Biodiesel is a promising renewable energy option that significantly reduces the emission of greenhouse gases and other toxic byproducts. However, a major challenge in the industrial scale production of biodiesel is the desired product purity. To this end, reactive distillation (RD) processes, which involve simultaneous removal of the byproduct during the transesterification reaction, can drive the equilibrium towards high product yield. In the present study, we first optimized the heat exchange network (HEN) for a high purity RD process leading to a 34% reduction in the overall energy consumption. Further, a robust control scheme is proposed to mitigate any feed disturbance in the process that may compromise the product purity. Three rigorous case studies are performed to investigate the effect of composition control in the cascade with the temperature control of the product composition. The cascade control scheme effectively countered the disturbances and maintained the fatty acid mon... [more]

The aim of this research work is to modulate the pitch angle of both types of wind turbines based on fuzzy logic control (FLC), as changes in the pitch angle have various functions in horizontal and vertical axis wind turbines. For HAWT, pitch angle control is applied to shield the electrical components of the turbine when the wind speed exceeds the rated speed without shutting down the turbine. FLC is used to control the angular velocity using two inputs and one output with three membership functions for both inputs and output. In VAWT, pitch angle control is applied to boost the performance of the turbine and its self-starting torque. FLC utilizes two inputs and one output with five membership functions for both inputs and output. For both turbine types, FLC produces a control signal that drives the actuator to achieve the desired pitch angle. The dynamics of HAWT and VAWT are simulated by the MATLAB/Simulink to demonstrate the influence of pitch controls on their dynamics. For HAWT,... [more]

A pouring silicate wick was manufactured to explore the influence of process and physical properties on the production and performance of loop heat pipes (LHP). This paper theoretically analyzed the advantages of pouring porous wick and introduced the technology of pouring silicate directly on evaporator. Based on this, the heat transfer performance of copper-methanol LHP system with pouring porous wick was tested under different positions. The results showed that with the input of multiple heat sources, the LHP could start up and maintain a stable temperature from 40 W to 160 W. When the vapor grooves were located above the compensation chamber, it was difficult to start up positively. By adding gravity assistance, the system could obtain more stable liquid supply and vapor flow, so as to realize start up. In the variable heat load test, the LHP showed good adaptability to the change of heat load. The thermal resistance of the system decreased with the increase of heat load. The therm... [more]

Air pollution, especially in large cities around the world, is associated with serious problems both with people’s health and the environment. Over the past few years, there has been a particularly intensive demand for alternatives to fossil fuels, because when they are burned, substances that pollute the environment are released. In addition to the smoke from fuels burned for heating and harmful emissions that industrial installations release, the exhaust emissions of vehicles create a large share of the fossil fuel pollution. Alternative fuels, known as non-conventional and advanced fuels, are derived from resources other than fossil fuels. Because alcoholic fuels have several physical and propellant properties similar to those of gasoline, they can be considered as one of the alternative fuels. Alcoholic fuels or alcohol-blended fuels may be used in gasoline engines to reduce exhaust emissions. This study aimed to develop a gasoline engine model to predict the influence of different... [more]

In order for the operation of the condensing heat exchanger to be efficient, the flue gas temperature at the inlet to the heat exchanger should be reduced so that condensation can start from the very beginning of the exchanger. A possible way to reduce the flue gas temperature is the injection of water into the flue gas flow. Injected water additionally moistens the flue gas and increases its level of humidity. Therefore, more favorable conditions are created for condensation and heat transfer. The results presented in the second paper of the series on condensation heat transfer indicate that water injection into the flue gas flow drastically changes the distribution of temperatures along the heat exchanger and enhances local total heat transfer. The injected water causes an increase in the local total heat transfer by at least two times in comparison with the case when no water is injected. Different temperatures of injected water mainly have a major impact on the local total heat tra... [more]

