bluuebunny/crossref_metadata_2025 huggingface dataset:
A Periodic Transient Method Using Liquid Crystals for the Measurement of Local Heat Transfer Coefficients
Authors: Baughn James W. , Anderson Michael R. , Mayhew James E. , Butler Robert J.
Published: March 2022

A new periodic transient method for the measurement of local heat transfer coefficients is described. In this method, the freestream temperature is periodically heated while the local surface temperature fluctuation is measured. The local heat transfer coefficient can be determined from the frequency, the ratio of the surface temperature fluctuation to the free stream temperature fluctuation and the wall thermal properties. Measurements on a Plexiglas flat plate with a laminar boundary layer are presented as a demonstration of this method. For this demonstration the free stream is electrically heated using a fine wire cloth. The surface temperature fluctuation is measured using liquid crystals with a hue analysis technique. The results show that this is a viable method for measuring local heat transfer coefficients. Its advantages are that it approximates a uniform temperature thermal boundary condition and it is not necessary to control or measure the initial wall temperature.
Thin Film Resistance Heaters for High Heat Flux Jet-Array Cooling Experiments
Authors: Younis Hesham F. , Dahbura Rudy S. , Lienhard John H.
Published: March 2022

This paper reports on efforts to use plasma-sprayed metal films as resistance heaters for generating heat fluxes on the order of 10 MW/m2. These heaters are intended for use in testing a jet-array cooling module designed for removing extremely high heat fluxes. Convective cooling of the rear surface of an externally heated metal faceplate is provided by an array of impinging water jets. The metal film heater is electrically isolated from the faceplate by a plasma-sprayed ceramic film beneath it. Heat fluxes have reached 7.2 MW/m2 over an area of 10.3 cm2. Design and fabrication issues associated with these heaters include physical property differences between sprayed and bulk materials, thickness variations in the sprayed materials, high thermal resistance associated with the ceramic films, and fracture of the heater film at high temperatures.
Natural Convection From Vertical Helical Coils in a Cylindrical Enclosure
Authors: Taherian Hessam , Allen Peter L.
Published: March 2022

Experiments were conducted to investigate natural convection heat transfer from single enclosed helical coils in a vertical orientation. Coils having different diameter, pitch, and tube diameters were placed inside a cylindrical shell of fixed height and diameter, to form a natural convection shell-and-coil heat exchanger. Effects of tube diameter, coil surface area and coil pitch on heat transfer coefficient were studied. Nu-Ra correlations were presented based on different characteristic lengths. The data was correlated well by NuDhx = 0.002RaDhx0.630 using heat exchanger hydraulic diameter as the characteristic length.
Quantitative Flow Visualization Using a Water Table
Authors: Rani Sarma L. , Wooldridge Margaret S.
Published: March 2022

The current work describes the development of a new, non-intrusive optical method for the evaluation of water heights along a gravity wave in shooting water flows in an experimental water table facility. The technique involves superimposing alternating dark and clear mechanical fringes on the water flow. Images of the fringe deviation patterns formed due to the gravity waves are obtained. The images are analyzed to determine the angles and the lengths of fringe deviations, which are related to the local flow heights. It is proposed that the deviations can be simulated using flat-topped optical prisms oriented along the direction of the gravity wave. The height of such a prism corresponds to the local water height. In the present work, shooting flows past a wedge profile for a zero angle of attack have been studied. The variation of flow field heights along a gravity wave has been obtained by the optical technique and by a conventional intrusive depth-gauge technique. The results are in good agreement.
A Generalized Asymptotic Theory of Mixed Convection Boundary Layers
Authors: Chen Michael M. , Paolucci Samuel
Published: March 2022

We propose the use of generalized boundary layer equations and governing dimensionless parameters for mixed convection of either the forced-convection-dominated case or the free-convection-dominated case. Such equations are derived by considering the asymptotic limits of high Reynolds number or high Peclet number, and high Rayleigh number or high Boussinesq number, with small or large Prandtl and Richardson numbers as the case may be. Here, we illustrate the ideas in the forced-convection-dominated case in the small Prandtl number limit. We show that the exercise provides a more convenient format for displaying the results of computational or experimental investigations of mixed convection, leading to more general quantitative results as long as the asymptotic conditions are met, and possibly general qualitative results even when the asymptotic conditions are not strictly satisfied. In addition the contributions of normal and tangential buoyancy are also clearly separated.
Simulations of Three-Dimensional Flow and Augmented Heat Transfer in a Symmetrically Grooved Channel With Constant Temperature Walls
Authors: Greiner M. , Faulkner R. J. , Wirtz R. A. , Fischer P. F.
Published: March 2022

Direct numerical simulations of three-dimensional flow and augmented convection in a channel with symmetric, transverse grooves on two opposite walls are performed using the spectral element technique. The flow is driven by a constant pressure gradient. A method employing an exponentially decaying temperature scale is developed and used to calculate the fully developed heat transfer coefficient for constant temperature boundary conditions. Results are presented for the Reynolds number range 180 < Re < 1175.

