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University of Nebraska - Lincoln

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Articles 31 - 49 of 49

Full-Text Articles in Heat Transfer, Combustion

Effects Of Forced Convection And Surface Tension During Methanol Droplet Convection,”, V. Raghavan, D. N. Pope, G. Gogos Feb 2006

Effects Of Forced Convection And Surface Tension During Methanol Droplet Convection,”, V. Raghavan, D. N. Pope, G. Gogos

Combustion Research at University of Nebraska-Lincoln

Effects of Forced Convection and Surface Tension during Methanol Droplet Convection,”


Numerical Simulation Of Fuel Droplet Extinction Due To Forced Convection,", D. N. Pope, G. Gogos Feb 2006

Numerical Simulation Of Fuel Droplet Extinction Due To Forced Convection,", D. N. Pope, G. Gogos

Combustion Research at University of Nebraska-Lincoln

Numerical Simulation of Fuel Droplet Extinction Due to Forced Convection,"


A New Multicomponent Diffusion Formulation For The Finite-Volume Method: Application To Convective Droplet Combustion, D. N. Pope, G. Gogos Feb 2006

A New Multicomponent Diffusion Formulation For The Finite-Volume Method: Application To Convective Droplet Combustion, D. N. Pope, G. Gogos

Combustion Research at University of Nebraska-Lincoln

A New Multicomponent Diffusion Formulation for the Finite-Volume Method: Application to Convective Droplet Combustion


Combustion Of Moving Droplets And Suspended Droplets: Transient Numerical Results, D. N. Pope, D. Howard, K. Lu, G. Gogos Feb 2006

Combustion Of Moving Droplets And Suspended Droplets: Transient Numerical Results, D. N. Pope, D. Howard, K. Lu, G. Gogos

Combustion Research at University of Nebraska-Lincoln

Combustion of Moving Droplets and Suspended Droplets: Transient Numerical Results


Surface Tension Effects During Low Reynolds Number Methanol Droplet Combustion, V. Raghavan, D. N. Pope, D. Howard, G. Gogos Feb 2006

Surface Tension Effects During Low Reynolds Number Methanol Droplet Combustion, V. Raghavan, D. N. Pope, D. Howard, G. Gogos

Combustion Research at University of Nebraska-Lincoln

Surface Tension Effects during Low Reynolds Number Methanol Droplet Combustion


Stability Of Transport And Rate Processes [Review], Yaşar Demirel Jun 2005

Stability Of Transport And Rate Processes [Review], Yaşar Demirel

Papers in Thermal Mechanics

About fifty years ago, the Turing instability demonstrated that even simple reaction-diffusion systems might lead to spatial order and differentiation, while the Rayleigh-Bénard instability showed that the maintenance of nonequilibrium might be the source of order in fluids subjected to a thermodynamic force above a critical value. Therefore, distance from global equilibrium in the form of magnitude of a thermodynamic force emerges as another constraint of stability; some systems may enhance perturbations, and evolve to highly organized states called the dissipative structures after a critical distance on the thermodynamic branch. Although the kinetics and transport coefficients represent short-range interactions, chemical …


Thermodynamic Analysis Of Separation Systems, Yaşar Demirel Dec 2004

Thermodynamic Analysis Of Separation Systems, Yaşar Demirel

Papers in Thermal Mechanics

Separation systems mainly involve interfacial mass and heat transfer as well as mixing. Distillation is a major separation system by means of heat supplied from a higher temperature level at the reboiler and rejected in the condenser at a lower temperature level. Therefore, it resembles a heat engine producing a separation work with a rather low efficiency. Lost work (energy) in separation systems is due to irreversible processes of heat, mass transfer, and mixing, and is directly related to entropy production according to the Gouy-Stodola principle. In many separation systems of absorption, desorption, extraction, and membrane separation, the major irreversibility …


Exergy Use In Bioenergetics, Yaşar Demirel Nov 2004

Exergy Use In Bioenergetics, Yaşar Demirel

Papers in Analytical Chemistry

Every developed and adapted biological system extracts useful energy from outside, converts, stores it, and uses for muscular contraction, substrate transport, protein synthesis, and other energy utilizing processes. This energy management in a living cell is called the bioenergetics, and the useful energy is the exergy, which is destroyed in every irreversible process because of the entropy production. The converted exergy is the adenosine triphosphate (ATP) produced through the oxidative phosphorylation coupled to respiration in which the exergy originates from oxidation of reducing equivalents of nutrients. A living cell uses the ATP for all the energy demanding activities; it has …


Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler Mar 2002

Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Bioenergetics is concerned with the energy conservation and conversion processes in a living cell, particularly in the inner membrane of the mitochondrion. This review summarizes the role of thermodynamics in understanding the coupling between the chemical reactions and the transport of substances in bioenergetics. Thermodynamics has the advantages of identifying possible pathways, providing a measure of the efficiency of energy conversion, and of the coupling between various processes without requiring a detailed knowledge of the underlying mechanisms. In the last five decades, various new approaches in thermodynamics, non-equilibrium thermodynamics and network thermodynamics have been developed to understand the transport and …


Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler Mar 2002

Thermodynamics And Bioenergetics, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Bioenergetics is concerned with the energy conservation and conversion processes in a living cell, particularly in the inner membrane of the mitochondrion. This review summarizes the role of thermodynamics in understanding the coupling between the chemical reactions and the transport of substances in bioenergetics. Thermodynamics has the advantages of identifying possible pathways, providing a measure of the efficiency of energy conversion, and of the coupling between various processes without requiring a detailed knowledge of the underlying mechanisms. In the last five decades, various new approaches in thermodynamics, non-equilibrium thermodynamics and network thermodynamics have been developed to understand the transport and …


Effects Of Concentration And Temperature On The Coupled Heat And Mass Transport In Liquid Mixtures, Yaşar Demirel, Stanley I. Sandler Mar 2001

Effects Of Concentration And Temperature On The Coupled Heat And Mass Transport In Liquid Mixtures, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Using published experimental data on the thermal conductivity, mutual diffusivity, and heats of transport, the degree of coupling between heat and mass flows has been calculated for binary and ternary nonideal liquid mixtures. The binary mixtures consist of two types: the first is six systems of six-to-eight-carbon straight and branched chain alkanes in chloroform and in carbon tetrachloride; and the second is mixtures of carbon tetrachloride with benzene, toluene, 2-propanone, n-hexane, and 11-octane. The ternary mixture considered is toluene-chlorobenzene-bromobenzene. The published data are available at 35°C, 30°C, and 35°C and ambient pressure. Using the linear nonequilibi-ium thermodynainics (LNET) and the …


Linear-Nonequilibrium Thermodynamics Theory For Coupled Heat And Mass Transport, Yaşar Demirel, Stanley I. Sandler Jan 2001

Linear-Nonequilibrium Thermodynamics Theory For Coupled Heat And Mass Transport, Yaşar Demirel, Stanley I. Sandler

Yaşar Demirel Publications

Linear-nonequilibrium thermodynamics (LNET) has been used to express the entropy generation and dissipation functions representing the true forces and flows for heat and mass transport in a multicomponent fluid. These forces and flows are introduced into the phenomenological equations to formulate the coupling phenomenon between heat and mass flows. The degree of the coupling is also discussed. In the literature such coupling has been formulated incompletely and sometimes in a confusing manner. The reason for this is the lack of a proper combination of LNET theory with the phenomenological theory. The LNET theory involves identifying the conjugated flows and forces …


Entropy Generation In A Rectangular Packed Duct With Wall Heat Flux, Yaşar Demirel, Ramazan Kahraman Sep 1998

Entropy Generation In A Rectangular Packed Duct With Wall Heat Flux, Yaşar Demirel, Ramazan Kahraman

Papers in Thermal Mechanics

The entropy generation due to heat transfer and friction has been calculated for fully developed, forced convection flow in a large rectangular duct, packed with spherical particles, with constant heat fluxes applied to both the top (heated) and bottom (cooled) wall. An approximate analytical expression for the velocity profile developed for packed bed with H/dp > 5 has been used together with the energy equation of fully developed flow to calculate the non isothermal temperature profiles along the flow passage. The velocity profile takes into account the increase in the velocity near the wall due to the higher voidage in this …


