Advances and obstacles in pressure-driven solid-state cooling: A review of barocaloric materials

Abstract

Solid-state caloric effects promise since decades a disruptive cooling technology that should be more efficient and cleaner than current vapor compression. However, despite relevant achievements have been made, it is still difficult to foresee the time left for the development and wide implementation of competitive devices. Recent progress in the response of materials under hydrostatic pressure offers hope for overcoming some of the shortcomings posed by other solid-state methods and augurs a good outlook for barocaloric cooling, but there are still many struggles ahead to address in order to demonstrate its viability as a commercial cooling technique. Here we briefly review the milestones achieved in terms of barocaloric materials and discuss the pending challenges and expectations for the oncoming years.

Reversible colossal barocaloric effects near room temperature in 1-X-adamantane (X=Cl, Br) plastic crystals

“…A comparison of ∆ and ∆ obtained upon a pressure change of ~1 kbar between different BC materials available in literature (see Fig. 8) reveals that the joint values for the compounds studied in this work outperform any other BC material reported so far [9]. The values obtained in this work compare also favorably to maximum reversible values driven by other fields, that for best MC materials reach about ~10 J K -1 kg -1 and ~5 K under 2 T created by permanent magnets, and ~15 K and 19 J K -1 kg -1 under 5 T, for best eC materials reach ~32 K and ~45 J K -1 kg -1 under 700 MPa and for best EC materials reach ~5 K and ~6 J K -1 kg -1 [49,50].…”

“…1-Cl-ada and 1-Br-ada, as plastic crystals in general, suffer from low thermal conductivities due to orientational disorder [9], which in the case of the plastic phase of adamantane reaches ~0.18 W m -1 K -1 under normal conditions [43]. Here, several aspects should be pointed out.…”

“…These issues may be overcome by applying high fields, but this is technologically challenging, energetically costly and may be destructive, leading to mechanical failure and/or dielectric breakdown. Pressure-induced (barocaloric, BC) effects have been less investigated but on the one hand they promise better efficiencies than vapor compression [8] and on the other hand the abundance of potential BC materials [9] has allowed the identification of BC effects that surpass in many aspects best MC, EC and eC effects reported so far.…”

Simple and Low-Cost Footstep Energy-Recover Barocaloric Heating and Cooling Device

“…In recent years, solid-state barocaloric materials have arisen as a promising solution for gas-free and eco-friendly refrigeration systems [1][2][3][4]. Barocaloric materials are solidstate compounds that exhibit large thermal changes, meaning isothermal entropy changes (∆S) or adiabatic temperature changes (∆S), defined as barocaloric effects.…”

Preliminary Numerical Investigation on the Optimization of a Single Bunch of Elastocaloric Elements to be Employed in an Experimental Device

“…When the field increases, a temperature increase is detected; conversely, if the intensity of the field is decreased, a temperature reduction is expected. To a magnetic field variation, a magnetocaloric effect is coupled [16,17]; electrocaloric cooling derives from the application of an electric field [18]; whereas a mechanical solicitation arises in elastocaloric [19] or barocaloric effect [20,21], respectively if the mechanical field is a structural stress (like traction) or a hydro-static pressure.…”