A series of flow transitions is observed as the Reynolds number is increased, from steady two-dimensional flow, to traveling two and three-dimensional wave structures, and finally to three-dimensional mixing. Periodic ejection of slow moving fluid from the grooves causes significant flow rate unsteadiness. Three-dimensional simulations predict friction factor and Nusselt number values to within 20% of measured values over the narrow Reynolds number range where overlapping data exists. Two-dimensional simulations are found to be inadequate to calculate transport in this channel for Re > 400.
Experimental Analysis of Thermal Instability in Natural Convection Inside Open-Ended Cavities With Uniform Heat Flux on Horizontal Walls
Authors: Manca Oronzio , Morrone Biagio , Nardini Sergio , Savarese Salvatore
Published: March 2022

An experimental investigation of air natural convection between heated parallel plates has been carried out by the visualization of the flow and the measurement of air temperature. Grashof numbers, based on the gap between the plates and the longitudinal aspect ratio (L/b), varied in the 3.8·102–1.1·105 range. The investigated distance between the plates, b, were 20.00, 32.25 and 40.00 mm, corresponding to aspect ratios L/b of 20, 12.4 and 10 and plate width/gap between the plates ratio of 22.5, 14 and 11.25. The Ohmic heat fluxes have been changed in the 60–240 W/m2 range. Furthermore, three heating modes have been tested in order to analyze their peculiar patterns and the onset of secondary motions. The typical main flow pattern resembles a C shape (C-loop). In fact, the flow penetrates inside the channel close to the leading edge of the lower plate and exits from the upper part, by reversing its motion inside the channel. The flow visualization shows that secondary flows add to the C-loop main flow, when the lower plate is heated. Such secondary structures start in the form of thermals and, then, they change into longitudinal vortex, whereas in the upper region of the open-ended cavity a chaotic motion is detected. The existence of these structures is confirmed by the measurement of istantaneous temperature values. They show that the greater the Grashof number the more chaotic the turbulent flow in the outflow region of the C-loop, when the lower plate is heated and the upper plate is unheated.
Application of a 3D Numerical Model for Shell-and-Tube Heat Exchanger Simulation and Comparison With Other Methods
Authors: Prithiviraj M. , Andrews M. J.
Published: March 2022

This paper describes a three-dimensional numerical model for simulation of turbulent flow and heat transfer inside shell-and-tube heat exchangers. A SIMPLE (Patankar and Spalding, 1972) type solution algorithm is used on a colocated grid. The simulation of shell-and-tube heat exchangers is based on a distributed resistance method that uses a modified two equation k-ε turbulence model. Volume porosities and non-homogeneous surface permeabilities account for tubes, nozzles, and an arbitrary arrangement of baffles. Sub-models are used for shellside pressure drop by tubes, turbulence generation and dissipation by tubes, baffle-shell and baffle-tube leakage, shellside and tubeside heat transfer. These sub-models use parameters that have not been altered from their published values. The details of the sub-models are described in detail by Prithiviraj and Andrews (1995, 1996).

The numerical model was validated by comparison with experimental data for shell-and-tube heat exchangers from University of Delaware (Bell, 1963) and Argonne National Labs (Halle et al., 1984) by Prithiviraj and Andrews (1996). Good agreement was obtained between the computations and experiments. This paper uses the model to simulate flow and heat transfer in Full Bundle and No Tubes In The Window (NTIW) bundle types (In the NTIW design, tubes in the window region are removed). The effect of shell type and bundle type on the pressure drop and heat transfer is examined. The performance of the numerical model is compared with the methods of Bell (1981), Kern (1950), and Donohue (1949), for a range of shellside Reynolds numbers. It is shown that at the price of an increased computation cost, the three-dimensional numerical model yields better predictions than the above methods, along with detailed flow, turbulence, and temperature fields.
High Resolution Single Crystal Silicon Accelerometer Using Silicon Fusion Bonding and Deep Reactive Ion Etching
Authors: van Drieënhuizen B. P. , Maluf N. I.
Published: March 2022

This paper presents a single crystal silicon accelerometer with high dynamic range fabricated in a CMOS compatible, low cost technology. This technology uses a combination of Silicon Fusion Bonding (SFB) and Deep Reactive Ion Etching (DRIE). which allows thick devices (up to several hundred μm) to be defined with high aspect ratios (up to 25). In addition to the advantages of single crystalline material, the high aspect ratio results in higher sensitivity thus providing significant performance improvement. Prototypes use a hybrid approach, with an 1.0 × 1.5 mm2 accelerometer and a capacitive sensor interface providing closed-loop force-balancing to minimize non-linearity. Characterization tests of a 2 G (1 G = 9.8 m/s2) full scale device have shown a sensitivity of 2.2 V/G. The non-linearity is below the noise level, limited by 1/f noise in the electronics inherent to the foundry CMOS process. At 100 Hz, the measured noise power spectral density is approximately 80 μGrms/√Hz, which is significantly higher than the estimated 6 μGrms/√Hz noise figure for the mechanical element due to Brownian motion.
MEMS for Fluidic Controls
Authors: Ho Chih-Ming , Tai Yu-Chong
Published: March 2022

