Large Temperature Span Research Articles

Temperature-dependent feeding behavior in the brown box crab, Lopholithodes foraminatus

IntroductionGrowing fishing pressures and ocean warming are potential concerns for populations of brown box crabs, Lopholithodes foraminatus, at the southern end of their geographic distribution. In Southern California, brown box crabs are thought to occupy a broad depth gradient (intertidal zone - 547 m), which exposes them to temperatures ranging from 8°C - 24°C. This large temperature span presents challenges for these ectothermic animals because the rates of their physiological processes, and ultimately their dietary needs, behavior, and health, vary with temperature. Here we examined how temperature affects the feeding behavior of brown box crabs to better understand their ecology in warmer regions of their distribution.MethodsAdult crabs were exposed to one of three temperature treatments (8°C, 15°C, and 20°C, N=10) for 2 months. Weekly throughout the exposure period, crabs were given two similar-sized prey items of different crushing strength (clam and mussel). Claw pinch force, prey preference, time to consume prey, and number of prey consumed were recorded prior to the start of the experiment and weekly for the duration of the study, with the exception of pinch force, which was recorded bi-weekly. We hypothesized that crabs will have a stronger pinch force at warmer temperatures, prefer prey items that require less breaking force at the coldest temperature, consume prey faster at warmer temperatures, and consume more prey at warmer temperatures.ResultsOur results confirm that pinch force is consistently greater at 15°C compared to 8°C, however, crabs at 8°C consumed more clams (higher strength) while those at 15°C consumed more mussels. Crabs at 8°C also consumed prey items faster than crabs at 15°C but ate a similar number of prey. Furthermore, there was 100% mortality at 20°C within 8 days of exposure, indicating their proximity to lethal limits within Southern California.DiscussionThese results show that brown box crab feeding behavior exhibits temperature thresholds, which may alter their nutritional state, community interactions, and distribution under both short-term and long-term changes in ocean temperature.

Water molecules and oxygen-vacancy modulation of vanadium pentoxide with fast kinetics toward ultrahigh power density and durable flexible all-solid-state zinc ion battery

Aqueous zinc ion battery (ZIB) with many virtues such as high safety, cost-effective, and good environmental compatibility is a large-scale energy storage technology with great application potential. Nevertheless, its application is severely hindered by the slow diffusion of zinc ions in desirable cathode materials. Herein, a technique of water-incorporation coupled with oxygen-vacancy modulation is exploited to improve the zinc ions diffusion kinetics in vanadium pentoxide (V2O5) cathode for ZIB. The incorporated water molecules replace lattice oxygen in V2O5, and function as pillars to expand interlayer distance. So the structural stability can be enhanced, and the zinc ions diffusion kinetics might also be promoted during the repeated intercalation/deintercalation. Meanwhile, the lattice water molecules can effectively enhance conductivity due to the electronic density modulation effect. Consequently, the modulated V2O5 (H-V2O5) cathode behaves with superior rate capacity and stable durability, achieving 234 mA h g−1 over 9000 cycles even at 20 A g−1. Furthermore, a flexible all-solid-state (ASS) ZIB has been constructed, exhibiting an admirable energy density of 196.6 W h kg−1 and impressive power density of 20.4 kW kg−1 as well as excellent long-term lifespan. Importantly, the assembled flexible ASS ZIB would be able to work in a large temperature span (from −20 to 70 °C). Additionally, we also uncover the energy storage mechanism of the H-V2O5 electrode, offering a novel approach for creating high-kinetics cathodes for multivalent ion storage.

An overview of microstructure, mechanical properties and processing of high entropy alloys and its future perspectives in aeroengine applications

Modern engineering applications continually strive to develop greater performance mechanical components with good microstructural stability, improved mechanical properties, corrosion resistance and decreased cost of repairing and maintenance. This necessitates the broad use of advanced high performance materials like high entropy alloys (HEAs). These alloys are created by combining five or more alloying elements in equal or substantial amount. About 5 to 35 at. % of the alloying element is present in HEAs. It is characterized primarily by greater entropy, slow diffusion, severe lattice distortion, and cocktail effects. Due to its advanced microstructural stability throughout a larger temperature span and for longer length of time, it demonstrates improved mechanical characteristics at ambient temperature, cryogenic temperature, and elevated temperature. The diversity of elemental contents and significantly higher mixing entropy of HEAs make them mechanically superior to classic metals and alloys. It also shows better strength to weight ratio. Hence, it qualifies as a possible structural and functional material for aeroengine applications. In this work, the studies on the HEAs are briefly reviewed. A basic explanation of the four core effects of HEAs is given. Discussion is held on microstructure and mechanical properties of HEAs. The processing routes for manufacturing of HEAs (arc melting, bridgman solidification, mechanical alloying and vapour deposition) are presented briefly. The influence of heat treatment on mechanical behavior and microstructure of HEAs is presented. The simulation approach of CALPHAD modeling for designing of HEAs is discussed briefly. The future scope for research and development of HEAs in aeroengine applications is briefed.

