Elastocaloric Cooling Research Articles

Comparison Between Two Different Rotary Configurations of an Elastocaloric Cooling Device

Comparison Between Two Different Rotary Configurations of an Elastocaloric Cooling Device

Comparing Elastocaloric Cooling and Desiccant Wheel Dehumidifiers for Atmospheric Water Harvesting

Approximately two billion people worldwide lack access to clean drinking water, negatively impacting national security, hygiene, and agriculture. Atmospheric water harvesting (AWH) is the conversion of ambient humidity into clean water; however, conventional dehumidification is energy-intensive. Improvement in AWH may be achieved with elastocaloric cooling, using temperature-sensitive materials in active thermoregulation. Potential benefits, compared to conventional desiccant wheel designs, include substantial reductions in energy use, size, and complexity. A nickel–titanium (NiTi) elastocaloric water harvester was designed and compared with a desiccant wheel design under controlled conditions of relative humidity, air volume, and power. In a 30 min interval, the NiTi device harvested more water on average at 0.18 ± 0.027 mL/WH, compared to the 0.1567 ± 0.023 mL/WH of the desiccant wheel harvester. Moreover, the NiTi harvester required half the power input and was thermoregulated more efficiently. Future work will focus on mechanical design parameter optimization. Elastocaloric cooling is a promising advancement in dehumidification, making AWH more economical and feasible.

Early Efforts on Elastocaloric Cooling (2002 to 2014)

Early Efforts on Elastocaloric Cooling (2002 to 2014)

Recent Developments in Elastocaloric Cooling

Recent Developments in Elastocaloric Cooling

Modeling of an Elastocaloric Cooling System for Determining Efficiency

When it comes to covering the growing demand for cooling power worldwide, elastocalorics offer an environmentally friendly alternative to compressor-based cooling technology. The absence of harmful and flammable coolants makes elastocalorics suitable for energy applications such as battery cooling. Initial prototypes of elastocaloric systems, which transport heat by means of thermal conduction or convection, have already been developed. A particularly promising solution is the active elastocaloric heat pipe (AEH), which works with latent heat transfer by the evaporation and condensation of a fluid. This enables a fast and efficient heat transfer in a compression-based elastocaloric cooling system. In this publication, we present a simulation model of the AEH based on MATLAB-Simulink. The model showed very good agreement with the experimental data pertaining to the maximum temperature span and maximum cooling power. Hereby, non-measurable variables such as efficiency and heat fluxes in the cooling system are accessible, which allows the analysis of individual losses including the dissipation effects of the material, non-ideal isolation, losses in heat transfer from the elastocaloric material to the fluid, and other parasitic heat flux losses. In total, it can be shown that using this AEH-approach, an optimized system can achieve up to 67% of the material efficiency.

ElastoCaloric (eC) Cooling: recent studies and preliminary results on materials and devices

Refrigeration is a process aimed at lowering the temperature of an environment compared to the outside temperature. It has always played a fundamental role in modern industry: food, for the preservation of food; in the air conditioning of buildings, to make them habitable and even in the field of medicine and biology, for the preservation of samples and particular therapies. Today refrigeration systems, are responsible for about 17% of the world's electricity consumption. Therefore, the scientific community is researching solid-state refrigeration, which is 50% more efficient than vapour compression systems. Solid-state refrigeration is based on some materials' caloric effect, which can release or absorb latent heat when subjected to an external field (magnetic, electric, pressure or strain) release. Elastocaloric Refrigeration is one of the most minor explored frontiers, unlike magnetocaloric and electro-caloric systems. Some preliminary studies confirm that the eC systems have the advantage of being able to decrease the intensity of the external field (with a relative increase of the COP). In this work, a review on Ec systems is carried out, with particular attention to the description of the properties of the materials used, the various types of stress application. The results have been presented in terms of temperature, entropy, latent heat and COP.

Continuous Rotating Bending NiTi Sheets for Elastocaloric Cooling: Model and Experiments

Continuous Rotating Bending NiTi Sheets for Elastocaloric Cooling: Model and Experiments

Superelasticity and Elastocaloric Cooling Capacity in Stress-Induced Martensite Aged [001]А-Oriented Ni54fe19ga27 Single Crystals

Superelasticity and Elastocaloric Cooling Capacity in Stress-Induced Martensite Aged [001]А-Oriented Ni54fe19ga27 Single Crystals

Research Progress in Elastocaloric Cooling Effect Basing on Shape Memory Alloy

Research Progress in Elastocaloric Cooling Effect Basing on Shape Memory Alloy

Elastocaloric Cooling: State-of-the-art and Future Challenges in Designing Regenerative Elastocaloric Devices

