Study on the Cooling Enhancement of LED Heat Sources via an Electrohydrodynamic Approach

This study is to investigate the cooling enhancement design of Light-Emitting Diodes (LED) heat sources through an electrohydrodynamic (EHD) approach, where the forced convection of air is achieved by the ion wind due to gas discharge phenomenon. A LED array with eight high-brightness LED units is adopted as the LED heat source in our study. The cooling enhancement system is composed of a heat sink with fins attached to our LED heat source and an array of electrodes connected to a high-voltage DC power supply. The electric field generated by parallel electrodes results in forced convection of air due to ionized particles between fins of heat sink, which significantly enhances the heat transfer from the heat source to outer atmosphere. Two different types of electrodes, i.e. line-type and needle-type, are employed in our experimental measurements. Different operation parameters, such as the number of electrodes, the pitch of electrodes, the input power and the distance between the heat sink and electrodes are systematically studied to evaluate their influences on the cooling enhancement of our LED source. For the purpose of comparison, a traditional cooling fan is also tested in our experiments. The needle electrode is proven more effective than the linear electrode. The proposed EHD approach is found to have the advantages in power saving, noise control and installment space over the cooling fan. With our design, the heat sink temperature can be maintained in the range of 20-30deg C from its peak value 65deg C (without external cooling) with an DC voltage between 15 and 23 kV.