Scientific test setup for investigation of shape memory alloy based elastocaloric cooling processes

Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan

doi:10.1016/j.ijrefrig.2015.03.001

Cited by 166 publications

(99 citation statements)

References 31 publications

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“…The arrows indicate the cycle direction, the numbers and the color of the curves assign the mechanical and thermal material behavior to the four phases of the adiabatic cooling process detailed description of the setup and an investigation of the influence of the control variables on the cooling process are given in Ref. [27]. The modular design of the setup allows characterization of different SMAs and also the study of training effects during mechanical cycling.…”

Section: Scientific Test Platform For Materials Characterization and Pmentioning

confidence: 99%

“…This characterization procedure includes tensile tests at different strain rates in order to determine the maximum temperature change of the SMA under adiabatic conditions [27,29]. Furthermore, the characterization includes the investigation of local temperature peaks which appear during the stressinduced phase transformation [21,24,32,33], whereas a homogenous temperature distribution is required for an efficient heat transfer during the cooling process.…”

Section: Materials Stabilization During Elastocaloric Mechanical Trainmentioning

confidence: 99%

“…Furthermore, the characterization includes the investigation of local temperature peaks which appear during the stressinduced phase transformation [21,24,32,33], whereas a homogenous temperature distribution is required for an efficient heat transfer during the cooling process. The homogeneity of the temperature distribution shows a strong rate dependency [24,28,34]; in order to optimize the heat transfer, the mean temperature change of the elastocaloric sample has to show a maximum [27]. Before the material can be characterized, however, it has to be trained in order to stabilize the material behavior, which is the focus of the presented work.…”

Section: Materials Stabilization During Elastocaloric Mechanical Trainmentioning

confidence: 99%

“…The investigation of the elastocaloric cooling process and the elastocaloric material properties requires a scientific test setup capable of performing cooling cycles and simultaneous measurement of mechanical parameters (strain and strain rate) as well as thermal parameters (temperature change and homogeneity of elastocaloric effects). Such a test platform was developed [27] and has been used to investigate cooling properties of NiTiCuV.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Stabilization of NiTiCuV Shape Memory Alloys: Observations During Elastocaloric Training

Schmidt

Ullrich

Wieczorek

et al. 2015

Shap. Mem. Superelasticity

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The paper presents novel findings observed during the training process of superelastic, elastocalorically optimized Ni-Ti-based shape memory alloys (SMA). NiTiCuV alloys exhibit large latent heats and a small mechanical hysteresis, which may potentially lead to the development of efficient solid-state-based cooling processes. The paper starts with a brief introduction to the underlying principles of elastocaloric cooling, illustrating the effect by means of a typical thermodynamic cycle. It proceeds with the description of a custom-built testing platform that allows observation of temperature profiles and heat transfer between SMA and heat source/sink during high-loading-rate tensile tests. Similar to other SMA applications, a training process is necessary in order to guarantee stable performance. This well-known mechanical stabilization affects the stress-strain hysteresis and the cycle-dependent evolution of differential scanning calorimetry results. In addition, it can be shown here that the training is also accompanied by a cycle-dependent evolution of temperature profiles on the surface of an SMA ribbon. The applied training leads to local temperature peaks with intensity, number, and distribution of the temperature fronts showing a cycle dependency. The homogeneity of the elastocaloric effect has a significant influence on the efficiency of elastocaloric cooling process and is a key aspect of the specific material characterization.

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Section: Scientific Test Platform For Materials Characterization and Pmentioning

confidence: 99%

Section: Materials Stabilization During Elastocaloric Mechanical Trainmentioning

confidence: 99%

Section: Materials Stabilization During Elastocaloric Mechanical Trainmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermal Stabilization of NiTiCuV Shape Memory Alloys: Observations During Elastocaloric Training

Schmidt

Ullrich

Wieczorek

et al. 2015

Shap. Mem. Superelasticity

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show abstract

“…[12][13][14][15][16] Recently, first macroscale elastocaloric cooling demonstrators have been reported, reaching temperature differences between heat source and sink of 1.5 and 7 K for compressive and tensile loading of TiNibased SMA, respectively. 17,18 Due to favorable scaling behavior, elastocaloric cooling becomes highly attractive also for microcooling, which gains importance, e.g., in microelectronics and lab-on-chip systems. 19,20 Thin SMA films and foils are predestined for miniature applications because of their large surface-tovolume ratio, which allows for fast heat transfer.…”

mentioning

confidence: 99%

TiNi-based films for elastocaloric microcooling— Fatigue life and device performance

et al. 2016

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The global trend of miniaturization and concomitant increase of functionality in microelectronics, microoptics, and various other fields in microtechnology leads to an emerging demand for temperature control at small scales. In this realm, elastocaloric cooling is an interesting alternative to thermoelectrics due to the large latent heat and good down-scaling behavior. Here, we investigate the elastocaloric effect due to a stress-induced phase transformation in binary TiNi and quaternary TiNiCuCo films of 20 μm thickness produced by DC magnetron sputtering. The mesoscale mechanical and thermal performance, as well as the fatigue behavior are studied by uniaxial tensile tests combined with infrared thermography and digital image correlation measurements. Binary films exhibit strong features of fatigue, involving a transition from Lüders-like to homogeneous transformation behavior within three superelastic cycles. Quaternary films, in contrast, show stable Lüders-like transformation without any signs of degradation. The elastocaloric temperature change under adiabatic conditions is −15 K and −12 K for TiNi and TiNiCuCo films, respectively. First-of-its-kind heat pump demonstrators are developed that make use of out-of-plane deflection of film bridges. Owing to their large surface-to-volume ratio, the demonstrators reveal rapid heat transfer. The TiNiCuCo-based devices, for instance, generate a temperature difference of 3.5 K within 13 s. The coefficients of performance of the demonstrators are about 3.

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Materials with Giant Mechanocaloric Effects: Cooling by Strength

2016

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The search for materials with large caloric effects has become a major challenge in material science due to their potential in developing near room-temperature solid-state cooling devices, which are both efficient and clean, and that can successfully replace present refrigeration technologies. There are three main families of caloric materials: magnetocaloric, electrocaloric, and mechanocaloric. While magnetocaloric and electrocaloric materials have been studied intensively in the last few decades, mechanocaloric materials are only very recently receiving a great deal of attention. The mechanocaloric effect refers to the reversible thermal response of a solid when subjected to an external mechanical field, and encompasses both the elastocaloric effect, corresponding to a uniaxial force, and the barocaloric effect, which corresponds to the response to hydrostatic pressure. Here, the state of the art in giant mechanocaloric effects is reviewed and a critical analysis of the thermodynamic quantities that characterize the major families of barocaloric and elastocaloric materials is provided. Finally perspectives for further development in this area are given.

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Scientific test setup for investigation of shape memory alloy based elastocaloric cooling processes

Cited by 166 publications

References 31 publications

Thermal Stabilization of NiTiCuV Shape Memory Alloys: Observations During Elastocaloric Training

Thermal Stabilization of NiTiCuV Shape Memory Alloys: Observations During Elastocaloric Training

TiNi-based films for elastocaloric microcooling— Fatigue life and device performance

Materials with Giant Mechanocaloric Effects: Cooling by Strength

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