Predicting large comprehensive refrigeration performance of plastic crystals by compositing carbon architectures for room temperature application

Abstract

Plastic crystals PE (pentaerythritol) possess colossal barocaloric effect (BCE) that is promising for solid-state refrigeration; however, the high phase transition temperature (> 400 K) and low thermal conductivity (<0.5 W·m−1·K−1) greatly hinder its practical application at room temperature. Here, we propose to complex plastic crystal (PC) with carbon nanotube/graphene architectures (CNT-Gra) to form [PC/CNT-Gra] composites and investigate the BCE based on molecular dynamics simulations. It is found that phase transition temperature of molecular order to disorder can be tuned by alloying PA (neopentane) or NPG (neopentyl glycol) into PE imbedded in CNT-Gra architectures. Importantly, we find that PE0.8PA0.2/CNT-Gra and PE0.75NPG0.25/CNT-Gra demonstrate both giant isothermal entropy changes ΔS (∼200 J·kg−1·K−1) and adiabatic temperature change ΔT (∼18 K) at room temperature. The large BCE mainly comes from the order–disorder transition of PC molecules imbedded in CNT-Gra architectures through analysis of the dynamic process of the composites. Importantly, the thermal conductivity of these campsites is as high as ∼10 W·m−1·K−1, enabling efficient thermal exchange that is vital for improving cooling performance of the cyclic refrigeration process. This work provides important insights for designing PC-based composites with optimized comprehensive cooling performance for potential room temperature refrigeration.