The environmental impact of solid-state materials working in an active caloric refrigerator compared to a vapor compression cooler

Abstract

Caloric refrigeration is an emerging class of cooling technologies based on caloric effects detected in ferro-caloric solid-state materials. Depending of the nature of the driving field, it is possible distinguishing four main caloric refrigerations: magnetocaloric, electrocaloric, elastocaloric and barocaloric. Therefore, caloric refrigeration is based on solid-state materials, unlike vapor compression, nowadays still the most diffused cooling technique, whom employs fluids as refrigerants. Solid-state materials do not provide a direct contribution in global warming, since they do not disperse in the atmosphere, but only an indirect impact is registered when they are employed as refrigerants in cooling systems. On the other side, a vapor compression plant is characterized by both direct and indirect contributions to global warming. The main parameter to evaluate global warming impact and carbon-dioxide emissions coming out from a cooler is the Total Environmental Warming Impact (TEWI) index, which accounts both the direct and indirect contributions produced. In this paper a numerical ∆TEWI analysis is presented, comparing the environmental impact of a caloric refrigerator, operating with different caloric materials, with the one of a vapor compression cooler working with HFC134a.

Energy Applications of Magnetocaloric Materials

“…Furthermore, they showed that the TEWI of an AMR cycle using a FOMT material was always better than that of one using a SOMT material. In 2018, the study was extended to consider other caloric materials . The recycling of rare‐earth elements was also investigated in the comprehensive study of Tunsu and Petranikova .…”

“…In 2018, the study was extended to consider other caloric materials. [196] The recycling of rare-earth elements was also investigated in the comprehensive study of Tunsu and Petranikova. [197] This study also considered the use of hydrometallurgy for the recovery of rare earth metals from commercial magnetocaloric materials containing Ce, Fe, La, Mn, and Si.…”

Nanofluids as Heat Transfer Fluids for High-efficiency Caloric Heat Pumps

“…Solid-state caloric heat-pumping is the new frontier of Not-In-Kind (NIK) technologies arisen as possible future replacement of vapor-compression-based systems [1][2][3]. This technology has the strong point to not employ greenhouse gases, that can result toxic or damaging for the environment and that can contribute to increase global warming, together with presenting improvements in energy efficiency and exhibiting the potential of recycling its components [4][5][6][7].…”

Enhancing the Heat Transfer in an Active Barocaloric Cooling System Using Ethylene-Glycol Based Nanofluids as Secondary Medium

“…In this paper, we numerically investigate the effect on heat transfer of working with nanofluids as auxiliary fluids in an active barocaloric refrigerator operating with a vulcanizing rubber. The results reveal that, as a general trend, adding 10% of copper nanoparticles in the water/ethylene-glycol mixture carries to +30% as medium heat transfer enhancement.Energies 2019, 12, 2902 2 of 15 effects (ECE) [20][21][22], and mechanical fields provoke elastocaloric (eCE) [23] or barocaloric effects (BCE) [24], respectively, as consequences of stretching or of hydrostatic pressure application.Caloric cooling is classified as environmentally friendly because it employs solid-state materials as refrigerants that do not directly impact global warming since they do not disperse in the atmosphere, as confirmed by a certain number of investigations [25][26][27][28] that asserted the eco-friendliness of all the techniques belonging to magneto- [29,30], electro-[31,32], elasto-[33,34], and baro-caloric [35] cooling.The reference and well-established systems for caloric cooling are based on the active caloric regenerative refrigeration (ACR) cycle, a thermodynamic Brayton-based cycle in which the caloric solid-state material acts as both the refrigerant and the regenerator, thus recovering heat fluxes through the help of an auxiliary fluid that vehiculates them with the final purpose of subtracting heat from the cold heat exchanger (and therefore the cold environment) [36]. To improve the efficiency of a caloric cooler, the ACR system works with the optimal operative parameters (such as the geometry of the regenerator, the fluid velocity, and the frequency of the cycle) [37-39] but the bottleneck is employing materials due of high caloric effect in the temperature range toward the application is devoted to [40].…”

“…Caloric cooling is classified as environmentally friendly because it employs solid-state materials as refrigerants that do not directly impact global warming since they do not disperse in the atmosphere, as confirmed by a certain number of investigations [25][26][27][28] that asserted the eco-friendliness of all the techniques belonging to magneto- [29,30], electro-[31,32], elasto-[33,34], and baro-caloric [35] cooling.…”