bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Based Power Augmentation for Modular Pumped Hydro Storage in Smart Buildings Operation
Authors: Chen Yang , Abu-Heiba Ahmad , Kassaee Saiid , Liu Chenang , Liu Guodong , Starke Michael , Smith Brennan T. , Momen Ayyoub M. 
Published: July 2021

Abstract
In the U.S., building sector is responsible for around 40% of total energy consumption and contributes about 40% of carbon emissions since 2012. Within the past several years, various optimization models and control strategies have been studied to improve buildings energy efficiency and reduce operational expenses under the constraints of satisfying occupants’ comfort requirements. However, the majority of these studies consider building electricity demand and thermal load being satisfied by unidirectional electricity flow from the power grid or on-site renewable energy generation to electrical and thermal home appliances. Opportunities for leveraging low grade heat for electricity have largely been overlooked due to impracticality at small scale. In 2016, a modular pumped hydro storage technology was invented in Oak Ridge National Laboratory, named Ground Level Integrated Diverse Energy Storage (GLIDES). In GLIDES, employing high efficiency hydraulic machinery instead of gas compressor/turbine, liquid is pumped to compress gas inside high-pressure vessel creating head on ground-level. This unique design eliminates the geographical limitation associated with existing state of the art energy storage technologies. It is easy to be scaled for building level, community level and grid level applications. Using this novel hydro-pneumatic storage technology, opportunities for leveraging low-grade heat in building can be economical. In this research, the potential of utilizing low-grade thermal energy to augment electricity generation of GLIDES is investigated. Since GLIDES relies on gas expansion in the discharge process and the gas temperature drops during this non-isothermal process, available thermal energy, e.g. from thermal storage, Combined Cooling, Heat and Power system (CCHP), can be utilized by GLIDES to counter the cooling effect of the expansion process and elevate the gas temperature and pressure and boost the roundtrip efficiency. Several groups of comparison experiments have been conducted and the experimental results show that a maximum 12.9% cost saving could be achieved with unlimited heat source for GLIDES, and a moderate 3.8% cost improvement can be expected when operated coordinately with CCHP and thermal energy storage in a smart building.
Comparison of the Performance of a Solar Thermal Absorption Chiller and a Novel Sub-Wet Bulb Evaporative Chiller for Cooling Processes in Food Manufacturing
Authors: Fricke Emily , Narayanan Vinod 
Published: July 2021

Abstract
The food processing industry exists at the nexus between food, energy, and water systems. Improving the sustainability of this industry is critical to reduction of carbon emissions and enhanced utilization of vital resources such as water. The overarching aim of the present research is to create a process-based modeling platform for food processing systems that would allow the most appropriate combination of water-sustainable, energy-efficient, and renewable energy (WERE) technologies to be determined for a system. This paper focuses on one specific process in a thermal processing line: the cooling step after sterilization and prior to packaging. A typical process might use groundwater in a once-through loop. To reduce water use, two sustainable alternatives are considered and compared: (a) solar thermal coupled with an absorption chiller and (b) evaporative cooling of chilled water using a sub-wet bulb evaporative chiller (SWEC). The former uses a parabolic trough solar field with thermal storage that is connected to a single-effect water/lithium bromide (LiBr) chiller. The field and thermal storage are modeled using NREL’s System Advisor Model software and coupled to in-house Python code for the chiller and process heat exchanger. For the latter option, a novel SWEC is used as a chiller. The energy and water use, and capital cost of the two alternative technologies are presented.
Feasibility Analysis of Refuelling Infrastructure for Compressed Renewable Natural Gas Long-Haul Heavy-Duty Trucks in Canada
Authors: Yaïci Wahiba , Longo Michela 
Published: July 2021

