bluuebunny/crossref_metadata_2025_split huggingface dataset:
Airflow Characteristics and Thermal Comfort of Air Diffusers
Authors: Eraslan Tolga Arda , Keskin Cem , Mengüç Mehmet Pınar 
Published: September 2023

Abstract
Indoor environment quality control is very important for building operations as occupant of buildings spend up to 90% of their time indoors. After Covid-19 pandemic break out, indoor environment quality has become even more crucial to the society because of health concerns. Indoor Environmental Quality (IEQ) covers conditions such as air quality, lighting, thermal conditions, ergonomics inside a building and their effects on the occupant or occupants of the building. Thermal conditions and air quality are usually achieved with the mechanical or natural ventilation systems or by HVAC equipment. As buildings became more complex structures, different airflow distribution systems to be developed to fulfill such requirements. For this purpose, not only the airflow distribution systems need to be modified but also diffusers that provide which supplies/draws air to/from systems are to be improved. Detailed analysis of these subcomponents is needed to assure that such devices provide high levels of comfort effectiveness and energy efficiency. The objective of this study is to develop a comprehensive analysis for air characterization and indoor air regime of different diffusers (square diffuser, operable flap diffuser) and their effect on comfort level of occupants Fanger’s model of thermal comfort is used with CFD simulations and a tool is considered for the validation experiments. Using more than 16 thermal sensors including one on a mannequin head, on a table and at foot level, the readings were correlated by using anemometers to measure air flow at supply diffuser and at different operating levels. CFD simulations were according to different scenarios which are to provide a comparison between diffusers and understand indoor airflow regimes. The results considering the flow interaction between diffusers and surroundings showed a detailed visual illustration in CFD simulations and their relation to perceived comfort levels.
Pathways for Atmospheric Water Harvesting to Reach Cost Parity With Distributed Desalination
Authors: Kocher Jordan D. , Menon Akanksha K. 
Published: September 2023

Abstract
With water consumption increasing, populations growing, and climate change affecting natural freshwater sources, global water stress is of increasing concern. To meet the freshwater demand, methods of artificially producing clean water are being explored. Desalination is among the most mature of these freshwater production technologies, though it is often claimed that seawater desalination (centralized) and transportation of this water from the coast to inland locations is expensive. More recently, there is growing interest in atmospheric water harvesting (AWH) as a method of producing fresh water from ambient air. AWH is touted to be a cost-effective method of producing fresh water locally where water is needed (decentralized), and thus does not require water to be transported. However, few studies have attempted to quantify the energy costs associated with AWH, and a direct comparison with desalination has not been reported. In this work, we analyze an AWH based on active cooling (like a vapor compression air conditioner) that condenses water from air. We find that using these systems to harvest water from outdoor air is an order of magnitude more expensive than the combined costs of coastal seawater desalination and transportation of the clean water to inland locations. Instead, we show that an indoor cooling system based on AWH that cogenerates both water and building cooling is a more practical and cost-effective use case of this technology.
Design Strategies for Biomass-Based CHP Systems in Rural Communities
Authors: Maharjan Krisha , Hwang Joonsik , Cho Heejin 
Published: September 2023

Abstract
Unreliable electricity supply and constrained heating networks are major challenges facing rural communities. Combined Heat and Power (CHP) systems can alleviate these energy security issues by utilizing readily available biomass resources in rural areas by producing two forms of energy from a single process. Biomass-fueled CHP systems called b-CHP can effectively reduce energy costs and consumption while having a minimal environmental impact. This paper presents strategies for the design process of b-CHP systems and insights into the factors to consider for sustainable operation. For biomass to compete with fossil fuels, selecting optimal system component sizes and operational strategies is necessary to satisfy consumers’ varying electric and thermal demand patterns. Furthermore, the system performance must be evaluated in relation to a range of biofuel, fossil fuel, and grid utility prices in a specific location. The comparative analysis of the b-CHP system with traditional separate heat and power generation in terms of performance parameters such as operational cost (OC), primary energy consumption (PEC), and carbon dioxide emission (CDE) can be used to determine the ideal plant design. The net metering policy is another crucial factor from the economic standpoint of b-CHP systems. Therefore, an investigation of the b-CHP system with and without net metering is also necessary. With properly assessed and designed b-CHP systems, rural areas can increase their resilience and achieve energy independence.
Waste Heat Assessment of a Manufacturing Facility
Authors: Zeller Alexander , Gladen Adam C. 
Published: September 2023

