International Journal of Thermophysics最新文献

{"title":"A Ti/Pt Hot Wire Anemometer and its SiO₂ Enhanced Structural Implementation for Mechanical Ventilators","authors":"I. R. Chávez-Urbiola,&nbsp;G. León-Muñoz,&nbsp;J. J. Alcantar-Peña,&nbsp;J. Ponce-Hernández,&nbsp;N. A. Rodríguez-Olivares,&nbsp;F. Jimenez-Oronia,&nbsp;R. Sánchez-Fraga","doi":"10.1007/s10765-025-03540-6","DOIUrl":"10.1007/s10765-025-03540-6","url":null,"abstract":"<div><p>This study presents the development and implementation of a microfabricated hot-wire anemometer designed for mechanical ventilators. The sensor is fabricated using MEMS techniques, incorporating a SiO₂ bridge that enhances structural integrity while enabling precise airflow measurement up to 326 lpm (63.3 m⋅s⁻¹). The design leverages the principles of thermal anemometry, utilizing a platinum heating element with optimized mechanical support to ensure high sensitivity and durability. Performance evaluations confirm the sensor’s compliance with ISO 80601–2-12 standards for mechanical ventilators, demonstrating high stability, minimal hysteresis, and fast response times. Additionally, endurance testing validates the sensor's robustness under extreme conditions. These results highlight the potential of this hot-wire anemometer for clinical applications, providing an alternative to conventional airflow sensors with improved structural resilience and measurement accuracy.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of the Thermal Performance of Non-residential Building Envelope Prototype Specimens Insulated with Porous Cementitious Nanocomposites Containing Phase Change Materials, Using a Hot Box Apparatus","authors":"Benjamin A. Tourn,&nbsp;Christina Strunz,&nbsp;Juan C. Álvarez Hostos,&nbsp;Cornelia Stark,&nbsp;Barbara Klemczak","doi":"10.1007/s10765-025-03537-1","DOIUrl":"10.1007/s10765-025-03537-1","url":null,"abstract":"<div><p>The NRG-STORAGE project aimed to develop innovative, energy-efficient cementitious foams (NRG-Foams) as a sustainable alternative to conventional insulation materials for non-residential building envelopes. NRG-Foams were designed to balance thermal insulation and heat storage capacity while maintaining volume stability and mechanical integrity. The base material consists of a highly conductive cement paste with air bubbles that provide insulating properties. Enhanced heat storage performance is achieved by incorporating microencapsulated phase change materials (MPCM). This study evaluates the thermal performance of wall prototypes constructed from masonry bricks or concrete, insulated with NRG-Foam panels containing MPCM volume fractions ranging from 0% to 20%. Key thermal indicators—including thermal transmittance, decrement factor, time lag, periodic thermal transmittance, energy savings, and dynamic thermal resistance—were assessed using a NETZSCH HotBox Test Chamber TDW 4040 under both steady-state and dynamic conditions. While thermal performance improved progressively with increasing MPCM content, reaching a maximum at 20% MPCM, it did not surpass the performance of specimens with standard insulation materials. Nevertheless, the findings highlight significant potential for further optimization, particularly with higher MPCM volume fractions. Such enhancements could enable NRG-Foams to outperform conventional insulation materials, especially in long-term thermal analyses conducted under more realistic conditions. In addition, the influence of issues encountered during the experimental procedure on the thermal performance assessment of NRG-Foams is also discussed.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Density and Thermal Expansion of Mg–Li Alloys with Lithium Content Up to 30 at%","authors":"Rasul N. Abdullaev,&nbsp;Yurii M. Kozlovskii,&nbsp;Alibek Sh. Agazhanov,&nbsp;Rashid A. Khairulin,&nbsp;Dmitrii A. Samoshkin,&nbsp;Sergei V. Stankus","doi":"10.1007/s10765-025-03543-3","DOIUrl":"10.1007/s10765-025-03543-3","url":null,"abstract":"<div><p>An experimental study of the relative elongation and the thermal expansion of a number of the magnesium–lithium alloys containing 5, 10, 17, 21, 25, and 30 at% lithium in a wide temperature range from 100 K to 650 K was carried out using the dilatometric method. The density of the alloys at room temperature was measured using the Archimedes method. The temperature and composition dependences of the studied properties were constructed using the obtained results. A comparison with literature results and an analysis of the behavior of the density and the linear thermal expansion coefficient (LTEC) of the Mg–Li alloys