During the past decade, micromachining technology has become available to fabricate micron-sized mechanical parts. Micromachines have several unique features. First, typical micromachined transducer sizes are on the order of 100 microns, which can be one or more orders of magnitude smaller than traditional sensors and actuators. The drastic reduction in inertia due to these smaller sizes means a substantial increase in the frequency response. Second, the batch processing, which is characteristic of IC fabrication, can be used to make a large number of transducers for distributed sensing and actuation over a wide area. This capability enables us to sense certain flow characteristics in a 2-D domain and to perform control at the proper locations. Potential application areas include the reduction of surface shear stress in a turbulent boundary layer. Third, micromachine manufacturing technology is derived from, though not completely compatible with, IC fabrication so it is possible to integrate the IC with micro transducers to provide logic capability. The integrated microelectronics and micromachines constitute an integrated micro system, which is capable of executing sense-decision-actuation on a monolithic level.

A micro system for shear stress reduction was fabricated on a 1-cm × 1-cm die; 18 micro shear-stress sensors, 3 micro flap actuators, as well as circuits for logic sensor drivers, and actuator drivers are monolithically integrated. The lifetime of the high-speed streaks is short, and a large number of the streaks need to be controlled at the same time. If all of the sensor outputs were to be sent to a central computer and the control command were to be sent from the computer to each actuator, a very high bandwidth signal path and large number of leads would be required. Implementing local and simple signal processing is obviously a necessity for alleviating these problems. Neural networks are a viable approach. A neural-network-based circuit was developed to determine the time and the spatial extent of the high-speed streaks passing the shear-stress-sensor array. The output of the circuit was used for actuation.
Designing High-Performance Micro-Pumps Based on No-Moving-Parts Valves
Authors: Bardell Ron L. , Sharma Nigel R. , Forster Fred K. , Afromowitz Martin A. , Penney Robert J.
Published: March 2022

Micro-pumps utilizing no-moving-parts (NMP) valves, driven by a piezoelectric element bonded to a flexible membrane have been developed by a number of research groups (Olsson et al, 1995a; Forster et al, 1995; Gerlach and Wurmus, 1995). Recently, pump heads of over 7 m of H2O have been achieved (Olsson et al, 1996). However, no systematic methods have been reported that predict pump performance and guide the design of optimally performing pumps. We have developed a linearized dynamic system model that provides a detailed understanding of the relationship between a realistic set of system parameters and pump performance. These parameters include flow characteristics of the NMP valves, characteristics of the working fluid, pump geometry, and materials used in fabrication. Utilization of the model as a design tool, resulted in a dramatic improvement from previous “flexible” pump designs with maximum heads of approximately 0.24 m of H2O to a “stiff” design with a maximum head of 4.75 m of H2O, a twenty-fold increase in performance. Corresponding flow rates increased from 85 to 750 μl/min, a nine-fold increase.
A Lateral Repulsive-Force Drive Using Asymmetric Electrostatic Field
Authors: Lee Ki Bang , Cho Young-Ho
Published: March 2022

We present a new electrostatic actuation method using a lateral repulsive-force induced by an asymmetric distribution of electric field. The asymmetric electric field is induced when an electrostatic induction voltage is applied between a movable electrode and a pair of adjacent fixed electrodes. A simple analytical equation of the repulsive force has been derived from a finite element simulation. A set of repulsive-force polysilicon microactuators has been designed and fabricated by a 4-mask surface-micromachining process. Static and dynamic drive tests of the fabricated microactuators have been performed at atmospheric pressure for a varying induction voltage. The static displacement of the fabricated microactuator is proportional to the square of the DC induction voltage and is obtained as 1.27μm for the DC induction voltage of 140V. The dynamic amplitude of the fabricated microactuator has been measured as 1.9μm for the DC induction voltage of 140V with the AC drive voltage of 20V. The resonant frequency of the repulsive-force microactuator increases from 11.7 kHz to 12.7 kHz when the DC induction voltage increases up to MOV. The characteristics of the repulsive-force drive have been discussed and compared with those of the conventional attractive-force actuation.
Characterization of Thin-Film Impact Microactuators
Authors: Hipwell Roger L. , Muller Richard S. , Pisano Albert P.
Published: March 2022

This paper presents analysis for surface-micromachined, thin-film impact microactuators. Empirical data are given for the characterization of such a linear microactuator. These data include actuator performance trends due to slider design parameters, as well as measurements to model thin-film microscale impact. The impact is modeled by planar impulse-momentum techniques that include the effects of tangential sliding motion between the impactor and the slider during contact. The physical placement and size of the slider guides are shown to affect the magnitude of slider displacement subsequent to impact.
Periodic Heat Flux-Temperature Phase Difference for Thin Metal Films
Authors: Hays-Stang Kathy J. , Haji-Sheikh A.
Published: March 2022

