Experimental Study On LED Heat Dissipation Based On Thermoelectric Refrigeration And Nanofluid-cooled Microchannel Heat Sink

As the fourth-generation lighting source,light-emitting diodes(LED)has a series of advantages over the traditional halogen lamp s and energy saving lamp s.However,the heat dissipation problem have not been well solved,which limits the development of LED to the miniaturization and high density integration.In this paper,an LED heat dissipation method combing thermoelectric cooler(TEC),microchannel heat sink(MHS)and nanofluid coolant was proposed,which is suitable for high-power LED used at high ambient temperature and can ensure that the junction temperature does not e xceed the limit value(120°C).Through the analysis of LED heat dissipation flow,the heat dissipation system integrating thermoelectric refrigeration-microchannel and LED was designed.The experimental platform of LED heat test was built.Ti O₂ nanofluids with good dispersion stability were used as coolant for heat dissipation.The main work are as follows:The starting characteristics of LED&air-cooled heat sink(AHS),LED&TEC&AHS,LED&MHS,LED&TEC&MHS modes were compared.The primary and secondary order of the influence of on LED heat dissipation was studied,which included the current of thermoelectric refrigeration(I_TEC),ambient temperature(T_a),coolant inlet temperature(T_i),flow velocity(u).The influence of the main factors was experimentally investigated.TiO₂ nanofluids with good dispersion stability were prepared.The LED substrate temperature(Ts)was measured at different TEC power,nanofluid concentration(?)and ambient temperature(Ta).The total thermal resistance(Rt)from the LED substrate to the environment was analyzed.The relationship between the thermal resistance and nanofluid concentration was fitted.The effects of nanofluid concentration and ambient temperature on the LED substrate temperature,thermal resistance(Ro)of heat dissipation system and heat transfer capacity in the microchannel heat exchanger were investigated.The effectiveness of the heat dissipation system was evaluated.The experimental results show that the LED&TEC&AHS heat dissipation system showed the worst heat dissipation effect because the heat at the hot side of the TEC cannot be effectively dissipated.The TEC&MHS heat dissipation system can decrease the LED substrate temperature to lower than ambient temperature and coolant temperature,which showed its enhanced heat dissipation ability.The main factors affecting the heat dissipation are:I_TEC>T_i>T_a>u.The substrate temperature T_s decreases with the increase of I_TEC,the decrease of T_i,the decreasesof T_a,or the increase of u.The heat dissipation system can improve LED heat dissipation when the nanofluid was used as coolant.The the LED substrate temperature was lower as the mass fraction of nanofluid increased within a certain range.Compared to the use of water as coolant,the use of nanofluids as coolant allows LED to maintain lower temperature at higher ambient temperature.