Fresh rice noodle was usually coated in a large amount of oil to avoid stickiness and extend the shelf life. Pre-treatment has been applied to reduce the quantity of oil in rice noodle. In this research, the pre-treatment and temperature effect on the rice noodle quality subjected to hot air drying, heat pump drying, and freeze drying was investigated. Texture, color, oil content, and starch gelatinization of the dried noodle was further evaluated. Results revealed that there were significant differences (p < 0.05%) in texture, color, oil content, and starch gelatinization in rice noodle subjected to pre-treatment. Furthermore, the texture, color, oil content, and starch gelatinization demonstrated a significant difference (p < 0.05%) in freeze drying rather than hot air drying and heat pump drying. The findings indicate that the qualitative features of the dehydrated noodle are synergistic to pretreatment and drying temperature. Despite superior quality shown by freeze drying, t... [more]

Global warming and the increase in organic waste from agro-industries create a major problem for the environment. In this sense, microbial fuel cells (MFC) have great potential for the generation of bioelectricity by using organic waste as fuel. This research produced low-cost MFC by using zinc and copper electrodes and taking blueberry waste as fuel. A peak current and voltage of 1.130 ± 0.018 mA and 1.127 ± 0.096 V, respectively, were generated. The pH levels were acid, with peak conductivity values of 233. 94 ± 0.345 mS/cm and the degrees Brix were descending from the first day. The maximum power density was 3.155 ± 0.24 W/cm2 at 374.4 mA/cm2 current density, and Cándida boidinii was identified by means of molecular biology and bioinformatics techniques. This research gives a new way to generate electricity with this type of waste, generating added value for the companies in this area and helping to reduce global warming.

In this work, an effective numerical simulation method was developed and used to analyze the effects of natural gas mixing ratio and pilot-main injection, main-post injection, and pilot-main-post injection strategies on the combustion and emission characteristics of diesel engine fueled with dual fuel. Firstly, the one-dimensional calculation model and three-dimensional CFD model of the engine were established by AVL-BOOST and AVL-Fire, respectively. In addition, the simplified chemical kinetics mechanism was adopted, which could accurately calculate the combustion and emission characteristics of the engine. The results show that the cylinder pressure and heat release rate decrease with the increase of the natural gas mixing ratio and the NOx emission is reduced. When the NG mixing ratio is 50%, the NOx and CO emission are reduced by 47% and 45%, respectively. When the SODI3 is 24 °CA ATDC, the NOx emission is reduced by 29.6%. In addition, with suitable pilot-main injection and pilot-... [more]

A collaborative framework by the synergy of Hazard and Operability (HAZOP) process and the Decision-Matrix Risk Assessment (DMRA) in association with safety-color mapping (SCM) is presented, in order to identify critical points and prioritize risks, and also to visualize the occupational safety and health (OSH) situation, at the workplaces (i) of a sour crude-oil processing industry (SCOPI), and (ii) of a measurement and regulatory station (MRS) in a gas transportation system (GTS), situated in Greece. Firstly, the conventional HAZOP analysis is executed in order to identify the potential fault causes of abnormal conditions (deviations) in the plants. The application of the DMRA-modus is valuable to rank the identified risks (hierarchy of risks). In view of the results, both of the HAZOP pattern (for identifying the hazards) and also the DMRA one (for assessing and ranking the risks), SCMs have been derived for the specific workplaces of the SCOPI and the MRS/GTS station, which could b... [more]

A Kentucky coal sample treated by microwave irradiation (MI) combined with sodium hydroxide solution was performed using a thermo-gravimetric analyzer (TGA) coupled to a Fourier transform infrared spectrometer (FTIR). The combustion properties and structural changes of coal under different conditions were investigated and compared. The results show that the desulfurization efficiency of coal samples increases with the increase of sodium hydroxide solution concentration. Microwave irradiation can significantly improve the desulfurization efficiency. The whole combustion process of the treated coal sample becomes longer; the combustion performance becomes worse. The total mass loss of coal treated samples is significantly reduced, and the temperature corresponding to the maximum weight loss rate decreases with the increase of sodium hydroxide concentration. The infrared spectra of the coal samples treated with microwave and 5% sodium hydroxide solution were basically unchanged, while the... [more]

