bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leveraging HVAC Set Point Changes for Operational Energy Performance Efficiency and Flexibility in Commercial Buildings: Experiments in a Moist Climate Zone
Authors: Grekin Rebecca , de Chalendar Jacques 
Published: September 2023

Abstract
In this work, real-world demand flexibility experiments for Heating, Ventilation, and Air Conditioning (HVAC) systems were conducted over the summer of 2022 in sections of a commercial building at a corporate campus in New Jersey (US Climate Zone 5A, Moist Cold). These experiments measured the decrease in cooling load observed associated with an increase in the temperature set point for the air discharged from eight central air handling units (AHU) serving approximately 17,500 square meters. It was found that using outside air enthalpies for estimating cooling loads in climates that have higher humidity is more accurate than using the mean daily temperatures, the parameter most used in the literature. For the median observed outside air enthalpy of 60 kJ/kg, it was found that temperature set point increases of 2°F (1.11°C) for the AHU discharge air temperature decreased expected cooling load by 3.5–11.9% per AHU. These results highlight the importance of considering outside air humidity in addition to temperature in flexibility models. These experiments also show that it is possible to implement load reduction techniques in buildings with limited controls, which reinforces the large potential for electricity and emissions savings from leveraging these opportunities across the US.
Investigation on a Double-Pass Tubular Absorber for Application in Solar Towers
Authors: Ebadi Hossein , Cammi Antonio , Savoldi Laura 
Published: September 2023

Abstract
The present study combines the concept of double-pass flows with high-temperature solar receivers, introducing a novel design to reduce heat losses and increase performance. A tubular absorber from the billboard solar tower systems was used to develop the new double-pass (DP) design, working with air as the heat transfer fluid. To assess the effectiveness of such a system, a numerical study was performed using CFD analysis with Star CCM+ commercial software. Several simulations were made based on the thermal models, validated with real data obtained from a solar furnace tested during an experimental campaign in June 2022. The thermo-hydraulic characteristics were analyzed for various solar peak fluxes (50, 100, and 200 kW/m2) and air mass flow rates (30, 40, 50 L/min) to provide a comprehensive comparison between the single pass (SP) and DP absorbers. The computed numerical results suggested that using the DP design instead of SP absorbers under all the test conditions, the average energy and exergy efficiency enhancement are 35% and 55%, respectively, while the pressure drop increases with an average of 62%. As a result, the DP design can be used as an alternative for future solar tower designs, bringing higher heat removal efficiency in air-based solar systems.
Time-Dependent Solution of Unsteady Flow Equations for Nanoscale Heat and Mass Transfer, Advanced Fluidics, and High Energy Blast Propagations
Authors: Sinha Ramlala P. 
Published: September 2023

Abstract
A new innovative stable time-dependent compressible flow solution over the order of nanoseconds is provided here for wide-ranging critically important challenging applications. Specifically, a solution of the highly complex unsteady high speed oscillating compressible flow field inside a cylindrical tube, closed at one end with a piston oscillating at very high resonant frequency at the other end, has been obtained numerically, assuming one dimensional, viscous, and heat conducting flow, by solving the appropriate fluid dynamic and energy equations. An iterative implicit finite difference scheme is employed to obtain the solution. The scheme permits arbitrary boundary conditions at the piston and the end wall and allows assumptions for transport properties. In successfully predicting the time dependent results/data, an innovative simple but stable solution of unsteady fluid dynamic and energy equations is provided here for wide ranging research, design, development, analysis, and industrial applications in solving a variety of complex fluid flow heat transfer problems. The method is directly applicable to pulsed or pulsating flow and wave motion thermal energy transport, fluid-structure interaction heat transfer enhancement, nanoscale heat and mass transfer, diverse range of advanced fluidics, and fluidic pyrotechnic initiation devices. It can further be easily extended to cover muzzle blasts and high energy nuclear explosion blast wave propagations in one dimensional and/or radial spherical coordinates with or without including energy generation / addition terms. No other solution exists for such applications.
Flow and Heat Transfer Characteristics of Aerothermodynamic Loading on a Double Cone at Mach 12
Authors: Gamertsfelder Jacob , Redding Jeremy , Bravo Luis , Khare Prashant 
Published: September 2023

