bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantifying Part-to-Part Flow Variations and Cooling Effectiveness in Engine-Run Blades
Authors: McCormack Kelsey E. , Gailey Nicholas L. , Berdanier Reid A. , Barringer Michael D. , Thole Karen A. 
Published: September 2023

Abstract
As turbine inlet temperatures continue to increase for modern gas turbine engines, the lifing of hot section components operating in a range of environments is becoming increasingly challenging. Engine operations in harsh environments can cause a reduction in cooling capability leading to reduced blade life relative to existing experience. This study analyzes the effects of harsh environments on the deterioration of blade flow and cooling effectiveness in turbine blades by comparing three commercially operated engines with varied operational times referenced against a baseline blade. Spatially resolved surface temperatures measured using infrared thermography at high-speed rotating conditions were evaluated to determine variations in cooling effectiveness as a function of engine operation and blade-to-blade variability from the different commercial applications. Engine-run blades were found to have reduced flow as well as greater part-to-part variation when compared to baseline blades. Blade surface temperature measurements on the deteriorated operational blades indicated film cooling traces dissipated closer to the hole exit relative to baseline blades. Furthermore, the cooling effectiveness varied significantly even between blades from the same engines. The reduction in cooling effectiveness in the engine-run blades led to higher blade temperatures and significantly shorter component life, with some exhibiting as much as an 18% reduction in life compared to baseline blades. This knowledge allows lifing models to be developed toward predicting blade operational effects in harsh environments.
A Multiple-Burner Approach to Passive Control of Multiple Longitudinal Acoustic Instabilities in Combustors
Authors: Sultanpur Supreeth S. , Chakravarthy Satyanarayanan R. 
Published: September 2023

Abstract
Presently, passive methods of controlling combustion instability fall short when one considers stabilizing multiple acoustic modes. In this paper, we present a passive control approach based on the locations of the burners to stabilize multiple acoustic modes. The approach is demonstrated using linear stability analysis performed on a canonical open–open rectangular tube enclosing a flame. A linear flame model based on the kinematic description of the flame surface is used. A simultaneous solution method, as opposed to a segregated method, is developed to calculate the mean flow and to evaluate mode shapes and eigenvalues. The stability analysis is performed both on single and on multiple-burner combustors. In the latter case, the axial and transversal arrangement of burners considered preserves the net volumetric heat release rate and exit temperature. The problem of stabilizing the first three acoustic modes is cast as a multi-objective optimization problem for both types of combustors using the location(s) of the burner(s) as decision variable(s). We show that the use of multiple burners markedly increases the stability of the first three modes while not disturbing the combustor design parameters.
Enhancing Thermal Resistance of Building Walls by Utilizing Fluid Flow in Microchannel Within the Wall
Authors: Shafiee Shahin , Dicko Hamed 
Published: September 2023

Abstract
Microchannels were initially developed for cooling electronic systems. But this innovative system can also be deployed for enhancing thermal resistance of building walls, where they can substitute conventional insulations in building envelop that include the use of certain materials such as wool, polystyrene, wood fiber, cotton denim, etc. This article presents the modelling and simulation results on performance of microchannels in a typical building wall to provide dynamic thermal resistance for the building envelop. The simulations are performed for aluminum microchannels with air and water as working fluids to compare the performance of the system when different fluids are utilized. The microchannels are of rectangular profile and kept with the same geometry for all different cases. Also, to ensure that the simulations are performed under laminar regime for both working fluids, the Reynolds number was maintained between 100 and 900 for different runs. The simulation and analysis results show that microchannels can be used in building envelop to provide dynamic thermal resistance and increase the energy efficiency in different buildings. The results also show that flow of a water-based fluid in microchannels has better heat transfer and heat sinking capabilities as compared to the flow of an air-based fluid.
Fabrication, Modeling, and Testing of a Prototype for Particle Thermal Energy Storage Containment
Authors: Gifford Jeffrey , Davenport Patrick , Wang Xingchao , Ma Zhiwen 
Published: September 2023

