Electrocaloric Cooling Materials and Devices for Zero-Global-Warming-Potential, High-Efficiency Refrigeration

Abstract

Electrocaloric cooling technologies, enabled by the discovery of the giant electrocaloric effect in dielectrics more than a decade ago, represents a zero-globalwarming-potential, environment-benign cooling alternative. Benefited from its nature as an electricity-driven capacitor, the electrocaloric working body renders the great advantages in the energy efficiency and the device integration. The decade-long efforts on advancing the technology revealed many promising material candidates with matured manufacturing protocols, as well as intriguing device prototypes for applications beyond the traditional vapor compression based cooling. This article presents the recent advances in electrocaloric cooling technologies, from material improvements to device demonstrations. The environmental impact and the energy efficiency of the technology were evaluated by the total effective warming impact and the material COP, respectively. In addition to the current progresses achieved by the decade-long research effort, the existing challenges and potential opportunities brought by the electrocaloric refrigeration will be discussed.

Multifunctional barium titanate ceramics via chemical modification tuning phase structure

“…Electrocaloric effect refers to the electric filed ( E )‐induced isothermal entropy change (Δ S ) or adiabatic temperature change (Δ T ) in polar materials. Electrocaloric effect is reversible, and it can be applied for electrocaloric cooling technology, which is considered as an environment‐friendly cooling alternative with high‐energy efficiency and miniaturized integration to replace current vapor‐compression‐based refrigeration 138‐145 . Figure 9A displays electrocaloric refrigeration cycle based on adiabatic temperature change in ferroelectrics 146 .…”

“…Copyright 2019, The Royal Society of Chemistry. H and I, Electric field dependence of Δ T near room temperature for BT‐, BNT‐, KNN‐ and Pb‐based ceramics 19,62,138‐146,148‐163 …”

“…The currently direct method is actually to measure the electrocaloric Δ T by self‐built systems employing thermocouple or IR sensors, or measure the exothermic peak by differential scanning calorimeter (DSC) with the applied electric field. The indirect method is to calculate Δ T based on Equation (2) and polarization change against temperature 138‐145 . However, this equation is not suitable for the assessment of all electrocaloric materials, such as some relaxor ferroelectrics showing obvious electric field‐induced phase transitions.…”

Self‐Actuating Electrocaloric Cooling Fibers

“…Furthermore, how to instantaneously and reversibly form good thermal contact between the EC material and the heat source and sink is also a critical challenge in achieving high heat flux. [ 13 ]…”

Energy Applications of Magnetocaloric Materials

“…Several researchers have concluded that caloric (ferroic) refrigeration and heat‐pumping technologies, which are still in the research and development phase, are the most important option for the future . These solid‐state technologies variously utilize magnetocaloric, electrocaloric, and mechanocaloric effects. A material that exhibits more than one of these effects is described as a multicaloric (multiferroic) material with multicaloric effects .…”