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The purposes of this research are to prepare and investigate the characterization of 0.7MgO-xY2O3-(99.3-x)Al2O3 by varies x at 0.0, 2.0, 4.0, 6.0, 8.0 and 10.0 wt% (AMY). AMY samples were synthesized by solid state reaction under two different sintering methods conventional sintering method (NS) and two stage sintering method (TS). Ceramic samples were sintered by conventional sintering at 1600°C for 5 h and using two stage sintering with the first sintering temperature (T1) at 1600°C for 30 min and cooling down to the second sintering temperature (T2) at 1450°C for 10 h. The phase composition of the samples were characterized using XRD technique. XRD patterns from two method sintering revealed phase combination of Al2O3, MgAl2O4, MgO and Y2O3. It was found that it is not different XRD patterns from two method sintering. SEM micrographs form NM and TS showed that the shape of the ceramic grains were polyhedron and ellipsoid, while the grain sizes form NS were in the range of 0.91-1.00 μm and the grain sizes from TS were in the range of 0.34-0.48 μm. The samples from NS and TS is showed optimum mechanical properties by AMY with Y2O3 additions between 4-6 wt%.

This research aims to the effect of evaporator section lengths and working fluids on operational limit of closed loop oscillating heat pipes with check valves (CLOHP/CV) with R123 Ethanol and Water were used as the working fluids. A set of CLOHP/CV was made of copper tubes in combination of following dimension: 1.77 mm inside diameter: 10 turns: 5, 10 and 15 cm equal lengths for evaporator, adiabatic and condenser sections. The working fluid was filled in the tube at the filling ratio of 50%. The evaporator section was given heat by heater while the condenser section was cooled by volume water in a cold bath. The adiabatic section was properly insulated. In the test operation. Which the temperature at the adiabatic section was controlled at 60°C in steady-state condition. From The obtained results obtained, it could be concluded as follows. When the evaporator lengths increased from 5 cm to 10 and 15 cm the critical heat transfer flux decreased. There was working fluids change from R123 to Ethanol and water the critical heat flux decreased.

Al2O3-ZrO2 ceramics containing 5-50 mol% ZrO2 were prepared by solid state reaction method. The bulk density, average grain size and microhardness of Al2O3-ZrO2 ceramics system as function of ZrO2 content were investigated. The dense Al2O3-ZrO2 ceramics were successfully by means of carefully control processing parameters that include sintering temperature and heating/cooling rates. These ceramics with higher ZrO2 content was obtained high bulk densities and small grain sizes. However, the high hardness values were exhibited from Al2O3-ZrO2 ceramics with dopants ZrO2 between 1-10mol% and its tend to decrease with concentration of ZrO2. It can be found that the fast heating/cooling rates are controlled grain growth and obtained high hardness in materials. The results gave good correlation between stoichiometry characteristics, heating/cooling rates in sintering and microstructure of fabricated dense and mechanical properties.

A visualization study of the internal flow patterns of a closed-loop oscillating heat-pipe with check valves (CLOHP/CV) at normal operating condition for several evaporator lengths (Le), and ratio of check valves to number of turns (Rcv) has been conducted. This article describes the effects of varying Le, and Rcv on flow patterns. The CLOHP/CV used a Pyrex glass tube with inside diameter of 2.4 mm. The evaporator length of 50 and 150 mm. (the lengths of evaporator, adiabatic and condenser were equal) were employed with 10 turns, with Rcv of 0.2 and 1. R123 was used as the working fluid with filling ratio of 50% of internal volume of tube. It was found that the internal flow patterns could be classified according to the Le and Rcv as follows: At the high heat source when the Le decreases the main flow changes from the bubble flow with slug flow to disperse bubble flow. The Rcv decreases the main flow changes from the disperse bubble flow with bubble flow to disperse bubble When the velocity of slug increases, the length of vapor bubbles rapidly decreases and the heat flux rapidly increases.

