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  1. Article ; Online: Structural, Thermal, and Mechanical Characterization of a Thermally Conductive Polymer Composite for Heat Exchanger Applications

    Jamieson Brechtl / Yuzhan Li / Kai Li / Logan Kearney / Kashif Nawaz / Alexis Flores-Betancourt / Michael Thompson / Orlando Rios / Ayyoub M. Momen

    Polymers, Vol 13, Iss 1970, p

    2021  Volume 1970

    Abstract: Polymer composites are being considered for numerous thermal applications because of their inherent benefits, such as light weight, corrosion resistance, and reduced cost. In this work, the microstructural, thermal, and mechanical properties of a 3D ... ...

    Abstract Polymer composites are being considered for numerous thermal applications because of their inherent benefits, such as light weight, corrosion resistance, and reduced cost. In this work, the microstructural, thermal, and mechanical properties of a 3D printed polymer composite with high thermal conductivity are examined using multiple characterization techniques. Infrared spectroscopy and X-ray diffraction reveal that the composite contains a polyphenylene sulfide matrix with graphitic fillers, which is responsible for the high thermal conductivity. Furthermore, differential scanning calorimetry determines that the glass transition and melting point of the composite are 87.6 °C and 285.6 °C, respectively. Thermogravimetric analysis reveals that the composite is thermally stable up to ~400 °C. Creep tests are performed at different isotherms to evaluate the long-term performance of the composite. The creep result indicates that the composite can maintain mechanical integrity when used below its glass transition temperature. Nanoindentation tests reveal that modulus and hardness of the composite is not significantly influenced by heating or creep conditions. These findings indicate that the composite is potentially suitable for heat exchanger applications.
    Keywords polymer composites ; microstructure analysis ; thermal analysis ; creep modeling ; mechanical properties ; Organic chemistry ; QD241-441
    Subject code 621
    Language English
    Publishing date 2021-06-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: An energy-efficient method for direct-contact ultrasonic cloth drying

    Peng, Chang / Ayyoub M. Momen / Saeed Moghaddam

    Elsevier Ltd Energy. 2017 Nov. 01, v. 138

    2017  

    Abstract: A novel ultrasonic transducer driving method, in which the power supply to the transducer is regulated by a binary modulating signal, is introduced for the first time for use in direct-contact ultrasonic drying of fabrics. First, the drying ... ...

    Abstract A novel ultrasonic transducer driving method, in which the power supply to the transducer is regulated by a binary modulating signal, is introduced for the first time for use in direct-contact ultrasonic drying of fabrics. First, the drying characteristics of different fabrics on two types of transducers are studied using continuous transducer driving mode. Then, the effects of duty cycle and frequency of modulating power signals on fabric drying characteristics are investigated. The energy efficiency of the proposed transducer driving method is compared with that of the continuous transducer driving mode. The results suggest that drying using a modulating signal consists of nonlinear and linear regimes similar to those of the continuous driving mode. The results also show that drying time of a fabric depends not only on the fabric type, but also on the duty cycle and the modulating frequency. However, there exists a critical duty cycle beyond which the drying time does not change. The proposed transducer driving method is more energy-efficient compared to continuous driving mode, consuming 7–16 times less energy. Higher energy efficiencies maybe achieved by operating the transducer at higher modulating frequencies and shorter duty cycles.
    Keywords direct contact ; drying ; energy efficiency ; fabrics ; ultrasonics
    Language English
    Dates of publication 2017-1101
    Size p. 133-138.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2019804-8
    ISSN 0360-5442 ; 0360-5442
    ISSN (online) 0360-5442
    ISSN 0360-5442
    DOI 10.1016/j.energy.2017.07.025
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: A numerical analysis of a magnetocaloric refrigerator with a 16-layer regenerator

    Mingkan Zhang / Omar Abdelaziz / Ayyoub M. Momen / Ahmad Abu-Heiba

    Scientific Reports, Vol 7, Iss 1, Pp 1-

    2017  Volume 12

    Abstract: Abstract A numerical analysis was conducted to study a room temperature magnetocaloric refrigerator with a 16-layer parallel plates active magnetic regenerator (AMR). Sixteen layers of LaFeMnSiH having different Curie temperatures were employed as ... ...

