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 research 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.

This research then has two main objectives. The first objective is to fabrication of bioactive glass ceramics containing BaFe12O19 (BF) crystals has been carried out for the application in hyperthermia treatment. The BaFe12O19 powder was firstly prepared and subsequently mixed with the non-silicate P2O5-CaO-Na2O bioactive glass with various BF concentrations. After that the glass ceramics were produced via a sintering method at 600◦C and their crystal phases were examined by XRD and in vitro test was carried out by soaking in simulated body fluid. Remanence and saturation magnetization and coercivity were deduced from magnetic measurement. It was found that the samples exhibited magnetic behavior which is similar to hard magnetic materials. Our second objective is the effects of sintering temperatures on the physical and bioactivity of SrFe12O19 (SF)-P2O5-CaO-Na2O bioglass ceramics were investigated. XRD results confirmed the existence of the strontium ferrite and calcium phosphate phases. SEM images showed that grain size and hardness were related to density and liquid phase present in the samples. A maximum coercivity value of 3138 Oe was obtained for the bioglass ceramic sintered at 600 ºC. The remanence (Mr) and saturation magnetization (Ms) of the bioglass ceramic sintered at 500 ºC possess the maximum value of 6.35 and 10.64 emu/g respectively. Moreover the apatite was formed on the surface layers of the bioglass ceramics confirming their biocompatibility

This research then has two main objectives. The first objective is to fabrication of bioactive glass ceramics containing BaFe12O19 (BF) crystals has been carried out for the application in hyperthermia treatment. The BaFe12O19 powder was firstly prepared and subsequently mixed with the non-silicate P2O5-CaO-Na2O bioactive glass with various BF concentrations. After that the glass ceramics were produced via a sintering method at 600◦C and their crystal phases were examined by XRD and in vitro test was carried out by soaking in simulated body fluid. Remanence and saturation magnetization and coercivity were deduced from magnetic measurement. It was found that the samples exhibited magnetic behavior which is similar to hard magnetic materials. Our second objective is the effects of sintering temperatures on the physical and bioactivity of SrFe12O19 (SF)-P2O5-CaO-Na2O bioglass ceramics were investigated. XRD results confirmed the existence of the strontium ferrite and calcium phosphate phases. SEM images showed that grain size and hardness were related to density and liquid phase present in the samples. A maximum coercivity value of 3138 Oe was obtained for the bioglass ceramic sintered at 600 ºC. The remanence (Mr) and saturation magnetization (Ms) of the bioglass ceramic sintered at 500 ºC possess the maximum value of 6.35 and 10.64 emu/g respectively. Moreover the apatite was formed on the surface layers of the bioglass ceramics confirming their biocompatibility

Frozen fish thawing method using an Electrostatic Technology from a High Voltage Electricity (ETHVE) is one of an alternative method. Due to this method the material has a uniform temperature and also increase the temperature of the material resulting in a short time thawing process. Therefore the objective of this research is to develop the thawing method for frozen tunas using an ETHVE compared to some water immersion method. The experiment was carried out by using frozen tunas with an initial temperature of -18 °C then thawing frozen tunas with the ETHVE until the temperature of the tunas increased to 5 °C. Then the tunas were steamed until the temperature of 60 °C compared to that water immersion method. The qualities of steamed tunas were determined by percentage of tunas meat and tunas blood. The results showed that the tunas thawing techniques using the ETHVE provided a uniform temperature of tunas meat both the surface and the center the piece of tunas. In addition this technique also provided a higher percentage of tunas meat and tunas blood and some surface area has slight burns compared to that water immersion method. The frozen tuna which was thawed by using the ETHVE method which some surface and center using temperature at 5 °C and –2 °C respectively. The tunas surface area were slightly burned the percentage of tunas meat and tonas blood were 45% and 5% respectively. During the frozen tuna thawing using the water immersion method has the surface and center temperature at 12 °C and –2 °C respectively; The tunas surface area were very burnt the percentage of tunas meat and tunas blood were 42% and 3% respectively.

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.