Exergy Analysis of a Novel Cryogenic Concept for the Liquefaction of Natural Gas Integrated Into an Air Separation Process

The increasing demand for primary energy leads to a growing market of natural gas and the associated market for liquefied natural gas (LNG) increases, too. The liquefaction of natural gas is an energy- and cost-intensive process. After exploration, natural gas, is pretreated and cooled to the liquefaction temperature of around −160°C. In this paper, a novel concept for the integration of the liquefaction of natural gas into an air separation process is introduced. The system is evaluated from the energetic and exergetic points of view. Additionally, an advanced exergy analysis is conducted. The analysis of the concepts shows the effect of important parameters regarding the maximum amount of liquefiable of natural gas and the total power consumption. Comparing the different cases, the amount of LNG production could be increased by two thirds, while the power consumption is doubled. The results of the exergy analysis show, that the introduction of the liquefaction of natural gas has a positive effect on the exergetic efficiency of a convetional air separation unit, which increases from 38% to 49%.

Hydrogen Generation From Acetic Acid Catalyzed Magnesium Hydride Using an On-Demand Hydrogen Reactor

This study reports an acetic acid catalyzed hydrolysis reaction for hydrogen generation from magnesium hydride (MgH2) using an on-demand hydrogen reactor. Acetic acid, a weak and benign organic acid, has been reported as a single catalyst in hydrolysis reaction for hydrogen generation using other substrates, but this is the first study where acetic acid has been employed as a catalyst in a magnesium hydride hydrolysis reaction for hydrogen generation. In this study, the effects of MgH2 weight, acetic acid concentration and external temperature on hydrogen generation from MgH2 were examined. The results of the hydrolysis reaction indicated that the weight of MgH2 was the major factor influencing hydrogen generation, followed by the concentration of acetic acid while the effect of external temperature was insignificant. Similarly, hydrogen yield was proportional to the weight of MgH2 with a reported maximum hydrogen yield at each weight been: 0.4g (∼ 0.07 L); 0.8 g (∼ 0.125 L) and 1.2 g (∼1.285 L). The successful use of acetic acid in the study reinforced the versatility of the on-demand hydrogen reactor and as a scalable technology for hydrogen generation.

Wireless Power Efficiency and Quality in Metal Shaft Environment With Eddy Current Losses and Electromagnetic Interference

Wireless power transmission efficiency and ripple interference attract more and more attention nowadays, but in some special metal environments the transmission efficiency of wireless power will be greatly influenced. In some practical engineering application, we need to use wireless energy to power the sensor on the high speed rotating parts. In order to improve the transmission efficiency and quality of the wireless power supply, researches are conducted to evaluate the eddy current loss and electromagnetic interference of wireless power in high-speed rotating component parameter test system. In this paper, electromagnetic coupling wireless power supply system is established as the transmission model. Then the analytical expressions of eddy current loss are derived by solving Maxwell’s equations, and after that the eddy current loss characteristics is analyzed by combining with the electromagnetic coupling model and eddy current losses model in metal medium. To verify the theoretical results, Maxwell electromagnetic field simulation software is used to analyze the characteristics of the eddy current. Finally, experiments are carried out to illustrate the effect of ferrite magnetic shielding material on the eddy current loss and the shielding effect on the external electromagnetic interference in the metal shaft environment.

Conjugated Dynamic Modeling on Vanadium Redox Flow Battery With Non-Constant Variance for Renewable Power Plant Applications

A parametric modeling study has been carried out to investigate the effect of change in operating conditions on VRFB performance. The objective of this research is to develop a computer program to predict the dynamic behavior of single cell VRFB combining fluid mechanics, reaction kinetics, and electric circuit. This paper deals with the exact solutions obtained by solving the governing differential equations of VRFB by using Maple 2015. Calculations were made under electrolyte concentrations of 1M–3M of V2+, charging-discharging current of 1.85A–3.85A, and tank to cell ratio of 5:1 to 10:1. Results show that the discharging time increases from 2.2 hours to 6.7 hours when the value of electrolytes concentration of V2+ increases from 1M to 3M. However, the charging time decreases from 6.9 hours to 3.3 hours with the increment of applied current from 1.85A to 3.85A. Additionally, when the tank to cell ratio is increased from 5:1 to 10:1, the charging-discharging time increased from 4.5 hours to 8.2 hours. Ampere-hour capacity of the cell was found to increase when molar concentration of vanadium and, tank to cell ratio were increased.

