Shape memory heat engines

Salzbrenner, R.

doi:10.1007/bf00550253

Cited by 19 publications

(25 citation statements)

References 8 publications

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“…Equation (4.24) is usually expressed as a scalar equation and the average demagnetization factor is used instead of the demagnetization tensor [95]. The internal demagnetization field is, in general, spatially dependent over the magnetized body.…”

Section: The Demagnetization Fieldmentioning

confidence: 99%

“…In the case of an AMR, which is a non-uniformly magnetized body, the demagnetization field therefore strongly depends on its geometry, the temperature span at which it operates, the magnetocaloric material(s) applied and the applied magnetic field. Its fully correct application is therefore non-trivial and cannot be solved analytically (analytical solutions are only available for an uniformly magnetized body, like ellipsoidal bodies or an infinite sheet and cylinder [95]). Recently, a 3-D magnetostatic numerical model for the calculation of the demagnetization tensor and subsequently the demagnetization field was presented for a non-uniformly magnetized rectangular prism [46] and a stack of rectangular prisms [96] (e.g., a parallel-plate AMR).…”

Section: The Demagnetization Fieldmentioning

confidence: 99%

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Magnetocaloric Energy Conversion

Kitanovski

Tušek

Tomc

et al. 2015

Green Energy and Technology

240

152

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Section: The Demagnetization Fieldmentioning

confidence: 99%

Section: The Demagnetization Fieldmentioning

confidence: 99%

Magnetocaloric Energy Conversion

Kitanovski

Tušek

Tomc

et al. 2015

Green Energy and Technology

240

152

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“…An important milestone came in 2006 when Mischenko et al [8] reported the so-called giant electrocaloric effect in PbZr 0. 95 Ti 0.05 O 3 (PZT) ceramic thin films. Using indirect measurements, they demonstrated that the material undergoes an adiabatic temperature change of 12 K for an electric field change of 48 MVm −1 .…”

Section: Electrocaloric Materialsmentioning

confidence: 99%

“…However, the shape-memory-based heat engine has various advantages, from its simple design, potential passive operation (only requires the appropriate high-and low-temperatures media) and applicability to different operating conditions, so there might still be a promising and intriguing future for this technology. More details on shape-memory heat engines can be found in, e.g., [94][95][96].…”

Section: Introduction To the Elastocaloric Effectmentioning

confidence: 99%

Alternative Caloric Energy Conversions

Kitanovski

Tušek

Tomc

et al. 2014

Green Energy and Technology

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In this chapter, some alternative, "ferroic", solid-state energy conversion technologies are presented. These are the electrocaloric (pyroelectric), the barocaloric and the elastocaloric energy conversions. In their nature, they are analogous to magnetocaloric energy conversion; however, different external influences are needed to initialize the caloric effect. In the case of electrocaloric energy conversion, this is related to a change in the electric field; in the case of barocalorics, to a change in the hydrostatic pressure and in the case of elastocaloric energy conversion, to a change in the mechanical stress. Each group, to some extent, possesses possible advantages as well as some disadvantages in comparison with magnetocaloric energy conversion. However, since all three alternative solid-state energy conversion technologies are at an early stage of development, it is not yet reasonable to compare them with magnetocaloric energy conversion. It is only time and further research that will show the full potential of these alternative solid-state energy conversion technologies.This chapter is divided into three sections. In each section, the physical principle behind the discussed ferroic effect will be presented and an overview of existing materials with their physical properties will be made. Furthermore, different possibilities for designing an energy conversion device using these materials will be reviewed (especially for electrocalorics). However, since the technology based on these three effects is at an early stage of development, only a few prototypes of energy conversion devices have been presented. Electrocaloric and Pyroelectric Energy ConversionIn this subsection, the electrocaloric and pyroelectric energy conversions are presented and discussed. In general, the electrocaloric energy conversion stands for the heat pumping processes (or refrigeration), whereas the pyroelectric energy conversion stands for the power generation.The underlying mechanism of the electrocaloric energy conversion is the so-called electrocaloric effect. The electrocaloric effect is expressed as the temperature change of dielectric materials subjected to a varying electric field. To simplify, as the electrocaloric material is subjected to a positive electric field change the material heats up, yet as the electric field is turned off the opposite occurs and the material cools down. Speaking thermodynamically, the electrocaloric effect is analogue to the magnetocaloric effect, though instead of the magnetic field change an electric field change is required to induce the caloric effect in the material. However, the electrocaloric energy conversion has some potential advantages over the magnetocaloric energy conversion, such as higher power density and higher compactness of the energy conversion devices, no dependence on rare-earth materials, no moving parts of the device, operation of the devices with less vibrations, silent operation, etc. Nevertheless, the area of the electrocaloric energy conversion only recently attracted m...

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“…attraction for the manufacture of heat machines, because it has the efficiency that comes closest the efficiency of the Carnot machine [1]. This paper shows a mechanical thermal model of a heat machine that uses as motor element, a helical spring made of alloy equiatomic NiTi shape memory may affect reversible.…”

mentioning

confidence: 99%

Analytical Solutions of the Equations One Mechanical Thermal Model of a Helical Spring NiTi for Use in Heat Engine

Monteiro¹,

Roberto²,

Rolim³

et al. 2014

JMEA

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Shape memory effect is capability of certain materials to recover its original shape after an apparently permanent deformation. The NiTi alloy of the composition is approximately equiatomic and it is the materials that exhibit the best characteristics for application of these properties, especially in the biomedical area, because of their excellent biocompatibility as: in the manufacture of medical and dental instruments, orthodontic wires, orthopedic materials, guide wires, stents, filters and components to realize the less invasive surgeries. In other areas, they are used for confections of electronic keys, spectacle frames, application in controllers, junction of pipes and electronic connectors among others. New research topics involving the application of these alloys super-elasticity are also known as pseudo elasticity. This event has an isothermal nature and involves the storage of potential energy in the shape memory effect and super-elasticity. In this context, this work falls within the scope of use of the technologies being an example of the work undertaken, in the course Graduate of Federal University of Pernambuco in skills in these technologies. It will present the results of a heat engine which engine element is a helical spring made of a NiTi alloy equiatomic with memory effect reversibly. The spring is triggered by a hot source (~ 373.15 K) and a cold source (273.15 K). The machine is capable of producing a reciprocating oscillating between the two sources. Heat equations and the equations that describe the dynamic behavior of the spring were developed. Through the development of dynamic equations, it can determine the minimum mass for the motion of the machine, as well as the instantaneous and average power and overall efficiency. You can check the functionality of the machine by way of the inclination angle of the propeller and the coefficient of static friction. Among the main results, it was observed that the overall performance of the machine compared to the machines of this category showed the feasibility of the project.

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Shape memory heat engines

Cited by 19 publications

References 8 publications

Magnetocaloric Energy Conversion

Magnetocaloric Energy Conversion

Alternative Caloric Energy Conversions

Analytical Solutions of the Equations One Mechanical Thermal Model of a Helical Spring NiTi for Use in Heat Engine

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