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Research Papers: Air Emissions From Fossil Fuel Combustion

J. Energy Resour. Technol. 2014;137(1):011101-011101-12. doi:10.1115/1.4027898.

Biofuels are attracting global attention as alternate transportation fuels due to advantages of their being produced from locally available renewable resources, lower pollution potential, and biodegradable nature. Butanol is fast emerging as one of the competitive biofuels for use in transportation engines. Homogeneous charge compression ignition (HCCI) engines have shown great potential for higher engine efficiency and ultralow NOx and particulate matter (PM) emissions. This experimental study is therefore carried out to combine the advantages of biofuels and HCCI engines, both. Detailed performance, combustion, and emission characteristics of n-butanol fueled HCCI engine are investigated experimentally. The study is conducted on a four cylinder diesel engine, whose one cylinder was modified to operate in HCCI combustion mode. Port fuel injection technique was used for homogeneous charge preparation in the intake manifold. Auto-ignition of fuel in the engine cylinder was achieved by intake air preheating. In-cylinder pressure-crank angle data acquisition with subsequent heat release analyses and exhaust emission measurements were done for combustion and emission characterization. In this paper, the effect of intake air temperature and air–fuel ratio on the combustion parameters, thermal and combustion efficiency, ringing intensity (RI), and emissions from n-butanol fueled HCCI engine were analyzed and discussed comprehensively. Empirical correlations were derived to fit the experimental data for various combustion parameters.

Commentary by Dr. Valentin Fuster

Research Papers: Alternative Energy Sources

J. Energy Resour. Technol. 2014;137(1):011201-011201-8. doi:10.1115/1.4027764.

An investigation of the transient exergy property term, exergy storage, for a new desalination tray design was performed. It was illustrated that exergy destruction rates provide a means of comparing alternative energy solutions and a measure of their sustainability. To satisfy these objectives one needs accurate calculation of exergy destruction rates. It was confirmed that neglecting the exergy storage term is not a valid approximation for the hourly and daily averaged values of the second law analysis. For a solar desalination system neglecting the exergy storage terms introduced a maximum difference in the exergy destruction rate of 7.4% and a difference of 7.3% in the daily average. In the solar desalination process with energy recovery the second law performance is greater than that for the reverse osmosis (RO) process, the chief competitor, when the exergy storage terms are correctly included in the analysis. The results demonstrate that for variable energy sources such as renewable energy systems, the second law analysis provides a measure of the sustainability of competing system and that the exergy storage terms should be included in the analysis.

Commentary by Dr. Valentin Fuster

Research Papers: Energy Systems Analysis

J. Energy Resour. Technol. 2014;137(1):012001-012001-11. doi:10.1115/1.4027962.

Modeling and simulations of steam methane reforming (SMR) process to produce hydrogen and/or syngas are presented in this article. The reduced computational time with high model validity is the main concern in this study. A volume based reaction model is used, instead of surface based model, with careful estimation of mixture's physical properties. The developed model is validated against the reported experimental data and model accuracy as high as 99.75% is achieved. The model is further used to study the effect of different operating parameters on the steam and methane conversion. General behaviors of the reaction are obtained and discussed. The results showed that increasing the conversion thermodynamic limits with the decrease of the pressure results in a need for long reformers so as to achieve the associated fuel reforming thermodynamics limit. It is also shown that not only increasing the steam to methane molar ratio is favorable for higher methane conversion but the way the ratio is changed also matters to a considerable extent.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012002-012002-5. doi:10.1115/1.4027961.

Near-critical CO2 flow has been studied because of its potential application in carbon dioxide capture and sequestration, which is one of the proposed solutions for reducing greenhouse gas emission. Near the critical point the thermophysical properties of the fluid undergo abrupt changes that affect the flow structure and characteristics. Pressure drop across a stainless steel tube, 2 ft long with 0.084 in. ID, at different inlet conditions and mass flow rates have been measured. The effects of variations of inlet conditions have been studied. The results show extreme sensitivity of pressure drop to inlet conditions especially inlet temperature in the vicinity of the critical point. Also, shadowgraphs have been acquired to study the flow structure qualitatively.

