Fabrication On Domestic Refrigerator

CHAPTER THREE
DESIGN CALCULATIONS FOR REFRIGERATION SYSTEM
Having described the component parts of the refrigerator in thes necessary to design the system according to the requirement of the project.
The system consists of the following component parts:
    Compressor
    Condenser
    Capillary tube
    Evaporator
    Piping (discharge and suction line).
    Insulation
    cabinel
    body
3.1    REFRIGERANT SELECTION
The choice of a refrigerant must be made and the proper refrigerant selection is dependent primarily on the condenser and evaporator temperature. A desirable refrigerant should not give rise toeither unduly high condenser pressure or very low evaporator pressure. Having desire and determine on the refrigerant to be used in the condensing and evaporating temperature respectively, the pressure aredirectly obtained by looking up the saturation pressure corresponding to these two temperature.
DETERMINATION OF FLOW RATE
In determining the flow rate of refrigerant, the capacity of the refrigerator, the cooling effect and temperature of operation measured atthe evaporator and condenser are required.
Refrigerant load is commonly expressed in the unit of tones of refrigeration William, (2005).
From the thermo dynamic table of properties:
h_1  = 178.73kg/kg
h_2= 206.kg
h_3= 64.49kg/kg
h_4Evaporator load = 2160walts
Assuming no sub-cooling of the liquid leaving the evaporator, refrigerating effect = h1- h2
= h1- h2 = 178.73 – 64.59 = 114.4x10-3kg/kg
Mass flow rate = (total cooling load)/(Dxre frigerating efficiency)
OsareO1 A1 (1999)
Mass flow rate =2160/〖18.14 x 10〗^(-3)  = 18.924 x 10kg/kg
The lone of refrigeration in some times define on the basis of long ton or taken equal to a cooling water of one kilocalorie per second. The itore larger than the us ton by 12 and 18.8% respectively. The refrigeration perforrmed per pound of refrigerant flow rate.
01le o refrigeration)200
W = (toneofrefrigeration)200/(h_f h_3 )poundsperminute
hf—h3
The work necessary for compression is obtained frorn the relation.
Wk Comp = (w(h_1 h_2))/42.42hp
Where 1hp = 42 BTU per minute Osane OA (1.999).