The global focus on the use of renewable energy resources was mainly reignited by the signing of the Kyoto Protocol Agreement in 1997. Since then, the world has seen a great deal of progress in terms of the production and consumption of renewable energy. This in turn is rapidly powering economic growth and social development around the globe. Contrary to popular belief, the use of renewable energy is not limited to developed countries only. The developing countries are also rapidly endorsing renewable energy as a vital engine of economic growth and societal development. In this regard, even though renewable energy production and consumption are in their infancy in BRICS, these countries are taking concrete steps towards the development of renewable energy resources. The results of previous studies have indicated that with an increase in the GDP of a country its carbon footprint also tends to increase; the Brazil, Russia, India, China, and South Africa (BRICS) countries are no exception... [more]

In this study, the convective mode heat transfer phenomena of bi-phase elasticoviscous (non-Newtonian) nanofluid is quantified by forcefully flowing it through a specially designed microchannel test section. The test section, which is rectangularly cross-sectioned and annexed internally with cylindrical needle ribs is numerically investigated by considering the walls to be maintained at a constant temperature, and to be susceptible to a magnetizing force field. The governing system-state equations are numerically deciphered using control volume procedure and SIMPLEC algorithm. With the Reynolds number (Re) varying in the turbulent range from 3000 to 11,000, the system-state equations are solved using the Eulerian−Eulerian monofluid Two-Phase Model (TPM). For the purpose of achieving an apt geometry based on the best thermo-hydraulic behavior, an optimization study must be mandatory. The geometry of the cylindrical rib consists of h (10 × 10−3, 15 × 10−3, 20 × 10−3), p (1.0, 1.5), and d... [more]

The authors of the present paper sought to conduct a numerical study on the convection heat transfer, along with the radiation and entropy generation (EGE) of a nanofluids (NFs) in a two and three-dimensional square enclosure, by using the FVM. The enclosure contained a high-temperature blade in the form of a vertical elliptical quadrant in the lower corner of the enclosure. The right edge of the enclosure was kept at low temperature, while the other edges were insulated. The enclosure was subjected to a magnetic field (MGF) and could be adjusted to different angles. In this research, two laboratory relationships dependent on temperature and volume fraction were used to simulate thermal conductivity and viscosity. The variables of this problem were Ra, Ha, RAP, nanoparticle (NP) volume fraction, blade aspect ratio, enclosure angles, and MGF. Evaluating the effects of these variables on heat transfer rate (HTR), EGE, and Be revealed that increasing the Ra and reducing the Ha could incre... [more]

Metal magnesium (Mg) fuels have been widely used in rocket propellants. The combustion study on individual Mg microparticles is crucial to the in-depth unveiling of the combustion mechanism of Mg-based propellants. In this paper, a new experimental setup was proposed to directly observe the combustion of individual micron-sized Mg particles, based on laser ignition and microscopic high-speed cinematography. The combustion process of individual Mg microparticles could be directly and clearly observed by the apparatus at high temporal and spatial resolutions. Individual Mg microparticles took gas phase combustion, and mainly underwent four stages: expansion, melting, gasification, ignition, and combustion. The ignition delay time and total combustion time had an exponential decay on the particle diameter, and they had a linear decay on the ignition power density. The melting took a dominant role in the whole burnout time. The gas-phase combustion flame seemed thick, inhomogeneous, and ri... [more]

Global climate change is putting humanity under pressure, which in many areas poses an unprecedented threat to society as we know it. In an effort to mitigate its effects, it is necessary to reduce the overall production of greenhouse gases and thus, dependence on fossil fuels in all areas of human activities. The presented paper deals with an evaluation of energy mix of the Slovak Republic and four selected neighboring countries in the context of achieving their carbon neutral or carbon negative future. The development of the evaluated energy mixes as well as greenhouse gas emissions is presented from a long-term perspective, which makes it possible to evaluate and compare mutual trends and approaches to emission-free energy sectors.