    Abstract Abstract A numerical analysis was conducted to study a room temperature magnetocaloric refrigerator with a 16-layer parallel plates active magnetic regenerator (AMR). Sixteen layers of LaFeMnSiH having different Curie temperatures were employed as magnetocaloric material (MCM) in the regenerator. Measured properties data was used. A transient one dimensional (1D) model was employed, in which a unique numerical method was developed to significantly accelerate the simulation speed of the multi-layer AMR system. As a result, the computation speed of a multi-layer AMR case was very close to the single-layer configuration. The performance of the 16-layer AMR system in different frequencies and utilizations has been investigated using this model. To optimize the layer length distribution of the 16-layer MCMs in the regenerator, a set of 137 simulations with different MCM distributions based on the Design of Experiments (DoE) method was conducted and the results were analyzed. The results show that the 16-layer AMR system can operate up to 84% of Carnot cycle COP at a temperature span of 41 K, which cannot be obtained using an AMR with fewer layers. The DoE results indicate that for a 16-layer AMR system, the uniform distribution is very close to the optimized design.
    Keywords Medicine ; R ; Science ; Q
    Subject code 620
    Language English
    Publishing date 2017-10-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Experimental and analytical evaluation of a hydro-pneumatic compressed-air Ground-Level Integrated Diverse Energy Storage (GLIDES) system

    Odukomaiya, Adewale / Ahmad Abu-Heiba / Samuel Graham / Ayyoub M. Momen

    Elsevier Ltd Applied energy. 2018 July 01, v. 221

    2018  

    Abstract: In recent times, there has been a significant increase in intermittent renewable electricity capacity additions to the generation mix. This, coupled with an aging electrical grid that is poorly equipped to handle the ensuing mismatch between generation ... ...

    Abstract In recent times, there has been a significant increase in intermittent renewable electricity capacity additions to the generation mix. This, coupled with an aging electrical grid that is poorly equipped to handle the ensuing mismatch between generation and use, has created a strong need for flexible, advanced bulk energy storage technologies. In this paper, one such technology recently invented and demonstrated at Oak Ridge National Laboratory is introduced and characterized. Similar to compressed-air energy storage, the Ground-Level Integrated Diverse Energy Storage (GLIDES) technology is based on gas compression/expansion, however, liquid-piston compression and expansion are utilized. In common with pumped-storage hydroelectricity, hydraulic turbomachines (pump/turbine) are utilized for energy storage and recovery, however, pressure vessels are utilized to create artificial elevation (head) difference, allowing pressure head of several thousands of feet to be reached. This paper reports on the experimental performance of the first GLIDES proof-of-concept prototype, and presents formulation and results from a validated physics-based simulation model.
    Keywords electricity ; energy ; feet ; head ; hydroelectric power ; prototypes ; simulation models ; storage technology
    Language English
    Dates of publication 2018-0701
    Size p. 75-85.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000772-3
    ISSN 0306-2619
    ISSN 0306-2619
    DOI 10.1016/j.apenergy.2018.03.110
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Effect of Composition on the Phase Structure and Magnetic Properties of Ball-Milled LaFe 11.71-x Mn x Si 1.29 H 1.6 Magnetocaloric Powders

    Jamieson Brechtl / Michael R. Koehler / Michael S. Kesler / Hunter B. Henderson / Alexander A. Baker / Kai Li / James Kiggans / Kashif Nawaz / Orlando Rios / Ayyoub M. Momen

    Magnetochemistry, Vol 7, Iss 132, p

    2021  Volume 132

    Abstract: Magnetocaloric alloys are an important class of materials that enable non-vapor compression cycles. One promising candidate for magnetocaloric systems is LaFeMnSi, thanks to a combination of factors including low-cost constituents and a useful curie ... ...