The two-step parabolic model approximately describes microscale heat transfer in metals. Heat transfer in thin films with sinusoidal heat flux input on one surface is described by a Green’s function solution of the two-step parabolic model. The dimensionless phase angle between the sinusoidal energy input and the lattice temperature response at the opposite surface of a thin film is calculated for several dimensionless parameters that include the energy input frequency, electron-phonon coupling factor, thermal conductivity, thickness of the film, and electron and lattice heat capacities. For low dimensionless frequencies, the temperature behavior is essentially Fourier except for very thin metal films and/or for materials with very low electronphonon coupling factors. The departure from Fourier behavior as input frequency increases could allow future experimental determination of electron-phonon coupling factor and electron heat capacity. Comparison with previous calculations for thermal wave and Fourier heat transfer models shows that the dimensionless phase angle for the two-step model is generally less than for the other models.
Numerical and Experimental Study on Thermal Performance of Low Temperature Heat Pipe With Two Heaters
Authors: Park Jong Heung , Lee Seong Pal
Published: March 2022

A study on the operation of a heat pipe with two heat sources has been performed to optimize the heat distribution of two heaters. A numerical modeling is used to predict the temperature profiles for the heat pipe assuming cylindrical two dimensional laminar flow for the vapor, and the conduction heat transfer for the wall and wick. An experimental study using the copper-water heat pipe with a length of 0.45 m has been performed to evaluate the numerical model developed. Temperature profiles at the outer wall and the comparison of temperature distribution for the total heat input range from 29W to 94W are presented. Also the correlation between the heat input and the temperature increase is presented for the optimum distribution on two heaters. The result shows that the outer wall temperature can be controlled by redistribution of heat sources.
Development of Numerical Simulation System on Residual Gravity and Marangoni Convection
Authors: Imai Ryoji , Yoda Shinichi , Nakamura Hirohiko , Murata Keiji , Watanabe Nobuhiro , Takahashi Shingo , Isaka Norikatsu
Published: March 2022

A numerical simulation system to calculate residual gravity and Marangoni convection has been developed by NASDA (National Space Development Agency of Japan) in order to support researchers who conduct material processing experiments in microgravity. Boundary fixing methods and finite difference methods are applied to solve the governing equations. Residual gravity convection, solidification combined convection, and Marangoni convection are calculated by this system, and are evaluated by comparison with experimental results.
Thermionic Cascade Converter Concept for High-Efficiency Space Power
Authors: Begg Lester L. , Van Hagan Thomas H. , Smith Joe N.
Published: March 2022

This paper presents trade studies that address the use of the thermionic/AMTEC cell — a cascaded, high-efficiency, static power conversion concept that appears well-suited to space power applications. Both the thermionic and AMTEC power conversion approaches have been shown to be promising candidates for space power. Thermionics offers system compactness via modest efficiency at high heat rejection temperatures, and AMTEC offers high efficiency at modest heat rejection temperature. From a thermal viewpoint, the two are ideally suited for cascaded power conversion: thermionic heat rejection and AMTEC heat source temperatures are essentially the same. In addition to realizing conversion efficiencies potentially as high as 35–40%, such a cascade offers the following perceived benefits:

• Survivability — capable of operation in the Van Allen belts.

• Simplicity — static conversion, no moving parts

• Long lifetime — no inherent life-limiting mechanisms identified

• Technology Readiness — Large thermionic database; AMTEC efficiencies of 18% current being demonstrated, with more growth potential available

• Technology Growth — applicable to both solar thermal and reactor-based nuclear space power systems

Mechanical approaches and thermal/electric matching criteria for integrating thermionics and AMTEC into a single conversion device are described. Focusing primarily on solar thermal space power applications, parametric trends are presented to show the performance and cost potential that should be achievable with present-day technology in cascaded thermionic/AMTEC systems.
Analysis and Evaluation of Malfunctions in Thermomechanical Systems
Authors: Royo Javier , Zaleta Alejandro , Valero Antonio
Published: March 2022

In previous papers, two new parameters related to the performance of thermal components have been shown: the internal parameters θ (Royo and Valero 1995) and the dissipation temperature (Royo et al. 1996).

When the behavior of a component of a thermal plant is impaired due to internal deteriorations, cause a modification in the behavior of another components. This implies a variation in the global efficiency of the plant. But how can this influence be quantified? This question is of utmost importance when it comes to making an energetic and economic assessment of carrying out a repair on a component, or undertaking an improvement on such a component.

The aim of this paper is to show an example of the use of the internal parameters 9 and the dissipation temperatures to answer analytically this question. The example chosen is a power plant with reheating.

Analytical and numerical results and their analysis are provided in the paper. For example, using this procedure, it is possible to obtain that, in the chosen plant, a diminution of 1% in the isoentropic efficiency of their high pressure steam turbine causes 0.13% diminution in the efficiency of the whole plant.

