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TECHNICAL PAPERS

J. Energy Resour. Technol. 2000;123(2):110-118. doi:10.1115/1.1368122.

The prevailing beliefs in the scientific and engineering literature are that: (i) thermodynamics is explained and justified by statistical mechanics; (ii) entropy is a statistical measure of disorder; and (iii) for given values of energy, volume, and amounts of constituents, the largest value of entropy corresponds to both a thermodynamic equilibrium state and the ultimate disorder. In this paper, we provide: (i) a summary of the beliefs as stated by some eminent scientists; (ii) experimental evidence that casts serious doubt about the validity of the beliefs; (iii) an outline of a nonstatistical unified quantum theory of mechanics and thermodynamics; (iv) an outline of a nonquantal, nonstatistical exposition of thermodynamics, valid for all systems (both macroscopic and microscopic), and for all states (both thermodynamic equilibrium and not thermodynamic equilibrium); (v) the definition and analytical expression of the entropy of thermodynamics; (vi) the interpretation of entropy as both a measure of the quantum-theoretic spatial shape of a molecule, and an indicator of order; and (vii) nonstatistical answers to the questions that motivated the introduction of statistical mechanics.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):119-126. doi:10.1115/1.1369112.

The fluids in horizontal wells can exhibit complicated flow behaviors, in part due to interaction between the main flow and the influxes along the wellbore, and due to completion geometries. An existing small-scale test facility at Tulsa University Fluid Flow Projects (TUFFP) was used to simulate the flow in a horizontal well completed with either circular perforations or slotted liners. Single phase liquid flow experiments were conducted with Reynolds numbers ranging approximately from 5000 to 65,000 and influx to main flow rate ratios ranging from 1/50 to 1/1000. For both the perforation and slot cases, three different completion densities and three different completion phasings are considered. Based on the experimental data, new friction factor correlations for horizontal well with multiple perforation completion or multiple slots completion were developed using the principles of conservation of mass and momentum.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):127-132. doi:10.1115/1.1367272.

A theory for the stabilization of annular liquid-liquid flow (i.e., core-annular flow) in a horizontal pipe is proposed. Based upon the analysis of the momentum conservation equation in the cross section of the flow, including the effects of peripheral flow in the annulus and interfacial tension, an equation is obtained which describes the interface shape. Results for the height-to-width aspect ratio of the core are compared with laboratory measurements done by the author for a heavy oil-water core-annular flow. A criterion for stabilization of this interesting flow pattern is proposed.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):133-137. doi:10.1115/1.1365157.

This paper presents a novel approach to measure and estimate running force for various laboratory and field conditions. The experimental and simulation procedures of different rod/pipe sizes running through various laboratory/field conditions are described in detail. Tests were conducted on rods to measure the running force for various laboratory cases obtained from dimensional analysis. The generated experimental results were used to calibrate a typical laboratory finite element model from which calibrated parameters are used to estimate the running force for prescribed field cases. Both the experimental and simulated field results revealed that the running force depends on the radius of curvature, hole clearance, horizontal section, and contact scenario significantly. Stress analysis of pipes running through curved and horizontal sections showed that pipes undergo elastic and plastic deformation, and the nature of deformation depends on the pipe size and radius of curvature.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):138-143. doi:10.1115/1.1367857.

Previous research in stability of drillstrings was based on the assumption of constant material specific force, i.e., a bit force that is proportional to the area of cut. Moreover, earlier work used a simplified bit model that consisted of planar radial blades. In this paper, correlation between the material specific force and area of cut is obtained for Sierra White granite and Berea sandstone from test data developed at Sandia National Laboratories in Albuquerque, NM. These correlations, together with an improved bit model in which cylindrical cutters are arrayed in an overlapping pattern over a flat surface, are used to obtain the stability equations. Laboratory testing shows good correlation between measured bit vibrations and relative instability as predicted by the stability equations. These results are useful in predicting the appropriate operating conditions for stable drilling and serve as a basis for future development of more accurate models of PDC bits.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):144-149. doi:10.1115/1.1368121.