Heat Transfer In Rarefied Gas At A Gas-Solid Interface, Yaşar Demirel, Satish C. Saxena Feb 1996

Heat Transfer In Rarefied Gas At A Gas-Solid Interface, Yaşar Demirel, Satish C. Saxena

Papers in Physical Chemistry

Modified expressions for the heat-transfer fluxes at the interface of a solid surface and a gas are given for different Knudsen-number regimes. These expressions for diatomic gases contain both a gas-reflection and a thermal accommodation coefficient. Parallel-plate, coaxial-cylindrical and concentric spherical surfaces are considered. A general expression for the thermal accommodation coefficient is based on experimental data. Sample numerical calculations of heat flux in different heat-transfer regimes are presented in terms of the reciprocal Knudsen number.


Excess Heat Capacity Surfaces For Water-Alkanol Mixtures By The Uniquac Model, Yaşar Demirel, Halime Ö. Paksoy Mar 1995

Excess Heat Capacity Surfaces For Water-Alkanol Mixtures By The Uniquac Model, Yaşar Demirel, Halime Ö. Paksoy

Papers in Physical Chemistry

Hydroorganic mixtures are industrial solvents that can serve as media to solubilize either water in hydrocarbon or a hydrophobic substance in water. In many cases the solubilizing capability is obtained via a homogeneous complex aqueous mixtures containing an alcohol. Since excess heat capacity CPE, is very sensitive to structural changes in mixtures, concentration and temperature dependence of CPE have been calculated by using the UNIQUAC model for the mixtures methanol(l)-water(%, ethanol(l)-water(2), and l-propanol(l)-water(2). The temperature-dependent parameters of the model estimated directly from CPE data at more than one different isotherm are used in …


Portable Electric Home Milk Pasteurizers, A. E. Baragar, P. A. Downs Oct 1948

Portable Electric Home Milk Pasteurizers, A. E. Baragar, P. A. Downs

Nebraska Agricultural Experiment Station: Historical Research Bulletins

Two batch-type and one in-the-bottle type home milk pasteurizers were investigated to determine whether they comply with U.S. Public Health code temperature and time requirements for pasteurizers.


Further Studies Of Selected Types Of Domestic Gas Stoves, Arnold E. Baragar Apr 1939

Further Studies Of Selected Types Of Domestic Gas Stoves, Arnold E. Baragar

Nebraska Agricultural Experiment Station: Historical Research Bulletins

This bulletin is a supplement to Nebraska Agricultural Experiment Station Research Bulletin 86. Tests were conducted in the same manner as were those described in Bulletin 86; hence, no reference has been made to experimental methods unless a test has not been previously reported. This paper is primarily concerned with (1) a discussion of cooking tops producing excessive carbon-monoxide gas, (2) more data relative to cooking-top burner efficiencies, (3) a further discussion of automatic lighters, and (4) a detailed study of ovens.


Factors Affecting The Performance Of Kerosene Cook Stoves, Edna B. Snyder Nov 1932

Factors Affecting The Performance Of Kerosene Cook Stoves, Edna B. Snyder

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The purpose of this investigation was to learn the effect of constructional details of the burner and the framework on the performance of kerosene stoves. Six stoves were used, four of the long-chimney type and two of the short-chimney type. Of the long-chimney burners, three were from the same manufacturer; the fourth was similar in appearance, but differed in performance. Of the short chimneys one burner used a wick, the other a lighting ring. The effect of: (1) draft variations and constructional details and (2) the framework on the heating time and thermal efficiency of stoves was studied.


A Study Of Kerosene Cook Stoves, Edna B. Snyder Jul 1930

A Study Of Kerosene Cook Stoves, Edna B. Snyder

Nebraska Agricultural Experiment Station: Historical Research Bulletins

The purpose of this study was to learn the advantages and disadvantages of various types of kerosene cook stoves used in Nebraska. Kerosene cook stoves have burners of four types. Ten stoves representing the four types were studied as follows: four stoves having long-chimney wick burners; three stoves having short-chimney wick burners; two stoves having short chimneys with asbestos kindlers or lighting rings; one stove having wickless burners. To determine comparative performance of the four types of burners, they were tested for: (1) time required to heat a known quantity of water through a known range of temperature; (2) thermal …