The results obtained have been checked by means simulation (GATE Cycle 1995). The difference between both set of results are in all the cases lower than 4%.
Performance Evaluation of a Binary Geothermal Power Plant in Nevada
Authors: Kanoglu Mehmet , Çengel Yunus A.
Published: March 2022

First and second law analysis of a 12.9 MW binary geothermal power plant in Nevada is performed using actual plant data obtained in 1996, and alternatives are investigated to evaluate its performance. Exergy destruction throughout the plant is quantified and illustrated using an exergy cascade. The primary sites of exergy destructions are the turbine-generator assembly where power is generated, the condenser where the working fluid is condensed, and the reinjection well where the brine is reinjected into the ground after passing through heat exchangers. The exergy destruction at these sites account for 30.5%, 26.4%, and 21.4% of total exergy destruction in the plant, respectively.

The first and second law efficiencies of major plant components are determined in an attempt to assess their individual performances. The overall first and the second law efficiencies of the plant are calculated to be 5.6%, and 26.9%, respectively, based on the exergy of the geothermal fluid at reservoir, and 5.9%, and 29.2%, respectively, based on the exergy of the geothermal fluid at wellhead. Thermodynamic analysis of alternative designs (single and double flash systems) indicates that the existing binary design is best suited for this site, and thus it should be preferred at similar sites.
A Thermodynamic Analysis of Fever in Chemotraphs
Authors: Annamalai K. , Morris T. , McNichols D.
Published: March 2022

Temperature regulation of chemotraphs (animals and humans) is one of the most sophisticated processes in nature. The basal condition is characterized as the absolute minimum energy state during consciousness. The conditions necessary are: no food for twelve hours, restful sleep, complete rest when awake, no excitement, and an ambient temperature of 20–27°C. The body’s metabolism of chemotraphs is constantly producing excess heat, even at rest that must be removed in order to maintain thermal equilibrium. Under normal conditions the heat produced by the bio-chemical reactions within the body must be the same as the heat loss. A first law analysis is conducted in determining the net rate of heat-loss while the body is at rest. The results are then compared with data obtained by physiologists for humans and checks to within 5%. The analysis is extended to predicting the occurrence of fever. Dimensional results are then presented for the body temperature vs time. Fever can occur either through increased slow oxidation/combustion (metabolic oxidation) of a mix of carbohydrates and fats, or by reduced heat-loss from the skin due to reduced blood flow (which causes shivers). If all the energy released during oxidation/combustion results in direct heat production then it is possible to predict I) temperature vs time, and ii) the initial metabolic rate from nasal exhaust measurements during initial periods of fever. Good agreement has been obtained between model results and experimental data on cats during heat-up periods.
The Influence of Fouling on the Heat Transfer Characteristics of Boiler Tubes: A Comparison Between a Numerical Simulation and an Industrial Test Case
Authors: Delle Site Corrado , Sciubba Enrico , Trissati Marco
Published: March 2022

The paper presents a numerical simulation of the effects of fouling on a representative section of the vertical boiler tubes in a pulverised coal boiler for a thermoelectric power plant. The fouling, which in the real case is produced by agglomeration of sticky, low-melting ash deposits, unburned particulate and incombustibles on the gas side of the tube wall, is here simulated by a uniform coating of solid homogeneous material with average thermal properties derived by experimental data. Both heat transfer modes (convection and radiation) are simulated in the numerical calculation, that has been performed via a commercial finite-element code, FIDAP of FDI Inc.

After a two-dimensional numerical test, necessary to calibrate the simulation parameters and to determine a suitable mesh, a fully three dimensional simulation was carried out. Full account has been taken of the properties of the real fluid (the hot gas is assumed to be viscous, Newtonian and homogeneous) and of the real characteristics of its flow (fully turbulent and subject to strong radiation effects). The heat transfer in the coating and in the tube wall has been calculated without introducing heat exchange coefficients, but imposing instead a well-established heat transfer correlation for the boiling water side. Turbulent effects have been simulated using a modified k-ε model. Periodic flow in the vertical direction and forced velocity on the core side have been imposed as boundary conditions.

The results of the numerical computation are compared with those of an extensive experimental campaign conducted in 1992 on an industrial boiler for a pulverised coal, 240 MW power plant: the steam conditions at design point are 17 MPa and 540°/540°C. It is shown that the numerical results agree very well with the experimental data for the selected test section: it is therefore proposed to extend the generality of the numerical simulation to implement and complete the results of future tests on the effects of fouling.
A Study of a Refrigeration Cycle Driven by a Liquid Refrigerant Injected Compressor
Authors: Yanagisawa Tadashi , Fleming John S. , Dutta Asit K. , Fukuta Mitsuhiro
Published: March 2022

The performance of a refrigeration cycle driven by a liquid refrigerant injected compressor is investigated to examine its energy saving characteristics and performance improvement. Mathematical models of the compressor, the condenser and their combination in a complete cycle are used. The model shows an increase of the suction mass flow, an associated increase of the compression power and a small change of the overall efficiency due to the reduced temperatures of the refrigerant discharge and the compressor body. A condenser fed with refrigerant of lower superheat and greater mass flow shows an improvement in performance due to an increase in the two-phase region, though the improvement depends on the secondary fluid flow conditions. The thermal capacity and coefficient of performance of the total cycle increases with the injection ratio due to the combined effects of the compressor and the condenser.
Innovative High Temperature Lift Heat Pump Technologies for Industrial Processes
Authors: Olszewski Mitch , Zaltash Abdi
Published: March 2022

The process integration approach has been extended with a plant utility emphasis by the Department of Energy (DOE) Industrial Heat Pump (IHP) Program. In this approach, reject heat from a process is upgraded to plant utility conditions and fed into the plant distribution system. Therefore, the reject heat from any process can be used as input and the output can be used at any location within the plant. With this design philosophy, the unit can be easily integrated into existing industrial applications, and all reject heat streams become potential targets of opportunity.