Abstract
Although a significant body of research exists on shock-wave shear layer interactions (SWSLI), the scientific literature is lean with respect to the physics underlying SWSLI at extreme Mach number regimes. It is well known that small perturbations can lead to significant fluid dynamic changes (e.g., transition and associated heat transfer characteristics) at high Mach numbers, especially when the flow is in thermal and chemical non-equilibrium. While experiments have investigated the physics of flow over compression ramps, the physio-thermo-chemical processes remain elusive at high enthalpy condition. The dynamics are further complicated in the presence of non-smooth surface (due to the impact of debris, uncertainties in manufacturing processes, etc.) that drastically enhances the near-wall interactions. This is of great importance to accurately predict the aerothermal performance and trajectory of high-speed vehicles operating with realistic material surfaces (e.g., roughness elements, cavities, or protrusions). To address this, this research aims to investigate the influence of thermochemical non-equilibrium flow over a smooth double cone, and the influence of concave cavity on a double cone on the resulting post-shock non-equilibrium high-speed aerodynamic flow, and the associated SWSLI and heat transfer characteristics. In the present work, the massively parallel computational fluid dynamic solver, Eilmer, is utilized to simulate compressible high-speed fluid dynamics and near-body flow physics. Eilmer is a structured/unstructured grid flow solver based on finite-volume discretization of the time-accurate compressible Navier-Stokes equations with validated turbulence models, finite-rate internal energy excitation, and chemical kinetics. The work first targets a validation case study conducted based on measurements at the CUBRC facility that investigated the high-speed flow over a 25/55-degree double cone at a Mach number of 11.9 on an idealized smooth surface. Next, an in-depth overview of the thermochemical non-equilibrium flow physics is presented for the 2D axisymmetric 25/55-degree double cone. From there, a series of 2D axisymmetric double cone computations are conducted with a semi-circular cavity on the 55-degree surface region with a radius ranging from L/R (length of the ramp/cavity radius) of 100 to 33. The evolution of near-surface phenomena of interest, such as shear layer mixing and heat transfer are quantified showing increased intensities due to the presence of the cavity. The results from this study provide much-needed insights into the underpinning behavior governing SWSLI in the presence of non-ideal surfaces, and the effect of thermochemical non-equilibrium in higher Mach number flows.
Hydrogen-Fueled Regenerative Burners in a Reheating Furnace
Authors: Karambelkar Anurag , Uzor Chukwunedum , Walla Nicholas , Silaen Armin , Johnson Kurt , Zhou Chenn 
Published: September 2023

Abstract
In steel production, reheat furnaces are used to heat steel slabs to prepare them for further processing. However, the traditional use of natural gas burners as the primary heat source in these furnaces results in significant carbon dioxide emissions. As a result, the steel industry has been focusing on decarburization efforts, with research aimed at identifying viable alternatives to natural gas, such as hydrogen. Furthermore, the use of regenerative burners in reheat furnaces is being explored as a means of improving heating efficiency and reducing fuel usage. This system employs a thermal reservoir and alternating burner activity to preheat inactive burners and quickly reach combustion temperatures. This preheating increases the efficiency of the system as combustion temperatures are reached more-quickly. This increased efficiency reduces fuel usage and can improve the heat output of the furnace. The present study compares the operation of traditional and regenerative burners with methane and hydrogen as fuel. It was observed that the inclusion of regenerative burners in the system provide a more uniform temperature distribution and a longer flame compared to the traditional burners. They also showed an increase of more than 120°C in peak temperatures near the slab despite having lower max flame temperature than the traditional case. The use of regenerative burners in a hydrogen fueled furnace was shown to increase the production efficiency by 14.14% compared to traditional burner methane fueled furnace. Additionally, the use of hydrogen as a fuel in place of the natural gas results in carbon-free emissions, thus reducing the environmental impact of the process and advancing decarburization efforts.
Thermal and Flow Characteristics in a Tube with Helical Ridges
Authors: Chen Tailian 
Published: September 2023

Abstract
Use of tubes with helical ridges to make shell/tube heat exchangers has been an industry practice for many decades. However, understanding of thermal and flow characteristics with helical ridges is far from being sufficient. In this paper, thermal and flow characteristics of single-phase water flow in a cylindrical tube with spiral helical ridges is investigated to understand the enhancement in heat transfer and the associated penalty in the increased pressure drop. The experiments were conducted in the range of Reynolds number 3,700 to 75,000 and Prandtl number 3.8 to 10.0. The measurements show that thermal and flow characteristics are different from those reported in the literature for flow in commercial pipes with roughness. An analysis of friction factors measured in this work delineates the flow characteristics in a tube with helical ridges, which would help further explore the underlying physics. A comparison against the Moody chart and Churchill correlation indicates that the transition region covers a wider range of Reynolds number and extends into a much larger Reynolds number. It is postulated that the much wider transition region is attributed to helical ridges providing a channeling effect for the fluid flowing on the surface, which is absent for flow on a general rough surface. The heat transfer enhancements and the penalty of pressure drop measured in this work are further quantified and compared with suggested correlations available in the literature.
Quadrature Point Selection in the Full-Spectrum K-Distribution Method for Nongray Radiation in Combustion Gases
Authors: Jajal Nehal , Mazumder Sandip 
Published: September 2023