A conceptual design of a thermal switch capacitor in a magnetocaloric device: experimental characterization of properties and simulations of operating characteristics

The quest for better performance from magnetocaloric devices has led to the development of thermal control devices, such as thermal switches, thermal diodes, and thermal capacitors. These devices are capable of controlling the intensity and direction of the heat flowing between the magnetocaloric material and the heat source or heat sink, and therefore have the potential to simultaneously improve the power density and energy efficiency of magnetocaloric systems. We have developed a new type of thermal control device, i.e., a silicon mechanical thermal switch capacitor (TSC). In this paper we first review recently developed thermal switches based on micro-electromechanical systems and present the operation and structure of our new TSC. Then, the results of the parametric experimental study on the thermal contact resistance, as one of the most important parameters affecting the thermal performance of the device, are presented. These experimental data were later used in a numerical model for a magnetocaloric device with a thermal switch-capacitor. The results of the study show that for a single embodiment, a maximum cooling power density of 970 W m−2 (510 W kgmcm −1) could be achieved for a zero-temperature span and an operating frequency of 5 Hz. However, a larger temperature span could be achieved by cascading multiple magnetocaloric elements with TSCs. We have shown that the compact TSC can be used in caloric devices, even with small temperature variations, and can be used in a variety of practical applications requiring thermal regulation.

High-performance multimode elastocaloric cooling system.

Developing zero-global warming potential refrigerants has emerged as one area that helps address global climate change concerns. Various high-efficiency caloric cooling techniques meet this goal, but scaling them up to technologically meaningful performance remains challenging. We have developed an elastocaloric cooling system with a maximum cooling power of 260 watts and a maximum temperature span of 22.5 kelvin. These values are among the highest reported for any caloric cooling system. Its key feature is the compression of fatigue-resistant elastocaloric nitinol (NiTi) tubes configured in a versatile multimode heat exchange architecture, which allows the harnessing of both high delivered cooling power and large temperature spans. Our system shows that elastocaloric cooling, which only emerged 8 years ago, is a promising direction for commercializing caloric cooling.

Performance assessment of a two-stage evaporation grade compression heat pump system for double temperature level drinking water production

The heat pump is widely used for space and water heating, but it has problems of low heating efficiency and inadequate heating at a large temperature span. According to the concept of energy cascade utilization and production, a two-stage evaporation grade compression heat pump (TE-GCHP) system is proposed in this paper for double temperature level boiled drinking water production. In this novel system, the application of grade compression matching multistage evaporation process realizes cascade utilization of the low grade thermal energy and cascade production of the hot drinking water, i.e. the refrigerant vapor from the intermediate-temperature water-cooling evaporator is sucked into the intermediate pressure suction port of the compressor to undergo the compression process of low compression ratio, while the refrigerant vapor from the low-temperature air-cooling evaporator is sucked into the low pressure suction port of the compressor to undergo the compression process of high compression ratio, so as to improve heating performance of the TE-GCHP system at large temperature spans. The energetic and exergetic analysis methods are used to evaluate heating performance of the proposed system and comparisons with the conventional waste heat-recovery single-stage compression heat pump (WH-SCHP) system are also discussed. The results indicate that there are the optimum water inlet temperature of medium-temperature water chamber and the optimum first-stage compression ratio to obtain the highest COP and exergy efficiency as well as the lowest power consumption, and energy-saving and economic performances of TE-GCHP system are markedly superior to those of WH-SCHP system and electric boiler. At evaporating temperature in the range of −10 °C to 30 °C, COP of TE-GCHP system is increased by1.06～1.29, and its exergy efficiency is improved by 2.17 %～10.62 %, while exergy loss of TE-GCHP system is reduced by 27.49 % on average, as compared to WH-SCHP system. In addition, as condensing temperature declines from 130 °C to 100 °C, power consumption of TE-GCHP system is decreased by 20.13–35.07 % compared with WH-SCHP system, whereas exergy efficiency of TE-GCHP system is on average 7.99 % higher than that of WH-SCHP system. In addition, the annual costs of the proposed system are 53.20 % and 69.68 % lower than those of the WH-SCHP system and electric boiler respectively.

