Liquid cooling system for a high power light emitting diode of an automotive headlamp and its effect on light intensity

The automotive lighting industry is adopting compact cooling systems for high power light emitting diodes (HPLED) to overcome the heating issues in headlamps. Today, nano-particle based fluids are becoming popular as coolants as it is more effective than conventional coolant like water. The present work uses nano-fluid which is prepared using 100 percent ethylene glycol with 35 nm spherical shaped alumina nanoparticle with 1 percent volume concentration for HPLED cooling system. Using a custom made copper tube heat exchanger, experiments were conducted to study the performance of the cooling system using nano coolant and double distilled pure water as second coolant and results were compared. A popular Indian SUV headlamp that uses a halogen bulb was chosen for the study as it has space to accommodate the cooling system. Experiments were conducted by operating the HPLED at its maximum power and by varying the coolant flow rate. The performance of headlamp is studied by means of the light intensity measured at 49 test points on the floor surface and temperature measured at various points like LED junction and heat exchanger input and output. The junction temperature influences the light intensity of the LED. Lesser the junction temperature more will be the light intensity. It was found from the results that the junction temperature reduced by 26 percent with the help of the nano-fluid based cooling system. It is also found that the light intensity improved by 30 percent when the nano coolant was circulated at 0.3 m/s.