Showing papers in "Energy Conversion And Management: X in 2022"

Effective Dispatch Strategies Assortment According to the Effect of the Operation for an Islanded Hybrid Microgrid

Abstract: The optimized design of a freestanding hybrid microgrid for various distinct dispatch controls is assessed in this paper, which considers the optimal sizes of individual components, system response, and reliability analysis. The effective design and management of stand-alone islanded hybrid smartgrids are getting increasingly importance and influences as the prevalence of renewable energy in microgrids grows. Melville Island, off the coast of eastern Queensland, Australia, is taken as the test microgrid in this study. For the optimal sizing and techno-economic assessment of the intended hybrid microgrid system consist of of solar diesel generator, PV , battery storage, and wind turbine, four dispatch approaches have been unitized: load following, generator order, combined dispatch, and cycle charging strategy. The proposed off-grid microgrid's CO2 emissions, total net present cost (NPC), and the Levelized cost of energy (LCOE) have all been optimized. In HOMER software, all the possible dispatch algorithms were analyzed, and the power system responses and reliability study were carried out using DIgSILENT PowerFactory. The findings of the study are useful for determining the optimum hybrid combination and available resources for the best performance of an off-grid microgrid employing various dispatch mechanisms. Following the simulation data, load-following is the best dispatch mechanism for stand-alone microgrid architecture since it has the lowest LCOE and NPC.

Impacts of EGR on RCCI Engines Management: A comprehensive review

Abstract: • Benefits and drawbacks of EGR on RCCI engine management are discussed. • EGR has a great impact on the RCCI engine's emission and performance characteristics. • The higher EGR percentage has more benefits on lowering soot and NOx emissions. • The collaborated regulation is important between EGR, premixed ratio, and DI timing. Exhaust gas recirculation (EGR) has been one of the essential aspects to manage combustion phasing, in-cylinder reactivity, performance, and emissions in innovative RCCI engine operation. In this review, the effect of EGR on RCCI engine operations is reviewed and different techniques to employ EGR are discussed. Generally, RCCI engine operation needs EGR support, especially at high engine loads to limit the pressure increase rate, and around 50 percent of EGR may be essential based on fuel used and engine load. The RCCI combustion engine needs a substantially low EGR rate since the rate of burning is regulated by altering the mixture reactivity by employing two fuels having significantly varied reactivity. RCCI operation with cooled EGR yielded lower pressure rise rate, cyclic variation, and NOx emissions but greater THC emissions than hot EGR operation. Internal EGR and lower pressure of intake air achieved generally greater net indicated efficiencies and reduced emissions than that of the conventional RCCI combustion at low loads. At high load, the internal EGR mode is required to be turned off to minimize fuel efficiency loss. The higher EGR percentage has more benefits on extending maximum load and lowering soot and NOx emissions, whereas the combustion and indicated thermal combustion efficiencies decline to utilize higher EGR percentage. Thus, to accomplish the greater performance and efficient process of combustion, the collaborated regulation is important between EGR rate, premixed ratio, and direct-injection timing.

Influence of reaction parameters on thermal liquefaction of plastic wastes into oil: A review

Abstract: The use-and-throw culture of plastic products has generated a massive amount of plastic wastes each year, posing a threat to the environment with the absence of proper disposal methods of the wastes. Conventional disposal methods including landfill and incineration cease to be the ultimate solution to the problem, in addition to further causing soil and air pollution. Liquefaction technology has emerged to become one of the alternatives in reducing the amount of accumulated wastes simultaneously generating valuable liquid products for applications such as transportation fuel and chemical feedstock in industries. Additionally, the recovery of plastics through this method poses great potential in reducing the dependency on non-renewable fossil fuels, creating an alternative energy source. This review exploits the liquefaction of common types of plastics found in the wastes and some key parameters affecting the yield and properties of end products including the type of reactor, temperature, pressure, reaction time, types of solvent, solvent to plastic ratio and the initial size of plastic used.

Review on the sustainability of phase-change materials used in buildings

Abstract: Phase-change materials have become a vital solution for saving energy and reducing greenhouse gas emissions from buildings. However, the production processes of phase-change materials affect their cost, impact societies, and may result in harmful emissions to the environment. In this study, we perform a review on the sustainability of phase-change materials considering performance, economic, environmental, and social aspects. While there is an extensive literature on the performance and efficiency of phase-change materials, there is limited consideration of social fairness and the environmental impact. So, we analyze the lifecycles of four different phase-change materials: a salt hydrate, a hydrocarbon, and two types of biobased materials. Our results show that hydrocarbon phase-change materials have the highest purchasing cost, the highest effect on the environment, and their production is associated with social risks related to safety and health. On the other hand, biobased (plant-based) materials are affordable, safe, provide new market opportunities for crops, and have minimal environmental harm if biofertilizers are used. The use of manurial fertilizers do not give biobased phase-change materials an advantage over other types. We also note that social fairness in production should be respected for sustainable phase-change materials solutions.