Abstract
A waste heat assessment of a manufacturing facility with low-quality waste heat is conducted. A physical survey identified seven potential waste heat sources with fluid exhausts: the boiler flue, the chiller loop for the HVAC system, the exhaust from polypropylene dryers, from the compressed air dryer, from the plant vacuums, and from an electroplating air handler, and the deaerator. The temporal fluctuations in temperature and flow rate, and the frequency of occurrence of the waste heat, were determined from measurements, calculations, and company records. Variations were observed in the boiler flue and in the dryers. The monthly energy and exergy of the waste heat were calculated for a reference temperature of 25 °C. The total annual waste heat is calculated to be 36.5 TJ of energy which represents 0.84 TJ of exergy. The boiler, plant vacuums, and chiller comprise 96% of the energy rejected and are the major contributors to the rejected exergy. Matching the waste heat to space heating is evaluated. Based on fuel consumption in the boiler, the annual energy for space heating is estimated 8.5 TJ. Waste heat from the boiler flue, polypropylene dryers, and plant vacuums could meet up to 39% of this energy without storage and 63% with thermal storage to better overlap waste heat supply with demand. Simply allowing the vacuum exhausts to cool in the building could theoretically meet up to 27%. The study highlights the need to consider fluctuations in the waste heat supply and sink demand, the need for thermal storage, and identifying relatively simple modifications to recover waste heat.
Pathways to Improve the Energy Efficiency of Residential Air-Conditioning Systems in Saudi Arabia
Authors: Alotaibi Abdulaziz M. , Makhdoom Taha K. , Alquaity Awad Bin Saud 
Published: September 2023

Abstract
The residential sector in Saudi Arabia consumes more than half of the total electricity generated, with room air conditioners being among the most significant contributors. The current work aims to estimate the current and future energy savings and CO2 emission reductions possible under three different scenarios: Business as Usual (BAU), Continuous Improvement Scenario (CIS), and Accelerated Improvement Scenario (AIS) up to 2030. The BAU scenario presents the energy consumption and CO2 emissions assuming the current Energy Efficiency Ratio (EER) of 11.8 BTU/Wh is maintained till 2030. CIS takes into account an improvement of 5% in EER of new air conditioner (AC) stock every 2 or 5 years, and AIS considers an improvement of 10% in EER of new ACs every 2 or 5 years. Additionally, the energy savings and CO2 emission reductions possible through varying penetration levels of newly introduced refrigerant (R32) have been estimated for all three scenarios with 2 year intervals. The BAU scenario is promising resulting in energy savings of up to 21.4 TWh in 2030 compared to 2020 energy consumption figures. However, implementing AIS with 2 year intervention intervals leads to significant additional energy savings of 12.7 TWh by 2030 as compared to BAU scenario. Even implementing CIS with 2 year intervention intervals leads to additional energy savings exceeding 3 TWh by 2030. The introduction of the new refrigerant (R32) leads to modest cumulative energy savings of 2.5 TWh in the best-case scenario and suggests that the policy focus can be directed towards increasing the EER of residential AC systems.
On the Effect of Sudden Contraction of CO2 in Microchannels for Enhancing the Cooling Performance
Authors: Niazi Soroush , Parahovnik Anatoly , Peles Yoav 
Published: September 2023