    Abstract Magnetocaloric alloys are an important class of materials that enable non-vapor compression cycles. One promising candidate for magnetocaloric systems is LaFeMnSi, thanks to a combination of factors including low-cost constituents and a useful curie temperature, although control of the constituents’ phase distribution can be challenging. In this paper, the effects of composition and high energy ball milling on the particle morphology and phase stability of LaFe 11.71-x Mn x Si 1.29 H 1.6 magnetocaloric powders were investigated. The powders were characterized with optical microscopy, dynamic light scattering, X-ray diffraction (XRD), and differential scanning calorimetry (DSC). It was found that the powders retained most of their original magnetocaloric phase during milling, although milling reduced the degree of crystallinity in the powder. Furthermore, some oxide phases (<1 weight percent) were present in the as-received and milled powders, which indicates that no significant contamination of the powders occurred during milling. Finally, the results indicated that the Curie temperature drops as Fe content decreases (Mn content increases). In all of the powders, milling led to an increase in the Curie temperature of ~3–6 °C.
    Keywords magnetocaloric ; milling ; X-ray diffraction ; particle size ; morphology ; Chemistry ; QD1-999
    Subject code 669
    Language English
    Publishing date 2021-09-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article: Preliminary analysis of market potential for a hydropneumatic ground-level integrated diverse energy storage system

    Chen, Yang / Adewale Odukomaiya / Saiid Kassaee / Patrick O’Connor / Ayyoub M. Momen / Xiaobing Liu / Brennan T. Smith

    Elsevier Ltd Applied energy. 2019 May 15, v. 242

    2019  

    Abstract: With the increasing share of renewable energy in the power grid, energy storage is considered a viable and effective solution to mitigate intermittency and improve power system stability. To quantify and estimate market potential for a recently developed ...

    Abstract With the increasing share of renewable energy in the power grid, energy storage is considered a viable and effective solution to mitigate intermittency and improve power system stability. To quantify and estimate market potential for a recently developed Ground-Level Integrated Diverse Energy Storage (GLIDES) technology, the first operation model is developed for this hydropneumatic system and the bilinear pressure-volume terms are then linearized using the binary McCormick Relaxation method to improve solving efficiency. Based on up-to-date 5-min price data in four different real-time markets, several sets of experiments have been designed with three objective scenarios: maximize arbitrage, maximize arbitrage + reserve, maximize arbitrage + reserve + regulation. The experimental results show that the monetary value of GLIDES could be boosted by participation in ancillary markets and that regulation service might contribute more than half of the total revenue, even as high as 90% in PJM and ISONE markets. In addition, a case study for 1-day operation is used to illustrate the volume control of the GLIDES system.
    Keywords case studies ; economic valuation ; energy ; income ; markets ; models ; prices ; renewable energy sources
    Language English
    Dates of publication 2019-0515
    Size p. 1237-1247.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000772-3
    ISSN 0306-2619
    ISSN 0306-2619
    DOI 10.1016/j.apenergy.2019.03.076
    Database NAL-Catalogue (AGRICOLA)

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  7. Article: Physics of direct-contact ultrasonic cloth drying process

    Peng, Chang / Ayyoub M. Momen / Saeed Moghaddam / Saitej Ravi / Viral K. Patel

    Elsevier Ltd Energy. 2017 Apr. 15, v. 125

    2017  

    Abstract: Existing methods of drying fabrics involve energy-intensive thermal evaporation of moisture from clothes. Drying fabrics using high-frequency vibrations of piezoelectric transducers can substantially reduce drying time and energy consumption. In this ... ...

    Abstract Existing methods of drying fabrics involve energy-intensive thermal evaporation of moisture from clothes. Drying fabrics using high-frequency vibrations of piezoelectric transducers can substantially reduce drying time and energy consumption. In this method, vibrational energy generates instability on the liquid-air interface and mechanically ejects water from a wet fabric. Here, for the first time, the physics of the ultrasonic fabric drying process in direct-contact mode is studied. The kinematic and thermal responses of water droplets and fabrics on piezoelectric crystal transducers and metal mesh–based transducers are studied. The results suggest that on piezoelectric crystal transducers, the response of a droplet subjected to ultrasonic excitation is dictated by the relative magnitude of the surface tension and the ultrasonic excitation forces. The drying process for a fabric on the studied transducers consists of two regimes—vibrational and thermal. When the water content is high, the vibrational forces can eject bulk water rapidly. But the more strongly bound water within the smaller fabric pores evaporates by the thermal energy generated as a result of the viscous losses. This study finds that a metal mesh–based transducer is more suitable for dewatering fabrics, as it facilitates the ejection of water from the fabric–transducer interface to the opposite side of the mesh. A demonstration unit developed consumes 10–20% of the water latent heat energy at water contents greater than 20%.
    Keywords clothing ; dewatering ; direct contact ; droplets ; drying ; energy ; evaporation ; fabrics ; heat ; surface tension ; ultrasonics ; water content
    Language English
    Dates of publication 2017-0415
    Size p. 498-508.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2019804-8
    ISSN 0360-5442 ; 0360-5442
    ISSN (online) 0360-5442
    ISSN 0360-5442
    DOI 10.1016/j.energy.2017.02.138
    Database NAL-Catalogue (AGRICOLA)

