Active magnetocaloric heat pipes provide enhanced specific power of caloric refrigeration

Abstract

Today almost all refrigeration systems are based on compressors, which often require harmful refrigerants and typically reach 50% of the Carnot efficiency. Caloric cooling systems do not need any detrimental fluids and are expected to reach 60–70% of the Carnot limit. Current caloric systems utilise the active magnetocaloric regeneration principle and are quite cost-intensive, as it is challenging to achieve large cycle frequencies and thus high specific cooling powers with this principle. In this work, we present an alternative solution where the heat transfer from the heat exchangers to the caloric material is predicated on condensation and evaporation of a heat transfer fluid. Using thermal diodes, a directed heat flow is generated. Thereby we were able to build a cooling unit achieving a specific cooling power of 12.5 W g−1 at a cycle frequency of 20 Hz, which is one order of magnitude larger than the state-of-the-art.

The numerical study on performance evaluation of a thermal switch capacitor in a magnetocaloric cooling device

“…This value corresponds to a specific cooling power of 2025 for 250-μm-thick Gd, which is more than seven times higher than the achieved cooling power at the zero temperature span of most Gd-based magnetocaloric devices with active magnetocaloric regeneration studied so far. 50

Figure 7 Influence of cooling-power density on thermal performance Cooling-power density dependence of temperature difference between ambient temperature and heat-source temperature for (A) lower and (B) higher values of during stationary state for operating frequencies in the range 0.1 Hz–15 Hz. (C) Cooling-power density dependence of the temperature difference between ambient temperature and heat-source temperature for operating frequencies of 15, 20 and 25 Hz.

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Long-term stable compressive elastocaloric cooling system with latent heat transfer

“…Active elastocaloric heat pipe (AEH). Passive latent heat transfer is commonly used in heat pipes as well as thermosiphons 37 and was already realized in a magnetocaloric cooling system 38 . Here, a fluid present in both liquid and gaseous state is contained in a hermetically sealed container.…”

Recent advances on air heating system of cabin for pure electric vehicles: A review

“…Active magnetic regeneration (AMR) as a reversible thermal cycle technology that can be used for heating, cooling and mechanical power generation, and can even reach 60% Carnot efficiency it is one of the most promising alternative technologies for the development of heat pumps [ 61 ]. The magnetic HP system is based on the AMR principle.…”