Abstract
A comparison between two microchannels is studied with carbon dioxide near critical condition — one with an orifice and another without orifice. A heater was placed beneath both microchannels and was located immediately downstream the orifice. Resistive temperature detectors (RTDs) were embedded in both microchannels downstream the orifice for transient temperature measurements. Rapid changes in the thermophysical properties of carbon dioxide near critical point make it a superior coolant for enhancing convective and boiling heat transfer. Large pressure drop that was provided by the sudden contraction in the microchannel resulted in considerable temperature drop of the downstream flow, which can be leveraged to assist the cooling managements in various thermal systems. The results show higher heat transfer coefficients for the microchannel with orifice compared to non-orifice channel, and also, indicate that near critical carbon dioxide is a good candidate for heat removal in components generating high heat fluxes especially electronic components.
The Effect of Immersion in Water on Internal Body Temperature Post-Mortem
Authors: Devashish Athena , Shrivastava Devashish 
Published: September 2023

Abstract
The internal body temperature change in a human body immersed in water post-mortem was studied in regards to variables such as level of immersion and body type/build to determine the effect of water on the temperature change and to better understand the role of the temperature change in estimating time since death. The temperature change was computed by solving the conduction energy equation in three whole-body human models (114.2 kg male, 78.91 kg male, 56.69 kg female) for up to 10 hours post-mortem. Three main comparisons are made regarding the effect of water on body temperature: different environments (air vs. water), various levels of immersion (up to neck vs. pelvis), and the difference between body types. The findings revealed that ambient environment (e.g., air vs water, level of water immersion) may significantly and nonuniformly influence internal body temperature change over time. Further, the internal body temperature change may depend on body type/build.
A Computational Assessment of Thermal Damage in Perfused Tissue due to Laser Irradiation
Authors: Goyal Rahul , Shrivastava Devashish 
Published: September 2023

Abstract
A computational assessment of in vivo thermal due to laser irradiation damage is presented as a function of the laser applicator length, total effective absorption coefficient, and heating duration for the peak tissue temperature of 100 °C. Spatio-temporal tissue heating is computed by solving the Generic Bioheat Transfer Model (GBHTM), a first principles based model that has been shown to estimate tissue heating more accurately compared to Pennes Model. Damage is estimated by computing thermal dose per Cumulative Equivalent Minutes at 43 °C (CEM43) and the Arrhenius integral with damage thresholds as CEM43 ≥ 60 minutes and Ω ≥ 1, respectively.
Results show that the damage increases as a function of the applicator length and heating duration but decreases as a function of the absorption coefficient. While ablation shape is generally ellipsoidal, sphere factor (ratio of the maximum damage along the applicator and normal to the applicator) increases as a function of heating duration, but decreases as a function of applicator length. The maximum damage diameter varies between 2–3 cm. The damage estimated per CEM43 ≥ 60 was ∼40%–60% larger relative to the damage estimate per Ω ≥ 1.
Hybrid Nongray Radiative Transfer Equation Solver Using Full Spectrum Correlated K-Distribution (FSCK) Method for Combustion Gases
Authors: Jajal Nehal , Mazumder Sandip 
Published: September 2023

Abstract
The Full Spectrum Correlated k-Distribution (FSK) method is a state-of-the-art popular method for the treatment of the extremely oscillatory spectral absorption coefficient of combustion gases. It offers high accuracy while requiring the RTE to be solved for only a few quadrature points in reordered spectral (or g) space. However, solution of the RTE for even a few quadrature points can be expensive for multidimensional problems. To further improve computational efficiency, the current study proposes a Hybrid nongray RTE solver. The Discrete Ordinates Method (DOM) or its variant, the Finite Angle Method (FAM), yields accurate solutions when used with sufficient angular resolution, especially when the medium is optically thin. However, this can be computationally expensive. On the other hand, the lowest order spherical harmonics approximation (P1) yields a single elliptic partial differential equation and is relatively efficient to solve. However, the P1 approximation is accurate only when the intensity field is fairly isotropic, as is the case in optically thick media. The new Hybrid solver utilizes the P1 method for optically thick parts of the spectrum (quadrature points), while using FAM for the remaining quadrature points. Another variation of the proposed approach where the FAM is used within a spectral window is also explored. Several test cases, both one-dimensional and two-dimensional, are considered to assess the Hybrid solver. The proposed Hybrid solver was found to offer a 2–3 times speedup from FAM while offering comparable accuracy to FAM solutions.
Measurement of the Thermal Diffusivity of Glass at High Temperatures
Authors: Capps Nicholas E. , Abioye Fiyinfolouwa , Kinzel Edward C. 
Published: September 2023

