DESIGN AND FABRICATION OF A MOBILE DEEP FREEZER

CHAPTER ONE

INTRODUCTION

Firstly refrigeration in the process of removing  heat from a substance or  space in order to make it cooler. A mobile deep freezer is not different from  all  other refrigeration the only difference is that it can be moved easily by wheel or rollers to different places in a given time with less force applied to effect the movement. In refrigeration the three mode   of heat transfer is employed causing heat to flow from high  temperature regions to low temperature regions.  The   substance used to carry heat in the refrigeration  is known as the refrigerant. Refrigerant  is the cooling  agent in refrigeration.  It  makes indirect contact  with the substance to be  cooled.  It  is circulated in the  refrigeration  circult  and  the attendant change of state  from liquid to vapour brings about the  necessary  cooling  that is  required in the system which also involves  INTENT OR SENSIBLE HEAT.

Refrigeration is accompanied  by various method such as the vapour compression system absorption system and steam jet refrigeration cycle. Refrigeration contributes greatly  to the raising of living standards of people its uses can not be over emphasized in  this book.  The  most common used and one that is readily recognized is the preservation of food.  Most products in our homes businesses  industries laboratories  hospitals  farms etc are affected by refrigeration. Its application is also extended to other areas  apart  from  food in medicine it is used in blood banks for antibiotic  for  making ice  for compression and low  temperature  surgery for presenting certain tissues that pathologist work on. It is very essential in genetic engineering  to preserve sperms and eggs or longer years before they work on them  to bring life. Deep freezer is an Electro- mechanical appliance which  maintains the temperature of substance space or material as requires by the user it produce  artificial cooling. It operates on the principal of reversed cannot  cycle that is to say that  it absorbs heat from a low temperature and  rejects it to a high temperature region. The compressor provides the conversion of energy that is  used in circulating the refrigerant round  the circult. The crankshaft drives the piston through the connecting  rod and it’s moved by the tongue produced by electric  motor.  The pumping effect of the piston produces the  high pressure on the refrigerant which sets it in  motion.  In the causes of circulation and attendant  change of state the refrigerant  returns to the initial state and ready for another cycle. In a deep freezer the condenser performs function  similar to that of the radiator in an auto mobile.  It cools the hot refrigerator gas by giving out hear to the dryer which traps moisture that can block the metering  device.  The liquid refrigerant passes through the metering device which expands the liquid into the evaporator pipe which is of  large  cross sectional area. The pipe is laid on the  inside of the deep freezer. A lot of insulation is done to isolate the refrigerated space from the surrounding its heating effect.

 PROBLEM OF THE STUDY

Looking into the present situation of things the menace  caused by road side craftsmen who tends to spoil other  progress  in pretence to repairing  or constructing of deep freezer so that they will enrich their  pocket and then gives out fake freezers that will last for few months we then decided to embark on this project.

PURPOSE OF THE PROJECT

The purpose or objective of the project is to achieve the following

1.  Designing  and constriction of a portable domestic cooling equipment that would improve on existing design taken into consideration.

2.  Designing  and constructing a cooling  / freezing system that is efficient  with little or no complexity in maintenance.

3.  Improving  the designs and construction of cooling  freezing equipment  with a reduced weight.

4.  To  design and construct  a cooling equipment  that will be mobile economical and cost that  a common man can afford.

 SIGNIFICANCE OF THE PROJECT

The project is designed to accomplish a fast freezing system without destruction of bottles at very low temperature it is designed in such a way that the freshness and nutrient of food material is refined. It  is based on reduced weight cost fast freezing techniques compactness longer life span also to improve on existing designs.