Numerical and experimental study on a tube-in-tube heat exchanger working at liquid-hydrogen temperature with a large temperature span

With the advantages of no moving parts at low temperature and a flexible and simple structure, the precooled Joule–Thomson cryocooler working at liquid-hydrogen temperature has the potential to be used in the liquid-hydrogen zero-boil-off storage system. The recuperative heat exchanger is one of the key components of Joule–Thomson cryocoolers, and it is usually a tube-in-tube heat exchanger (T-THX). In this study, a numerical model of a T-THX working from room temperature to liquid-hydrogen temperature was developed. Based on the requirement that the heat-exchanger efficiency should be at least 97%, a T-THX was designed and tested. The performance of the T-THX with a temperature span of 280 K was obtained at pressure of 0.539–0.982 MPa and mass flow rate of 4.57–25.81 mg/s. The heat-exchanger efficiency varied from 95.83% to 97.50%, by which the feasibility of the numerical model was preliminarily verified. To improve the calculation accuracy, the T-THX model was modified. Compared with further experimental results, using the modified T-THX model, the relative deviation of the outlet temperature was within 0.3% and the deviation of the heat-exchanger efficiency was less than 0.05%.

Study on the ammonia-water two-stage evaporation absorption refrigeration system for the cooling process with temperature-distributed heat load

The absorption refrigeration system can recover low-grade heat and produce cooling capacity, which can realize low-carbon refrigeration. However, due to the constant-temperature evaporation, the conventional system fails to provide efficient cooling for temperature-distributed heat load with large temperature spans, including process cooling, mixture liquefaction and ice slurry making. In this paper, a modified ammonia-water absorption refrigeration system with two pairs of evaporation and absorption processes at different pressure levels is proposed, in order to enhance the temperature matching with the temperature-distributed heat load and promote the absorption heat recovery. A process model is developed and validated, and comparison and parametric studies are conducted to illustrate the advantages of the new system and optimize operating conditions. Results show that the proposed system is suitable for the cooling process with temperature-distributed heat load with large temperature span, and the exergy destruction during the cooling process with temperature-distributed heat load decreases by nearly 40%. Moreover, the system internal heat recovery is improved by harvesting absorption heat. As a consequence, the COP increases by 31% and reaches 0.75, when providing cooling capacity with temperature below -10 °C. It is hoped that this study raises concerns about the characteristics of temperature-distributed heat load and provides feasible approach for efficient cooling with large temperature span.

A Novel Dual-Differential Edge Sensor Based on the Eddy Current Effect

In this article, a kind of edge sensor based on the eddy current effect is proposed to realize accurate detection of the nano-level resolution in a large temperature span. Compared with edge sensors with different principles used in optical telescope projects, eddy current edge sensor has the advantages of being insensitive to nontarget direction and immune to nonferromagnetic medium. The proposed dual-differential edge sensor (DDES) greatly simplifies its installation and reduces the number of support components for sensors to half by replacing the complementary symmetrical installation method. By analyzing the detection principle, a kind of precise demodulation circuit and real-time temperature compensation method is also designed to guarantee the sensor’s ultrahigh stability. The prototype of the sensor is manufactured and verified that the resolution can reach within 2 nm in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300 ~\mu \text{m}$ </tex-math></inline-formula> , and the temperature drift (TD) performance is less than 6 nm/°C under the large temperature span from −25 °C to +25 °C. The installation error measurement convinced that the current structure has an excellent installation error tolerance, which has the potential to apply in the engineering application of astronomical telescope mirror splicing.