Abstract
Increasing penetration of variable renewable energy resources requires the deployment of energy storage at a range of durations. Long-duration energy storage (LDES) technologies will fulfill the need to firm variable renewable energy resource output throughout the year. Conventional electrochemical batteries (e.g., lithium-ion) are uneconomical in this role due to high energy capacity costs. Thermal energy storage (TES) is one promising technology for LDES applications because of its siting flexibility and ease of scaling. Particle-based TES systems use low-cost solid particles that have higher temperature limits than the molten salts used in traditional concentrated solar power systems. A key component in particle-based TES systems is the containment silo for the high-temperature (&gt; 1100 °C) particles. This study combined experimental testing and computational modeling methods to design and characterize the performance of a particle containment silo for LDES applications.
A containment silo prototype was built at a laboratory scale and used to validate a congruent transient finite element analysis (FEA) model. The validation compared the actual and predicted temperature profile through the prototype over six days as the particles cooled from their initial temperature. The performance of a commercial scale (&gt; 5 GWhth) was then characterized using the validated model. The transient FEA model was subject to several charge-discharge cycles to mimic a possible operating schedule. The commercial-scale model predicted a storage efficiency in excess of 95% after five days of storage with a design storage temperature of 1200 °C. Insulation material and concrete temperature limits were considered as well. The validation of the methodology means the FEA model can simulate a range of scenarios for future applications. This work supports the development of a promising LDES technology with implications for grid-scale electrical energy storage, but also for thermal energy storage for industrial process heating applications.
A Transdisciplinary Approach and Design-Thinking Methodology for Energy Transition
Authors: Ozsoy Canan M. , Mengüç M. Pinar 
Published: September 2023

Abstract
The World is facing a climate crisis today. Since it is primarily due to the emissions from the use of fossil fuels, we must re-think and re-act on how we generate, transmit, distribute, and consume energy in industry, buildings, and transportation. Development of creative solutions and strategies to decrease emissions requires an energy transition framework and should involve every person, company, entity, and all governments. Such a framework can only be achieved with efforts at both local and global scales, which needs to convince (a) industries to change their traditional operation modalities, (b) people to alter their consumption behaviors, and (c) governments to change their rules, regulations, and incentives. The complexity and the magnitude of this enormous task demand coordination and collaboration of all stakeholders, besides the need for technological innovations.
In this paper, we outline a transdisciplinary approach and design-thinking methodology (TADTM) to tackle this challenging task. Our premise is that such complex problems need a fundamental understanding of not only engineering solutions but also those for business operations, financing, socio-economic governance, legislation, and regulations. Also, these problems need to be considered by different decision-makers with seamless interactions and structured teamwork. Towards this, we emphasize the need for a solid transdisciplinary framework for industrial corporations to change their energy policies with the help of either/both practical and doable energy efficiency measures and using renewable/alternative energy in their operations.
Energy Analysis of a Solar-Powered Heating System for a Greenhouse in the Martian Environment
Authors: Madhusudhan Nivedha Karigiri , Najafi Hamidreza 
Published: September 2023

Abstract
Greenhouses are considered critical platforms for developing sustainable living conditions for extraterrestrial environments. The extreme environmental conditions as well as the limitations in energy sources lead to major challenges is the development of proper environments for plant growth in support of manned planetary space missions. The present paper is focused on developing a mathematical model to perform an energy analysis on the heating requirements for a greenhouse in the Martian environment. The extreme cold temperatures and lower amount of solar radiation, as compared to Earth, necessitate the use of the proper heating system for greenhouse in the Martian environment. Energy scarcity, on the other hand, is a crucial factor that must be considered for supplying the heating system in an extra-terrestrial environment. For this study, weather data are obtained from Rover Environmental Monitoring System on board the Curiosity Rover, located near the Gale crater. Using the daily minimum and daily maximum temperature values recorded, a model is developed and the heating load calculation for a greenhouse with a fixed geometry is performed. The amount of energy needed to address the annual heating demands is determined. The available solar radiation for solar power generation using photovoltaic panels for a period of one Martian year (668 Sols) is also evaluated. Several atmospheric parameters are taken into consideration, and the seasonal variations of solar irradiance are studied. The size of a solar photovoltaic array for addressing the energy demands of the heating system is calculated accordingly. Several other parameters including solar panel efficiency, solar cell temperature based on the ambient conditions and wind velocity and the effects of extreme temperature conditions on solar cell degradation are discussed. The results from this study can be used to help with addressing the potential challenges to support sustainable living conditions in extra-terrestrial environmental conditions.
Multi-Objective Optimization of Distributed Energy Systems Considering Time-of-Use Pricing Impacts
Authors: Maharjan Krisha , Zhang Jian , Cho Heejin , Chen Yang 
Published: September 2023

Abstract
Distributed energy systems (DES) have been considered as a promising solution due to the benefits on efficiency and environment sides. However, despite the rapid development of distributed energy resources and technologies, the share of the distributed energy generation is still small in comparison to that of traditional generation. Time-of-use (TOU) pricing can be an important incentive strategy to encourage the penetration of distributed energy systems. In this paper, a multi-objective optimization considering the time-of-use pricing impacts is proposed to determine the optimal configuration and capacity of distributed energy system involving different technologies including solar photovoltaic (PV), solar thermal collector (STC), combined heating and power system (CHP), and integrated energy storage (ES). The distributed energy system is designed to satisfy the electric and thermal load of commercial buildings (large hotel and medium office) partially or entirely. The proposed multi-objective optimization is utilized to configurate the optimal combination of distributed energy technologies as well as the system capacity to reduce both the cost and environment impact of the system in different locations. Results show that the proposed optimization method can achieve a tradeoff between system cost and environment impact based on the existing time-of-use pricing structure.
Steady State Modeling of a Regenerative Rankine Cycle for the Natrium System
Authors: Meek Aiden S. , Dana Seth J. , Bryan Jacob , Basnet Manjur , Wang Hailei 
Published: September 2023

