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RESEARCH PAPERS

J. Energy Resour. Technol. 1990;112(2):79-83. doi:10.1115/1.2905726.

When a fluid is circulated in a wellbore, the temperature profile is determined by the transfer of heat from surrounding formations to the fluid. An analytical solution of the differential equations describing the transfer of heat has been developed. The solution assumes steady flow of heat in the wellbore and is coupled to the transient conduction of heat in the formation. The solution is validated by comparison to temperature measurements from the literature. A parametric study of the sensitivity to operating conditions is included.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):84-89. doi:10.1115/1.2905727.

Axial vibrations of drillstrings produce pressure variations within the drilling fluid column. These pressure variations are imposed on controlled pressure pulse signals from Measurement-While-Drilling (MWD) tools producing background noise in pressure pulse data measured at the rig. The paper shows the effect on signal-to-noise ratio for various operating conditions, such as vibration frequency, valve opening/closing time, pulsing interval, and flow rate.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):90-95. doi:10.1115/1.2905728.

It has been observed that, under certain conditions, the oil retained by planar boom will escape under it. In this work it is proposed that this escape is due to the instability of the interface brought about by the pressure gradient along the face of the boom. This instability is studied analytically and experimentally and some guidelines to prevent the escape of oil are presented.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):96-102. doi:10.1115/1.2905729.

The generation of three-dimensional (3-D) images and map building are essential components in the development of an autonomous underwater system. Although the direct generation of 3-D images is more efficient than the recovery of 3-D data from 2-D information, at present for underwater applications where sonar is the main form of remote sensing, the generation of 3-D images can only be achieved by either complex sonar systems or with systems which have a rather low resolution. In this paper an overview is presented on the type of sonar systems that are available for underwater remote sensing, and then a technique is presented which demonstrates how through simple geometric reasoning procedures, 3-D information can be recovered from side scan-type (2-D) data. Also presented is the procedure to perform map building on the estimated 3-D data.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):103-113. doi:10.1115/1.2905716.

A two-degree-of-freedom model of a rotating machine with nonlinear springs of quadratic type is studied. The multiple scales method is used to investigate the nonlinear oscillations of the forced system where the forcing is due to the eccentricity e of the rotor about its center of mass. The behavior of the system for the primary resonances Ω = ω 1 , Ω = ω 2 , and internal resonance ω 2 = 2ω 1 is analyzed. Other features, such as amplitude jump and saturation phenomenon, have been observed. The amplitudes versus detuning parameters for both cases are plotted. The critical values of mass ratios and spring ratios for the presence of an internal resonance are studied and interpreted for this particular application.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):114-123. doi:10.1115/1.2905717.

This paper presents the results of mathematical modeling of the performance of solid electrolyte fuel cells. The system of fundamental physical equations has been solved using a computer program which was developed expressly for this purpose, in order to simulate the performance of arrays of fuel cells for which experimental data exists in the literature. The comparison of experimental data and simulated performance is excellent. The results of the simulation show the influence of each irreversible process within the fuel cell, quantitatively; that is, the relative importance of each source of inefficiency—and the consequent voltage loss—is determined. Because certain rate constants (for diffusion and for chemical kinetics) employed in the model were obtained by regression, it cannot be claimed that the ability to fit the experimental data is a definitive test of the model; more work is needed for that purpose. Nevertheless, it is shown that (a) modeling of fuel cells on the basis of basic physical principles is a worthwhile venture, (b) the model presented here simulates performance well and warrants further development, and (c) it not only simulates the overall performance of the cells, but also provides the important breakdown of the effects of each irreversibility in the cells. Furthermore, specific recommendations are made in this paper for improving the model.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):124-129. doi:10.1115/1.2905718.