Effects of Compression and mixing ratio on nh3/h2 fueled si engine performance, combustion stability, and emission

Abstract: Carbon-free fuels for the worldwide decarbonization movement are ammonia and hydrogen. The experiment is conducted under WOT conditions with a constant ignition timing of 24°CA BTDC to evaluate performance, combustion stability, and emissions with varying CR (12 to 15), hydrogen energy fractions (5 to 21%), and engine speeds between 1500 and 1700 RPM. BP increased by 31.2% at 1700RPM and BTE increased by 39.0% at 1500RPM, despite a 9% decrease in volumetric efficiency at 1700RPM, from 5% hydrogen fraction at CR12 to 21% hydrogen fraction at CR15.The combustion process is sped up by the effect of hydrogen fraction and CR, causing the flame development and propagation period to shorten. NOx emission was increased significantly with hydrogen and CR, with an increase of 42.34% from 5% hydrogen at CR12 to 21% hydrogen at CR15 at 1700 RPM. Excessive NOx emissions are a drawback that can be successfully controlled by installing after treatment or exhaust gas recirculation technologies. Ammonia is another important key element used to reduce NOx emissions from vehicles because it is used in SCR.

Extraction and characterization of coffee husk biodiesel and investigation of its effect on performance, combustion, and emission characteristics in a diesel engine

Abstract: Biodiesel and its blends with diesel are used in engines to overcome the problems of environmental pollution and fast depletion of conventional fuels. The purpose of this research is to extract oil from coffee husk, convert it into coffee husk oil methyl ester (CHOME) by transesterification, and test the suitability of this biodiesel as an alternate, renewable, sustainable fuel for a diesel engine. The physicochemical characteristics of the developed biodiesel are studied and compared with regular diesel. The results showed that the fundamental properties of the produced fuel are comparable to that of diesel. The performance, combustion, and emission characteristics of a diesel engine fueled with CHOME biodiesel are investigated. The experiments are conducted in a single-cylinder direct injection diesel engine at a constant speed by varying the loads (0, 25, 50, 75, and 100%) for different biodiesel-diesel blends (B10, B20, B30, B40, B50, and B80), and the results are compared with the baseline diesel. The brake thermal efficiency (BTE) of the blends, B10, B20, B30, and B50 dropped by 0.6, 0.7, 1.29, and 3%, respectively compared with the neat diesel. Similarly the brake specific energy consumption (BSEC) is reduced by 0.1, 0.3, 0.44, and 0.77% for B10, B20, B30, and B50, respectively. Exhaust gas emissions are reduced for all biodiesel-diesel blends. Compared to regular diesel, at full load, CO, HC, and smoke opacity of B30 reduced by 13.2%, 4%, and 12%, respectively. CO2 of B30 at full load is increased by 8.63%. In general, it can be stated that CHOME biodiesel is a promising alternate biodiesel that can be used in an internal combustion engine without major modifications.

A review of the synthesis of activated carbon for biodiesel production: Precursor, preparation, and modification

Abstract: • Overview of the synthesis of activated carbon as catalysts for biodiesel production. • Key factors affecting the properties and catalytic performance of activated carbon. • A guide to design activated carbon catalyst with optimal surface morphology. Activated carbon (AC) is a porous material with unique chemical and physical properties that has been used widely in various applications. The production process of AC involves precursor treatments, carbonization, and physical and/or chemical activation. Besides, surface modifications are commonly carried out to improve the AC properties, particularly as a catalyst. This paper provides an overview of the recent development in each of these steps. The temperature and time, as well as the impregnation ratio of activating agent to the precursor were found to have a significant influence on the surface morphology of the AC during an activation process. The effects of these variables on AC yield, BET surface area, and pore volume during synthesis from various raw materials synthesis are discussed. The use of AC as a catalyst in the production of biodiesel is also being studied. This work could serve as a guideline to design a high-performance activated carbon based catalyst for biofuel production.

Thermodynamic modeling of hydrogen–water systems with gas impurity at various conditions using cubic and PC-SAFT equations of state

Abstract: Hydrogen (H2) has emerged as a viable solution for energy storage of renewable sources, supplying off-seasonal demand. Hydrogen contamination due to undesired mixing with other fluids during operations is a significant problem. Water contamination is a regular occurrence; therefore, an accurate prediction of H2-water thermodynamics is crucial for the design of efficient storage and water removal processes. In thermodynamic modeling, the Peng–Robinson (PR) and Soave Redlich–Kwong (SRK) equations of state (EoSs) are widely applied. However, both EoSs fail to predict the vapor-liquid equilibrium (VLE) accurately for H2-blend mixtures with or without fine-tuning binary interaction parameters due to the polarity of the components. This work investigates the accuracy of two advanced EoSs: the Schwartzentruber and Renon modified Redlich–Kwong cubic EoS (SR-RK) and perturbed-chain statistical associating fluid theory (SAFT) in predicting VLE and solubility properties of H2 and water. The SR-RK involves the introduction of polar parameters and a volume translation term. The proposed workflow is based on optimizing the binary interaction coefficients using regression against experimental data that cover a wide range of pressure (0.34 to 101.23 MPa), temperature (273.2 to 588.7 K), and H2 mole fraction (0.0004 to 0.9670) values. A flash liberation model is developed to calculate the H2 solubility and water vaporization at different temperature and pressure conditions. The model captures the influence of H2-gas (CO2) impurity on VLE. The results agreed well with the experimental data, demonstrating the model’s capability of predicting the VLE of hydrogen-water mixtures for a broad range of pressures and temperatures. Optimized coefficients of binary interaction parameters for both EoSs are provided. The sensitivity analysis indicates an increase in H2 solubility with temperature and pressure and a decrease in water vaporization. Moreover, the work demonstrates the capability of SR-RK in modeling the influence of gas impurity (i.e., H2–CO2 mixture) on the H2 solubility and water vaporization, indicating a significant influence over a wide range of H2–CO2 mixtures. Increasing the CO2 ratio from 20% to 80% exhibited almost the opposite behavior of H2 solubility compared to the pure hydrogen feed solubility. Finally, the work emphasizes the critical selection of proper EoSs for calculating thermodynamic properties and the solubility of gaseous H2 and water vaporization for the efficient design of H2 storage and fuel cells.