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  8. Article ; Online: Harnessing strong metal–support interactions via a reverse route

    Peiwen Wu / Shuai Tan / Jisue Moon / Zihao Yan / Victor Fung / Na Li / Shi-Ze Yang / Yongqiang Cheng / Carter W. Abney / Zili Wu / Aditya Savara / Ayyoub M. Momen / De-en Jiang / Dong Su / Huaming Li / Wenshuai Zhu / Sheng Dai / Huiyuan Zhu

    Nature Communications, Vol 11, Iss 1, Pp 1-

    2020  Volume 10

    Abstract: Strong metal–support interactions (SMSI) are effective in tuning the structures and catalytic performances of catalysts but limited by the poor exposure of active sites. Here, the authors develop a strategy to engineer SMSI via a reverse route, which is ... ...

    Abstract Strong metal–support interactions (SMSI) are effective in tuning the structures and catalytic performances of catalysts but limited by the poor exposure of active sites. Here, the authors develop a strategy to engineer SMSI via a reverse route, which is in favor of metal site exposure while embracing the SMSI.
    Keywords Science ; Q
    Language English
    Publishing date 2020-06-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article: Thermal analysis of near-isothermal compressed gas energy storage system

    Odukomaiya, Adewale / Ahmad Abu-Heiba / Ayyoub M. Momen / Claus Daniel / Kyle R. Gluesenkamp / Omar Abdelaziz / Roderick K. Jackson / Samuel Graham

    Elsevier Ltd Applied energy. 2016 Oct. 01, v. 179

    2016  

    Abstract: Due to the increasing generation capacity of intermittent renewable electricity sources and an electrical grid ill-equipped to handle the mismatch between electricity generation and use, the need for advanced energy storage technologies will continue to ... ...

    Abstract Due to the increasing generation capacity of intermittent renewable electricity sources and an electrical grid ill-equipped to handle the mismatch between electricity generation and use, the need for advanced energy storage technologies will continue to grow. Currently, pumped-storage hydroelectricity and compressed air energy storage are used for grid-scale energy storage, and batteries are used at smaller scales. However, prospects for expansion of these technologies suffer from geographic limitations (pumped-storage hydroelectricity and compressed air energy storage), low roundtrip efficiency (compressed air energy storage), and high cost (batteries). Furthermore, pumped-storage hydroelectricity and compressed air energy storage are challenging to scale-down, while batteries are challenging to scale-up. In 2015, a novel compressed gas energy storage prototype system was developed at Oak Ridge National Laboratory. In this paper, a near-isothermal modification to the system is proposed. In common with compressed air energy storage, the novel storage technology described in this paper is based on air compression/expansion. However, several novel features lead to near-isothermal processes, higher efficiency, greater system scalability, and the ability to site a system anywhere. The enabling features are utilization of hydraulic machines for expansion/compression, above-ground pressure vessels as the storage medium, spray cooling/heating, and waste-heat utilization. The base configuration of the novel storage system was introduced in a previous paper. This paper describes the results obtained from a transient, analytical, physics-based thermodynamic system model used for the system design and evaluation of three design configurations (including base configuration). The system model captures real gas effects and all loss mechanisms. The model demonstrates an energy storage roundtrip efficiency of 82% and energy density of 3.59MJ/m3. Experimental evaluation of system performance and detailed cost-analysis will be presented in future publications.
    Keywords air ; batteries ; cooling ; cost analysis ; electricity ; energy ; energy density ; heat ; hydroelectric power ; models ; storage technology ; systems engineering ; thermal analysis
    Language English
    Dates of publication 2016-1001
    Size p. 948-960.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000772-3
    ISSN 0306-2619
    ISSN 0306-2619
    DOI 10.1016/j.apenergy.2016.07.059
    Database NAL-Catalogue (AGRICOLA)

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