Commentary by Dr. Valentin Fuster

Research Papers: Fuel Combustion

J. Energy Resour. Technol. 2014;137(1):012201-012201-10. doi:10.1115/1.4027897.

Alcohols (ethanol and methanol) are being widely considered as alternative fuels for automotive applications. At the same time, homogeneous charge compression ignition (HCCI) engine has attracted global attention due to its potential of providing high engine efficiency and ultralow exhaust emissions. Environmental legislation is becoming increasingly stringent, sharply focusing on particulate matter (PM) emissions. Recent emission norms consider limiting PM number concentrations in addition to PM mass. Therefore, present study is conducted to experimentally investigate the effects of engine operating parameters on the PM size–number distribution in a HCCI engine fueled with gasoline, ethanol, and methanol. The experiments were conducted on a modified four-cylinder diesel engine, with one cylinder modified to operate in HCCI mode. Port fuel injection was used for preparing homogeneous charge in the HCCI cylinder. Intake air preheating was used to enable auto-ignition of fuel–air mixture. Engine exhaust particle sizer (EEPS) was used for measuring size–number distribution of soot particles emitted by the HCCI engine cylinder under varying engine operating conditions. Experiments were conducted at 1200 and 2400 rpm by varying intake air temperature and air–fuel ratio for gasoline, ethanol, and methanol. In this paper, the effect of engine operating parameters on PM size–number distribution, count mean diameter (CMD), and total PM numbers is investigated. The experimental data show that the PM number emissions from gasoline, ethanol, and methanol in HCCI cannot be neglected and particle numbers increase for relatively richer mixtures and higher intake air temperatures.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012202-012202-5. doi:10.1115/1.4027980.

Spectroscopic measurements of flames are amongst the most important analytical diagnostic techniques that allow one to improve thermal and energy efficiency of industrial furnaces. A chemical seeding laser-induced plasma spectroscopy (CS-LIPS) was successfully developed and applied for mixing analysis of a methane–air diffusion flame. The results obtained showed that sensitivity of this system was much improved using silica rod as the target material in place of the tungsten material used in our previous studies. Profiling of Mg spectral emission and mixing in the flame was made more clearly with the introduction of magnesium aerosols as a tracer into the combustion air flow.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012203-012203-10. doi:10.1115/1.4028070.

A scale-invariant model of statistical mechanics is described leading to invariant Enskog equation of change that is applied to derive invariant forms of conservation equations for mass, thermal energy, linear momentum, and angular momentum in chemically reactive fields. Modified hydro-thermo-diffusive theories of laminar premixed flames for (1) rigid-body and (2) Brownian-motion flame propagation models are presented and are shown to be mathematically equivalent. The predicted temperature profile, thermal thickness, and propagation speed of laminar methane–air premixed flame are found to be in good agreement with existing experimental observations.

Topics: Flames
Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012204-012204-6. doi:10.1115/1.4028363.

Laminar burning speeds and flame structures of spherically expanding flames of mixtures of acetylene (C2H2) with air have been investigated over a wide range of equivalence ratios, temperatures, and pressures. Experiments have been conducted in a constant volume cylindrical vessel with two large end windows. The vessel was installed in a shadowgraph system equipped with a high speed CMOS camera, capable of taking pictures up to 40,000 frames per second. Shadowgraphy was used to study flame structures and transition from smooth to cellular flames during flame propagation. Pressure measurements have been done using a pressure transducer during the combustion process. Laminar burning speeds were measured using a thermodynamic model employing the dynamic pressure rise during the flame propagation. Burning speeds were measured for temperature range of 300–590 K and pressure range of 0.5–3.3 atm, and the range of equivalence ratios covered from 0.6 to 2. The measured values of burning speeds compared well with existing data and extended for a wider range of temperatures. Burning speed measurements have only been reported for smooth and laminar flames.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012205-012205-10. doi:10.1115/1.4028519.

The characteristics of combustion, emissions, and thermal efficiency of a diesel engine with direct injection (DI) neat n-butanol were investigated. The engine ran at a load of 6.5–8.0 bar indicated mean effective pressure (IMEP) at 1500 rpm engine speed and the injection pressure was controlled to 900 bar. The intake boost pressure, injection timing, and EGR rate were adjusted to investigate the engine performance. The tests demonstrated that neat n-butanol had the potential to achieve ultralow emissions. However, challenges related to reducing the pressure rise rate and improving the ignition controllability were identified.

Commentary by Dr. Valentin Fuster

Research Papers: Petroleum Engineering

J. Energy Resour. Technol. 2014;137(1):012901-012901-7. doi:10.1115/1.4027564.

Deepwater shallow sediment is less-consolidated, with a rock mechanical behavior similar to saturated soil. It is prone to borehole shrinkage and downhole leakage. Assume the deepwater shallow sediments are homogeneous, isotropic, and ideally elastoplastic materials, and formation around the borehole is divided into elastic and plastic zone. The theories of small deformation and large deformation are, respectively, adopted in the elastic and plastic zone. In the plastic zone, Mohr–Coulomb strength criterion is selected. The stress and deformation distributions in these two zones, and the radius of plastic zone are derived. The collapse pressure calculation formula of deepwater shallow sediments under the control of different shrinkage rates is obtained. With the introduction of excess pore pressure theory in soil mechanics, the distribution rule of excess pore pressure in these two zones is obtained. Combined with hydraulic fracturing theory, the fracture mechanism of shallow sediments is analyzed and the theoretical formula of fracture pressure is given. The calculation results are quite close to the practically measured results. So the reliability of the theory is confirmed.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012902-012902-8. doi:10.1115/1.4028230.