H2-powered aviation at airports – design and economics of LH2 refueling systems

Abstract: In this paper, the broader perspective of green hydrogen (H2) supply and refueling systems for aircraft is provided as an enabling technology brick for more climate friendly, H2-powered aviation. For this, two H2 demand scenarios at exemplary airports are determined for 2050. Then, general requirements for liquid hydrogen (LH2) refueling setups in an airport environment are derived and techno-economic models for LH2 storage, liquefaction and transportation to the aircraft are designed. Finally, a cost trade-off study is undertaken for the design of the LH2 setup including LH2 refueling trucks and a LH2 pipeline and hydrant system. It is found that for airports with less than 125 ktLH2 annual demand a LH2 refueling truck setup is the more economic choice. At airports with higher annual LH2 demands a LH2 pipeline & hydrant system can lead to slight cost reductions and enable safer and faster refueling. However, in all demand scenarios the refueling system costs only mark 3 to 4% of the total supply costs of LH2. The latter are dominated by the costs for green H2 produced offsite followed by the costs for liquefaction of H2 at an airport. While cost reducing scaling effects are likely to be achieved for H2 liquefaction plants, other component capacities would already be designed at maximum capacities for medium-sized airports. Furthermore, with annual LH2 demands of 100 ktLH2 and more, medium and larger airports could take a special H2 hub role by 2050 dominating regional H2 consumption. Finally, technology demonstrators are required to reduce uncertainty around major techno-economic parameters such as the investment costs for LH2 pipeline & hydrant systems.

Low-Carbon Technologies and Just Energy Transition: Prospects for Electric Vehicles

Abstract: The impacts of low-carbon technologies are spread across countries and lifecycle stages in ways that can compromise the achievement of an inclusive and equitable energy transition. Based on an exploratory review, this paper identifies the main activities of the electric vehicles (EVs) life cycle, where they occur, and potentially associated injustices. Through a whole systems approach, energy justice tenets are extended to the EV technology, highlighting how it might fail to fully support a low-carbon and just energy transition. Results provide insights into how EVs can contribute to flexibility justice through smart grids and vehicle-to-grid developments, cosmopolitan justice as a consequence of greenhouse gas (GHG) emissions and global resource depletion, and restorative justice through laws and standards that demand environmental restoration and social compensation over affected communities. However, reviewed documents indicate that efforts must be directed toward reducing distributional, procedural, and recognition injustices across the North-South divide, especially those related to mining activities in the resource extraction and processing stage. EVs upfront costs and charging infrastructure issues may also exclude poor and rural communities during its operational stage. Recommendations for future research include technical aspects such as battery composition and recycling, which will determine the overall impact of EVs on resource extraction and end of life stages, and social aspects of EV-technology such as social innovations that can promote its inclusiveness, the achievement of the Sustainable Development Goals, and the quantification of social impacts of low-carbon technologies.

Techno – economic analysis of activated carbon production from spent coffee grounds: Comparative evaluation of different production routes

Abstract: Activated carbon (AC) has gained immense popularity owing to its excellent physicochemical properties and its ability to remove carbon dioxide (CO2) from flue gas stream. This study examines the potential of spent coffee grounds (SCG) as a precursor for activated carbon (AC) production via prominent thermochemical conversion technologies. Different production routes, such as slow pyrolysis, activation, and deep eutectic solvent (DES) functionalization were compared in terms of their economic viability. Three scenarios (Scenario 1–3) involving combinations of the technologies and production routes were evaluated. Scenario 1 comprises of slow pyrolysis, CO2 activation and flue gas recycling for activation. Scenario 2 includes flue gas combustion while the third scenario comprise of flue gas combustion and DES impregnation. All processes were simulated with Aspen plus, while a detailed cash flow analysis was used to estimate the profitability parameters. The price of AC was found to be the most crucial determinant of an AC production plant’s viability and feasibility. The minimum selling price (MSP) of AC samples produced from scenarios 1,2 and 3 are U.S $0.15/kg, $0.21/kg, $0.28/kg respectively. The price of pristine AC and DES treated AC were lower than the commercially available activated carbon (U.S $0.45/kg).

Design and scale-up challenges in hydrothermal liquefaction process for biocrude production and its upgradation

Abstract: Renewables are going to play an important role in meeting the greenhouse gas (GHG) emission targets to mitigate the effects of climate change. Most of the bioenergy production processes available today can be broadly categorized into two types of technologies - biological and thermochemical processes. Worldwide, the major practiced methods are Combustion/Incineration, Pyrolysis, Gasification, Anaerobic digestion, Fermentation etc. These methods have their own benefits and limitations based on their capability and capacity to process various feed stocks, energy efficiency, operational challenges, product quality and economics. Hydrothermal liquefaction (HTL) process is one such method, which has recently attracted attention of many scientific and practicing community across the world on various platforms. HTL process has the ability to convert all kinds of biomasses to crude bio-oil, which is comparable to fossil crude oil and can be upgraded in existing refinery set-up. Although it has significant benefits over other conversion technologies, HTL process is yet to be commercialized. Several technical and operational challenges have been reported in literature that need to be addressed for successful scale-up and design of continuous scale HTL process. Large number of review and research articles pertaining to batch and pilot scale are available on the process and product development aspect of HTL process. However, limited information is available on the design and scale-up issues that are envisaged in the scale-up of HTL technology. This review article identifies various design, scale-up and operational challenges in HTL technology and proposes potential ways to mitigate those challenges.