Magnetocaloric Effect in Lightly‐Doped Fe5Si3 Single Crystals

AbstractDevelopment of promising new materials for above room temperature magnetic cooling applications relies on careful balancing of structure and composition to maximize accessible metastable phases that can drive a strong magnetocaloric effect (MCE). However, the working temperatures of these materials may fall outside of desired application windows. In this work, it is shown that it is possible to control metastable phase stability temperatures of Fe5Si3 through selection of appropriate spin and charge doping. Here, the parent material's desired structure appears only within a narrow temperature range from 1098 to 1303 K. Doping with Mn and P is shown to allow stabilization of the parent's high temperature phase and resulting MCE to room temperature. The structural and magnetic properties, and the magnetocaloric effect of single crystal Fe4.83Mn0.16Si2.91P0.09 (FMSP) are investigated experimentally and theoretically. A first‐order magneto‐elastic transition is observed at 348 K, where magnetic onset is accompanied by a change in lattice volume without an apparent change in crystal symmetry. Although the trace Mn and P doping are found to decrease the TC, the maximum magnetic entropy change ΔSMax(T) and the relative cooling power (RCP) of FMSP are enhanced compared to polycrystalline Fe5Si3. As a result, an intrinsically broader entropy change over a larger temperature span is generated in the lightly doped single crystal of Fe5Si3. The magnetic moment of the system is also enhanced. Density functional theory (DFT) calculations are performed to gain microscopic insights into the experimental findings. The results suggest that the hexagonal Fe5Si3 is a new giant room temperature MCE material that is on par with La–Fe–Si and Fe‐Mn‐P‐Si systems.

Magnetic properties and magnetocaloric effect of (Fe70Ni30)96Mo4 thin films grown by molecular beam epitaxy

Thin films of ferromagnetic (Fe70Ni30)96Mo4 were grown via molecular beam epitaxy. Their magnetic properties and magnetocaloric effects were investigated. X-ray diffraction and vibrating sample magnetometry measurements confirmed the crystalline ferromagnetic (Fe70Ni30)96Mo4 phase, with a Curie point near room temperature. To determine the suitability of this material for magnetocaloric applications, we observed a large magnetic entropy change with a large temperature span as well as high relative cooling power near Curie temperature comparable to rare-earth-based materials operating near room temperature.

High performance of carbon nanotube elastocaloric refrigerators over a large temperature span

Compression of greenhouse gases still dominates the market of refrigeration devices. Although well stablished and efficient, this technology is neither safe for the environment nor able to be scaled down to nanoscale. Solid-state cooling technologies are being developed to overcome these limitations, including studies at nanoscale. Among them, the so-called elastocaloric effect (eC) consists of the thermal response, $\Delta T$, of a material under strain deformation. In this work, fully atomistic molecular dynamics simulations of the eC in carbon nanotubes (CNTs) are presented over a large temperature span. The efficiency of the CNTs as solid refrigerators is investigated by simulating their eC in a model of refrigerator machine running under Otto-like thermodynamic cycles (two adiabatic expansion/contraction plus two isochoric heat exchange processes) operating at temperatures, $T_\mbox{O}$, ranging from 300 to 2000 K. The coefficient-of-performance (COP), defined as the ratio of heat removed from the cold region to the total work performed by the system per thermodynamic cycle, is calculated for each value of $T_\mbox{O}$. Our results show a non-linear dependence of $\Delta T$ on $T_\mbox{O}$, reaching a minimum value of about 30 K for $T_\mbox{O}$ between 500 and 600 K, then growing and converging to a linear dependence on $T_\mbox{O}$ for large temperatures. The COP of CNTs is shown to remain about the same and approximately equal to 8. These results are shown to be weakly depend on CNT diameter and chirality but not on length. The isothermal entropy change of the CNTs due to the eC is also estimated and shown to depend non-linearly on $T_\mbox{O}$ values. These results predict that CNTs can be considered versatile nanoscale solid refrigerators able to efficiently work over a large temperature span.

The Schottky emission effect: A critical examination of a century-old model

Using a quantum mechanical calculation, we investigate the fundamental limitations of the Schottky emission (SE) model for its applications to electron injection into dielectrics from a metal or semiconductor electrode. This work covers a wide range of electric fields from 0.01 to 10 MV/cm and a large temperature span with many barrier height values (ΦB). We conclude that the SE model is only applicable for a very small class of dielectrics under 0.1 MV/cm and at high temperatures over ∼330 K. For many defective dielectrics with large barrier heights (ΦB ≥ ∼1.5 eV) in back-of-line/middle-of-line/metal–insulator–metal capacitor applications, the corresponding electric fields for the measurable currents far exceed 0.1 MV/cm, and up to 10 MV/cm, the application of the SE model is likely invalid so that the extracted ΦB values may not be correct. We provide a quantitative guide to avoid future misapplications of the SE model.

