Engineering and Technology Journal

This study investigated the thermal performance of the heat pipe and conducted on the effects of working fluids with wick and vertical position. The experiments were conducted using a copper heat pipe with ) a 20.8( mm inner diameter, and the length of the evaporator, the condenser, and the adiabatic regions were 300 mm, 350 mm, and 300 mm, respectively. The working fluids selected were water, Methanol, Ethanol, and different binary mixtures (50: 50) %, (30: 70) %, and (70: 30) % mixing ratios. The filling ratio for all working fluids remained constant with the value of  50% of the evaporator volume, and the heat input values were 20, 30, 40, and 50 watts. The results show that the heat pipe charged with Methanol has a thermal resistance of (0.7666 ^oC/W) which is the lowest value of thermal resistance. The lowest thermal resistance of using mixtures is (0.7466 ^oC/W) for (70 % methanol: 30% ethanol). Both are achieved at 50 W heat input. Also, the highest value of heat transfer coefficient when using water as a working fluid is (519.1073 W/m². ^oC), and for using a mixture (70 % water: 30% methanol) is (805.89 W/m². ^oC). Both are achieved at 50 W heat input.

The present work aims to study the effects of working fluids on the thermal performance of the heat pipe with a wick and in a horizontal position. The experiments were conducted using a copper heat pipe with a 20.8 mm inner diameter, and the length of the evaporator, condenser, and the adiabatic regions were 300 mm, 350 mm, and 300 mm, respectively. The working fluids selected were water, Methanol, ethanol, and different binary mixtures (50: 50) %, (30: 70) %, (70: 30) % mixing ratios. The filling ratio was 50% of the evaporator volume for all working fluids, and the heat input values were 20, 30, 40, and 50 W. The results show that the heat pipe charged with Methanol has a thermal resistance of (0.85166^oC/W), the lowest thermal resistance value. The lowest thermal resistance of using mixtures is (0.785 ^oC/W) for (50 % methanol: 50% ethanol). Both are achieved at 50 W heat input. Also, at 50 W heat input, the highest value of heat transfer coefficient when using water as a working fluid is (510.386 W/m². ^oC), and for using a mixture (70 % water: 30% methanol) is (556.78 W/m². ^oC).

The present work investigated the thermal performance of thermosyphon by using distilled water as a working fluid at different filling ratios (50%, 60%, and 70 %). The thermosyphon was manufactured from a copper tube with outer and inner diameters (26 and 24) mm, respectively. The thermosyphon was tested experimentally at different input power (100, 200 and 300) Watt. The operating temperature of the oil was chosen below 85°C. Experimental results revealed that the filling ratio of 60% exhibited the best heat dissipation at the highest operating temperature. While the low operating temperature and 50 % filling ratio show better heat dissipation. Further, it was found that the thermal resistance of the thermosyphon was obviously decreased with increasing the input power. The percentage decrease in the thermal resistance of the thermosyphon at a filling ratio of 0.6 was 14.6 % compared with that filling ratio of 0.5 at an input power of 300 W.

The low thermal resistance of polymeric materials to high temperatures considered
the main limitation to used these materials in such applications required high thermal
resistance ,so ,the present research aimed to study the possibility to increasing flame
retardancy of advanced polymeric composite materials reinforced by fibers by
coating by a flame retardant layer represent antimony tetroxide (Sb2O4) as a coating
layer (4mm) thickness to react and prevent spread of flame on surface of composite
material consist of araldite resin(AY103) reinforced by woven roving carbon - Kevlar
fibers (0°-45°) and exposed this coating layer to direct flame generated from
oxyacetylene flame with different exposure distances (10mm,15mm,20mm) and
study the range of resistance of flame retardant material layer to the flames and
thermal resistance and flame retardancy after coating by antimony tetroxide as well
as rising flame resistance increased exposure distances to flame .