Abstract
The effective thermal diffusivity of a glass sample is extracted at different temperatures using a modified Angstrom’s method. A modulated CO2 laser beam (λ = 10.6 μm) with a Gaussian profile is incident on one surface of the sample. This wavelength couples well to the silicate phonon modes and is strongly absorbed by the glass (an optical penetration depth of less than 5 μm). The opposite surface is observed with a thermal camera. The thermal camera is fitted with a filter to block direct CO2 laser radiation from affecting the measurements. The experiments are performed in the frequency domain with a modulated laser. The amplitude and phase of the temperature on the back surface of the glass slide is determined using a least-square algorithm. In this approach, the laser heat flux can be decomposed to a sinusoidal and constant portion. The steady-state portion heats the glass. The relatively small thickness of the glass slide results in minimal differences in the steady-state temperature. The frequency-dependent amplitude and phase of the back surface temperature are compared to finite-difference conduction models solved in the frequency domain. A 1D model is developed to extract the thermal diffusivity by minimizing the error between the model and experiment. Adjusting the constant offset of the laser allows the material to be heated and the diffusivity estimated at elevated temperatures. The experimental results compare well to literature for fused quartz glass up to 1200 °C.
A Co-Flow Millifluidic Device for Nanoparticle Synthesis
Authors: Yang Ruibo , Sun Hongwei 
Published: September 2023

Abstract
Encapsulation of phase change material (PCM) into nanoparticles has received increasing attention due to its potential applications in heat transfer fluids and thermal energy storage. However, the conventional batch-based synthesis processes such as nanoprecipitation, sol-gel, and ultrasonic techniques have shortcomings such as limited batch-to-batch reproductivity and nonhomogeneous chemical and physical properties. Micro- and millifluidic technologies have been studied over the past decades as a potential platform for nanoparticle synthesis. In this work, a co-flow millifluidic device where vortex and turbulence can be formed was developed to achieve a rapid and precise control of the mixing of two fluids with a potential application in nanoparticle encapsulation. The device was fabricated by soft lithography method in which the master model was made by 3D printing technology. Parylene conformal coating was utilized to deposit a thin parylene C layer on the polydimethylsiloxane (PDMS) channel walls to prevent the absorption of organic solvents and molecules into PDMS material. The flow behavior phase diagram was developed by operating the millifluidic device under different flow rates of the inner and outer fluids, including laminar, transition, and turbulence flow regimes. At last, polystyrene (PS) nanoparticles (NPs) were synthesized using the developed device to demonstrate its capability in nanoparticle synthesis. The comparison of the number and volume distributions of the PS nanoparticles with those from bulk synthesis method shows that the co-flow millifluidic device can synthesize NPs at a much smaller size and more uniform size distribution.
Numerical Study on Natural Convection With Nanofluids in Vertical Channels Asymmetrically Heated
Authors: Buonomo Bernardo , Manca Oronzio , Nardini Sergio , Sarli Gianluca 
Published: September 2023

