Design, Fabrication & Testing of a Grooved Heat Pipe

• The work reported here involves the fabrication and testing of an axial grooved heat pipe of outer diameter 8mm, inner diameter 4mm and length 150mm. The testing of the heat pipe is carried out for three different orientations i.e. 0°, 90° and 180°.

• The experimental setup consists of a heat pipe with wick, a mica heater, J-type thermocouples, temperature indicator, a data acquisition system, a computer, a dimmerstat, moisture trap, pressure gauge and a vacuum pump.

• Three different working fluids i.e. methanol, acetone and distilled water are used. The maximum heat transfer coefficient of the grooved heat pipe for methanol in the gravity assisted position was found to be 400 W/m2°C at 60% fill ratio and 500 mbar vacuum pressures which is greater than the heat transfer coefficient value (374 W/m2°C) of gravity assisted heat pipe for the same parameters.

• Similarly the maximum heat transfer coefficient of the grooved heat pipe for acetone in the gravity assisted position was found to be 800 W/m2°C at 60% fill ratio and 500 mbar vacuum pressures which is greater than the heat transfer coefficient value (489 W/m2 °C) of gravity assisted heat pipe for the same parameters.

• Finally. the maximum heat transfer coefficient of the grooved heat pipe for distilled water in the gravity assisted position was found to be 640 W/m2°C at 60% fill ratio and 500 mbar vacuum pressures which is greater than the heat transfer coefficient value (454 W/m2°C) of gravity assisted heat pipe for the same parameters.

• The concept of orientation in heat pipes was not covered since the wickless heat pipes do not perform at an angle greater than 4°. Hence the heat transfer values for horizontal position cannot be obtained using a wickless heat pipe. The heat pipe can be used in varied application in cooling systems in the HVAC & R industry to replace the existing methods.