with an increase in lithium content to 30 at% (11 wt%) were carried out. It was shown that the addition of lithium up to 17 at% has virtually no effect on the LTEC value. Whereas in the range of 17 at% to 30 at% Li, the change in the LTEC value of the alloys reaches up to about 40%. It was found that in the Mg–Li alloys with a lithium content of 21 at% to 30 at% a phase transition occurs in the range of 226 K to 248 K, where the linear thermal expansion coefficient change abruptly. Moreover, the magnitude of the LTEC jump increases with lithium content. This kind of transition was found earlier in the study of the Mg–Li eutectic alloy and is presumably related to the martensitic-type transformation of the lithium-rich bcc magnesium–lithium alloys to the hcp structure.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating Design Considerations and Offsets in Body Infrared Thermometer Accuracy","authors":"Efrem Kebede Ejigu","doi":"10.1007/s10765-025-03539-z","DOIUrl":"10.1007/s10765-025-03539-z","url":null,"abstract":"<div><p>During the COVID-19 pandemic, body infrared thermometers have gained global popularity for their non-invasive, rapid temperature readings. Operating like industrial counterparts, they sense emitted radiation using optical and electrical components. Yet, their accuracy varies due to design and component quality. Many fall short of claimed precision and lack effective calibration options. Recognizing this issue, the National Metrology Institute of South Africa (NMISA) has taken the proactive step of assembling its own body infrared thermometer to investigate design factors that could impact accuracy and traceability. The initiative involves controlling the entire design process, starting from characterizing the thermopile and thermistor, determining instrument factors, and establishing accurate lookup tables for body temperature determination. This initiative aims to ensure accuracy and traceability to international standards. The research underscores the need to consider design factors and offsets, striving for a final design that allows easy recalibration, ensuring sustained accuracy and alignment with metrological standards.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal Conductivity of Solid Carbon Dioxide","authors":"Md Saiduzzaman,&nbsp;Viacheslav A. Konstantinov,&nbsp;Ove Andersson","doi":"10.1007/s10765-025-03541-5","DOIUrl":"10.1007/s10765-025-03541-5","url":null,"abstract":"<div><p>The thermal conductivity <i>κ</i> of solid CO₂ was studied in the temperature <i>T</i> range of 100–220 K and at pressures up to 200 MPa using the transient hot-wire method. The results are consistent with those expected for a polycrystal composed of small molecules, with <i>κ</i> increasing significantly as the temperature decreases and as pressure and density increase. The variation in <i>κ</i> with temperature is primarily attributed to changes in phonon–phonon scattering and density. The thermal conductivity behaviour is described using a two-basis model, where heat is transported by both phonons and diffuse modes. The density <i>ρ</i> dependence of the thermal conductivity, represented by the Bridgman parameter <i>g</i> = (d ln <i>κ</i>/d ln <i>ρ</i>)_<i>T</i>, was found to be <i>g</i> = 6.7 at 190 K, increasing to 9.4 at 110 K as the temperature decreases. This increase is attributed to an enhanced phonon contribution to the total <i>κ</i>.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10765-025-03541-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat Transfer Performance Study of Magnetic Fe2O3/Graphene Nanofluid in DASC","authors":"Mengmeng Ma,&nbsp;Shan Qing,&nbsp;Xiaohui Zhang,&nbsp;Mingci Hu,&nbsp;Zhihui Jia","doi":"10.1007/s10765-025-03542-4","DOIUrl":"10.1007/s10765-025-03542-4","url":null,"abstract":"<div><p>Magnetic nanofluids have come to attention due to their special physical properties, but their poor thermophysical properties limit their generalized use in DASC. In this study, Fe₂O₃/graphene nanoparticles were obtained by attaching magnetic Fe₂O₃ to graphene sheets with excellent thermophysical properties, which enhanced the thermophysical properties of magnetic nanofluids. The study first analyzed the effects of different reaction conditions on the structural composition of the nanoparticles as well as the thermophysical properties of the nanofluids, and then applied the Fe₂O₃/graphene nanofluids in a DASC simulator to analyze the photothermal conversion performance of the nanofluids. The results show that the saturation magnetization strength of the G3 sample reaches 47.47 emu·g⁻¹, and the thermal conductivity of the nanofluid after its preparation into a nanofluid reaches 0.642 W·m⁻¹·K at 80 °C, whereas the thermal conductivity of the base fluid is only 0.41 W·m⁻¹·K. For the photothermal conversion performance, with the increase of the proportion of Fe₂O₃, the photothermal conversion efficiency shows a trend of increasing and then decreasing, and the highest value of its photothermal conversion efficiency appears in the G2 sample at 200 ppm, reaching 58.21 %, which is 31.9 % higher than that of the base fluid.