In some applications, deep desulfurization and deoxidation of steels without the use of aluminum are required, using Si as a deoxidant instead, with double-saturated slags in the CaO-SiO2-CaF2-MgO system. This work studied the desulfurization and nonmetallic inclusion evolution for the system using an induction furnace and compared the results with FactSage kinetic simulations. Steel samples were taken from the steel melt and analyzed with ICP-MS and combustion analysis for chemistry, and SEM/EDS for nonmetallic inclusion quantity, size, and composition. The results indicate that the steel was deeply desulfurized, with a final sulfur partition coefficient of 580; MgO was reduced from the slag, yielding dissolved [Mg] that transformed liquid Mn−silicate inclusions into forsterite and MgO. Intentional reoxidation of the melt with oxidized electrolytic iron demonstrated a significant concentration of dissolved [Mg] in the steel, by the formation of additional forsterite and MgO upon reoxi... [more]

The accuracy of the power battery model and SOC estimation directly affects the vehicle energy management control strategy and the performance of the electric vehicle, which is of great significance to the efficient management of the battery and the improvement of the reliability of the vehicle. Based on the research of domestic and foreign battery models and the previous results of SOC estimation, this paper classifies power battery models into electrochemical mechanism models, equivalent circuit models and data-driven models. This paper analyzes the advantages and disadvantages of various battery models and current research progress. According to the choice of battery model, the previous research results of the power battery SOC estimation method are divided into three categories: the direct measurement method not based on battery model, the estimation method using black box battery model, and the battery model SOC estimation method based on state space. This paper will summarize and... [more]

The fire-extinguishing system is an indispensable fire-protection facility on the aircraft. In order to guide weight reduction of the aircraft’s fixed gas fire-extinguishing system by improving its release efficiency, so as to improve fuel economy and reduce carbon emissions, the influence of filling pressures and filling amounts on the release efficiency of gas extinguishing agent along pipelines were studied based on numerical simulations. The release process of the fire-extinguishing system was analyzed. The effects of the filling pressure and filling amount of Halon 1301 agent on the release characteristics, such as release time, mass flow rate, and gasification ratio, were studied. Results show that the release process can be divided into three major phases, which are firstly the initial rapid filling of the pipeline, secondly the concentrated release of the liquid extinguishing agent, and thirdly the gas ejection along the pipeline. The second phase can also be subdivided into tw... [more]

Pump as turbine (PAT) is one of the micro-hydro system components. It can be used alone as a generator in remote areas without power supply, and in hydraulic networks instead of pressure-reducing valves. However, its hydraulic optimization still remains an open research problem. One of the optimization techniques is the rounding of the sharp edges at the blade periphery. Existing studies are mostly based on prototype experiments to obtain the optimization effect. In order to more intuitively analyze the influence of this structural optimization on the internal flow of PAT, this paper uses the CFD method to study the influence of the leading edge of the centrifugal pump blade and the fillet of the impeller on the turbine performance. By simulating the PAT performance at different flow rates and speeds, the internal hydraulic performance changes caused by the inverted circular blade are analyzed. Simulation results show that, under various operating conditions, the impeller inverted circ... [more]

Currently, most wastewater treatment plants do not meet the legal requirements, especially regarding phosphorus and nitrogen contents. In this work, real primary urban wastewater (P-UW) was used as culture medium for the growth of Chlorella vulgaris. Experiments were carried out in batch photobioreactors at laboratory scale. To determine the maximum nutrient removal levels and the optimal pH value for C. vulgaris growth, the following pH values were studied: 5, 6, 7, 8, 9, 10, and 11. Additionally, two control experiments were conducted using UW and tap water at the same conditions but without microalgae inoculation. The operational conditions were agitation rate = 200 rpm, T = 25 °C, aeration rate = 0.5 L/min, and continuous light with illumination intensity = 359 µE m−2 s−1. Significant higher growth was obtained at pH = 7. The direct use of C. vulgaris for P-UW treatment demonstrated high removal percentages of organic (COD and BOD5 removal = 63.4% and 92.3%, respectively) and inorg... [more]

