bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Integration of Absorption Heat Pump in a Milk Powder Dairy
Authors: Andersen Jens Møller 
Published: November 2021

Abstract
Heat integration with absorption heat pumps requires investigation of many types of plant designs. In this article, it is concluded that in many cases high temperature absorption systems for heat recovery are more economically feasible than absorption systems for cooling purposes. The conclusion is based on a project where the scope was to investigate technical and economical possibilities for heat integration of an absorption heat pump in a milk powder plant. The first idea behind the project was to use the waste heat from the rejected air to drive an absorption cooling system to reduce the electricity consumption for cooling proposes. The model of the plant was based on simulations as a background for a time averaged COP model. It was concluded that an absorption system for generating low temperature steam is more feasible.
Development of a Micro-Channel Evaporator Model for a CO2 Mobile Air-Conditioner
Authors: Kim M.-H. , Yin J. M. , Bullard C. W. , Hrnjak P. S. 
Published: November 2021

Abstract
This paper presents the development and verification of a heat exchanger model for evaluating thermal performance of an evaporator for a CO2 mobile air-conditioning system. The model has been developed, based on the finite volume method, with emphasis on the air-side heat and mass transfer process. The governing equations are derived from mass and energy balances using newly developed air-side heat transfer and friction loss correlations for micro-channel heat exchangers under dry and wet conditions. The calculated air-side heat transfer and pressure drop data are in good agreement with measured data. However, the refrigerant-side pressure drop estimation for micro-channel tubes usually underestimates the measured value. The simulation results and importance of selecting appropriate heat transfer and pressure drop correlations for the micro-channel heat exchanger are addressed.
Numerical Simulation of Thermal and Fluid-Dynamic Behaviour of Reciprocating Compressor
Authors: He Zhilong , Peng Xueyuan , Shu Pengcheng 
Published: November 2021

Abstract
This paper presents a numerical method for simulating the thermal and fluid-dynamic behavior of hermetic compressors in the whole compressor domain. The model of fluid flow is developed by integrating transient one-dimensional conservation equations of continuity, momentum and energy through all of the elements from suction line to discharge line. The model describing thermal behavior is based on heat balance in the components such as muffler, connecting tubes and orifices. The calculation of the thermodynamic and transport properties for different refrigerants at various conditions has been considered, and some numerical results for a hermetic compressor are presented. The present study has demonstrated that the numerical simulation is a fest and reliable tool for compressor design.
Grid Aspects of Screw Compressor Flow Calculations
Authors: Kovacevic Ahmed , Stosic Nikola , Smith Ian K. 
Published: November 2021

Abstract
Dynamic flow losses and leakage decrease screw compressor adiabatic efficiency, thereby increasing power consumption. These effects can be determined more precisely by use of Computational Fluid Dynamics analyses to estimate the flow and pressure distribution within them based on 3-D flow patterns. Numerical grids of the suction, compression and discharge chambers were generated by application of a 2-D transfinite interpolation combined with a layer meshing technique in an independent stand-alone CAD-CFD interface program developed by the authors. Flow calculations were then obtained by use of Comet, a commercial CCM solver.
Application of the Small-Scale Combined Heat and Power Installations in the District Heating Systems
Authors: Zwierzchowski Ryszard , Dzierzgowski Mieczysław 
Published: November 2021

Abstract
This paper is concerned with the application of the Small-Scale Combined Heat and Power (SSCHP) installations as a perspective way of the District Heating System (DHS) modernization programs in Poland. The small-scale installations analyzed hereto, mean the installations with an overall capacity (heat plus power generation) of less than 30 MW.
For the purpose of selection of appropriate type and capacity of the SSCHP installation, operational analysis of the DHS and investigation of possible implementation of the Thermal Energy Storage (TES) systems were performed. Also, the criteria for application of the SSCHP installations in the District Heating Plant (DHP) assuring continuous and efficient operation were presented.
Operational analysis of the DHS covered supply and demand side of the annual heat generation and electricity consumption by the DHP and heat consumption by the consumers. Detailed heat consumption analysis during summer season was carried out in order to increase operational time for the SSCHP installations and for investigation of TES systems application in the DHS.
Heat storage in the DHS and its influence on capacity and operation of the SSCHP was also investigated. Heat accumulation by the District Heating Network (DHN) and by the vertical, stratified TES systems were analyzed. Additionally, heat accumulation by the non-pressure TES system was proposed as an alternative to the vertical, stratified TES system.
Finally, results of calculation of the required capacity of the TES systems assuring continuous and efficient operation of the SSCHP installation in the DHS, especially during summer season were shown. Some advantages of the TES system implementation in the DHS in case where the SSCHP installation is applied in the DHP were presented as well.
Heat Transfer in the Regenerator of a Liquid Air Energy Storage System
Authors: Araki Hidefumi , Kitoh Kazuaki , Chino Kooichi 
Published: November 2021

