(616e) Experimental Investigation of Self-Heat Recuperation Using Magnetocaloric Effect for Energy Saving in Thermal Processes

The reduction of carbon dioxide (CO₂) and the fossil fuel consumption has been one of our major concerns over the past few decades. In chemical processes that involve heating, heat is mainly provided by fossil fuel combustion, which is associated with great exergy loss. In 2009, self-heat recuperation technology based on the exergy recuperative heat utilization principle has been developed. In a self-heat recuperative process, the exergy of process stream heat is recuperated and so that it can be circulated within the process. By compressing gas at its highest temperature in the process for heat elevation, the energy consumption for heating can be reduced drastically compared to conventional heat-recovery technology due to 1) absence of combustion, and 2) small temperature difference during heat exchange.

  In the conventional self-heat recuperative process, the recuperation of process stream heat exergy is caused by enforcing a change of state; change of pressure through compression. However, but means to recuperate heat exergy by enforcing a reversible temperature change is not limited to pressure variation. When a magnetocaloric material is subjected to a varying magnetic field, the entropy change of the magnetic moments inside the material enforces a reversible temperature change, which is the magnetocaloric effect (MCE). In this research, an active magnetic regenerative (AMR) heat circulator that utilizes MCE in self-heat recuperation is proposed. Its energy saving potential has been evaluated through a one-dimensional numerical model and its results has been compared with experimental results.

 From the simulation, it was found that when the process stream heat of 21.6 J was circulated in between 293 K and 299.5 K, 1.2 J of work is needed. This is equivalent to heat pump with COP 18. The results showed that AMR heat circulator has the potential of being one of the energy saving options for thermal processes where compressors cannot be applied.