Design And Fabrication Of Domestic Deep Freezer

3.3.4 CAPILLARY TUBE
This device operate on the principle that a given weight of refrigerant liquid will pass through a capillary more readily than the same weight of gas will do at the same pressure. Immediately the condensed refrigerant enters the capillary tube, the mass flow of this refrigerant will be reduced them by giving more room for cooling time.
ADVANTAGE OF THE TYPES OF CAPILLARY TUBE USED FOR THIS PROJECT LIES IN
a. Its simplicity
b. Ease of being welded to the suction for heat exchanging purpose.
3.3.5 DRIER
The drier is used to absorb moisture content from refrigerant. It contains desiccant made up of silica gel a material that has absorb any acid already formed and has grate 4r affinity for moisture.
These desiccants are made such that they do not react with the refrigerant oil or the refrigerant itself.
This drier is a very important component of the system because it helps in removing foreign material and dirt from the refrigerant so that they will not be able to cause damage in a refrigerating system because it helps in removing for compressor value and the controlling devices in a refrigerating system. The presence of a very fine filter in it enables it to perform this purpose
3.3.6 LAGGING MATERIAL
The function of lagging material in the system is to prevent heat loss by conduction and radiation. The must commonly used lagging materials is polystyrene because it is more effective and readily available. It also gives the system stability and strength against any load.
3.3.7 COOLING FAN
Function of the fan is to serve as the cooling medium for the compressor to avoid over heating which could have otherwise caused damage to the motor winding and the mechanical devices in the compressors.
3.3.8 SHEET METAL
The sheet metal used is made up of mild steel of 0.7mm thickness, the thickness selected is optimum for the system otherwise it will lack strength and stability.
3.3.9 REFRIGERANT
A refrigerant is a substance or mixture, usually a fluid used in heat pump and refrigeration cycle. In most cycle it undergoes phase transition from a liquid to a gas and back again. Fluoro carbons, especially chloro fluro carbon, became common place in the 21 century, but they are being phased out because of their ozone depletion effects. Other common refrigeration used in various applications are ammonia, sulphur dioxide, and non-halogenated hydrocarbon such as propane.
The ideal refrigerant would have favorable thermodynamic component and be safe, including free from toxicity and flammability. It would not cause ozone depletion or climate change. Since different fluids have the desired traits in different degree, choice is a matter of trade- off
The desire thermodynamic properties are a boiling point, some that below the target temperature a high heat of vaporization, a moderate density in liquid form, a relatively high density are affected.
by pressure, refrigerants may be made more suit able for a particular application by choice of operating pressures.
The refrigerant used for this project if R600 a because of some
properties such as:
1. Non-toxicity
2. Non-inflammability
3. Low cost
4. Availability