Abstract
An energy storage system that stores energy in the form of liquid air has been studied. In this system, the thermal storage regenerator recovers cold heat from liquid air during the daytime, and it is utilized to produce the liquid air during the nighttime. The energy storage efficiency is greatly improved by the regenerator that consists of steel pipes inserted in a concrete medium. A computer code, that simulates unsteady-state heat transfer between air and a concrete medium, was developed. The calculation results showed the good agreement with the experimental results. The required volume of the concrete regenerator was less than 1/100 of that of reservoirs for a pumped-hydro power station.
Thermodynamic Model of the Loss Factor Applied to Steam Turbines
Authors: Zaleta Alejandro , Vega Luis F. , Gallegos Armando , Hernandez Abel 
Published: November 2021

Abstract
Erosion, roughness, steam path damage, etc., are factors that reduce power capacity in a steam turbine. Any power loss occurring locally in intermediate stages of a steam turbine results in more available energy in the downstream stages, this effect is well-known as the Loss Factor (Salisbury, 1974; Stodola, 1927; Husain, 1984). Currently, the Loss Factor is been calculated by graphical methods (Cotton, 1996). In this work a new thermodynamic expression for the Loss Factor (LF) is introduced, in order to improve applications to evaluate malfunctions in the first and intermediate stages of steam turbines. The new thermodynamic expression for the Loss Factor, is based on Second Law Analysis; and concepts like the internal parameter θ, and the dissipation temperature Td; (Royo, 1992). An Example of a steam turbine in a conventional power plant of 158 MW is analyzed by comparing a classical graphical method (ASME/ANSI PTC-6, 1970; and Cotton, 1993), and the proposed expression of the Loss Factor (LF). Special emphasis is made on the thermoeconomical deviations that could arise by an imprecise application of the Loss Factor Method, during an energy audit of the steam turbine internal parts.
Water and Thermal Management of an Indirect Methanol Fuel Cell System for Automotive Applications
Authors: Eggert Anthony , Badrinarayanan P. , Friedman David , Cunningham Joshua 
Published: November 2021

Abstract
Proton exchange membrane (PEM) fuel cell systems using steam-reformed methanol are currently under consideration for first generation commercial fuel cell vehicles. Proper water and heat management of such a system is critical in achieving high overall efficiency and maintaining water self-sufficiency.
The first part of the paper briefly describes the key aspects of the water and thermal management (WTM) model developed as part of the Fuel Cell Vehicle Modeling Program (FCVMP) at the University of California – Davis. The main purpose of this model was to determine the water self-sufficiency and temperature management requirements of the indirect methanol fuel cell system and to evaluate the associated parasitic losses. This model has imbedded in it the main components of the fuel cell system, such as the fuel cell stack, air compressor, and fuel processor as seen by the WTM system.
The second half of the paper discusses the results obtained from the model and their implications. We find that the cooling and humidification of the anode and cathode inlet streams can be accomplished with water injection and therefore, a separate heat exchanger is not needed for additional cooling. Additionally we find that the instantaneous and cumulative excess water is determined by factors such as air supply characteristics, condenser efficiency, ambient air humidity, and stack attributes. We find that these factors can affect the ability of the vehicle to achieve true water self-sufficiency.
The Full-Spectrum Correlated-K Distribution and Its Relationship to the Weighted-Sum-of-Gray-Gases Method
Authors: Modest Michael F. , Zhang Hongmei 
Published: November 2021

Abstract
A new Full-Spectrum correlated-k distribution has been developed, which provides an efficient means for accurate radiative transfer calculations in absorbing/emitting molecular gases. The Full-Spectrum correlated-k distribution can be used together with any desired solution method to solve gray-medium radiative transfer equations for a small number of gray absorption coefficients, followed by numerical quadrature. It is shown that the Weighted-Sum-of-Gray-Gases model is effectively only a crude implementation of the Full-Spectrum correlated-k distribution approach.
Within the limits of the Full-Spectrum correlated-k distribution model (i.e., an absorption coefficient obeying the so-called “scaling approximation”), the method is exact. This is demonstrated by comparison with line-by-line calculations for a one-dimensional CO2-N2 gas mixture with varying temperature and concentration fields.
An Upwinding Procedure for Numerical Radiation Heat Transfer
Authors: Rousse Daniel R. , Gautier Guillaume , Sacadura Jean-François 
Published: November 2021

