phase change heat storage thermal solutions
With the continuous improvement of the integration of electronic devices, electronic devices are becoming smaller and smaller, but the volume power or area power density increases gradually, resulting in a sharp increase in the heat flux density of devices. High heat flow electronic equipment puts forward higher requirements for thermal cooling, so the thermal management of electronic devices has become a research hotspot at home and abroad. It should be pointed out that in some special occasions, the thermal management of electronic devices is faced with extremely high thermal load, and the devices are in a short-time intermittent working state.
To meet this special demand, the thermal management technology of phase change heat storage electronic devices came into being. Phase change heat storage technology uses the characteristics of phase change materials (PCM) absorbing / releasing high-density energy in the process of solid-liquid phase change to store / release heat energy, so as to buffer the thermal shock of high thermal load of electronic devices, so as to ensure the safe and stable operation of electronic devices. The application of phase change heat storage technology in thermal management of electronic devices mainly includes PCM heat sink, heat storage heat pipe and heat storage fluid circuit.
PCM heat sink is to reduce the temperature level of heat sink by using the constant temperature characteristics of phase change materials in the process of phase change. In order to enhance the thermal conductivity of PCM, a metal framework is configured in the heat sink, and the high thermal conductivity of metal is used to accelerate the heat transfer rate of PCM. As shown in Figure 1, there are single cavity heat sink, multi cavity parallel fin heat sink, multi cavity cross fin heat sink and honeycomb structure heat sink. The cavity of the heat sink is filled with PCM. It should be pointed out that the honeycomb heat sink shows superior heat transfer performance and is an optimal scheme for thermal management of electronic devices.
Heat pipe has high thermal conductivity and heat transfer capacity. In order to deal with the impact of extreme thermal load, a heat storage heat pipe is proposed, which combines the high thermal conductivity of the heat pipe with the high energy storage capacity of PCM. Moreover, the heat pipe can also enhance the heat transfer rate of PCM. Figure 2 shows the phase change heat storage heat pipe heat sink module. The working principle of the composite heat sink is that the heat generated by the heat source is transferred to the cold plate, and the heat pipe absorbs the heat from the cold plate and transfers the heat efficiently to the PCM heat storage area.
In the two-phase circuit, the circulating pump is added, and the evaporator is coupled with the condensation heat accumulator through the pipeline to form a heat storage two-phase circuit system, which can effectively improve the cooling efficiency of electronic devices. Figure 3 shows the structure of heat storage two-phase circuit system. In this system, the cold fluid absorbs the heat of the heat source of the electronic device, releases heat through the PCM area under the action of the circulating pump, becomes the cold fluid again, absorbs heat through the heat source again and works circularly. It should be noted that in this device, the heat transfer performance of PCM can be effectively enhanced by increasing the heat transfer area on the PCM side.