Exergo-economic comparison of waste heat recovery cycles for a cement industry case study

Abstract: This work evaluates the performance regarding exergo-economic and emissions requirements of Waste Heat Recovery configurations (Organic Rankine cycle, Trilateral flash cycle, and Kalina cycle) under different operating conditions and working fluids. It was found that the best economic performance is presented by the Organic Rankine cycle that operates with Cyclo-Pentane and has two intermediate heat exchangers since it pushes the expansion temperature up while allowing a higher heat input to the cycle. As a result, it delivers 6.2 MW with a net present value, the net present value of 0.74 million dollars, saving up to 11480 tonnes of carbon dioxide per year. This performance far exceeds that obtained in the previous work, around 50% higher net-work with 80% higher net present value, and constitutes the best alternative in terms of performance to recover waste heat from the source evaluated. Regarding the Trilateral flash cycle, it can be stated that the net work and the exergetic performance are independent of the working fluid as long as there is not a very large volume change in the expander. The Kalina cycle presents slight exergy destruction, but the power delivered does not compensate for the high total capital cost due to the high pressures that must be handled, 55–120 bar, compared to the Organic Rankine cycle, 4–40 bar. An approach was made to more realistic cases where the methodology used facilitates selecting the best alternative when there is a budget restriction using the total capital cost and net work alternatively like a fixed requirement and net present value as the primary decision criterion.

Thermodynamic assessment of a triple cascade refrigeration system utilizing hydrocarbon refrigerants for ultra-low temperature applications

Abstract: • Triple cascade refrigeration system is implemented for ultra-low temperature applications. • System performance analyzed for hydrocarbon-based environment friendly refrigerants. • Temperatures of MTC and LTC condenser are evaluated for maximum COP values. • At different evaporator temperatures, better performance is gained by different pairs. • Heptane and Toluene are recommended in MTC for −120 °C to −110 °C, and −100 °C to −90 °C, respectively. This work presents a detailed thermodynamic analysis of a triple cascade vapor refrigeration system (TCRS) utilizing hydrocarbon refrigerants for ultra-low temperature application. Different hydrocarbon refrigerants pairs are used in different circuits (High temperature circuit HTC, Mid temperature circuit MTC, and Low temperature circuit LTC) to obtain the most suitable refrigerant combination by mathematical modeling of the system. The design and operating parameters considered in this study include (1) evaporator temperature (2) LTC condensation temperature (3) MTC condensation temperature. A thermodynamic analysis consisting of energy and exergy analysis were employed in terms of operating conditions to obtain COP, total compressor work, exergy efficiency, total exergy destruction, mass flow rate and discharge temperatures of compressors. Furthermore, an analysis on component exergy destruction was conducted to show the possibilities of improvement of TCRS utilizing the hydrocarbon refrigerants. The results suggest that at different evaporator temperatures different hydrocarbon refrigerants on TCRS give higher COP and exergy efficiency. The highest COP and exergy efficiency at −100 °C evaporator temperature was calculated to be 0.5931 and 54.446 %, respectively. This study also suggests that hydrocarbon refrigerants can be used in ultra-low temperature applications without compromising the thermodynamic performance of the refrigeration system.

An accurate approach for modeling I-V characteristics of photovoltaic generators based on the two-diode model

Abstract: In this paper, the two-diode circuit model with seven parameters is used to model the electrical properties and the physical effects of photovoltaic modules. In this article, only the available information about the photovoltaic panel on its manufacturer’s datasheet is required to extract the model’s seven parameters. The newly proposed method is based on the reduced forms approach; the search space is reduced from seven to only three unknown parameters to extract numerically. In order to make the extraction simple and faster, just one iterative process is required to get the values of the three unknown parameters simultaneously. The four remaining parameters are calculated analytically using four analytical equations gotten by exploiting the values of the three remarkable points of the current–voltage (I-V) characteristic under standard test conditions provided by the manufacturer and without using any approximations. In addition to the simplicity that characterizes the method in this paper, the high efficiency of the proposed model is proved using three photovoltaic panels of different technologies for which the current approach provides the lowest errors compared to other recent numerical methods of the literature. Next, the proposed method is also transformed and used as an optimization algorithm that achieves higher levels of precision and speed of convergence than the most recent and advanced meta-heuristic optimization algorithms.

Enhancing the activity of Zn, Fe, and Ni-embedded microporous biocarbon: Towards efficiently catalytic fast co-pyrolysis/gasification of lignocellulosic and plastic wastes