Abstract
This paper presents a skewed upwinding procedure for application to the Control Volume Finite Element Method (CVFEM) in the context of radiation heat transfer problems involving participating media. The proposed first order scheme is stable, economical, accurate and it inherently precludes the possibility of computing negative coefficients in the discretized algebraic equations while accounting for the direction of radiant propagation. The suggested first-order skew positive coefficients upwind scheme (SPCUS) is validated by application to several basic test problems, acknowledged by the radiative heat transfer community: its performance has proven to be excellent.
Numerical Modeling of Microporosity Formation in Aluminum-Rich Aluminum-Copper Alloys in Microgravity Conditions
Authors: Xiong M. , Kuznetsov A. V. 
Published: November 2021

Abstract
The microporosity formation in a vertical unidirectionally solidifying Al-4.1%Cu alloy casting is modeled in both microgravity and standard gravity as well as in the conditions of decreased (Moon, Mars) and increased (Jupiter) gravity. Due to the unique opportunities offered by a low-gravity environment (absence of metallostatic pressure and of natural convection in the solidifying alloy) future microgravity experiments will significantly contribute to attaining a better physical understanding of the mechanisms of microporosity formation. One of the aims of the present theoretical investigation is to predict what microporosity patterns will look like in microgravity in order to help plan a future microgravity experiment. To perform these simulations, the authors suggest a novel three-phase model of solidification that accounts for the solid, liquid, and gas phases in the mushy zone. This model accounts for heat transfer, fluid flow, macrosegregation, and microporosity formation in the solidifying alloy. Special attention is given to the investigation of the influence of microporosity formation on the inverse segregation. Parametric analyses for different initial hydrogen concentrations and different gravity conditions are carried out.
Analysis and Design of Soldering Splice in Superconducting Magnets
Authors: Tong Wei , Zhuo Zhang Qing 
Published: November 2021

Abstract
In superconducting magnets, soldering splices are used to connect superconducting cables for providing electrical current paths. One of the main considerations in the splice design is the splice electrical resistance across the joint. High joint resistance can increase the Joule heat generation and thus result in conductor instability.
A finite element analysis has been performed to determine the key parameters affecting soldering splice resistance for superconductors with high purity aluminum stabilizers. The parameters investigated include: high purity aluminum RRR value, copper RRR value, solder layer thickness, magnetic field, splice configuration, and operating temperature. The results obtained from this work can benefit splice cooling and the design optimization.
A Helium II Heat Transfer Level Meter
Authors: Zhang T. , Smith M. R. , Van Sciver S. W. 
Published: November 2021

Abstract
This paper presents the design and measurement techniques for a new type of liquid helium level meter. The measurement principle is given by the change of heat transfer rate with the liquid level. Detailed heat transfer analysis has been done to show the anticipated behavior and accuracy of the meter.
To verify our design, a prototype level meter was fabricated and tested in saturated He II bath with temperature from 1.7 K to 2.0 K. With the experiment, we obtained the relationship between overall heater power and liquid level. The data indicate that the device can measure liquid level with the uncertainty of ±1 mm in a practical system.
A Study of Three-Dimensional Mixed Convective Heat Transfer From Short Vertical Cylinders in a Horizontal Forced Flow
Authors: Scott David A. , Oosthuizen P. H. 
Published: November 2021

Abstract
Heat transfer from relatively short vertical isothermal cylinders in a horizontal forced fluid flow has been considered. The flow conditions are such that the buoyancy forces resulting from the temperature differences in the flow are in general significant despite of the presence of a horizontal forced flow of air, that is, mixed convective flow exists. Because the cylinders are short and the buoyancy forces act normal to the forced flow, three-dimensional flow exists. The experiments were performed in a low velocity, open jet wind tunnel. The study involved the experimental determination of the mean heat transfer coefficient and a comparison of the results with a previous numerical analysis. Mean heat transfer rates were determined using the ‘lumped capacity’ method. The mean Nusselt number has the Reynolds number, Grashof number and the height to diameter ratio of the cylinders as parameters. The results have been used to determine the conditions under which the flow departs from purely forced convection and enters the mixed convection regime, i.e., determining the conditions for which the buoyancy effects should be included in convective heat transfer calculations for short cylinders.
Experimental Investigation of Contact Resistance Across Pressed Lead and Aluminum Contact in Vacuum
Authors: Ma Xiao , Khan Jamil A. , Rhodes Curtis A. , Smith Allen , Hamm L. Larry 
Published: November 2021

