THERMAL ANALYSIS OF THERMOSYPHON FOR WASTE HEAT RECOVERY FROM AUTO EXHAUST USING LIMITED FLUID CHARGE

An experimental investigation was carried out to analyze the thermal performance of a thermosyphon that recovers waste heat from automobile exhaust using a limited fluid charge in this study. The thermosyphon was constructed from Inconel alloy 625. The outer diameter of the thermosyphon measures 27 mm, with a thickness of 2.6 mm, and an overall length of 483 mm, which includes a 180-mm evaporator, a 70-mm adiabatic section, a 223-mm condenser, and a 97-mm finned exchanger. The study involved directing exhaust gas onto the evaporator end cap at a flow rate ranging from 0-10 g/sec, with temperatures varying from 300-900 degrees C. The impact of three parameters, namely the inclination angle (ranging from 5 degrees-45 degrees), water mass (ranging from 2 g-5.3 g), and the amount of non-condensable gas Argon (ranging from 0 g-0.6 g), were analyzed to determine their effects on the thermal performance of the thermosyphon. Based on the experimental results, it was observed that when the thermosyphon contained 3 g of water and 0.0564g of argon, the condenser achieved a maximum temperature of approximately 200 degrees C. The optimal fuel loading rate for the thermosyphon lies within the range of 0.2 g/s to 0.7 g/s. Furthermore, outer wall temperatures of the thermosyphon increase as inclination angles increase due to the explicit expansion of the actual heating area within the evaporation section of the thermosyphon, accompanied by an augmented gravitational component of the water flux. An increase in the quantity of non-condensable gas (NCG) can diminish temperature gradients on the outer wall of the thermosyphon, leading to a reduction in the thermosyphon's performance. The insulation applied at the adiabatic section proved effective in increasing temperature gradients on the outer wall of the thermosyphon and thereby enhancing the performance of the thermosyphon. With an increase in the water charge within the thermosyphon, heat transfer rates from the exhaust to the thermosyphon and from the thermosyphon to the fuel increase.