Abstract
Radiation is the dominant mode of heat transfer in combustion environments. Combustion gases, such as carbon dioxide and water vapor, have oscillatory spectral properties. Solving the Radiative Transfer Equation (RTE) is challenging in such scenarios and requires a nongray model. The Full-Spectrum k-distribution (FSK) model is a popular state-of-the-art model that offers high accuracy while requiring the RTE to be solved for only a few quadrature points in reordered spectral (or g) space. The selection of optimal quadrature points has been investigated in the literature, broadly suggesting that 8 to 10-point schemes, with more points for larger g-values, work best. In this study, a new split scheme is tested for quadrature point distributions wherein the g-space is first split into two zones prior selecting quadrature points for each zone. The split scheme is tested for one-dimensional gas slabs with uniform properties of carbon dioxide, water vapor and a mixture for different temperatures. Slab thicknesses are varied to vary the optical thicknesses. Errors for radiative heat source and radiative wall flux are computed against benchmark line-by-line (LBL) solutions. Results are compared with existing quadrature schemes. Overall, the split scheme resulted in an improvement in accuracy compared to existing quadrature schemes more consistently across different length scales for the same number of quadrature points.
Integrated Greenhouse for Food and Water Production
Authors: Abedi Mahyar , Tan Xu , Klausner James , Benard Andre 
Published: September 2023

Abstract
Large greenhouses are increasingly used for modern farming, occupying vast areas, and consuming considerable amounts of energy to maintain their functionalities. In this study, the performance of an energy-efficient greenhouse comprised of a transparent solar water heater, coupled with a spectrum-shifting material, and a water desalination unit, is investigated. A transparent solar water heater is installed on the greenhouse roof and provides warm water to be used for desalination. The addition of a spectrum-shifting material to the solar water heater can enhance the efficiency of the thermal system by absorbing wavelengths near-infrared waveband (NIR) or shifting the light to a spectrum more favorable to specific crop growth. Moreover, a desalination unit allows the treatment of a wide range of contaminated or saline waters to satisfy the crops’ potable water needs. The investigated desalination system utilizes direct-contact evaporation and condensation through a packed-bed material. Based on the simulation results for Phoenix Arizona, the transparent solar water heater is able to increase the water temperature by up to 25°C, while allowing sufficient light to pass through to maintain plant growth. Moreover, the implementation of a transparent solar water heater decreases the cooling and heating loads. The investigated greenhouse design is able to sustain hydroponic lettuce cultivation, for example, throughout the year, and satisfy the potable water requirements, thus producing up to 400 kg of fresh lettuce per month.
Numerical Simulation of Particle Evolution in Spray Drying Using Droplet Drying Kinetics
Authors: Bhattacharjee Anurag , Gnanaskandan Aswin 
Published: September 2023

Abstract
Spray drying is a method for producing dry powder particles (e.g., instant coffee, milk, starch, cheese, bio-therapeutics, etc.) by atomizing a slurry and rapidly drying it using a hot gas in a drying chamber. Understanding the evolution of particle formation in a spray dryer is important as it directly influences the final product quality. Experiments inside a spray dryer are often not able to shed light on the physical processes governing the particle formation at the scale of an individual particle. Hence, we are developing a numerical method that uses complex mass and heat transfer equations to account for the change in properties of a single droplet based on advanced droplet drying kinetics. Such a model can be later incorporated into full-scale drying chamber simulations, where CFD modeling of the drying gas flow can be coupled to these single droplet models. The drying model is divided into two stages of drying with distinct equations accounting for heat and mass transfer during these stages. The first stage consists of droplet shrinkage with loss of moisture and diffusion of dissolved or suspended solid particles inside the droplet. At the end of the first stage, the volume fraction of the dissolved or suspended solid content on the droplet surface reaches a critical saturation level at which point a porous crust is formed indicating the start of the second stage. Heat and mass transfer from the droplet is assumed to occur through the porous crust. The model is validated using single droplet drying experiments from the literature showing reasonable agreement with the experimental data for temperature and mass evolution. The model is then used to conduct parametric studies to understand the role of the different factors that influence the final droplet morphology. The results show that the droplet mass and temperature evolution are affected greatly by the drying gas velocity and temperature, while the relative humidity of the drying gas has only a moderate effect. The model can be applied to ascertain the optimal external conditions needed to obtain particular particle characteristics.
Transient Thermal Spreading From a Circular Heat Source in Polygonal Flux Channels
Authors: Goudarzi Sahar , Steigerwalt Lam Lisa , Muzychka Yuri , F. Naterer Greg 
Published: September 2023