The elastocaloric cooling, utilizing latent heat associated with martensitic transformation in shape-memory alloys, is being considered in the recent years as one of the most promising alternatives to vapour compression cooling technology. It can be more efficient and completely harmless to the environment and people. In the first part of this work, the basics of the elastocaloric effect (eCE) and the state-of-the-art in the field of elastocaloric materials and devices are presented. In the second part, we are addressing crucial challenges in designing active elastocaloric regenerators, which are currently showing the largest potential for utilization of eCE in practical devices. Another key component of elastocaloric technology is a driver mechanism that needs to provide loading for active elastocaloric regenerators in an efficient way and recover the released energy during their unloading. Different driver mechanisms are reviewed and the work recovery potential is discussed in the third part of this work.

NiTi‐Based Elastocaloric Cooling on the Macroscale: From Basic Concepts to Realization

AbstractSolid‐state cooling is an environmentally friendly, no global warming potential alternative to vapor compression‐based systems. Elastocaloric cooling based on NiTi shape memory alloys exhibits excellent cooling capabilities. Due to the high specific latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. The small required work input enables a high coefficient of performance. An overview of elastocaloric cooling from basic principles, such as elastocaloric cooling cycles, material characterization, modeling, and optimization, to the design of elastocaloric cooling devices is presented. Current work performed within the DFG (Deutsche Forschungsgemeinschaft) Priority Program SPP 1599 “Ferroic Cooling”, which is focused on the development and realization of a continuously operating elastocaloric cooling device, is highlighted. The cooling device operates in a rotatory mode with wires under tensile loading. The design allows maximization of cooling power by suitable wire diameter scaling as well as efficiency optimization by implementing a novel drive concept. Finally, computer‐aided design (CAD) models of the discussed solid‐state air cooling device are presented.

Elastocaloric Cooling on the Miniature Scale: A Review on Materials and Device Engineering

AbstractThis Review covers the fundamentals of operation and scaling of elastocaloric cooling devices as well as current developments of elastocaloric shape‐memory alloy (SMA) films and the engineering of SMA film‐based cooling devices. Sputter‐deposited TiNiCuCo alloys showing ultra‐low fatigue enable unique functional properties such as tailored transformation temperature gradients. Two substantially different concepts for the development of elastocaloric cooling demonstrators are discussed. One concept relies on heat transfer by mechanical contact between the elastocaloric SMA film and solid heat sink and source elements. The second concept makes use of the heat transfer between the elastocaloric SMA film and a heat transfer fluid, including the advanced technology of active regeneration. Demonstrators based on a single SMA film reach device temperature spans of 14 K and a high specific cooling power of up to 18 W g−1. The performance characteristics are compared with other solid‐state caloric cooling technologies.

Cover Feature: Elastocaloric Cooling on the Miniature Scale: A Review on Materials and Device Engineering (Energy Technol. 8/2018)

Cover Feature: Elastocaloric Cooling on the Miniature Scale: A Review on Materials and Device Engineering (Energy Technol. 8/2018)

Energy-Efficient Elastocaloric Cooling by Flexibly and Reversibly Transferring Interface in Magnetic Shape-Memory Alloys.

Elastocaloric cooling is currently under extensive study owing to its great potential to replace the conventional vapor-compression technique. In this work, by employing multiscale characterization approaches, including in situ neutron diffraction in a loading frame, in situ transmission electron microscopy observation at different temperatures, in situ synchrotron X-ray Laue microdiffraction, and high-resolution infrared thermal imaging, we have investigated the thermal and stress-induced martensitic transformation, the stability of superelastic behavior and the associated elastocaloric effect for a Heusler-type Ni50.0Fe19.0Ga27.1Co3.9 single crystal. On the basis of transformation from cubic austenite into monoclinic martensite with a flexibly and reversibly transferring interface, this unique single crystal exhibits a giant elastocaloric effect of 11 K and ultralow fatigue behavior during above 12 000 mechanical cycles. The numerical simulation shows that the Ni50.0Fe19.0Ga27.1Co3.9 alloy offers 18% energy saving potential and 70% cooling capacity enhancement potential compared to the conventional shape-memory nitinol alloy in a single-stage elastocaloric cooling system, making it a great candidate for energy-efficient air conditioner applications.