Abstract
With environmental concerns and limited natural resources, there is a need for cleaner sources of energy in the transportation sector. Renewable natural gas (RNG) is being considered as a potential fuel for heavy-duty applications due to its comparable usage to diesel and gasoline in vehicles. The idea of compressed RNG vehicles is being proposed especially because it will potentially significantly reduce harmful emissions into the environment. This initiative is taken in order to decrease vehicle emissions and support Canada’s commitments to the climate plans reinforcing active transportation infrastructure, in concert with new transit infrastructure, and zero emission vehicles.
This study examines the feasibility of implementing a nationwide network of compressed RNG refuelling infrastructure in order to accommodate a conversion of Canada’s long-haul, heavy-duty truck fleet from diesel fuel to RNG. Two methods, Constant Traffic and Variable Traffic, along with data about compressed RNG infrastructure and vehicles, were developed and used to predict fuelling requirements for Canada’s long-haul, heavy-duty truck fleet. Then, a detailed economic analysis was conducted on various test cases to estimate how different variables impact the final selling price of RNG. This provided insight with the understanding of what factors go into pricing RNG and if it can compete against diesel in the trucking market.
Results disclosed that the cost to purchase RNG is the greatest factor in the final selling price of compressed RNG. Due to the variability in RNG production however, there is no precise cost, which makes predictions difficult. However, results revealed that it is possible for compressed RNG to be competitive with diesel, with the mean compressed RNG price being 16.5% cheaper than diesel, before being taxed.
Future studies should focus on the feasibility of the production of RNG and the associated costs, with emphasis on the Canadian landscape. An in-depth analysis on operational and maintenance costs for compressed RNG refuelling stations may also provide predictions that are more accurate.
A Study of Cost-Saving Potential of Load Flexibility Measures in Grid-Interactive Multifamily Buildings
Authors: CaraDonna Chrisopher , Woldekidan Korbaga , Xiong Jie 
Published: July 2021

Abstract
With recent advances in smart technologies, more and more smart devices are penetrating the residential and commercial buildings market. The introduction of these smart devices is also helping IoT companies emerge with load aggregator roles in the sector. With more utility companies on the track of supporting OpenADR protocols, the aggregators could play a significant role in providing load flexibilities by automatically responding to demand response (DR) events and coordinating load flexibility measures between customers. This would benefit utility companies by reducing stress on the grid during critical peak demand hours as well as customers by allowing them to utilize utility rate structures advantageous to those able to reduce electric usage during high-demand hours.
This study evaluates cost and energy savings from adopting multiple load flexibility measures in multifamily buildings. Combinations of different load flexibility measures, including space temperature floating, light dimming, automatic window shading, and water heater temperature floating, are considered. The simulations are performed using OpenStudio®, an open-source U.S. Department of Energy (DOE) simulation platform. For the case study, we used a midrise apartment building with weather conditions from Denver, Colorado. To compare climate zone differences, simulations were also performed for Los Angeles, California, and Chicago, Illinois.
Initial results indicate that the application of automated load flexibility measures without careful consideration of dispatching strategies and DR program enrollments could significantly affect the savings. To get meaningful cost savings, aggregators need to encourage tenant awareness to curtail energy usage through occupant behavior in addition to dispatching automatic load flexibility measures. The outcomes from this study are believed to help load aggregators understand the risks and benefits of load flexibility opportunities.
Enhancement the Solar Still Performance Using Chimney Exhaust Gases
Authors: Hassan Hamdy 
Published: July 2021

Abstract
In this paper, a theoretical study is presented on enhancement of the solar still performance by using the exhaust gases passing inside a chimney under the still basin. The impact of the exhaust gases temperature on the solar still temperature, productivity, and efficiency are considered. The performance of solar still with chimney is compared with that of conventional solar still. The study is carried out under the hot and climate conditions of Upper Egypt. A complete transient mathematical model of the physical model including the solar still regions temperatures, productivity, and heat transfer between the solar still and the exhaust gases are constructed. The mathematical model is solved numerically by using fourth-order Runge-Kutta method and is programmed by using MATLAB. The mathematical model is validated using an experimental work. The results show that the solar still saline water temperature increases and productivity with using and rising the exhaust gases. Furthermore, the impact of using exhaust gases on the still performance in winter is greater than in summer. using chimney exhaust gases at 75 °C and 125 °C enhances the daily freshwater yield of the conventional still by more than three times and about six times in winter, respectively, and about two and half times and more than three times in summer, respectively.
A Forward Feedback Control Scheme for a Solar Thermochemical Moving Bed Countercurrent Flow Reactor
Authors: Al Sahlani Assaad , Randhir Kelvin , Ozalp Nesrin , Klausner James 
Published: July 2021