Mass transfer studies in oil-containing multiphase flow provide fundamental knowledge towards the understanding of hydrodynamics and the subsequent effect on corrosion in pipelines. Mass transfer coefficient measurements in two-phase (oil/ferri-ferrocyanide) and three-phase (oil/ferri-ferrocyanide/nitrogen) flow using limiting current density technique were made in 10-cm-dia pipe at 25 and 75 percent oil percentage. Mass transfer coefficients in full pipe oil/water flow and slug flow were studied. A relationship is developed between the average mass transfer coefficient in full pipe flow and slug flow. The mass transfer coefficient decreased with a decrease of in-situ water cut. This was due to the existence of oil phase, which decreased the ionic mass transfer diffusion coefficient.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2001;123(2):150-157. doi:10.1115/1.1369359.

A Joint Industry Project to investigate paraffin deposition in multiphase flowlines and wellbores was initiated at The University of Tulsa in May 1995. As part of this JIP, a computer program, based on the molecular diffusion theory, was developed for prediction of wax deposition during multiphase flow in pipelines and wellbores. The program is modular in structure and assumes a steady-state, one-dimensional flow, energy conservation principle. This paper will describe the simulator developed for predicting paraffin deposition during multiphase flow that includes coupling of multiphase fluid flow, solid-liquid-vapor thermodynamics, multiphase heat transfer, and flow pattern-dependent paraffin deposition. Predictions of the simulator are compared and tuned to the experimental data by adjusting the film heat transfer and diffusion coefficients and the thermal conductivity of the wax deposit.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):158-166. doi:10.1115/1.1368120.

Venturi-cascading is a technique to control pollutant emissions from diffusion flames by modifying air infusion and fuel-air mixing rates through changing the flow dynamics in the combustion zone with a set of venturis surrounding the flame. A propane jet diffusion flame at a burner-exit Reynolds number of 5100 was examined with a set of venturis of specific sizes and spacing arrangement. The venturi-cascading technique resulted in a decrease of 33 percent in NO emission index along with a 24-percent decrease in soot emission from the flame, compared to the baseline condition (same flame without venturis). In order to understand the mechanism behind these results, laser-induced fluorescence (LIF) spectroscopy was employed to study the concentration field of the radicals (OH, CH, and CN) in the baseline and venturi-cascaded flames. The LIF measurements, in the near-burner region of the venturi-cascaded flame, indicated an average decrease of 18, 24 and 12 percent in the concentrations of OH, CH, and CN radicals, respectively, from their baseline values. However, in the midflame region, a 40-percent average increase in OH from its baseline value was observed. In this region, CH or CN radicals were not detected. The OH radical concentration in the downstream locations was mostly affected by soot rather than by temperature.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):167-172. doi:10.1115/1.1367858.

An investigation of the effects of burner exit Reynolds number on the relative effects of burner geometry (circular and elliptic with an aspect ratio 2:4) in a propane jet flame is presented. Circular and elliptic burners of the equivalent area of a circular burner of diameter 5.2 mm were studied. Air entrainment into the nonreacting jets, emission indices of NO, NO2, and CO, visible flame length, flame temperature profiles, radiative fraction of heat release, and soot concentration were measured. Results show that an increase in Re decreases the benefits of higher air entrainment into the flame due to elliptic burner geometry. Similarly, the effects of changes in NO and CO emission indices level off at higher burner Re. The measurements of visible flame length, radiative fraction of heat release, temperature profiles, and soot concentrations corroborate the observed emission index results.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2000;123(2):173-178. doi:10.1115/1.1367856.

The reaction between water and partially sulfated lime particles was studied under isothermal conditions using a microcalorimeter. Experiments were performed with spent sorbent particles from two industrial circulating fluidized bed combustors and with lime particles sulfated in the laboratory using a thermogravimetric analyzer. The rate of hydration of the partially sulfated lime particles was found to be independent of particle size, to increase with increasing temperature, and to decrease with increasing level of sulfation of the particles. A first-order kinetic model is shown to correlate well the effect of time and temperature on the extent of hydration of spent sorbent particles from fluidized bed combustors. The apparent activation energy of the hydration reaction is 45 kJ/mol.

Commentary by Dr. Valentin Fuster

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