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cross Second Virial Coefficients of the N2–H2, O2–H2, and CO2–H2 Systems from First Principles","authors":"Robert Hellmann,&nbsp;Eckard Bich","doi":"10.1007/s10765-025-03524-6","DOIUrl":"10.1007/s10765-025-03524-6","url":null,"abstract":"<div><p>The cross second virial coefficients <span>(B_{12})</span> for interactions of molecular nitrogen (N₂) with molecular hydrogen (H₂), of molecular oxygen (O₂) with H₂, and of carbon dioxide (CO₂) with H₂ were obtained at temperatures ranging from 36 K to 2000 K for the former two systems and from 100 K to 2000 K for the latter system from new rigid-rotor intermolecular potential energy surfaces (PESs) for the three molecule pairs. Each PES is based on interaction energies calculated for a large number of pair configurations employing high-level quantum-chemical <i>ab initio</i> methods up to coupled cluster with single, double, triple, and perturbative quadruple excitations [CCSDT(Q)]. Core-core and core-valance correlation and relativistic effects were accounted for as well. <span>(B_{12})</span> values were extracted from the PESs classically and semiclassically using the Mayer-sampling Monte Carlo approach. The deficiencies of the semiclassical calculations at the lowest temperatures were partly remedied by a more rigorous treatment of translational quantum effects using the phase-shift method. The results for the N₂–H₂ and CO₂–H₂ systems are in excellent agreement with the most accurate experimental data. For the O₂–H₂ system, there are no experimental <span>(B_{12})</span> data because this mixture is highly explosive. There are, however, previous first-principles results for <span>(B_{12})</span> of this system by Van Tat and Deiters [Chem. Phys. <b>457</b>, 171–179 (2015)], which were obtained at a much lower level of sophistication for both the PES and the method to extract <span>(B_{12})</span> and differ significantly from the present <span>(B_{12})</span> values.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10765-025-03524-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Emissivity and Reflectivity Measurements for Passive Radiative Cooling Technologies","authors":"A. Adibekyan,&nbsp;J. Schumacher,&nbsp;L. Pattelli,&nbsp;J. Manara,&nbsp;S. Meriç,&nbsp;Ö. Bazkir,&nbsp;C. Cucchi,&nbsp;C. Sprengard,&nbsp;G. Pérez,&nbsp;J. Campos,&nbsp;J. Hameury,&nbsp;A. Andersson,&nbsp;S. Clausen,&nbsp; A. Rasmussen,&nbsp;C. Belotti,&nbsp;S. Efthymiou,&nbsp;M.-N. Assimakopoulos,&nbsp;D. Papadaki,&nbsp;F. Manoocheri,&nbsp;A. Llados,&nbsp;J. Jaramillo-Fernandez,&nbsp;T. Gionfini,&nbsp;M. Ortisi,&nbsp;A. Peter,&nbsp;M. Kleinbub,&nbsp;J. Bante,&nbsp;L. Donath,&nbsp;H. Herzog,&nbsp;C. Monte","doi":"10.1007/s10765-025-03532-6","DOIUrl":"10.1007/s10765-025-03532-6","url":null,"abstract":"<div><p>Due to their optical properties, passive radiative cooling (PRC) materials can effectively reflect solar radiation while simultaneously dissipating heat through the infrared transparency windows using outer space as a cold and renewable heat sink. This makes it possible to achieve sub-ambient temperatures even in direct sunlight without using any electricity for cooling or air-conditioning. However, the accurate determination of these peculiar optical properties is challenging and subject to high uncertainty levels when using commercial instruments available to industrial end users and research laboratories. Within the EU project PaRaMetriC, aiming at establishing a metrological framework for the comparable performance evaluation of PRC technologies, the Physikalisch-Technische Bundesanstalt is leading a work package dedicated to the development of accurate and traceable methods to determine the infrared optical and thermophysical properties of PRC materials. These include reflectivity and emissivity in the broad spectral range from 250 nm to 50 µm, encompassing both, the solar spectrum (250 nm–2500 nm) and the infrared transparency window of the atmosphere (7.1 μm–13 μm) with a target absolute uncertainty of less than 0.03. For this purpose, several candidate benchmark passive cooling materials have been characterized by PTB in the wavelength range between 1.4 µm and 50 µm. The range 250 nm to 1.4 µm will be covered in an upcoming paper. Characterizations of, and comparisons between, reference and end-user measurement techniques applied for the measurements of selected PRC materials will not only allow accurate determination of the thermophysical properties, but also identification of measurement problems and suitable approaches in this rapidly expanding field.