Abstract
In a proposed nuclear application (production of Tritium using an accelerator, Accelerator Production of Tritium (APT)) lead is proposed to be used as a shield in the blanket module. This lead will be encased in aluminum cladding. The energy transfer rate from the lead to the cooling water will be a function of the thermal contact resistance (TCR) between lead and aluminum. Presently, data for contact resistance for this application does not exists in the literature. An experimental investigation has been conducted to determine the thermal contact resistance between lead and aluminum in vacuum. In this study we investigate the effect of pressure, surface roughness and interface temperature on the contact resistance.
The experimentally determined range of contact resistance was found to be from 3.74×10−4K-m2/W to 11.45×10−4K-m2/W at 100°C∼200°C under 120∼370psi (0.827∼2.551MPa). The contact resistance increases to 168×10−4K-m2/W at small external pressure of 2.0∼3.9psi (0.013∼0.027MPa). The contact resistance decreases with increasing in contact pressure. Interface temperature and surface roughness do not affect the contact resistance significantly. There is a slight increase in contact conductance with increasing temperature. The experimental results provide contact resistance data, which should be a good reference for the APT design evaluation.
Liquid Crystal Imaging of Surface-Tension-Driven Convection
Authors: Dutton T. W. , Pate L. R. , Hollingsworth D. K. 
Published: November 2021

Abstract
Surface tension forces can drive fluid motion within thin liquid layers with a free surface. Spatial variations in the temperature of the free surface create surface tractions that drive cellular motions. The cells are most commonly hexagonal in shape and they scale on the thickness of the fluid layer. This investigation documents the formation of cells in the liquid film in the presence of a uniform-heat-flux lower boundary condition. Liquid crystal thermography was used to image the cells and measure the temperature distribution on the lower surface of the liquid layer.
A 1.1-mm deep pool of silicone oil was supported on a 50-μm-thick electrically heated metal foil. The oil was retained inside an independently heated acrylic ring mounted on the top surface of the foil, and a dry-ice cooling plate served as the low-temperature sink above the free surface of the oil. Color images of hexagonal convection cells were captured using liquid crystal thermography and a digital image acquisition and processing system. The temperature distribution inside a typical cell was measured using thermographic image analysis. Experimental issues such as the use of an independently heated retaining ring to control the height of the liquid film, and the utility of a flux-based Marangoni number are discussed.
Heat Transfer on a Film Cooled Inlet Guide Vane
Authors: Holmer Marie-Louise , Eriksson Lars-Erik , Sundén Bengt 
Published: November 2021

Abstract
The steady flow and temperature fields around a film cooled inlet guide vane are determined numerically by a CFD method. In particular the outer surface temperatures and heat transfer coefficient distributions are calculated. Static pressure distributions are also presented. The film cooling is achieved by 10 rows of film cooling holes. The computed results are compared with experimental data.
The governing equations are solved by a 3D finite-volume Navier-Stokes solver. The low Reynolds number version of the k-ω turbulence model by Wilcox is implemented to enable calculations of turbulent flow cases. A realizability constraint is applied to reduce the generation of unphysical turbulent kinetic energy, particularly close to the leading edge.
To handle the film cooling process a special procedure is used. An injection model was implemented in the computer code. This injection model adds the mass flow rate passing through the film cooling holes to the main flow as source terms in the equations for mass, momentum, energy and turbulent kinetic energy.
The grid used in the calculations is block-structured, and the total number of grid points is around 250,000.
In a related investigation for the same vane geometry but considering pure convective heat transfer, the authors have investigated the importance of the wall thermal boundary condition. Based on this a conjugate heat transfer approach was applied in this paper. The conjugate heat transfer condition means that the heat transfer coefficient distribution is prescribed on the inner surface of the vane and also the wall thickness and thermal conductivity of the vane material are prescribed. The vane outer surface temperature is then found as part of the numerical solution.
Some essential parameters in the injection model were varied and the calculated results for the vane outer surface temperature were found to compare favourably with measurements. The static pressure distribution on the vane surface agrees well with experiments. The Mach number distribution provides information of the flow field.
A Real-Time Neural Network Estimator for Workpiece Thermal Expansion Errors
Authors: Yoder A. D. , Smith R. N. 
Published: November 2021

Abstract
The importance of predicting and reducing thermal expansion errors in workpieces is becoming greater as better precision machining processes are developed. An artificial neural network model to estimate the workpiece thermal expansion errors in real-time during precision machining operations is developed and compared with experimental results. A finite element model of workpiece thermal expansion has been created to predict expansions in a thin cylinder undergoing a turning process. The neural network has been trained using finite element model solutions over a range of conditions to allow for changing machining parameters. To realize “on-line” capability, the measurable values of heat flux into the workpiece, surface heat transfer coefficient, and tool location are used as inputs and the expansion as the output for the neural network. The estimations of the network are compared with experimental results from a turning process on a large diameter aluminum cylinder. There is reasonable agreement between measured and estimated expansions with an average error of 18%. The neural network has not been trained at the cutting conditions used during the experiment. The speed of the neural network estimation is much greater than the solution to the finite element model. The finite element model required over 15 minutes to solve on a Pentium 133Mhz computer. The neural network calculated the expansions easily at 1 Hz during the experiment on the same computer. With real-time estimation using measurable data, compensation can be made in the tool path to correct for these errors. The application of this method to precision machining processes has the capability of greatly reducing the error caused by workpiece thermal expansions.