Abstract
With increasing penetration of renewable energy and the challenges that come with it, advanced nuclear energy systems will play an instrumental role for society to reach the goal of carbon-free power in the coming decades. Recently, an advanced nuclear power plant design (Natrium™), a sodium fast reactor with thermal energy storage, is slated to be deployed towards the end of this decade. With 5.5 hours of molten salt energy storage, the Natrium system will complement renewables and ease the intermittency challenges associated with solar and wind energy. In this work, a steady-state model of the Natrium system is modeled and optimized for efficiency. This model not only provides the state points within the regenerative Rankine cycle but also provides initial values for the variables of a dynamic system model in parallel development. With the molten salt storage temperature set by the sodium fast reactor (550 °C), the degree of superheat of the steam and its pressure for the regenerative Rankine cycle are determined. The states and mass fractions (turbine bleeding ratios) of the three regenerators are determined through optimization for maximum thermal efficiency. With the optimized cycle design, the model predicts 40% thermal efficiency. The model also checks to ensure no second law of thermodynamics violation for the regenerators. While high effectiveness is desired for regeneration (to maximize thermal efficiency), the physical sizes of the regenerators must be reasonably sized, to keep the cost managable. The heat exchanger sizes (area) are determined using ε-NTU method.
An Optimization Study of CO2 Heat Pump Water Heaters Using NSGA-II
Authors: Soleimani Shima , Schaefer Laura , Liaqat Kashif , Cole Aaron , Temming Jörg , Kösters Heiner 
Published: September 2023

Abstract
Due to growing concerns about the environmental impact of refrigerants, CO2 heat pumps have been increasingly evaluated as efficient alternatives for conventional heat pumps. Performance analyses of CO2 heat pump water heaters (HPWHs) have been the subjects of many studies, but these are typically limited to parametric analyses of air-source heat pumps. The interrelated behavior of the supercritical and subcritical thermodynamic properties, component operation, and efficiency means that a parametric study cannot adequately capture the inherent nonlinearity. Therefore, this paper, for the first time, aims to perform a multi-objective optimization on water-sourced HPWH performance in order to minimize the total component costs, maximize gas cooler (GC) heating capacity, and maximize the coefficient of performance (COP) using two different optimization scenarios. The decision variables are defined as GC pressure (75 to 140 bar), evaporator temperature (−19.5 to 0.2°C), and GC outlet temperature for CO2 (16 to 36°C). The model performance is constrained by the practical ranges of the GC and evaporator inlet and outlet temperatures for water. A coupled simulation-optimization model through Python is developed using Engineering Equation Solver (EES) software and the non-dominated sorting genetic algorithm II (NSGA-II). The result of the optimal Pareto front showed that the optimal GC heating capacity changes from 19.2 to 56.7 kW, with a lowest cost of $7,771 to a highest cost of $9,742, respectively. When the lower bound of the GC outlet temperature was set to 32°C, the Pareto front showed a maximum COP of 3.23, with a corresponding GC heating capacity of 44.36 kW.
Impact of Temperature and Ethanol Concentration on High Temperature Direct Ethanol-Based Proton Exchange Membrane Fuel Cell
Authors: Chowdhury Prantik Roy , Gladen Adam C. 
Published: September 2023

Abstract
This study examines the effect of cell temperatures and ethanol concentrations on the performance of a high temperature based direct-ethanol proton exchange membrane (PEM) fuel cell. A series of experiments were conducted at different combination of temperature (150 °C and 165 °C) and ethanol concentration (1 mol/L, 3 mol/L, 6 mol/L, and 9 mol/L) with an ethanol and air flow rate of 2 ml/min and 2 L/min, respectively. The resulting polarization and power curves show the overall effect of temperature and ethanol concentration on the cell performance. A two-factor analysis has been performed to investigate the main effect and interactions of temperature and concentration on maximum power and cell current at 0.2 V and 0.4 V. Result shows that the increase of cell temperature from 150 °C to 165 °C causes a significant improvement of cell potential and power output. At 165 °C, low concentration of ethanol (1mol/L) provides good power output until 150 mA/cm2, intermediate concentration (3 mol/L) gives high power output and allows for operation at high current density. It (3 mol/L) amplifies the effect of temperature at maximum power operation. Higher concentration causes the significant drop of cell performance. Therefore, the fuel cell operating condition of 3 mol/L and 165 °C provides balancing of ethanol and water molecules in the catalyst active side and gives the highest cell potential and power output.
Construction and Validation of a Pumped Loop Cycle for Characterizing Heat Transfer of Refrigerants and Alcohols Near Supercritical Points
Authors: Pepper Benjamin , Meek Aiden , Ghorbani Mahdi , Wang Hailei 
Published: September 2023