Performance analysis of a cascade room temperature magnetic refrigerator for improving temperature span

A two-stage cascade magnetic refrigerator (CMR) dedicated to improving the temperature span is developed in this paper. The magnetic field of the CMR is provided by two identical C-shaped permanent magnets with an average magnetic field intensity of 1.41 T. Gd is first filled in the active magnetic regenerators (AMRs) of both the high-temperature stage (HTS) and low-temperature stage (LTS), called Gd-Gd MCM configuration. Then, the AMRs of the HTS and LTS are packed with Gd and Gd0.965Er0.035, respectively, termed Gd-GdEr MCM configuration. The performance of the CMR with two MCM configurations and the single-stage magnetic refrigerator (SMR) using Gd as the MCM are tested and compared at the same hot end temperature of ∼293.1 K. The results show that the maximum no-load temperature spans of 4.2, 5.7, and 6.9 K are obtained by the SMR, the CMR with Gd-Gd MCM configuration, and the CMR with Gd-GdEr MCM configuration, respectively. Compared to the SMR, the maximum no-load temperature spans of the CMR with Gd-Gd and Gd-GdEr MCM configurations are increased by 35.7% and 64.3%, respectively. This indicates that a promising approach for increasing the temperature span is to employ the CMR and fill its HTS and LTS with the MCMs of high and low Curie temperatures, respectively. Moreover, the SCPs of the CMR with Gd-Gd and Gd-GdEr MCM configurations are 6.4 and 10.2 W kg−1, respectively, over a 5.0 K temperature span. This study may provide new ideas for the design of magnetic refrigerators with large temperature spans.

Role of fullerene carbon on tribological performance of polyimide composites at a large temperature span

The effect of fullerene carbon (C60) on the tribological performance of polyimide (PI) composites was explored at different temperature conditions. The results demonstrate the addition of 1.0 wt% C60 can greatly enhance the tribological performance of PI/1.0C60. The friction coefficients and wear rates of 0.03/0.07 and 1.0 × 10−5/1.6 × 10−5 mm3/Nm can be achieved at − 100 °C/200 °C, respectively, reducing by 86.4%/50.0% and 28.6%/30.1% compared with pure PI. It demonstrated the polymer states influenced the lubricated and loading carry capability of the sliding interfaces at different temperatures. XPS results indicated tribo-oxidation and organic-inorganic chelation reaction dominated the tribofilm growth. Moreover, molecular dynamics simulation showed the C60 enables the shear of PI easily due to the decreased intermolecular forces.

Achieving synergistic electromechanical and electrocaloric responses by local structural evolution in lead-free BNT-based relaxor ferroelectrics

• Inducing relaxor evolution by adjusting intrinsic A-site Na + /K + ratio. • Achieving large combined electromechanical and electrocaloric responses. • Realizing a larger electrocaloric endothermic peak at a low electric field. • Obtaining high electrocaloric strength and large electrostrictive coefficient. • Broadening the operating-temperature span. Self-actuating cooling materials based on synergistic electromechanical (EM) and electrocaloric (EC) responses are expected to lead next-generation of intelligent cooling devices. However, most current materials with the two responses present poor performance, narrow operation-temperature span and high driving electric field, and even contain toxic lead. Here, environmentally benign lead-free Bi 0.5 Na 0.5 TiO 3 -based (BNT) system was designed to achieve large combined response of two effects in a large temperature span by adjusting intrinsic A-site Na + /K + ratio to induce relaxor evolution. Simultaneously, high EC strength and large electrostrictive coefficient over a wide temperature range were obtained to resolve these challenges. The local-structural evolution is studied in detail to provide a theoretical basis for future application of this intelligent material. A novel asymmetric EC response presenting a larger endothermic peak was realized at a low electric field (<3 kV mm −1 ), which can provide a guideline for the development of low-driving-field EC materials to a certain extent. The phase-field simulation was performed to predict this unique behavior by describing the corresponding dipole coupling states under various electric fields.

Performance analysis of liquid air energy storage with enhanced cold storage density for combined heating and power generation

Liquid air energy storage (LAES), as a grid-scale energy storage technology, is promising for decarbonization and carbon-neutrality of energy networks. In the LAES, off-peak electricity or renewable energy is stored in the form of liquid air (i.e. air liquefaction); when electricity is needed, the liquid air is evaporated to generate electricity and meanwhile releases a great deal of cold energy in a temperature range of 85-300 K. The released cold energy is usually recovered for improving the air liquefaction, where fluids are popular as both cold recovery and storage media with the benefits of straightforward control strategy and high efficiency. However, two kinds of fluids are usually required to work together for cold recovery and storage (baseline LAES) as single fluid is not able to work in such a large temperature span (85–300 K). This leads to a four-tank configuration, making the cold storage bulky and complex. To address this issue, this paper investigates various fluids and it is found that their temperature ranges could be extended when they are under pressure (i.e., pressurized fluids). This makes it possible to recover and store the cold energy from liquid air by single pressurized fluid with a two-tank configuration, thus increasing cold storage density and decreasing capital cost. Therefore, a novel LAES configuration is proposed and analysed with pressurized propane (1 MPa) as an example for cold recovery and storage. Simulation results show that the proposed LAES system increases the volumetric cold storage density by ∼52% and improves the system energy storage density by 16.7% compared to the baseline LAES system . This saves the capital cost of cold storage by 37% and reduces the system capital cost by ∼7%. Besides, the proposed LAES system shows an electrical round trip efficiency of ∼50% and a combined heat and power efficiency of 74.9–81%. This study provides a feasible way to improve energy storage density and economic benefits of the LAES system.