Analysis of an Adsorption Chiller Cooling System for Various Types of Solar Collectors Using the F-Chart Cooling Method

Solar cooling systems offer a reliable and environmentally friendly alternative to conventional electrically driven vapor compression cooling units. Air conditioning systems powered by solar energy are very attractive because they have zero ozone depletion and global warming potential, their operational cost is low and they do not burden the electrical network during summer months. In this study, the installation of a solar cooling system in various Greek cities is examined. The system utilizes a single-stage, two-bed silica gel-water adsorption chiller driven by heat produced by solar collectors. A lumped parameter model is used to simulate the performance of the adsorption chiller. The optimum tilt of the solar collectors is calculated for each examined city in order for the collected solar energy to be maximized during the summer period (April to September). The climatic data are taken from the technical notes of Greek Regulation for Buildings Energy Performance. Then, using the f-chart cooling method the necessary collectors’ surface area is estimated for every examined city and for different types of flat plate collectors (including advanced flat plate, simple flat plate and hybrid photovoltaic thermal collectors).

Effect of Chemical Fuel Additives on Liquid Fuel Saving, and Emissions for Heavy Fuel Oil

As fossil fuel resources are considered non-renewable sources of fuel, they will be totally consumed in the near or far future. Due to the intensive and extensive consumption of these fossil fuels in all life sectors such as transportation, power generation, industrial processes, and residential consumption, it is important to find other new methods to cover this fuel demand. Fuel additives are chemicals used to enhance fuel combustion performance, save fuel amounts required for combustion, and correct deficiencies in power and efficiency during consumption. The fuel additives are blended with the traditional fuel even by parts per million range for controlling chemical contaminants and emission reduction. In the present work, the experimental measurements were done, to evaluate the effect of fuel additive blending with the raw heavy fuel oil (Mazut) on fuel saving which is of a great significance, emissions control, and combustion characteristics as well as the combustion efficiency. These measurements are as follows: initial temperature of Mazut, exhaust gas temperature at the end of combustor, air and fuel mass flow rates to determine the heat load, inlet and outlet temperatures of cooling water, mass flow rate of water, concentration of different exhaust gases, acoustic (noise level) measurements, smoke number, and flame length. These measurements are performed using swirled vanes, co-axial, and double heavy fuel nozzle (1.5 gal/hr for each one) burner with maximum heating load of 550 kW. GC-MS (Gas chromatography-mass spectrometry) analysis was performed by using Hewlett Packard model 5890 equipped with a flame ionization detector (FID) to identify the fuel additives substances within the tested samples. The results reveal that the use of fuel additives improves the combustion characteristics and play an important role in fuel saving as well as emission and combustion process.

The Behavior of Impurities During Producer Gas Implementation as Alternative Fuel in Steel Reheating Furnaces: A CFD and Thermo-Chemical Study

The use of available and cheap industrial producer gases as alternative fuels for the steel reheating furnaces is an attractive topic for steel industry. The application of producer gases for such furnaces introduces not only the complicated combustion system of Low Calorific Value (LCV) gases, but also several impurities that could be problematic for the quality of final steel products. The quality of steel can be highly affected by the interaction of impurities with iron-oxides at hot slab surfaces. In this research, the combustion of producer gases and the behavior of impurities at the steel slab surface are studied by aid of a novel coupled computational fluid dynamics (CFD) and thermodynamics approach. The impurities are introduced as mineral ash particles with the particle size distributions of 15–100 μm. The CFD predicted data regarding the accumulation of ash particles are extracted from an interface layer at the flaring gas media around the steel slab surface. Later on, these predicted data are used for the thermo-chemical calculations regarding the formation of sticky solutions and stable phases at the steel slab surface. The results show that the particles are more likely follow the flow due to the high injection velocity of fuel (70 m/s) and the dominant inertial forces. More than 90 percent of particles have been evacuated through the exhaust pipes. The only 10 percent of remaining particles due to the high recirculation zones at the middle of furnace and the impinging effect of front walls tend to stick to the side wall of slab in the heating zone more than the soaking zone.

Experimental Investigation of a Spark Ignited Engine Using Magnetic Air Conditioner (MAC) for Improved Performance and Reduced Emissions

