Abstract
Nickel-Titanium (NiTi)-based shape memory alloys (SMAs) enable new sustainable and environmentally friendly solid-state heating and cooling technologies. Elastocaloric (EC) heat pump systems exploit superelastic SMAs as a non-volatile, inflammable, and non-global-warming refrigerant, in contrast to the well-established vapor compression technology. The high specific latent heat released or absorbed during mechanical loading or unloading of the SMA material leads to a high temperature change in the material. As a result of the small required work input to induce the phase transformation, a high coefficient of performance (COP) can be achieved by this technology. The potential of these alloys can be exploited through an adequate thermodynamic cycle, efficient mechanical system design, and choice of suited EC materials.
A fully functional continuous operating EC heat pump system based on SMA was developed and realized recently. To assist the design process of an optimized device with given performance and efficiency requirements, the air-cooling behavior of single wires and simple bundle arrangement has been analyzed, and intensive parameter studies on different airflow rates have been performed.
For optimizing the heat transfer using bundles, the influence of different angles of attack between the wire arrangement and the airflow is investigated, and the temperature development in the bundle, as well as the effects on the thermal performance, are presented in this work.