Carbonate reservoir stimulation has been carried out for years using HCl or HCl-based fluids. High HCl concentration should not be used when the well completion has Cr-based alloy in which the protective layer is chrome oxide which is very soluble in HCl. HCl or its based fluids are not recommended either in shallow reservoirs where the fracture pressure is low (face dissolution) or in deep reservoirs where it will cause severe corrosion problems to the well tubular. Different chelating agents have been proposed to be used as alternatives to HCl in the cases that HCl cannot be used. Chelating agents, such as HEDTA (hydroxyl ethylene diamine triacetic acid) and GLDA (glutamic –N, N-diacetic acid), have been used to stimulate carbonate cores. The benefits of chelating agents over HCl are the low reaction, low leak-off rate, and low corrosion rates. In this study, the different equations and parameters that can be used in matrix acid treatment were summarized to scale up the laboratory conditions to the field conditions. The conditions where HCl or chelating agents can be used were optimized and in this paper. The leak-off rate was determined using the data from coreflood experiments and computed tomography (CT) scans. Indiana limestone cores of average permeability of 1 md and core lengths of 6 and 20 in. were used in this study. Chelating agents will be used at pH value of 4 and at concentration of 0.6M, and their performance will be compared with the 15 wt.% HCl. The experimental results showed that HCl has high leak-off rate and caused face dissolution at low injection rate. The model to scale up the linear coreflood results to radial field conditions was developed and can be used to design for the optimum conditions of the matrix acid treatments. Chelating agents can be used to stimulate shallow reservoirs in which HCl may cause face dissolution, because they can penetrate deep with less volume and also they can be used in deep reservoirs where HCl may cause severe corrosion to the well tubular.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012903-012903-9. doi:10.1115/1.4028251.

This paper presents finite-element simulation for hydraulic fracture's initiation, propagation, and sealing in the near wellbore region. A full fluid solid coupling module is developed by using pore pressure cohesive elements. The main objective of this study is to investigate the hypothesis of wellbore hoop stress increase by fracture sealing. Anisotropic stress state has been used with assignment of individual criteria for fracture initiation and propagation. Our results demonstrate that fracture sealing in “wellbore strengthening” cannot increase the wellbore hoop stress beyond its upper limit when no fractures exist. However, this will help to restore part or all of the wellbore hoop stress lost during fracture propagation.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):012904-012904-8. doi:10.1115/1.4028272.

Over the last few years, different types of bits have been introduced to meet the challenges of steerable as well as rotary steerable systems; and it is imperative that bits be utilized optimally in these systems. As challenges increase with increasing depths, it becomes even more important for one to efficiently utilize the available energy (Robello, S., 2013, “Modeling and Analysis of Drillstring Vibration in Riserless Environment,” ASME J. Energy Res. Technol., 135(1), p. 013101). A new correlation identifying inefficient drilling conditions is presented in this paper. Mechanical specific energy (MSE) has been used to improve drilling rates, with mixed results. Hydro MSE (HMSE), which is introduced here, encompasses hydraulic as well as mechanical energy. HMSE quantifies the amount of energy required to drill a unit volume of rock and remove it from underneath the bit. HMSE includes axial, torsional, and hydraulic energy and is different from MSE because it includes a hydraulic term. The initial MSE correlation (Teale, R., 1965, “The Concept of Specific Energy in Rock Drilling,” Int. J. Rock Mech. Min. Sci., 2, pp. 57–73.) was modified to accommodate the new hydraulic term. This paper attempts to better model downhole drilling by introducing the hydraulic energy term in the MSE correlation by defining it as HMSE. While the majority of the drilling occurs because of the bit, it is a well-known fact that some drilling occurs due to the “jet impact impingement” caused by the drilling fluid as well. Experimental and field data presented in this paper show that HMSE can identify inefficient drilling conditions. The new hydraulic term included in the specific energy correlation is the key to correctly match the amount of energy required to drill and overcome the strength and stresses of formation being drilled. Also, this new term illustrates how much hydraulic energy is needed to drill faster when the mechanical energy (axial and torsional) is increased. The results also show the importance of including the bit hydraulic energy term into any specific energy analysis for drilling optimization. Field results reveal specific patterns for inefficient drilling conditions and also reveal a good correlation between calculated HMSE and the expected requirements for rock removal under existent conditions of stress at the bit face (Mohan, K., and Robello Samuel, F. A., 2009, “Tracking Drilling Efficiency Using Hydro-Mechanical Specific Energy,” SPE/IADC Drilling Conference and Exhibition, March 17–19, Amsterdam, The Netherlands, No. SPE 119421).