Abstract: This study explored an energy-efficient and cost-effective method to synthesize three-dimensional metal-embedded microporous carbocatalysts. Pellet biochar manufactured with compressed and porous structure was used as the carbonaceous precursor, which was modulated by diverse metal chlorides in the single-step thermal process, fulfilling the synchronous pore-forming, metal-doping, and graphitization. The as-synthesized carbocatalysts were characterized in detail by using N2 physisorption, SEM, TEM, EDX, XRD, TPO, TGA, FTIR, XPS, Raman, CHNS elemental analysis, etc. It was found that the metal-embedded carbocatalysts possessed well-developed 3D microporous structures with the highest specific surface area of 964 m2/g. The catalytic activities of these catalysts were investigated during on-line and ex-situ catalytic fast co-pyrolysis of wheat straw and plastic waste. It was observed that the carbon yield of bio-oils could reach over 60 C% by using [email protected] as the catalyst at 500 °C, and the HHV of bio-oils peaked at 38.52 MJ/Kg in the presence of [email protected] at 500 °C. Moreover, these carbcatalysts at 500 °C favored production of hydrocarbons with a relative content up to 98%; in particular, monocyclic aromatics presented the highest selectivity (nearly 60%). Among metal-embedded carbcatalysts, [email protected] at 800 °C was in favor of H2 (157 NmL/gfeedstock) and syngas (273 NmL/gfeedstock) production; importantly, [email protected] also promoted the generation of carbon nanotubes. Additionally, the thermal degradation behaviors and kinetics of non-catalytic and catalytic co-pyrolysis of biomass and plastic waste over the as-synthesized catalysts were also tested by thermogravimetric analysis. Finally, a rational reaction mechanism regarding ex-situ catalyst fast co-pyrolysis of biomass and plastic waste over catalytically active sites on the as-synthesized catalysts was elucidated. Accordingly, this work provides a great potential of using the promising carbocatalysts to co-valorize biomass and plastic waste into the integrated harvests of monocyclic aromatics, syngas, and valuable carbons.

Experimental study on the electrical and thermal characteristics of a hybrid photovoltaic / thermal water solar collector model using photovoltaic solar modules of different brands

Abstract: In this work, the results of an experimental study on the thermal and electrical behavior of this hybrid collector model allowed us to determine the electrical and thermal characteristics of water-based PV/T collectors in the climatic conditions of the western region of Cameroon. A prototype was made with monocrystalline solar modules from Canadian solar brands; Trina Solar and Felicity Solar. Tests were carried out and the data collected led us to optimize the electrical and thermal production of photovoltaic solar modules. We obtained an average daily electrical energy gain of 12.3% or 42Wc (Canadian Solar); 11.8% or 35.99Wc (Trina Solar) and 11.1% or 26.5Wc (Felicity Solar) compared to conventional solar module. On the thermal side, we obtained an average daily thermal power of 659.88 W or 12 L of hot water with a temperature of 41 °C for the Canadian Solar module; 659.89 W or 12 L of hot water with a temperature of 41.5 °C for the Trina Solar module and 538.38 W or 10 L of hot water with a temperature of 41 °C for the Felicity solar module. These tests were carried out on an average solar irradiation of 877.88 W/m2 between 8:05 am and 3:30 pm. This approach allowed us to recover an amount of the electrical power of the modules lost as heat while determining the amount of hot water that can be produced by a PV module. This prototype was produced and experimented with. It also allowed us to observe that the performance of PV/T water systems also varies depending on the brand of solar module chosen.

A comprehensive review on the effects of diesel/biofuel blends with nanofluid additives on compression ignition engine by response surface methodology

Abstract: Due to the emissions restrictions and the speeding requirements for energy in different sectors, diesel and gasoline can't be able to face the rapid supply of internal combustion engines. The direction for using the renewable fuel resources partially or entirely in place of fossil diesel fuel becomes inevitable due to the availability, accepted environmentally and competitive. Alternative fuels have excellent usage as fuel without any modifications in the diesel engines. Alternative fuels can dampen combustion temperature, decreasing all emission percentages compared to using fossil diesel only. Biodiesel is an oxygenated fuel and one of the alternative fuels used as a blend for operating diesel engines. Its importance is in decreasing the brake specific fuel consumption and increasing the brake thermal efficiency. Nanoparticle additives are blended with diesel fuel and its alternatives in compression ignition engines to increase the surface contact area, increase the oxidation of fuels, provide short ignition delay, improve the engine performance attributes, and decrease engine emissions. Response surface methodology is a computer application used to design, predict and optimize the response variables according to the input variables. Response surface methodology is used in many applications in industrial fields to predict the performance and quality of products due to its accuracy in the responses and time consuming. The present paper reviews the importance of using response surface methodology in predicting the optimum performance and emission characteristics for diesel engines fuelled with blends of diesel, alternative fuels, and nano-particle additives. It is accomplished that the comparison between the experimental and the modeling by response surface methodology is similar.

Production of marine biofuels from hydrothermal liquefaction of sewage sludge. Preliminary techno-economic analysis and life-cycle GHG emissions assessment of Dutch case study

Abstract: The aim of this paper is to evaluate the costs and GHG emissions of advanced biofuels production through hydrothermal liquefaction (HTL) of sewage sludge in The Netherlands targeting the marine fuels market. The process evaluated consists of a distributed configuration of regional HTL plants co-located with wastewater treatment plants, with centralized hydrotreating co-located with an existing refinery at the Port of Rotterdam. The process is simulated in ASPEN + based on published experimental data and the mass and energy balances are used as input for techno-economic and environmental evaluation. Lifecycle GHG emissions of the HTL and hydrotreating processes are estimated using consequential modelling principles and background data from the Ecoinvent database and compared with the business-as-usual scenario of sludge mono-incineration and fossil marine fuels production. The results indicate that the HTL + hydrotreating configuration has potential to deliver on-spec marine biofuels at a minimum fuel selling price between 410 and 1300 EUR/t, being at least 3 times more beneficial compared to the business-as-usual scenario from a GHG emissions perspective. Future work is recommended to optimize the size and location of the HTL plants in order to decrease capital costs and to address uncertainties regarding the sludge gate fee and the costs associated with the aqueous and solid by-products treatment. The results indicate the potential of such configuration in locations with relatively high population density and good transport infrastructure. This can be the case of port areas around the North Sea with access to offshore renewable electricity for hydrogen production, where drop-in marine biofuels are expected to play a role with the increasing share of renewables in the marine fuels mix.

