ... Continue reading---
