Reversing the thermal equilibration by differential magneto-thermal force.

A special magnetic body force, the differential magneto-thermal (DMT) force, was proposed to reverse thermal equilibration by 'pushing' a fluid element colder than its surroundings to a colder region, and a fluid element hotter than its surroundings to a hotter region [1]. In this work, we discuss the fulfilment of the requirements for this force and the experiment to verify it. We present experimental and analytical results that clearly demonstrate: (1) approaching thermal equilibrium in our magnetic fluid sample was indeed 'reversed' as the magnetic body force introduces the localized flows that stop the conventional convective heat transfer; (2) the DMT force density calculated with experimental parameters agrees with the design principle. These results prove the feasibility of the predicted mechanism for a new generation of heat transfer apparatus that can transfer heat energy with higher efficiency than the ones discussed in textbooks, such as heat engines.