The plant utility approach cannot be implemented without heat pumps with high-lift capabilities (on the order of 150°F or 83°C). Currently available heat pumps have only about half the lift capability required. Thus the current emphasis for the DOE IHP Program is the development of high-lift chemical heat pumps that can deliver heat more economically to higher heat delivery temperatures. This paper details the proof-of-principle of innovative process cooling (refrigeration) and process heating technologies that are based on advanced cycles and/or advanced working fluids. In addition, it discusses the current status of the program to develop economically competitive, environmentally acceptable heat pump technologies that are capable of providing the delivery temperature and lift required to supply industrial plant utility-grade process heating and/or cooling.
Feasibility Study on Using Cooling Capacitance From Ice Storage System to Save Energy Costs of Operating Chiller AC System
Authors: Li Shan S.
Published: March 2022

This paper discusses the economical feasibility of various ways to apply the cooling capacitance from an ice storage system to a chiller air-conditioning system. A parameter of equivalent energy efficiency is defined for the ice-assisted chiller system, and a validity criterion is proposed to judge the feasibility.

Several possible ways of applying the ice storage cooling source are described. By using the proposed methodology, a case study via computer simulation is conducted. In this simulation, the validity criterion is so chosen that the improvement to the chiller system would be economically equivalent to increase a chiller efficiency from 0.55 kW/ton to 0.47 kW/ton.

A discussion of the simulation results is given. Under the assumed working conditions, to apply the cooling resources to the condensation process or to the liquid line sub-cooling is difficult to be economically feasible. The only better way to use the cooling resource is to cool the chilled water directly. However, in the best case, this system configuration would become one of the working modes of an ice storage system.
Two-Temperature Integral Analysis of a Compressor-Driven Metal Hydride Heat Pump
Authors: Lloyd George M. , Razani A. , Kim K. J. , Feldman K. T.
Published: March 2022

An integral method is used to analyze the performance of a complete system model of a compressor-driven metal hydride heat pump. CFD studies incorporating the transient non-isothermal fully compressible nature of such systems have confirmed that high specific powers and COPs comparable to vapour compression cycles are achievable. Finite-time thermodynamic studies focusing on specific aspects of external heat exchanger design have identified the need for less computationally intensive models which include in a detailed manner all parasitic thermal losses as well the capability of capturing the thermal phase lags which occur between the reactors and the heat exchangers during steady-state operation. This paper develops a rigorous intermediate model which captures these effects. Parametric studies are presented as well as comparision with data from a prototype device.
Compression Simulation, Heat Transfer and Work in Reciprocating Type Refrigeration Compressors
Authors: Chatzidakis Sot. K. , Rouvas Alex. K. , Chatzidakis Kon. S. , Kouremenos Ath. D.
Published: March 2022

An experimental study has been undertaken to evaluate some theoretical studies on the compression and heat transfer process in reciprocating compressors. A two cylinder unit was equipped with suitable pressure sensors to measure and store the pressure-time function of the refrigerant. From the known geometry of crank-piston mechanism and the related thermodynamic relations the heat transferred between refrigerant and cylinder wall can be obtained. The position of the Top Dead Center can be defined either in a thermodynamic way or by a magnetic pick-up. The influence of the rotating speed is examined by taking measurements at different speeds. The results are compared to existing heat transfer relations to investigate their efficiency. The model used predicts with sufficient accuracy the heat transfer process.
Numerical Simulation of a Split-Blade Impeller Configuration of a Centrifugal Pump With Zero-Curvature Blades
Authors: Delle Site Corrado , Sciubba Enrico
Published: March 2022

This paper reports the results of a numerical study on the performance of several zero-curvature blade impeller configurations for centrifugal pumps. A “standard” zero-curvature blade impeller has been modified by introducing in the centre of the blade passage split-blades of different lengths and locations. The “standard” impeller configuration is a seven-blade impeller with inlet and exit flow angles of 22° and 66° respectively, rotating at 400 r.p.m..

The flow field in the impeller passage has been numerically investigated using a standard version of a finite element code (FEDAP of FDI Inc.); turbulence has been modelled with a two-equation, k-ε model which requires Van Driest’s wall functions to represent the law-of-the-wall profiles.

The flow is computed on a 2-D, blade-to-blade (S1) mean stream surface in the rotating reference frame. The numerical simulation has been carried out at nominal flow rate and at two off-design flow rates in order to obtain a portion of the pump characteristic.

A slight increase in e dynamic head is caused by the split-blade; a higher increase in pump head is obtainable by doubling the number of blades with respect to the standard configuration.

