Electrocaloric Heat Pump Achieves High Efficiency, Cooling

Researchers have developed a solid-state electrocaloric cooling device that can generate a 20 kelvin temperature difference with high efficiency, according to a new study. The findings show that electrocaloric cooling can compete with other solid-state cooling strategies and offer a promising alternative to environmentally unfriendly vapor compression cooling. Cooling devices, including air-conditioning and heat pump systems, are estimated to consume roughly 20% of global electricity. Most of these systems operate through vapor-compression technologies, which are relatively inefficient and require environmentally harmful fluorinated refrigerants. Cooling through solid-state electrocaloric materials is an attractive alternative for vapor compression cooling. Electrocaloric technologies are based on ferroelectric materials exposed to an electric field, which triggers changes in the material's polarization, altering its temperature. This effect could form the basis of highly efficient cooling technologies. However, electrocaloric devices that are commercially competitive have not yet been achieved and, despite clear potential advantages, lag behind most other solid-state cooling technologies. Now, Junning Li and colleagues present a fluid-based double-loop electrocaloric heat pump that can generate a maximum temperature span of 20.9 kelvin (K) and a maximum cooling power of 4.2 watts. According to the authors, the temperature span and cooling power are, respectively, 50% and 15 times larger than those of the previous best electrocaloric device. Moreover, Li et al. show that their device reaches 64% of Carnot's efficiency (the theoretical maximum efficiency of a cooling system), which exceeds many vapor-compression and caloric cooling devices. "Although the performance of this system may fall short of the requirements of many practical applications, which often require cooling capacities of at least several hundred watts at temperature spans exceeding 20 K, the work of Li et al. underscores the immense future potential of electrocaloric technology," writes Jaka Tušek in a related Perspective.