A review on thermal performance enhancement of green cooling system using different adsorbent/refrigerant pairs

Abstract: Due to the ever-increasing cooling demand, alternative refrigeration is being explored for the last few decades that are less energy-intensive and can utilize ozoenvironmental friendly working fluid. Vapor adsorption refrigeration is one of the most promising alternatives among all heat-driven refrigeration systems. One of the most important requirements in an adsorption-based cooling system is to enhance the adsorption uptake capacity of the adsorbent materials for their impactful, effective, and economical operation. However, there are several working pairs explored during the recent decades but none of them could be suitable as an ideal one, for all the operating conditions. In this article, the various characteristics of different adsorbents including the highly porous activated carbons derived from waste biomass, the composites, and compounds developed, are thoroughly reviewed. Further, the synthesization, the optimal assortment, regeneration, coatings on adsorber, and commercial application of novel adsorbents including the advanced adsorption reactors and the current scenario of industrial adsorption chillers are discussed in detail. Finally, the impact of operating parameters, such as adsorbent-adsorbate mass ratio, desorption pressure, operating temperatures, and adsorption/desorption cycle time on the specific cooling power, coefficient of performance, and the chiller efficiency are summarized.

Comprehensive Experimental Study on Bluff Body Shapes for Vortex-Induced Vibration Piezoelectric Energy Harvesting Mechanisms

Abstract: Vortex-induced vibration (VIV) is an appropriate mechanism to harvest energy from the low-speed wind energy by flexible piezoelectric flags as transducers. To enhance the low-speed wind energy harvesting, this work proposes a novel study on finding the best possible combination of bluff body shape and flag configuration. This study considered several bluff body shapes in different cross sections and flag configurations as two crucial parameters for finding an appropriate combination. In high flexible piezoelectric flag, zero strain or electrical canceling point along the length of the flag is an important parameter that could be considered in energy harvester design. To this purpose, wind tunnel experiments were conducted to investigate the combination of proper bluff body shape and flag configuration to improve the harvester performance. The proposed bluff body shapes are classified by drag and lift coefficients which are calculated by a computational fluid dynamics (CFD) analysis. Then, several flag configurations in different active area length were clamped to these bluff bodies and tested in the wind tunnel in low wind speed range. The analysis in time and frequency domain of the acquired voltage lead to the conclusion that in low wind speed the bluff body with higher drag coefficients can excite more the longer full active piezoelectric flags, consequently generating more energy. However, for the same bluff body shapes, short full active flags generate more energy in higher wind speed. This study could develop a new experimental approach on finding the most favorable combination of bluff body shape and flag configuration which is as important as just considering bluff body shape to improve the efficiency of the low-speed wind piezoelectric energy harvesting system.

A case study of cascade supercritical CO2 power cycle for waste heat recovery from a small gas turbine

Abstract: • A single heated cascade sCO 2 cycle is studied as bottomer of a 4.7 MW gas turbine. • Around 1500 kW of net electric power can be recovered by the sCO 2 -based technology. • The specific cost of the considered sCO 2 -based technology is around 2000 $/kW. • Performance of the investigated cycle is similar to the one of the partial heating cycle. • Driving the compressor at the same rotational speed of the turbines is not possible. Among the technological solutions that can be applied to waste heat recovery, the supercritical CO 2 (sCO 2 ) cycle represents an innovative option. This work studies the performance of the single heated cascade sCO 2 cycle as the bottomer power system of a 5 MW-class gas turbine and follows a former study of the authors about the partial heating cycle. A number of parametric analyses has been carried out with attention paid to the selection of (i) minimum and maximum CO 2 pressures, based on a compressor Mach number selected to avoid highly loaded turbomachinery, (ii) maximum CO 2 temperature, and (iii) specific design parameters such as temperature difference at the cold side of the primary heater, recuperator effectiveness and single-stage radial-type turbine efficiency, the latter calculated according to Aungier’s correlations by taking actual size and running conditions into account. The results of this study suggest that around 1500 kW of net electric power can be recovered by the single heated cascade sCO 2 cycle. This figure is not so different from the power output previously calculated for the partial heating cycle as well as the specific cost of the technology, which is around 2000 $/kW, lower than a possible competing technology for waste heat recovery applications as the organic Rankine cycle. Nevertheless, the architecture investigated in this study needs two turbines which can rotate on the same shaft, but driving the compressor at the same rotational speed of the two turbines is not possible, as emerges from preliminary considerations about the size of the turbomachinery impellers.