The velocity distributions at four radial sections of the impeller passage, the streamline contours and the hydraulic efficiency distribution for the different impeller configurations are compared and discussed.
Admittance Fluctuations and the Observed Acoustic Scattering From a Cylindrical Shell With Many Internal Oscillators
Authors: Bucaro Joseph A. , Romano Anthony J. , Sarkissian Angie , Photiadis Douglas M. , Houston Brian H.
Published: March 2022

This paper considers how the details of internally mounted mechanical oscillators are related to the acoustic scattering features observed in the measurements of Bucaro et al. (1997) and Photiadis et al. (1997). These measurements — the monostatic scattering as a function of frequency and angle from a submerged shell with many internal oscillators — have been interpreted (Bucaro et al., 1997) in the context of local admittance fluctuations caused by the presence of the oscillators. The theoretical basis for this effect is reviewed and specific details in the scattering spectrum are connected with certain shell/ oscillator parameters.
Reconstruction of Acoustic Pressure Fields Inside a Vibrating Cavity
Authors: Wu Sean F. , Yu Jingyou
Published: March 2022

This paper extends the Helmholtz equation least squares (HELS) method previously developed by Wang et aL [1995] and Wang and Wu [1997] to reconstruction of acoustic pressure fields in an interior region. In this methodology, the acoustic pressures are reconstructed through an expansion of acoustic modes, or a set of independent functions generated via an orthonormalization with respect to the particular solutions to the Helmholtz equation on the particular surface under consideration. The coefficients associated with these acoustic modes are determined by requiring the assumed form solution to satisfy the pressure boundary condition at the measurement points. The errors incurred in this process are minimized by the least squares method. Numerical examples of partially vibrating cylinders with two spherical endcaps at various half-length to radius aspect ratios and frequencies are demonstrated. The reconstructed acoustic pressures are compared with numerical solutions obtained by using a direct boundary element method.
Series Expansion for a Propagating Pulse
Authors: Cohen Leon
Published: March 2022

A new approach is presented for calculating the approximate intensity of a propagating pulse in a dispersive media. The method is based on first obtaining exact time dependent low order spatial moments and then constructing the density from these moments. The time dependent moments can be obtained explicitly from the initial spatial spectrum and the dispersion relation. The method of constructing approximate densities is based on a generalization of the traditional Edgeworth/Gram-Charlier methods.
Parameter Studies in the Optimal Design of Unconstrained Beam Damping Layer Treatments
Authors: Lumsdaine Arnold , Scott Richard A.
Published: March 2022

The aim of this paper is to examine the optimal shape of an unconstrained viscoelastic damping material on an elastic beam, and to examine how changing the volume of damping material affects the optimal shape. The optimization objective is to minimize the peak displacement of the beam at the first resonant frequency. The material loss factor is monitored to determine the improvement in performance between an initial, uniform layer shape and the optimized shape. A fine mesh validation model is created to verify the optimized shape. The ABAQUS finite element code is used to model the structures. Elasticity theory based continuum elements are used so that all stress effects are taken into account in the models. The optimization code uses a Sequential Quadratic Programming algorithm. Optimization studies are performed for a range of different damping layer volumes, from layers with 10% to 200% of the volume of the base layer. Results show that significant improvements in performance are obtained in all cases by optimizing the damping layer shape, up to 6000% in some cases. The amount of improvement achieved increases as the damping layer volume increases up to a point. At a certain point, however, (depending on the thickness of the base layer), the amount of improvement between a uniform damping layer and the optimal damping layer may actually decrease significantly.
Analytical and Experimental Characterization of Damping and Stiffness in Polymer Composites Having Coated Fibers as Reinforcement
Authors: Finegan Ioana C. , Gibson Ronald F.
Published: March 2022

Polymer composites have generated increased interest in the development of damped structural materials because of their low density, and excellent stiffness and damping characteristics. The objectives of this paper are to study the improvement and optimization of damping in fiber reinforced structural composite materials at the micromechanical level by coating some of the fibers with special polymers which have high damping. Since shear deformation is essential for viscoelastic damping in polymers, and large shear strains are generated near the fiber/matrix interface in composites, the use of special viscoelastic polymer fiber coatings is an effective way to improve damping in such composites. Of particular interest are hybrid composites having a mixture of coated and uncoated fibers, since coating all the fibers would cause unacceptable reductions in other important properties like strength and stiffness.
Fatigue Behavior of Resin Infusion Processed S2-Glass Woven Composites
Authors: Kelkar Ajit D. , Sankar J. , Chaphalkar Pramod , Grace C. , Yarmolenko S. N. , Mall Shankar , Vaidya U. K.
Published: March 2022