Abstract
Pelletized thermochemical energy storage media has the potential for long duration energy storage. The production of charged solid state energy storage media can be done within a cylindrical cavity chemical reactor that captures concentrated solar radiation from a solar field. Temperature stability of a solar reactor is directly influenced by the solar flux intercepted. This paper presents a low-order physical model to simulate the dynamic response of temperature inside a tubular plug-flow reactor prototype. Solid granular particles are fed to the tube from the top whereas a counter-current flowing gas enters the tube from the bottom. An in-house code was developed to model transient heat transfer of the tube wall, gas, and moving particles. The model was preliminarily validated with packed beds for different temperatures ranges and two gas flow rates. Dynamic response of the reactor temperature is simulated for different input power and gas/particle flow rates. The results show that the system response can be controlled efficiently by utilizing input power (solar flux) as a control parameter. A conventional PI controller is designed to control the temperature inside the reactor and to maintain it during the solar flux intermittency. Controller parameters are tuned using the Ziegler-Nichols method to ensure optimal system response. The results show that the feedback control model is successful in tracking different reference reactor temperatures within reasonable settling time of 30 minutes and eliminated overshoot. This study can be extended to include a hybrid reactor with a multi-input, multi-output variable system.
Effect of Phase Change and Buoyancy-Driven Flows on an ROC-Based Thermal Energy Storage System
Authors: Lee Justin Andrew , Salerno Christopher N. , Girgis Karen U. , Aguirre Ulyses , Baghaei Lakeh Reza 
Published: July 2021

Abstract
Inorganic salts (e.g., chloride salts) have gained attention in the energy field as a new thermal energy storage medium. Low cost, high melting temperature and high heat capacity of inorganic salts make them attractive in utility-scale thermal storage applications as higher energy storage temperatures lead to higher efficiency in power generation. There is a potential to use the dry byproduct of water desalination, i.e., Reverse Osmosis Concentrate (ROC) as a thermal storage medium. Using ROC as a thermal energy storage medium would prevent a harmful waste to be released to the environment while introducing a novel and low-cost alternative for thermal energy storage medium. In this study, heat transfer behavior of an ROC-based thermal energy storage system is studied using CFD. A computational model is developed, verified, and validated to simulate the phase change process and buoyancy-driven flow in a square ROC-based thermal energy storage element. The computational results provide a predictive model for charge and discharge cycles of an ROC-based thermal energy storage system.
Onset of Bénard Convection in an Electromagnetic Heat Exchanger Under Laminar Flow Conditions
Authors: Mohekar Ajit A. , Tilley Burt S. , Yakovlev Vadim V. 
Published: July 2021

Abstract
Electromagnetic (EM) heat exchangers (HX) are critical components in power beaming applications where EM waves are radiated towards an EM HX, which then converts incident energy into heat or mechanical work. An EM HX consists of a lossy ceramic undergoing EM heating, and a fluid flow maintaining thermal contact transfers heat from the ceramic. Temperatures during high-power EM processing of ceramics materials such as zirconia suggest that liquids would be in gaseous phase, so models of EM HX with compressible gas dynamics may provide insights into experimental scenario. As a first step, we consider an EM HX such that plane Poiseuille flow of an incompressible coolant whose density drops linearly with temperature is situated above a lossy ceramic material. Compressible effects are negligible, but density gradients within the fluid can give rise to buoyancy-driven flow under the action of gravity, which may affect the performance of the device. We determine the power of incident waves at which Bénard convection is initiated, through a linear stability analysis, in the fluid layer. We show that in case of temperature dependent ceramic loss factor, perturbations in temperature give rise to an electric (fringe) field which then feeds back into the system promoting the Bénard instability.
A Comparative Study of 1-D and 3-D Simulation Methodologies To Predict the Thermal Performance of a Power Electronics Hardware
Authors: Tiwari Ankit , Whitaker Craig , Kendall Brian 
Published: July 2021

