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.