Woven composites have good properties in mutually orthogonal directions, more balanced properties than unidirectional laminates and have better impact resistance. The use of these composites for primary structural applications in place of conventional laminated composites has been increased considerably in the recent years. They are being manufactured by using new processes such as Resin Infusion (RI) and Resin Transfer Molding (RTM). These new processes are low cost, affordable and suitable for high volume manufacturing environment. One of the popular woven composites is fabricated using S2-Glass and C-50 resin system components by using Resin Infusion (RI) and Resin Transfer Molding (RTM) process. These woven composites are being evaluated for Integral Armor applications. These components are expected to be under fatigue loading. To assess the feasibility of this material manufactured through Resin Infusion (RI) and Resin Transfer Molding (RTM), it is very important to understand the fatigue behavior of these composite materials. In the first phase of the study the panels of this material were fabricated using Resin Infusion (RI) processing. Number of tests were performed to evaluate the basic properties such as modulus, ultimate tensile strength, and Poisson’s ratio of this woven composite. Tension-tension fatigue experiments with R ratio of 0.1 were conducted to generate two important curves to characterize the fatigue behavior of this material system: S-N diagram and stiffness degradation over the entire fatigue life of the specimens. All the fatigue tests were performed at 1 Hz frequency. To study the progressive damage of the textile composites under fatigue loading, one set of specimens was subjected to different number of fatigue cycles starting from 1 cycle to 300,000 cycles and was investigated for failure mechanism using optical microscopy and SEM.
Towards an Improved General Vibration-Based Method for Elastic Identification of Materials
Authors: Ayorinde Emmanuel O. , Yu Lin
Published: March 2022

Refinements and generalizations are made to a method developed by the first author and associates to obtain the elastic constants of composite materials using data from vibration tests on freely-supported plates. Elastic constants identified from different sets of vibration model data varied in accuracy. In this work, sensitivity analysis is automatically integrated into the procedure. The flexibility of using diagonally symmetric modes (in the case of isotropic, square panels), omitted from previous models, is also provided. Accurate identification of Poisson ratio values has been one of the main challenges in this area of research. Attempt is made to refine the search procedure for these values. Different example cases are considered.
Mean Flow Effects on Sound Generation and Propagation
Authors: Atassi H. M.
Published: March 2022

The effects of nonuniform flows on sound generation and propagation are examined. When the mean flow gradients, the Mach number and frequency are not too small, it is not, in general, possible to separate the processes of sound generation and propagation. The aeroacoustics of unsteady nonuniform flows is therefore closely connected to the field of unsteady aerodynamics. Sound generation and propagation for potential and vortical mean flows are analyzed using theories based on the rapid distortion approximation wherein Euler’s equations are linearized about a nonlinear mean flow. For mean potential flows, two sets of results are presented. For a single lifting airfoil, it is shown that the so-called quadrupole effects become very significant. For a cascade of loaded blades, the results show strong interference between the acoustic and unsteady aerodynamic loading. Finally, for vortical flows, the coupling between the mean flow vorticity and the unsteady part of the flow strongly affects the nature, intensity and propagation of the sound waves.
Dynamic Measurement of CNC Part Paths
Authors: Schmitz Tony L. , Ziegert John C.
Published: March 2022

The current procedure followed to manufacture a new part by CNC machining is to write the part program, machine a test part and measure the test part for conformance to the required dimensions and tolerances. If the test part dimensions out of tolerance, the part program is modified and the process repeated until a successful part is machined. In many applications, such as the aerospace industry, where material cost and machining time are high, this iterative process becomes economically unacceptable.

Research has been conducted to test the feasibility of using the Laser Ball Bar (LBB), a spatial coordinate measuring device, to measure dynamic continuous-path contours of CNC part programs to micrometer accuracy prior to machining. In this way, a virtual test part can be measured and compared to the design drawings to validate the CNC part program. This reduces or eliminates the costly and time-consuming steps involved in the machining of physical test parts.
Monitoring Technology for Achieving Intelligent Grinding System
Authors: Inasaki Ichiro
Published: March 2022

The paper deals with the monitoring technologies for making the grinding process more intelligent and reliable by applying the sensor fusion and artificial intelligence technologies. Increase of the practical application of CBN wheels requires a development of reliable monitoring system to utilize expensive abrasives more efficiently. Combination of an acoustic emission sensor and a power sensor makes the judgment of the wheel life possible with high reliability. One of the characteristic features of the proposed monitoring system is that the acoustic emission sensor is integrated in the CBN wheel, which makes it possible to detect a reliable signal. Monitoring of the dressing process is made possible by applying the same system. Concept of the intelligent data base system based on the genetic algorithms and fuzzy production rules is proposed.
A New Electromagnetic Contact Sensing Technique for Enhancing Machining Accuracy
Authors: Ostafiev V. A. , Venuvinod Patri K.
Published: March 2022

This paper describes a new electromagnetic contact sensing technique called the “Fine Touch” method which enables the cutting tool itself to be used as a probe during on-machine measurement of parts. The simple sensor design of the probe (the cutting tool) has resulted in a low cost system for workpiece set-up and inspection. Tests have shown that the sensor precision is of the order of 0.01 μm and, hence, could be used on coordinate measuring machines (CMM) as well. The sensor is effective irrespective of variations in cutting tool geometry, cutting insert coatings, insert geometry and size, cutting fluids, and workpiece material.