Abstract
Thermal spreading or constriction resistance plays an important role in thermal engineering problems. A numerical simulation is developed for transient constriction resistance considering various semi-infinite flux channel geometries, including circle on circle, circle on triangle, circle on square, circle on pentagon, and circle on hexagon. In this work, an isothermal circular heat source supplies heat in these polygonal flux channels. In this context, a finite volume method is considered to study the transient constriction resistance in mentioned geometries. After validating the steady-state mode for constant heat flux condition, the work is extended to study the transient heat conduction with constant temperature boundary condition. Observations of these various geometries clarify that similar results are produced for the non-dimensionalized constriction resistance and time. The appropriate characteristic length for this non-dimensionalization is the square root of the source area. Simple models are developed for predicting the transient spreading resistance for isothermal heat sources.
Estimation of Heat Flux From Gases Released During Thermal Runaway of Lithium-Ion Batteries
Authors: Qatramez Ala' E. , Kurzawski Andrew , Hewson John , Foti Daniel , Headley Alexander J. 
Published: September 2023

Abstract
A jet is formed from venting gases of lithium-ion batteries during thermal runaway. Heat fluxes to surrounding surfaces from vented gases are calculated with simulations of an impinging jet in a narrow gap. Heat transfer correlations for the impinging jet are used as a point of reference. Three cases of different gap sizes and jet velocities are investigated and safety hazards are assessed. Local and global safety hazard issues are addressed based on average heat flux, average temperature, and average temperature rise in a cell. The Results show that about 40% to about 70% of venting gases energy can leave the module gap where it can be transferred to other modules or causes combustion at the end of the gap if suitable conditions are satisfied. This work shows that multiple vents are needed to increase the temperatures of the other modules’ cells to go into thermal runaway. This work is a preliminary assessment for future analysis that will consider heat transfer to the adjacent modules from multiple venting events.
Study on the Effects of Temperature Distribution and Liquid Volume on the Growth of a Deuterium-Deuterium Ice in the Cryogenic Target
Authors: Wu Kewei , Yao Yina , Zhang Hui , Zheng Lili 
Published: September 2023

Abstract
Inertial confinement fusion (ICF) is one of the main ways to achieve controlled nuclear fusion. ICF experiments use high peak-power laser systems to compress the capsule with a layer of solid hydrogen inside, making the ice layer highly compressed so as to initiate ignition. To achieve an ignition with a cryogenic target, the fuel ice layer (DT or D2) in the target needs to be highly symmetrical, uniform and smooth. For a better control of the ice preparation process, there is a need to develop a deep understanding on the mechanism of the crystal growth process. Based on VOF model, Solidification/Melting model and the Evaporation/Condensation model, we establish a numerical model to simulate the coupled process of fluid flow, heat transfer, solidification and condensation of D2 fuel. Through assigning different temperature boundary and initial liquid fraction conditions, the impacts of temperature distribution and liquid volume on the crystal growth process are investigated. The results show that higher temperature gradient, bigger liquid volume and larger coefficient of heat transfer promotes the formation of radial temperature gradient in the capsule, which helps to ensure the global coverage of liquid film. Our work can help to optimize the relevant parameters in in the preparation process of D2 ice layer.
Variable Properties via Excel: Numerical and Computational Heat Transfer Methods
Authors: Abdelmessih Amanie 
Published: September 2023

Abstract
Most of us, engineers have, or will model or simulate project(s) or portions of projects. A couple of articles introduced computational methods using MS Excel. Three rectangular cross section conduction heat transfer computational cases using Microsoft Excel have been discussed in detail, in the first article. With the realization that circular cross sections such as cylinders, pipes, rods, etc. have unlimited applications in engineering practice, the second article addressed four computational heat transfer cases for circular cross sections using Microsoft Excel. These four circular cross section cases were modeled with two different Excel techniques and discussed. Unfortunately, both articles addressed only constant thermal properties.
Thermal properties dependent on temperature are included in all seven models introduced in this article. The first two models are rectangular with isothermal boundaries and variable properties for two different materials. The third and fourth models are for circular cross sections with isothermal boundary conditions, though they are modeled with two different methods. Model 5 is rectangular cross section with different boundary conditions, it has two versions one is approximate. Model 6 includes internal convective flow, where the heat transfer coefficient depends on variable thermal properties. Finally, Model 7 includes a heat source. The details of each model, derivation of equations and computations are discussed in this article.