Topics: Drilling
Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2015;137(1):012905-012905-12. doi:10.1115/1.4029267.

Based on the conventional approach, the trapped oil in rock pores can be easily displaced when a Winsor type (III) micro-emulsion is formed in the reservoir during surfactant flooding. On the other hand, the Winsor type (III) involves three phase flow of water, oil, and micro-emulsion that causes considerable oil phase trapping and surfactant retention. This work presents an experimental study on the effect of micro-emulsion phase behavior during surfactant flooding in sandstone and carbonate core samples. In this study, after accomplishing salinity scan of a cationic surfactant (C16–N(CH3)3Br), the effects of Winsor (I), Winsor (III) and Winsor (II) on oil recovery factor, differential pressure drop, relative permeability, and relative permeability ratio were investigated extensively. To carry out a comparative study, homogeneous and similar sandstone and carbonate rocks were selected and the effects of wettability alteration and dynamic surfactant adsorption were studied on them. The results of oil recovery factor in both rock types showed that Winsor (I) and Winsor (III) are preferred compared to Winsor (II) phase behavior. In addition, comparison of normalized relative permeability ratio at high water saturations revealed that Winsor (I) has more appropriate oil and water relative permeability than Winsor (II). The results presented in this paper demonstrate that optimum salinity which results in higher recovery factor and better oil displacement may occur at salinities out of Winsor (III) range. Therefore, the best way to specify optimum salinity is to perform core flood experiments at several salinities, which cover all phase behaviors of Winsor (I), Winsor (III), and Winsor (II).

Commentary by Dr. Valentin Fuster

Technical Brief

J. Energy Resour. Technol. 2014;137(1):014501-014501-8. doi:10.1115/1.4028270.

Application of nano or biomaterials for enhanced oil recovery (EOR) has been recently much attended by petroleum engineering researchers. However, how would be the displacement mechanisms and how would change the recovery efficiency while nano and biomaterials are used simultaneously is still an open question. To this end, a series of injection tests performed on micromodel containing shale strikes. Three types of biomaterials including biosurfactant, bioemulsifier, and biopolymer beside two types of nanoparticles including SiO2 and TiO2 at different concentrations were used as injection fluids. The microscopic as well as macroscopic efficiency of displacements were observed from analysis of images recorded during the tests. Microscopic observations revealed different mechanisms responsible for oil recovery including: wettability alteration, thinning oil film, interfacial tension (IFT) reduction, and water in oil emulsion formation. Contact angle experiments showed changes in the surface wetness from an oil-wet to neutral-wet/water-wet conditions when a layer of nano-biomaterial covered thin sections of a shaly sandstone. Also the results showed that the presence of shales causes early breakthrough and ultimate oil recovery reduction. Shales act as flow barriers and enhance injection fluid viscous fingering. Displacement efficiency in shaly systems is sharply related to the shale distribution. Oil recovery after breakthrough in shaly systems is progressive and considerable volume of oil in place is recovered after breakthrough. The highest efficiency, 78%, observed while injecting one pore volume of biopolymer and SiO2 nanoparticles. This work illustrates for the first time the mechanisms involved in nano-biomaterial-crude oil displacements.

Commentary by Dr. Valentin Fuster

Expert View

J. Energy Resour. Technol. 2014;137(1):014701-014701-3. doi:10.1115/1.4028362.

The sailing record was broken in the fall of 2012. The aerodynamically designed sail allowed the racing boat to skim the water at speeds higher than the prevailing wind speed. This speed sailing record was the initial inspiration of the current work to investigate the creative use of wind to generate electric power in an innovative manner. It has been known for a long time that land yachts have been able to achieve speeds over three times the speed of the prevailing wind. The uplifting message of the current work is that this amplification of the wind speed could be heralding a new breakthrough for power generation from the wind. The current work then proceeds to discuss the components required for a land-based vehicle using an aerodynamically designed sail. There is a discussion of the mechanical systems as well as the principles of the electrical generating system, and the closed loop travel system has been laid out.

Topics: Vehicles , Wind
Commentary by Dr. Valentin Fuster

Errata

J. Energy Resour. Technol. 2014;137(1):017001-017001-1. doi:10.1115/1.4028187.

The above referenced paper is being retracted from the Journal of Energy Resources Technology because of unrebutted allegations that it contains confidential and proprietary information used without permission.

Commentary by Dr. Valentin Fuster
J. Energy Resour. Technol. 2014;137(1):017002-017002-1. doi:10.1115/1.4028188.

The above referenced paper is being retracted from the Journal of Energy Resources Technology because of unrebutted allegations that it contains confidential and proprietary information used without permission.

Commentary by Dr. Valentin Fuster

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