Abstract
Extruded radial fin heat sinks are typically used in power electronics for temperature management. The goal of this study is to compare the temperature predictions of LPTN (Lumped Parameter Thermal Network), Finite element based thermal analysis (using ANSYS Mechanical) and Finite volume based CFD (Computational Fluid Dynamics) & thermal analysis in power electronics hardware. The power electronics hardware under study is used for control of compressors / heaters used in a medical thermal management device. The hardware consists of 2 SCRs (Silicon Controlled Rectifiers) and 2 TRIACs (TRIodes for Alternating Current) arranged in straight in-line configuration with the TRIACs having a higher internal heat generation (1.643E7 W/m3) than the SCRs (4.53E6 W/m3). Each of these four devices is bolted to a separate anodized aluminum heat sink using a TIM (Thermal Interface Material). It was found that CFD based Conjugate Heat Transfer (CHT) analysis with S2S (Surface to Surface) Radiation transfer gave the most accurate thermal predictions (within 6°C). These were comparable to the predictions from 3-D Solid energy equation with uniform convection and S2S radiation. Depending on the availability of computational time and resources, either full CHT study or 3-D Solid energy equation based thermal analysis with uniform convection and S2S radiation is recommended for initial design study.
Numerical Investigation of an Induced Draft Air-Cooled Condenser Under Crosswind Conditions
Authors: Louw Daniel L. , Meyer C. J. , van der Spuy S. J. 
Published: July 2021

Abstract
This study numerically investigated the performance of a 64-fan induced draft Air-Cooled Condenser (ACC) subjected to crosswind conditions. An Actuator Disk Model (ADM) was used to model the axial flow fans and a combination of the Darcy-Forchheimer porosity model and the Effectiveness Number of Transfer Units (ε-NTU) heat transfer model were used to model the heat exchangers. Crosswind conditions were applied to the ACC model in multiple directions and multiple reference velocities, with the results compared to a reference case where no wind was present.
The induced draft ACC attained a mean fan volumetric effectiveness of 1.065, a mean heat transfer effectiveness of 1.039 and a mean heat-to-power ratio of 120.6 when no crosswinds were present. At relatively high crosswind velocities of 9 m/s the mean volumetric effectiveness decreased by 10.1% from wind coming from the primary direction, and by 10.3% from wind coming from the secondary direction. Similarly, the mean heat transfer effectiveness decreased by 21.7% under primary cross-winds, and by 31.3% under secondary crosswinds. Finally, the heat-to-power ratio of the ACC decreased to 92.5 under primary crosswinds, and by 77.6 under secondary crosswinds.
Comparison of Radiation Models for a Turbulent Piloted Methane/Air Jet Flame: A Frozen-Field Study
Authors: David Chloe , Ge Wenjun , Roy Somesh P. , Modest Michael F. , Sankaran Ramanan 
Published: July 2021

Abstract
Numerical modeling of radiative transfer in nongray reacting media is a challenging problem in computational science and engineering. The choice of radiation models is important for accurate and efficient high-fidelity combustion simulations. Different applications usually involve different degrees of complexity, so there is yet no consensus in the community. In this paper, the performance of different radiative transfer equation (RTE) solvers and spectral models for a turbulent piloted methane/air jet flame are studied. The flame is scaled from the Sandia Flame D with a Reynolds number of 22,400. Three classes of RTE solvers, namely the discrete ordinates method, spherical harmonics method, and Monte Carlo method, are examined. The spectral models include the Planck-mean model, the full-spectrum k-distribution (FSK) method, and the line-by-line (LBL) calculation. The performances of different radiation models in terms of accuracy and computational cost are benchmarked. The results have shown that both RTE solvers and spectral models are critical in the prediction of radiative heat source terms for this jet flame. The trade-offs between the accuracy, the computational cost, and the implementation difficulty are discussed in detail. The results can be used as a reference for radiation model selection in combustor simulations.
Thermo-Hydraulic Performance of Heat Sinks With Microchannel Embedded With Pin-fins
Authors: Alkhazaleh Anas , Younes El-Saghir Selim Mohamed , Alnaimat Fadi , Mathew Bobby 
Published: July 2021