In 21st century, to cope up with exponential technological development, use of eco-friendly conventional energy system is a critical issue. Saving of energy is nothing but production of energy. Conventional fuel used in stationary power plant an IC engine is bulk in quantity, which will not be last longer and will exhaust very soon. Stationary power plants and Automobile propelled by I.C. engines have a problem of pollutant emission in environment which mainly depends on combustion process occurs in power plant and I.C. engines. Incomplete combustion of hydro-carbon fuel/s produce very large amount of harmful emission gases resulting into smog in cities & reduces performance of the system. These systems, equipped with Internal Combustion or External combustion produces large amount of exhaust gases CO, HC and NOx like monoxides etc. Since hazardous emissions which are harmful to human life and ecosystem resulting in many types of diseases of human especially in urban areas where automobile vehicle equipped with IC engine density is very high. These emissions have effect on result in environmental cycles also. In today’s globalised world, many attempts are made to reduce intensity of hazardous emissions of an IC engine through pre processing of fuels and post processing combustion exhaust gases in IC engine by many means like MPFI, PCV, EGR, catalytic converter, supercharger, turbocharger, etc. In order to handle, these issues, additional attempt is made. This attempt uses Air conditioner/Energizer for Pre-processing air and unit developed called as Magnetic air Conditioner (MAC). A permanent magnet, magnetic air conditioner (MAC) is mounted in path of air lines. Mounting MAC in air line enhances quality of air and air molecules properties like it aligns and orientations, especially in an oxygen molecule. Better atomization of an oxygen molecule which further enters into combustion chambers of SI engine along with air. In a conventional four stroke spark Ignited engine, oxygen molecules reacts with hydro -carbon, which assist for complete combustion of hydro-carbon. Use of such Magnetic air conditioners improves performance of SI engine. The specific fuel consumption also decreases, resulting in to decrease in BSFC with increase in load. Use of MAC in engine also reduces emissions like CO, HC, ultimately resulting into reduction in smog in urban areas. The present article describes the mechanism of MAC, objectives and its effect on SI engine, such as enhanced performance parameter, various efficiencies like mechanical, brake thermal, volumetric saving in fuel, and reduced emission. One case study is presented in which ferrite magnets are used as MAC which improves performance and reduces emissions.

Steam Gasification of Miscanthus in a Double Stage Downdraft Gasifier

Gasification is the incomplete combustion of biomass, which produces syngas, biochar and tar. A study of steam gasification of Miscanthus was done on a double stage down draft gasifier at Federal University of Itajuba. The main objective of this paper is to analyze and characterize the syngas produced from the double stage downdraft system. Compared to the previous publication that focused on the gasification of corn using air, this paper elaborates on the steam gasification of Miscanthus. In a double stage downdraft gasifier, Miscanthus with 12% moisture was inserted into the system from the top. The gasifier has two inlets: primary and secondary. The steam was inserted through these inlets. The Miscanthus briquettes entering the gasifier were passed through a drying zone where the moisture content was removed. The fuel was then passed through a combustion and pyrolysis zone followed by a reduction zone. The syngas produced exited the gasifier through a grate and was analyzed for a continuous period of time. When using steam as a gasifying agent, it was found that the syngas showed a 15 % increase in hydrogen, a 50% decrease carbon monoxide with no change in methane composition. The increase in hydrogen can be used for alternate energy such as in fuel cells. The syngas heating value was obtained to be 4.64 MJ/Nm3. This paper compares the syngas composition evolved from the gasification of Miscanthus when using air and steam as gasifying agents.

Thermo Mechanical Analysis of a Direct Injection Heavy Duty Diesel Engine Piston Using FEA

This paper involves simulation of a 4-stroke direct injection heavy duty diesel engine piston made of aluminum silicon alloy to determine its temperature field, stress distribution and deformation at the conditions of upgrading the engine power from 300 HP to 350 HP. Turbocharger is the way used to enhance the engine power from 300 HP to 350 HP beside improving the fuel injection system. When the engine power is upgraded, high temperature and pressure will be developed because the engine will run at high loads. The piston is subjected to the coupled action of the thermal effect due to the transfer of heat from the head to the body and the mechanical effect represented by the combustion pressure and the inertial load due to the important change of direction of the piston in the cylinder bore. This results in producing stresses in the piston and if these stresses exceed the designed values, the failure of the piston is the result. Finite element analysis (FEA) is considered as one of the best numerical tools to model and analyze the physical systems. The three dimensional piston model was developed in Solid-Works and imported into ANSYS software. Finite element analysis is considered Code for preprocessing, loading and post processing. The simulation parameters used in this paper were combustion pressure, inertial effects and temperature. Diesel RK software is used to simulate the thermal analysis of engine cycle at each case of engine power 300 HP and 350 HP. Also, this model included the effect of the heat flow on the piston to overcome the whole area of the piston is used to illustrate the temperature distribution on the total area of the piston. This area divided into piston surface area and sidle area of piston which included the groves of rings (pressure and oil). The heat transfer coefficient is determined in each area of the piston according to the mechanism of heat transfer. Finally, the results of two different piston conditions are compared with each other. The highest temperature appeared at the combustion chamber side which occurred at the edges of the piston top face in direct contact with the hot gases in the radial. The piston deformation value is within a safe margin and below the gap between the piston and the cylinder bore in case of engine power of 350 HP. The highest calculated value of stresses was below the yield stress of the piston material at elevated temperatures and engine brake power of 350 HP. Hence the piston would withstand the induced stresses during work cycles.