Implementation of the characteristic equation method in quasi-dynamic simulation of absorption chillers: Modeling, validation and first results

Abstract: Scheme of the Thermal Compressor of the prototype absorption chiller – A transient Behavior. • A quasi-dynamic approach to simulate an absorption refrigeration system was made; • The modeling was based on the characteristic equation method and thermal capacity; • A sensitivity analysis to verify the dynamic behavior of the chiller was conducted; • The behavior results by chillers with different solutions showed the same trend; • The comparison results showed good agreement with errors lower than 5%; This work presents a quasi -dynamic approach to an absorption refrigeration system that uses NH 3 /LiNO 3 as the working fluid. The goal is linked to the development and validation of a mathematical model, based on the characteristic equation method, to simulate the quasi -dynamic behavior of absorption chillers. The mathematical model was developed using the first law of thermodynamics through the conservation of mass and energy and the integration of the characteristic equation method, considering external parameters such as temperatures and flow rates of hot, cold, and chilled water circuits as the global heat transfer coefficients. The computational model was built using the F-Chart EES® software, the initial part, to facilitate the resolution of the equations (characteristic equation method). Finally, MATLAB software was used to perform the simulation with the characteristic equation and the transient model. The comparison between the experimental results found in the literature and those obtained by the developed model showed good agreement with relative errors lower than 5% within the values found in the measurement uncertainties. A sensitivity analysis was performed to verify the dynamic behavior of the absorption chiller, considering the activation, cooling, and thermal load temperatures and the products of the global heat transfer coefficients, checking the temperature, pressure, profiles, heat fluxes, and the COP of the chiller. The results showed a coherent behavior when the system was disturbed by varying activation, cooling, and chilled water temperature.

A novel hybrid numerical with analytical approach for parameter extraction of photovoltaic modules

Abstract: Building an accurate mathematical model of photovoltaic modules is an essential issue for providing reasonable analysis, control and optimization of photovoltaic energy systems. Therefore, this study provides a new accurate model of photovoltaic Panels based on single diode Model. In this case, the proposed model is the link between two models which are the ideal model and the resistance network. All parameters are estimated based on hybrid Analytical/Numerical approach: three parameters photocurrent, reverse saturation current and ideality factor are obtained using an Analytical approach based on the datasheet provided by the manufacturer under Standard Test Conditions. The series and shunt resistances are obtained by using a Numerical approach similar to the Villalva's method in order to achieve the purpose of modeling the resistance network part. Our model is tested with data from the manufacturer of three different technologies namely polycrystalline, Mono-crystalline silicon modules and thin-film based on Copper Indium Diselenide, and for more accurate performance evaluation we are introducing the Average Relative Error and the Root Mean Square Error. The simulated Current-Voltage and Power-Voltage curves are in accordance with experimental characteristics, and there is a strong agreement between the proposed model and the experimental characteristics. The computation time is 0.23 s lower than those obtained using others approach, and all obtained results under real environment conditions are also compared with different models and indicated that the proposed model outperforms the others approach such as villalva’s and kashif’s method.

Experimental and numerical investigation on a hybrid solar chimney-photovoltaic system for power generation in Kuwait

Abstract: A large percentage of solar energy is converted to accumulated thermal energy leading to temperature rise in the PV panel. The raised PV surface temperature could be utilized for fluid heating. The objective of the current work is to integrate the PV panels with an inclined solar chimney and carry out an experimental and numerical assessment of the developed hybrid system. An experimental model comprises a solar collector with a photovoltaic panel as an absorber, a chimney, and a convergent nozzle has been developed. A Series of measurements have been carried out at various weather conditions. A numerical simulation predicted the airflow and heat transfer characteristics utilizing ANSYS fluent software to extend the analysis and evaluation of the hybrid system. Results showed that the hybrid system produces power within a range of 9% to 11% efficiency, which is approximately two orders of magnitude higher than the typical solar chimney efficiency. In contrast, it increased by 18% compared to the stand-alone PV panel. A minor increase in output power with a negligible decrease in LCOE was expected to increase the size further.

Optimised Site Selection of Hybrid Renewable Installations for Flare Gas Reduction using Multi-Criteria Decision Making

Abstract: Gas flaring is an alarming issue for oil and gas fields across the globe which can be reduced by utilizing the waste flare gas to produce power using hybrid renewable energy systems. While installing the hybrid renewable energy systems at oil and gas fields, one of the critical concerns is the selection of the right location as it ensures high productivity and efficiency of the system throughout the system life-cycle. The presented research aims to select suitable sites for three different hybrid renewable energy systems installations for oil and gas fields. A novel combinational multi-criteria decision-making approach has been presented for site selection. Three methods, namely - equal distribution, intuitive distribution, and AHP, have been proposed to determine the weights of the criteria. After weight determination, the modified ‘technique for order of preference by similarity to ideal solution’ (TOPSIS) has been applied to determine the rankings of suitable gas flare locations. The proposed combinational algorithm has been tested for selecting the site for installing three different hybrid renewable energy system configurations. The resultant closeness to ideal solution indexing (Ci) concurs to choose the same locations for all three cases with a variation of 1.32% in Ci only. The concurrency of results for all the cases using different criteria weights proves the accuracy of the modified TOPSIS algorithm for assigning the rank of locations. The modifications in the existing Multi-Criteria Decision-Making methods are a necessary contribution of this paper as the current practices work well with either quantitative or qualitative data but are insufficient to deal with the complex (partially qualitative and quantitative) data obtained from the oil and gas fields. The oil and gas flaring locations are ranked based on ecological, technical, and sociological parameters for installing the hybrid renewable energy systems to reduce gas flaring and generate power from waste gas flares and other available renewable energy sources.

