Transformation thermodynamics: Heat flux control and device applications

Extended from its electromagnetic counterpart [1,2], transformation thermodynamics applied to thermal conduction equations can map a virtual geometry into a physical thermal medium, realizing the manipulation of heat flux with almost arbitrarily desired diffusion paths, which provides unprecedented opportunities to create thermal devices unconceivable or deemed impossible before [3,4]. In this talk we report our recent work on manipulation of transient heat flux employing this technique and showed two thermal devices: a heat flux cloak and an efficient plate heater. In the cloaking device we will show that heat flux can be guided by a transformed medium to flow around a vacuum obstacle and restore its diffusion direction as if nothing inhomogeneous exists in their trajectories [5]. In the second experiment we design an efficient plate heater that can transiently achieve a large surface of uniform temperature powered by a small thermal source [6]. As opposed to the traditional approach of relying on the deployment of a resistor network, our approach fully takes advantage of an advanced functional material system to guide the heat flux to achieve the desired temperature heating profile. Our research results are good examples of the powerful application of coordinate transformation on wave/flux manipulation and may help to broaden research in acquiring extraordinary ways to control and utilize heat energy or configure novel heat devices.