Fabrication And Performance Evaluation Of Cold Storage System

CHAPTER THREE
MATERIALS AND METHOD
3.1    Modified Area on the Cold Storage
       The following areas were modified on the cold storage structure in order to improve its performance.
i.    Compressor: the existing compressor was 1.5hp and was replaced with 2.0hp to improve the capacity of the evaporator
ii.    Capacitor: 30uf capacitor was replaced with 50uf capacitor to enhance the effectiveness of the 2.0hp compressor.
iii.    Condenser: 0.5hp condenser was added to the existing 2.0hp making it 2.5hp condenser in order to increase its performance.
iv.    Evaporation drier: the drier in the cold system was replaced because the existing drier was blocked; it is replaced to remove moisture and debris from the refrigerant.
v.    Temperature controller: a temperature controller was installed on the cold storage system in order to sense and regulate the temperature to a desired level or ranger.
vi.    Hygrometer: this was installed in order to determine the level of moisture in the system.
vii.    Flooring: this was done with comment to control the escape of heat within the system and enhance the efficiency of the system.                        
viii.    Adriano Displayer: it was installed to display the result of the temperature and relative humidity in the cold room system.
ix.    Light sensor: it was installed to protect and detect improper close or opening of the system door i.e. it senses when the door is not properly shut and serves as lighten to the system when opened.
3.2    Description of the Cold Room Storage System
         The cold storage structure taken for this study is situated at agricultural and bio-environment engineering department of institute of technology in Kwara state polytechnic Ilorin, Kwara state.
           The overall dimension of the cold room storage structure is 2.21m in length, 1.52m in width and 1.93m in height (2.21m x 1.52m x 1.93m) while the storage floor area is 2.21m in length by 1.52m in width (2.21m x 1.52m). The partitioned dimension of the cold room was measured to be 1.45m in height, 1.10m in width and 1.21m in length. The partitioning was further divided in to four equal parts of 0.34m each. The human occupancy area is 0.19m x 0.17m x 0.38m. The door is available at the immediate entrance of the cold room which is separate zone that serves as the area for incoming and outgoing products.
            The cold room storage is built of mild steel, and concrete in order to prevent the leakage, its floor and calling wall and door are properly insulated with special insulating material with law thermal conductivity.
    The cold storage consist of the following unit are compressor, condenser, receiver, evaporation value, evaporation and blower.
Compressor: is the heart of the cold storage plant, it raises the temperature and pressure of refrigerant vapor coming out from evaporation. Due to high pressure, the refrigerant boiling points gets increased and this it can be easily condensed at condenser temperature.
Condenser: Is a heat exchanger device which exchanges the heat from vapor refrigerant and water being circulated it condenses (i.e. phase change).     The high pressure and high temperature refrigerant to the high pressure and high temperature liquid. A condenser is a heat sink where heat is rejected.
Receiver: it receives the high pressure liquid condensate from the condenser and collects it.
Expansion value: It reduces the pressure and temperature of refrigerant from receiver pressure and temperature to evaporator pressure and temperature.
Evaporation: The heat exchanger where actual cooling takes place. It evaporate the low pressure. Low temperature liquid refrigerant (with low boiling PH by taking heat from storage compartment to be cooled).
Blower: it circulated chilled air in the refrigerated space to cool the fruit and vegetables by convection.