An exergy balance for an industrial glass furnace was constructed on the basis of measured thermodynamic variables. The experimental data were collected for different operating modes, especially in relation to oxygen enrichment. Losses were classified as belonging to one of three categories: 1) chemical reaction, 2) dissipation of heat (by radiation or sensible heat) to the environment, 3) heat transfer. Using this method, optimum conditions, with reference to oxygen enrichment of the combustion air, can be determined and the processes where the bulk of input exergy is destroyed can be identified. These results allow the designer to select modifications to furnace design and/or changes in operating modes that will be effective in enhancing plant efficiency. The last step is a thermoeconomic cost evaluation of the tested plant.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):130-135. doi:10.1115/1.2905719.

A second law analysis has been developed for an evaporative atomized spray in a uniform parallel stream of hot gas. Using a discrete droplet evaporation model, an equation for entropy balance of a drop has been formulated to determine numerically the entropy generation histories of the evaporative spray. For the exergy analysis of the process, the rate of heat transfer and that of associated irreversibilities for complete evaporation of the spray have been calculated. A second law efficiency (η II ), defined as the ratio of the total exergy transferred to the sum of the total exergy transferred and exergy destroyed, is finally evaluated for various values of pertinent input parameters, namely, the initial Reynolds number (Rei = 2ρg V i x i /μ g ) and the ratio of ambient to initial drop temperature (Θ ∞ ′/Θ i ′).

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):136-141. doi:10.1115/1.2905720.

The Canadian program of coal-water fuel (CWF) technology development has included the demonstration of “commercial” burners for CWF in both coal and oil-designed utility boilers. The demonstrations clearly showed that these burners were prototypes, and were, in fact, modified oil burners that were mismatched to the rheological properties of the CWF. As the demonstrations were proceeding, a simultaneous research program was undertaken by the Canada Centre for Mineral and Energy Technology (CANMET) of Energy, Mines and Resources (EMR) Canada in which the basic principles governing atomization and combustion of CWF were studied. Key results from the fundamental studies which led to the development of a novel prototype dual fuel CWF/oil burner are described. In the various stages of development, the burner was scaled up from 1.5 MWth to an industrial scale of 16MWth for demonstration in a 20-MW(e) oil-designed industrial utility boiler and for a single-burner commercial operation in an oil designed package steam boiler. A brief summary of the burner performance in these demonstrations is also given in this paper.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):142-144. doi:10.1115/1.2905721.

Wall forces on helically buckled pipe can cause large frictional forces that may prevent movement of the pipe in steeply inclined holes. A method of analyzing the dependency of the wall contact force on axial force and hole inclination is presented. The concept of an apparent wall force is introduced to explain phenomena associated with helix pitch variations during axial force unloading in inclined wells. Results of this analysis can have applications in friction modeling of buckled pipe in inclined holes.

Topics: Force , Wells , Pipes , Modeling , Friction
Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):145-148. doi:10.1115/1.2905722.

SALMON was a nuclear explosion in the Tatum salt dome, near Hattiesburg, Mississippi, that took place on October 22, 1964. Computational attempts to simulate the experimental results had been largely unsuccessful. Recent calculations suggest that the reason is that the salt yield strength is extremely sensitive to strain hardening. The hardening effect had not been observed in laboratory-scale measurements, which were not made at small enough strain levels and may not have been representative of in-situ pore-fluid pressure.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 1990;112(2):149-154. doi:10.1115/1.2905723.

Thin-walled structural members are used extensively in the offshore industry in applications ranging from marine risers to platforms and frames. Advanced fiber composite structural members may offer advantages over their conventional steel counterparts in certain situations. Use of composite members will require modifications to existing structural analysis codes. This paper presents a beam theory for thin-walled composite beams that can be incorporated into existing codes. Timoshenko beam theory is utilized to account for shear deformation effects, which cannot be neglected in composite beams, and for the variability in material properties in different walls of the beam cross section. The theory is applied to the analysis of the free vibration problem and shows the dependence of the natural frequencies and mode shapes on the in-plane properties of the laminates that form the walls of the beam. Forced periodic and forced arbitrary problems are also discussed and the deflected shapes and maximum deflections are shown as functions of wall layups.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

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