Abstract
In this work, an investigation of the heat sink performance employing sinusoidal microchannels embedded with pin fins was conducted. The effect of the sine wave frequency, the pin fins’ diameter, and the hydraulic diameter of the microchannel are studied. The results are quantified in terms of thermal resistance and pressure drop. The study was done using Reynolds numbers varying from 250 to 2000. As Reynolds number increases, the heat sink’s thermal resistance decreased while the pressure drop increased accordingly for all scenarios. The sinusoidal microchannels showed better performance — lower thermal resistance — but with the cost of higher pressure drop compared to the straight microchannel heat sink. The heat sink’s performance was improved by increasing the frequency, diameter of pin fins, and hydraulic diameter; however, this reduction in thermal resistance was associated with an increase in pressure drop. The reduction in thermal resistance of the different configurations of the sinusoidal microchannels was between 17% and 69% compared to the straight microchannel heat sink.
Effect of Geometric Configurations on the Thermal Performance Of Encapsulated PCMs
Authors: Mohaghegh Mohammad Reza , Mahmud Shohel , Tasnim Syeda 
Published: July 2021

Abstract
The integration of thermal energy storage (TES) systems with Phase Change Materials (PCMs) is a promising technique not only for storing thermal energy, also for thermal management applications. Encapsulation is a safe and efficient integration technique of using PCM, which has various advantages such as PCM protection, mechanical stability, leakage prevention and, diversified shapes and sizes. The thermal performance of these systems is heavily dependent on the form and geometry of the encapsulating PCM. Various literature has investigated PCM encapsulation for different applications; however, they were limited to just a few common geometries, i.e., rectangular, spherical, and cylindrical. The present research is aimed to investigate the effect of shape/geometry on the thermal performance of encapsulated PCMs and visualize the PCM melting process to a further improvement in the thermal performance of TES systems for different applications. For this purpose, transient heat transfer and the melting process of the same volume of PCM encapsulated in four different geometrical configurations of the capsules, including the common encapsulation shapes such as spherical, cubical, cylindrical, and conical shape as less studied and new proposed shape, are studied. A mathematical model is developed and numerically solved to study the energy transport processes inside the enclosures. The melting process is visualized numerically to track the solid-liquid interface during the phase change. Moreover, the heat transfer characteristics such as melting fraction and energy stored in the system and their temporal variation during the phase change process are determined. A comparison of the four cases in terms of melting rate and energy storage is carried out, as well. The results show that the conical capsule exhibits the best thermal performance with a total melting time of 72 minutes. While the cubical capsule requires 111 minutes to complete the melting process.
Numerical Thermal Performance Investigation of an Electric Motor Passive Cooling System Employing Phase Change Materials
Authors: Deriszadeh Ali , de Monte Filippo , Villani Marco 
Published: July 2021

Abstract
This study investigates the cooling performance of a passive cooling system for electric motor cooling applications. The metal-based phase change materials are used for cooling the motor and preventing its temperature rise. As compared to oil-based phase change materials, these materials have a higher melting point and thermal conductivity. The flow field and transient heat conduction are simulated using the finite volume method. The accuracy of numerical values obtained from the simulation of the phase change materials is validated. The sensitivity of the numerical results to the number of computational elements and time step value is assessed. The main goal of adopting the phase change material based passive cooling system is to maintain the operational motor temperature in the allowed range for applications with high and repetitive peak power demands such as electric vehicles by using phase change materials in cooling channels twisted around the motor. Moreover, this study investigates the effect of the phase change material container arrangement on the cooling performance of the under study cooling system.