A comprehensive design and optimization of an offset strip-fin compact heat exchanger for energy recovery systems

Abstract: • Parametric, sensitivity, and optimization of compact heat exchanger is presented. • A normalized sensitivity analysis is used to identify the critical parameters. • Geometric parameters and fluid velocity appeared as the most influential parameters. • The optimization reduced the operational cost by 78%, and the total cost by 77%. Energy recovery in conventional thermal systems like power plants, refrigeration systems, and air conditioning systems has enhanced their thermodynamic and economic performance. In this regard, compact heat exchangers are the most employed for gas to gas energy recovery because of their better thermal performance. This paper presents an economic optimization of a crossflow plate-fin heat exchanger with offset strip fins. A detailed software-based numerical code for thermal, hydraulic, economic, and exergy analysis is developed for three fin geometries. Genetic Algorithm, parametric, and normalized sensitivity analyses are used to discover the most influential parameters to optimize the total cost. The parametric study showed that with the increase of mass flow rates and plate spacing, outlet stream cost and operating cost increased due to the rise in pressure drops. Finally, the optimization reduced the operational cost by ∼78.5%, stream cost by ∼64.5%, and total cost by ∼76.8%.

Experimental and thermodynamic analysis of solar air dryer equipped with V-groove double pass collector: Techno-economic and exergetic measures

Abstract: Optimised solar air dryers, in terms of efficiency and performance, can solve some major concerns in the agro-industrial processing sector. Solar air dryers can reduce the large share of energy costs of a final product and can provide sustainable energy in rural areas where access to energy is often limited. In this study, a pilot scale v-groove double pass solar air collector has been analysed thermodynamically with real time solar radiation and mass flow rate (0.021–0.061 kg/s) inputs and validated experimentally in terms of first and second law efficiencies. Performance of the process was assessed using experimental drying measures including final moisture content, drying rate and exergy efficiency for drying of Pink Lady apples. Energy payback time and specific energy consumption were calculated to reveal the techno-economic value of the system. The maximum thermal efficiency of the collector was observed to be 88.8 % at 0.061 kg/s having exergy efficiency of 6.6 % which shows an efficient sourcing for the operation. In terms of the performance of the dryer, mass flow rate of 0.041 kg/s offers a higher moisture removal. Specific energy consumption (SEC) was 3.096 kWh/kg. Thermodynamic model was validated with matching experimentation with acceptable RMSE for the range of investigated measures. Energy payback period time calculated by the embodied energy of the system was obtained to be 0.78 years which implies that the system is capable of addressing a large capacity drying if it is to be scaled-up.

Combined influence of compression ratio and exhaust gas recirculation on the diverse characteristics of the diesel engine fueled with novel palmyra biodiesel blend

Abstract: The current study investigates the influence of compression ratio and EGR on the various characteristics of diesel engine operated with 20% Palmyra oil methyl ester (POME 20) blend at different load conditions. Transesterification process is used to produce the palmyra oil methyl ester from the palmyra crude oil, which is extracted from the palmyra seeds by the application of mechanical pressing operation. ASTM standards have been used to determine the physico-chemical characteristics of palmyra oil methyl ester and these properties are close competing with the diesel fuel. Preliminary tests are conducted with blends of palmyra oil methyl ester (POME 10, POME 20 and POME 30) on diesel engine working at standard conditions and it is found improved engine performance and reduced emissions for POME20. One of the viable techniques to enhance the engine characteristics is to change the operating parameters. In this context, the present work focuses on the influences of distinct compression ratios (16:1, 18:1 and 20:1) on the diverse characteristics of diesel engine fuelled with POME 20 blend. The experimental test findings indicate that the brake thermal efficiency is enhanced by 6.91% and BSFC is lowered by 10.2%; and considerable decreases in carbon monoxide, unburned hydrocarbons, and smoke opacity emissions by 13.33%, 8.82% and 8.2% respectively found at compression ratio 20:1 when compared to POME 20 operated at compression ratio 16:1. However, the NO x emissions are found to be higher. EGR is the simplest, cheapest and most effective technique used for reduction of NO x emissions for diesel and biodiesel fuelled diesel engine. In this, EGR is added 5% and 10% rates to the POME 20 operated at 20:1 compression ratio. The test results revealed that the addition of 10% EGR to the POME 20 is found 23% reduction of NO X emissions when compared to POME 20 operated at standard operating conditions.

Annualized exergoenvironmental comparison of solar-only and hybrid solar-biomass heat interactions with an organic Rankine cycle power plant

Abstract: This study is aimed at comparing the environmental performance of a solar-only and hybrid solar-biomass organic Rankine cycle (ORC) plant using the exergoenvironmental method. The system studied adopts the design features of a real ORC plant currently running at Ottana, Italy, rated nominally at about 630 kW. Established procedures of the exergoenvironmental methods were applied, which integrate the principles of exergy and life cycle analyses. The method quantifies the yearly environmental impact rates of each of the plant components. The eco indicator-99 impact assessment method was adopted to quantify impact rates. Results showed that implementing the biomass hybridization scheme would improve the annualized exergetic efficiency of the existing solar ORC plant by about 3 percentage points, from about 7% with solar-only to about 10% with hybrid solar-biomass heat sources, although a small increase in the relative irreversibility rate is observed (from 49% to 51%). It would as well improve the capacity factor of the plant. However, the environmental impacts would be impacted negatively. Particularly, the specific exergoenvironmental impact rates were obtained as 27.4 Pts/MWh for the hybrid solar-biomass ORC plant, as against 20.3 Pts/MWh obtained for the solar-only plant, implying that the hybridization strategy would increase impact rate by about 35%. Similarly, it was obtained that biomass hybridization would increase the overall exergoenvironmental impact rates of the ORC plant by about 92,000 Pts/year, due majorly to increased exergy destruction in the plant components and the polluting emissions of the combustor.