Abstract
A numerical investigation on two-dimensional steady state natural convection with nanofluids in a vertical channel asymmetrically heated at uniform heat flux is carried out. The nanofluid is modeled using the both the single phase and mixture models also to compare the two models. The thermophysical properties are assumed constant with temperature the fluid flow is considered laminar and incompressible. The two-dimensional governing equations are numerically solved with finite volume method by means of the ANSYS-FLUENT code. The computational domain is made up of the principal channel and two lateral extended reservoirs at the open sections. The channel has the heated plate with the height L equal to 400 mm whereas the adiabatic plate has the height of the extended computational domain. The distance between the two vertical parallel plates, b, ranges between 10 mm and 40 mm. The two external reservoirs allow to simulate the external ambient and to assign at the boundary of the reservoirs a velocity equal to zero and the ambient temperature. Rayleigh number values are examined, from 10 to 1000. The main aim of the present study is to analyze the effect of channel spacing and the nanofluid mixture. Different values of assigned wall heat flux are considered. Results are presented in terms of velocity and temperature fields, and both temperature and velocity profiles at different significant sections are shown, to obtain a description of the natural convection inside the vertical channel. Finally, Average Nusselt number values are also evaluated.
Thermal Transport in Thermoelectric Coupled Nanoantennas
Authors: Kinzel Edward , Finnan Collin , Dong Chao , Burghoff David , White Stephen M. , Aquino Hadrian , Orlov Alexei O. , Porod Wolfgang , Bernstein Gary H. , Szakmany Gergo P. 
Published: September 2023

Abstract
A Thermoelectrically Coupled Nanoantenna (TECNA) consists of a metallic antenna integrated with a thermoelectric junction. In its simplest form, a dipole antenna (∼λ/2 long) lies at the junction of two leads having different Seebeck coefficients. When radiation is absorbed by the antenna, the excited currents produce Joule heating that is transferred to the junction, generating an unbiased open-circuit voltage. Nanofabrication, specifically e-beam lithography, allows conventional microwave engineering to be scaled to mid/long-wave infrared and THz frequencies. The antenna allows the device to be engineered to respond to specific wavelengths and polarizations. At resonance, the effective absorption aperture of the antenna significantly exceeds its very small physical area. The subsequent small thermal mass results in measured bandwidths greater than 100 kHz. Understanding and engineering the thermal transport over nanoscale (50 × 100 × 7000 nm) leads is critical to improving device performance. This paper analyzes the thermal transport for dipole antennas suspended above hemispherical cavities. These cavities are etched into the substrate and provide thermal isolation to the antenna and feed structure, significantly improving the results. A frequency domain solution is driven by finite element analyzed absorption models in the antenna. These simplified models agree well with experiments using a CO2 laser. The modeled results are used to estimate an effective convection coefficient in air at this length scale. They are also analyzed to create design rules, including thermal transport for future devices.
Thermal Brine Concentration Using Air-Gap Diffusion Distillation: A Coupled Heat and Mass Transport Model
Authors: Parker Walter P. , Menon Akanksha K. 
Published: September 2023

Abstract
Freshwater reserves are being depleted at a rapid rate due to population growth, economic development, and water use across different sectors. Desalination can be used to address the growing demand for fresh water, but the high salinity byproduct of this process, referred to as brine, must be managed. This has led to a push towards zero liquid discharge (ZLD) to maximize water recovery by treating the brine close to saturation. To this end, we present air gap diffusion distillation (AGDD) as a thermally driven and membrane-less process that can achieve ZLD with minimal scaling/fouling on polymeric heat transfer surfaces. In this work, we evaluate the performance of AGDD in terms of the water flux (permeate collected) and energy consumption (gain output ratio). A coupled heat and mass transfer model is developed to simulate brine concentration from a salinity of 70,000 mg/L up to near ZLD conditions in a counterflow operation for latent heat recovery. In addition, a parametric study is performed to understand the impact of flowrate, inlet temperature, salinity, and surface area on the overall performance. The development of such a modular brine concentration process has the potential to enable widespread deployment of desalination in inland regions.