This study investigated the long-term effect of horizontal Ground-Source Heat Exchangers (GSHEs) on mitigating permafrost thaw settlement. In the conceptual system, a fan coil was used to chill the recirculating fluid in the linear High-Density Polyethylene (HDPE) ground loop system. A fully coupled thermo-hydro-mechanical finite element framework was employed to analyze multiphysics processes involved in the thaw settlement phenomenon. To investigate the sustainability of the system, a period of 50 years was simulated. Two operational modes were defined: one without and the other with HDPE. Different heat carrier velocities and inlet temperatures, and heat exchanger depths were examined to explore their effects on the thaw settlement rate. It was concluded that the proposed system can effectively alleviate the predicted permafrost thaw settlement over the study period. Moreover, the heat carrier temperature was found to have a prominent impact on the thaw settlement rate amongst other... [more]

Solar architecture is defined as a kind of building integrated photovoltaic (BIPV) in which the PV modules are deployed to passive solar concepts, to minimize the heating and cooling load, to upgrade the indoor environment, and to be adjustable for regional weather and to continuously succeed architectural culture. Solar architecture needs to consider the architectural culture and climate of the region through an ecological convergence. The ecological criteria lead to optimizing solar architecture through an ecological convergence of a passive intelligence and renewable energy system. The optimal angle of the bi-facial PV module as a shade is 23.5° considering the physical interaction and the traditional architecture in Korea according to the ecological criteria. The shading concept of the PV module reduces 27.5~34% of the building cooling load. Effective solar irradiance (ESR) is very important not only for PV efficiency but also for the system usage rate. This ESR should be controlle... [more]

Biodiesel is one of the more recent green fuel products in the world. It can be produced from several raw materials such as straight vegetable oils, animal fats, tallow, and waste cooking oils, and blended with diesel. Properties of biodiesel are different compared to fossil diesel in terms of production methods and emission levels released after combustion in an internal combustion engine. Kuwait consumes a huge amount of energy which is almost 8% to meet the increasing demand for electricity and water. Moreover, the use of electricity in the production of biodiesel increases energy use and cost of production. Kuwait is receiving an amount of solar irradiation ranging from 2050 kWh/m2 to 2100 kWh/m2. The present study is concerned with the evaluation of the potential to use solar energy to produce biodiesel from sheep fat waste as a raw material. An experimental test rig was set up for a single cylinder diesel engine in the laboratory, where a solar power system was used to assist the... [more]

The heat transfer efficiency of a regenerative thermal oxidizer with three canisters used for volatile organic compounds treatment was studied using numerical simulation methods. A one-dimensional model that took into account the variation of physical parameters with temperature was built. The results show that the preheating temperature and outlet temperature tend to be stable as the operation time is increased. The heat transfer efficiency of equipment was mainly evaluated by heat recovery efficiency and energy recovery ratio under steady state conditions, which was affected by the inlet gas flow and temperature, valve switch time, combustion temperature, materials and porosity of the regenerative medium, and packing height. With the increase in packing cross-sectional area and packing height, the increase in heat transfer efficiency leads to an increase in equipment cost. Simultaneously, the shorter the valve switch time and the higher the density of the regenerative medium battery... [more]

In this paper, the analysis and discussion are presented for two prominent types of wireless charging, namely inductive power transfer (IPT) and capacitive power transfer (CPT). The paper presents a comparative analysis between CPT and IPT. A comparison between different geometries of plates used in CPT is performed and it is shown that rectangular-shaped plates have the best power transfer efficiency. The effect of foreign particles between the capacitor plates of a single-module as well as a double-module CPT system on capacitance and energy transfer density are also investigated in the paper. The case of ceramic coating on the capacitor plates and its effects on the capacitance and energy transfer density with varying thickness are analyzed and presented. Different naturally occurring particles such as water, sand and wet sand have been simulated between the capacitor plates of the CPT system and their respective impact on power transfer is analyzed and the simulation results are de... [more]