Abstract
A clear understanding of heat transfer in fluid flow is often analyzed via heat input through a channel which has been thoroughly validated. Common refrigerants and light alcohols possess intrinsic heat transfer properties at supercritical conditions that are desirable for low- and mid-temperature sourced power cycles. In this experiment, heat transfer characteristics of novel fluids applied to a supercritical power cycle are controlled and analyzed in a pumped loop system. The controlled test section heat exchanger in designed in two phases: alpha design phase for initial validation of the test apparatus with non-corrosive fluids; and a beta design for tests of corrosive/hazardous fluids with improved high-pressure capability. The test section provides heat input to the fluid through discrete heat pipes that allow for the continuous measurement of heat transfer properties of local fluid packets along the length of the heat exchanger. Performance and heat transfer measures from the system are compared to similar experiments in the literature to validate the methodology. The system demonstrates the ability to isolate heat transfer properties of fluids in the pseudocritical region and their transitions. This experiment guides the design for further study of fluids of interest.
Hot-Zone Design of Carbon/Carbon-Metal Sandwich Structure Composite Using CVI/CVD Material Processing
Authors: Huang Xiaoqing , Zhang Hui 
Published: September 2023

Abstract
The sandwich structure is a composite structure that is widely used in aviation, construction, and other fields due to its superior performance. We have designed a vertical dual-temperature-zone-dual-channel chemical vapor infiltration/deposition system that includes a deposition zone and a preheating zone. Carbon fiber-reinforced matrix carbon composites are used as the inner and outer panels of the sandwich structural materials, while structurally designed metal grids are proposed as the core material. We establish flow, heat and mass transfer, and chemical reaction models to carry out optimal control of densification and the hot zone in the carbon/carbon-metal sandwich structure composite using numerical simulation methods. We use a single control variable approach, such as changing the mesh spacer size, heater temperature and length, and core-to-plate ratio, to explore the effects of different design parameters on the hot zone and densification of the carbon/carbon-metal sandwich structure composite. The results show that optimizing the heater power, the distribution of the metal grid, and other parameters can lead to lower Damkhler numbers. Consequently, higher axial temperature gradients and lower radial temperature gradients can be achieved during the densification process.
Understanding Saline Water Droplet-Membrane Surface Interaction Using Molecular Dynamics Simulations
Authors: El Kadi Khadije , Ali Mohamed I. Hassan , Islam MD Didarul , Janajreh Isam 
Published: September 2023

Abstract
In this work, we utilize molecular dynamics (MD) simulations to investigate the interfacial characteristics of water droplet on a membrane surface. The MD approach allows us to probe the system dynamics and identify the fundamental mechanisms that govern the surface interactions at various conditions. Through simulating the droplet deposition process at thermodynamic equilibrium, we gain a comprehensive understanding of the interactions between the water droplet and the membrane surface at the atomic level. At different levels of water droplet salinity, results showed the strong influence of droplet salinity on surface tension and thus on wettability. Specifically, increasing salt concentration to brine water level was found to increase both droplet contact angle and droplet height by 49% and 62%, respectively, indicating reduced surface hydrophilicity. These simulations provide valuable insight into the complex interactions of multicomponent water mixtures, with potential implications in the fields of membrane technology and water purification.
Thermal Conductivity Extraction From Frequency Domain Thermo-Reflectance Experiments Using the Phonon Boltzmann Transport Equation
Authors: Saurav Siddharth , Mazumder Sandip 
Published: September 2023

Abstract
The Boltzmann Transport Equation (BTE) for phonons was solved numerically in cylindrical coordinates and in time domain to simulate a Frequency Domain Thermo-Reflectance (FDTR) experimental setup. The phase lag between the pump and probe signals was computed for a pump laser modulation frequency ranging from 20–200 MHz. Results were obtained both with and without the inclusion of optical phonons, as well as with two different relaxation time-scale expressions (Holland versus Broido) obtained from the literature for silicon. It was found that inclusion of optical phonons significantly improved the agreement between the measured and the computed phase lag, while a clear superiority of one relaxation time-scale expression over the other could not be established. Subsequently, the thermal conductivity was extracted by fitting the Fourier heat conduction equation results — also solved numerically in time domain — to the measured and computed (using BTE) phase lag values. The BTE predictions resulted in thermal conductivity values that are slightly closer to the bulk value (smaller thermal conductivity suppression) than what the experimental data suggested.