This article describes the effects of varying bond numbers (Bo) and aspect ratios (Le/d) on flow pattern of a close-end oscillating heat-pipe (CEOHP). The CEOHPs used employed a glass tube with inside diameter of 3 mm. The length of evaporator of 100 and 150 mm (the lengths of evaporator adiabatic and condenser section were equal) were employed with 10 turns. Observation of the flow pattern was conducted at 90° from the horizontal plane, with bond numbers of 1.8 and 2.6 with aspect ratios of 33.3 and 50. R141b and ethanol were used as the working fluids with filling ratio of 50% of internal volume of tube. The evaporator section was heated by heater and the condenser section was cooled by distilled water. The working temperature was controlled at 50°C. The temperature at adiabatic section and the inlet-outlet of distilled water at condenser section were recorded. The photographs of flow patterns at specific times were recorded at evaporator section by a digital camera and video camera were used to observe the flow patterns at evaporator section condenser together with adiabatic section and total part of CEOHP. It was found that the maximum heat flux occurred with Le/d 33 and Bo 2.6 an inside phenomena occurred is a dispersed bubble flow and slug flow.

Mg0.7Zn0.3Fe2O4 (MZF) powder was prepared by a solid-state mixed oxide using ball-milling technique. The phase identification of calcined powders was performed using X-ray diffraction technique (XRD). It has been found that MZF powders were successfully obtained for calcination conditions of 800 oC for milling times of 36 h, whereas milling times of 12 h, unreacted ZnO, Fe2O3 and MgO phases (2θ ~ 54, 57 and 63) are detected from the original mixture up to 900°C. By increasing the calcination temperature to 1000°C, a single phase of MZF is formed. Moreover, the microstructure of powder were examined by scanning electron microscopy (SEM) and showed that the particle in size from 58-1200 nm. While, XRD patterns were obtained average size of particle, calculation by Scherrer's equation, between 30.54 - 66.59 nm.

The CEOHP cooling module consisted of two main parts, i.e., the aluminum housing and the CEOHP. The house casing was designed to be suitable for CEOHP. The housing to drilling for insert the CEOHP. The CEOHP design employed copper tubes: Two sets of capillary tubes with an inner diameter of 0.002 m, an evaporator length of 0.05 and a condenser length of 0.16 m and each of which has six meandering turns. The evaporator section was embraced in the aluminum housing and attached to the thermal pad of Pentium 4 CPU, model SL 6 PB, 2.26 GHZ. While the condenser section was embraced in the cooling fin housing and cooled by forced convection. R134a was used as the working fluid with filling ratio of 50%. In the experiment, the CPU chip with a power of 58 W was 70°C. Fan speed of 2000 and 4000 rpm. It was found that, if fan speed increases the cooling performance increases. The CEOHP cooling module had better thermal performance than conventional heat sink.

This heat transfer characteristics of a closed-end oscillating heat-pipe (CEOHP) depend on a number of parameters. They are the number of turns, inner diameter of the tube, aspect ratio and the dimensionless parameters of heat transfer. The CEOHPs used to employ a copper tube with inner diameter of 0.66, 1.09 and 2.03 mm. The lengths of the evaporator, adiabatic and condenser sections were equal and changed to 50,100 and 150 mm. R141b was used as the working fluids with filling ratio of 50% by total volume. The meandering turns of 10, 20 and 40.The evaporator section was heated by hot water and the condenser section was cooled by distilled water. The experimental inclination angles were 0, 20, 40, 60, 80 and 90 degree from the horizontal plane. The controlled temperature at the adiabatic section of 50°C. When the system reached the steady state, the temperature and the flow rate of the cooling substance was recorded in order to calculate the heat transfer rate of the CEOHPs. The experimental results showed that the heat flux decreases with an increasing number of turns and decreases with an increasing aspect ratio. The heat flux increases with an increasing inner diameter. A correlation to predict the heat transfer rate at vertical position can be established.