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10765-025-03532-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement and Empirical Model of Viscosity of the Novel Refrigerant R-1132(E)","authors":"Duc Xuan Tran,&nbsp;Atiqur R. Tuhin,&nbsp;Monjur Morshed,&nbsp;Ryuga Hirata,&nbsp;Akio Miyara","doi":"10.1007/s10765-025-03538-0","DOIUrl":"10.1007/s10765-025-03538-0","url":null,"abstract":"<div><p>This study focuses on conducting experimental measurements of the viscosity of R-1132(E) and on developing empirical models from the collected data to support engineering system design calculations. R-1132(E) is recognized as a potential candidate of next-generation refrigerant suitable for air conditioning applications, owing to its low global warming potential of less than 1. The viscosity of R-1132(E) in both its liquid and vapor phases was measured using the tandem capillary tube method. This technique utilizes a series arrangement of two capillary tubes to mitigate end effects, thus ensuring precise viscosity measurements. The experimental data were obtained over a range of temperatures from 233 K to 335 K in the liquid phase and from 333 K to 373 K in the vapor phase, with pressures varying from 2.0 MPa to 4.0 MPa. The research included two series of experiments, each targeting different temperature ranges: low temperatures (233 K to 293 K) and high temperatures (303 K to 373 K) maintaining adherence to consistent measurement principles. The expanded uncertainties of these measurements were calculated as 2.24% for the liquid phase and 2.28% for the vapor phase. In contrast, viscosity models for R-1132(E) were developed employing the Extended Corresponding States and the modified Residual Entropy Scaling techniques. These models, refined through adjustable parameters determined during the modeling process, accurately represent the experimental data within the reported uncertainties.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10765-025-03538-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and Development of Miniature Pd–C Eutectic Fixed Point at CSIR-NPL","authors":"Ashish Bhatt,&nbsp;Umesh Pant,&nbsp;Saroj Sharma,&nbsp; Babita,&nbsp;Hansraj Meena,&nbsp;Gaurav Gupta,&nbsp;Komal Bapna,&nbsp;D. D. Shivagan","doi":"10.1007/s10765-025-03525-5","DOIUrl":"10.1007/s10765-025-03525-5","url":null,"abstract":"<div><p>The calibration of thermocouples (TCs) up to 1600 °C at CSIR-NPL, at present, uses the ITS-90 defined fixed points and the secondary fixed points such as Au and Pd using the ‘wire-bridge technique.’ In this technique, there is a loss of 2 to 3 cm of wire from the hot junction end of TCs for each calibration. To prevent this wire loss, CSIR-NPL intends to replace the wire-bridge-technique with the use of metal–carbon eutectic fixed-point cells. CSIR-NPL has established Fe–C, Co–C, and Ni–C eutectic cells for calibration of thermocouples to 1329 °C. In this paper, we present the design, material used, and construction of miniature Pd–C (1492 °C) eutectic cell with in-house development efforts at CSIR-NPL. Particular attention has been given to the repeatability and long-term stability of the phase transition temperatures using Type-S TC and the mechanical robustness of the miniature Pd–C eutectic fixed-point cell. The temperature was assigned to a miniature Pd–C cell using a Type-S TC calibrated using ITS-90 fixed points at Sn, Zn, Al, Ag, Cu, and Pd wire. The assigned temperature to the miniature Pd–C eutectic fixed-point cell is 1491.45 °C with expanded uncertainty of ± 0.64 °C (<i>k</i> = 2). For robustness and long-term stability, the Pd–C fixed point performance was evaluated from Nov-2022 to Sep-2024, and the observed standard deviations were 0.35 µV (0.03 °C) and 2.07 µV (0.17 °C) for melting and freezing profiles, respectively. The miniature Pd–C eutectic fixed-point cell is being used for thermocouple calibration services.</p></div>","PeriodicalId":598,"journal":{"name":"International Journal of Thermophysics","volume":"46 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}