Effects of Strain Rate and Measuring Temperature on the Elastocaloric Cooling in a Columnar-Grained Cu71Al17.5Mn11.5 Shape Memory Alloy

Solid-state refrigeration technology based on elastocaloric effects (eCEs) is attracting more and more attention from scientists and engineers. The response speed of the elastocaloric materials, which relates to the sensitivity to the strain rate and measuring temperature, is a significant parameter to evaluate the development of the elastocaloric material in device applications. Because the Cu-Al-Mn shape memory alloy (SMA) possesses a good eCE and a wide temperature window, it has been reported to be the most promising elastocaloric cooling material. In the present paper, the temperature changes (ΔT) induced by reversible martensitic transformation in a columnar-grained Cu71Al17.5Mn11.5 SMA fabricated by directional solidification were directly measured over the strain rate range of 0.005–0.19 s−1 and the measuring temperature range of 291–420 K. The maximum adiabatic ΔT of 16.5 K and a lower strain-rate sensitivity compared to TiNi-based SMAs were observed. With increasing strain rate, the ΔT value and the corresponding coefficient of performance (COP) of the alloy first increased, then achieved saturation when the strain rate reached 0.05 s−1. When the measuring temperature rose, the ΔT value increased linearly while the COP decreased linearly. The results of our work provide theoretical reference for the design of elastocaloric cooling devices made of this alloy.

Modeling and analysis of an integrated solid state elastocaloric heat pumping system

Elastocaloric cooling (ECC) is considered as one of the candidates to replace vapor compression cycles, which use refrigerants with global warming potential (GWP) as working fluids. In order to properly understand the ECC system performance, it is critical to conduct analysis at the integrated system level. Also, due to the cyclic operation of an ECC system, dynamic modeling becomes necessary to capture the associated transients. In this study, for air conditioning applications, a unique air-to-air ECC dynamic system model has been developed to simultaneously simulate the elastocaloric effect of NiTi, heat transfer, and water transport in the system. Key parameters have been identified from sensitivity analysis of various options as well as the dynamic coupling among components. A systematic methodology has been further developed to identify practical solutions of the integrated ECC system, which provides a basis for comparison against other existing cooling technologies. Performance of an integrated ECC system with 1.2 kW net cooling capacity has been optimized using the NSGA-II method for maximum coefficient of performance (COP) within operational constraints. It has been demonstrated that effective system design and energy-efficient operation can only be achieved from optimization of the entire integrated system instead of a component or subsystem.

Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation.

Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor compression based cooling process. Nickel-Titanium (Ni-Ti) based alloy systems, especially, show large elastocaloric effects. Furthermore, exhibit large latent heats which is a necessary material property for the development of an efficient solid-state based cooling process. A scientific test rig has been designed to investigate these processes and the elastocaloric effects in SMAs. The realized test rig enables independent control of an SMA's mechanical loading and unloading cycles, as well as conductive heat transfer between SMA cooling elements and a heat source/sink. The test rig is equipped with a comprehensive monitoring system capable of synchronized measurements of mechanical and thermal parameters. In addition to determining the process-dependent mechanical work, the system also enables measurement of thermal caloric aspects of the elastocaloric cooling effect through use of a high-performance infrared camera. This combination is of particular interest, because it allows illustrations of localization and rate effects - both important for efficient heat transfer from the medium to be cooled. The work presented describes an experimental method to identify elastocaloric material properties in different materials and sample geometries. Furthermore, the test rig is used to investigate different cooling process variations. The introduced analysis methods enable a differentiated consideration of material, process and related boundary condition influences on the process efficiency. The comparison of the experimental data with the simulation results (of a thermomechanically coupled finite element model) allows for better understanding of the underlying physics of the elastocaloric effect. In addition, the experimental results, as well as the findings based on the simulation results, are used to improve the material properties.

Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation

Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation

Demonstration of high efficiency elastocaloric cooling with large ΔT using NiTi wires

Vapor compression (VC) is by far the most dominant technology for meeting all cooling and refrigeration needs around the world. It is a mature technology with the efficiency of modern compressors approaching the theoretical limit, but its environmental footprint remains a global problem. VC refrigerants such as hydrochloroflurocarbons (HCFCs) and hydrofluorocarbons (HFCs) are a significant source of green house gas emissions, and their global warming potential (GWP) is as high as 1000 times that of CO2 [Buildings Energy Data Book (Building Technologies Program, Department of Energy, 2009)]. There is an urgent need to develop an alternative high-efficiency cooling technology that is affordable and environmentally friendly [A. D. Little, Report For Office of Building Technology State and Community Programs, Department of Energy, 2001]. Here, we demonstrate that elastocaloric cooling (EC), a type of solid-state cooling mechanism based on the latent heat of reversible martensitic transformation, can have the coefficient of performance as high as ≈11, with a directly measured ΔT of 17 °C. The solid-state refrigerant of EC completely eliminates the use of any GWP refrigerants including HCFCs/HFCs.