Defrosting at evaporator panel is one of working cycles in freezer. Power consumption in defrosting does not meet the objective of using freezer therefore the approach to decrease power consumption in defrosting is one strategy for energy saving. Normally the cycle of defrosting in freezer is a constant time that specify by referring to the highest humidity period. With this control concept the problem of temperature exchange is not occurred from ice accumulation at evaporator panel but it makes the over necessity of defrosting process in the low humidity season and cause the unnecessary power usage in freezer. This thesis presents the control approach for defrosting by using the difference of the temperature at evaporator and the temperature at chilling area. By using this approach the defrosting process is operated depend on load and the fan is on or off relate to defrosting time. Test results demonstrate that about 12% of power can be saved by this control approach when compared to constant time control.

The objective of this research is to develop a small and low-cost weather station. The station will be wireless transmit and receive data via radio signals. The 45mW solar cell will be used as a solar irradiance sensor which is very expensive for the weather station and the PIC18F97J60 controller will control the transmitter and receiver system. Moreover the author has developed the weather monitoring software by using LabVIEW. After testing the measurement percentage errors with the reference weather station the results showed that the relative humidity measurement error is equal to 3.106% the temperature measurement error is equal to 0.685% the wind speed is about 4.527% the wind direction measurement error is equal to 5.236% and the solar irradiance measurement error is equal to 0.501%. The longest working distance between the weather sensor and receiver unit is equal to 145 meters.