Eco-friendly cooling materials with synergistic behavior of electromechanical and electrocaloric effects based on constructing B-site defect field

Nowadays, the materials with synergistic electromechanical (EM) and electrocaloric (EC) effects have gained significant inspiration and expectation for potential self-actuating cooling technology. Such a technique relies on high-performance materials that have both of two effects. Due to environmental consideration, lead-free Bi0.5Na0.5TiO3 (BNT) system was selected to construct the B-site local random field, which successfully achieved high mechanical and electrical performance in a large temperature span, to cope with the challenges of narrow operating temperature region, high driving electric field and poor performance. The relaxor evolution is induced by the difference in valence state, electronegativity and ion radius between substituted and original B-site ions. Going further, it is found that the B-site defects and oxygen vacancies produced by the process are crucial to the reversible polarization response. Phenomenological theory reveals that the essence of reducing the driving electric field in the optimized system lies in lowering the potential barrier from relaxor to ferroelectric phase transition. To a certain extent, our work should therefore motivate the exploration and development of environmental-friendly smart cooling materials.

Evolutions of superelasticity and elastocaloric effect of Ti50Ni48Fe2 and aged-hardened Ni-rich Ti49.2Ni49.3Fe1.5 shape memory alloys under cyclic compressive deformation

The transformation and superelasticity characteristics of solution-treated Ti50Ni48Fe2 and aged-hardened Ti49.2Ni49.3Fe1.5 shape memory alloys during cyclic compressive deformation were investigated. The Ti50Ni48Fe2 alloy could not be precipitation hardened, while the Ti49.2Ni49.3Fe1.5 alloy, aged at 400 °C, was hardened by Ti3Ni4 precipitates. During the cyclic deformation, the B2⇆R⇆B19′ transformation peaks broadened and spread to a large temperature span. At the same time, the superelasticity behavior became linear, and the associated elastocaloric cooling capacity decreased to a stable value. Among these samples, Ti49.2Ni49.3Fe1.5 alloy aged at 400 °C for 150 h exhibited the largest recoverable strain in superelasticity and retained the largest cooling effect after 1000 deformation cycles. Furthermore, it showed elastocaloric cooling of −4.1 °C to −7.0 °C at operating temperatures of −40–80 °C. Experimental results revealed that B19′ transformation was suppressed significantly by cyclic deformation, and thus the transformation occurred in a wide temperature range of −160 to −50 °C. Additionally, the linear superelasticity exhibited a low slope of the Clausius–Clapeyron relation of about 0.5 MPa/°C. These features allow the alloys to exhibit superelasticiy and the elastocaloric effect over a wider temperature range.

Application and analysis of multi-stage flash vaporization process in steam production in high-temperature heat pump system with large temperature difference

The high-temperature heat pump steam system (HTHPS) is an effective way to replace the calcining boiler's steam. However, the large temperature span of the system leads to colossal exergy loss of refrigerant in expansion valves and other components. Therefore, it is hoped to adopt the dual-flash vaporization process to improve the system's steam production performance. In this paper, three thermodynamic models and exergy models of HTHPS with a double flash evaporation process are established. Furthermore, this paper uses the multivariate simulated annealing algorithm to calculate the optimal COP of the system. Then, by comparing the single-stage compression (SC) system and the quasi-two-stage compression (QTC) system, the influence of the dual-flash vaporization process on HTHPS is analyzed. The results show that under the same environment, the COP of the dual-flash vaporization process compression system is 23.8% 44.54% higher than that of the SC system. With the increase of the system temperature span, the flash steam supplemental process brings the system to improved thermodynamic performance. Moreover, the exergy model of the dual-flash system is closest to the reversed Carnot cycle, when the evaporation temperature is 50 °C and the condensing temperature is 110 °C.