• Energy Research
• 2016-2025close
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Over the past few years, fuel prices have increased dramatically, and emissions regulations have become stricter in maritime applications. In order to take these factors into consideration, improvements in fuel consumption have become a mandatory factor and a main task of research and development departments in this area. Internal combustion engines (ICEs) can exploit only about 15–40% of chemical energy to produce work effectively, while most of the fuel energy is wasted through exhaust gases and coolant. Although there is a significant amount of wasted energy in thermal processes, the quality of that energy is low owing to its low temperature and provides limited potential for power generation consequently. Waste heat recovery (WHR) systems take advantage of the available waste heat for producing power by utilizing heat energy lost to the surroundings at no additional fuel costs. Among all available waste heat sources in the engine, exhaust gas is the most potent candidate for WHR due to its high level of exergy. Regarding WHR technologies, the well-known Rankine cycles are considered the most promising candidate for improving ICE thermal efficiency. This study is carried out for a six-cylinder marine diesel engine model operating with a WHR organic Rankine cycle (ORC) model that utilizes engine exhaust energy as input. Using expander inlet conditions in the ORC model, preliminary turbine design characteristics are calculated. For this mean-line model, a MATLAB code has been developed. In off-design expander analysis, performance maps are created for different speed and pressure ratios. Results are produced by integrating the polynomial correlations between all of these parameters into the ORC model. ORC efficiency varies in design and off-design conditions which are due to changes in expander input conditions and, consequently, net power output. In this study, ORC efficiency varies from a minimum of 6% to a maximum of 12.7%. ORC efficiency performance is also affected by certain variables such as the coolant flow rate, heat exchanger’s performance etc. It is calculated that with the increase of coolant flow rate, ORC efficiency increases due to the higher turbine work output that is made possible, and the condensing pressure decreases. It is calculated that ORC can improve engine Brake Specific Fuel Consumption (BSFC) from a minimum of 2.9% to a maximum of 5.1%, corresponding to different engine operating points. Thus, decreasing overall fuel consumption shows a positive effect on engine performance. It can also increase engine power output by up to 5.42% if so required for applications where this may be deemed necessary and where an appropriate mechanical connection is made between the engine shaft and the expander shaft. The ORC analysis uses a bespoke expander design methodology and couples it to an ORC design architecture method to provide an important methodology for high-efficiency marine diesel engine systems that can extend well beyond the marine sector and into the broader ORC WHR field and are applicable to many industries (as detailed in the Introduction section of this paper).

Abstract In order to solve the water and energy crisis problem, the thermal water desalination and parabolic trough solar collectors are used at the cogeneration plants. In this paper, an integrated structure for cogeneration of fresh water and power has been developed using a multi-stage thermal water desalination system and organic Rankine cycle. In order to supply the input heat, an integrated structure of parabolic trough solar collectors, and to supply the condenser cooling of organic Rankine cycle, the re-gasification operations have been used. This integrated structure is capable of fresh water generation of 3628 kgmol/h and electrical power of 459.9 MW. In this integrated structure, the efficiency of the organic Rankine cycle power plant and gain output ratio of the multi effect desalination system is 12.47% and 2.918, respectively. Exergy analysis has been used to examine the second law of thermodynamics and the quality of the integrated structure. The total exergy efficiency of the integrated structure is 87.11%, and also, the highest share of equipment exergy destruction is related to the heat exchangers and collectors by 50.23% and 38.18%, respectively. In order to simulate the dynamics of the integrated structure, according to the input climatic information of the studied location in Tehran, Iran. Furthermore, decisions are made upon the sensitivity analysis on economic important indicators within an integrated structure.

As renewable energy (RE) penetration has a continuously increasing trend, the protection of RE integrated power systems is a critical issue. Recently, power networks developed for grid integration of solar energy (SE) have been designed with the help of multi-tapped lines to integrate small- and medium-sized SE plants and simultaneously supplying power to the loads. These tapped lines create protection challenges. This paper introduces an algorithm for the recognition of faults in the grid to which a solar photovoltaic (PV) system is integrated. A fault index (FI) was introduced to identify faults. This FI was calculated by multiplying the Wigner distribution (WD) index and Alienation (ALN) index. The WD-index was based on the energy density of the current signal evaluated using Wigner distribution function. The ALN-index was evaluated using sample-based alienation coefficients of the current signal. The performance of the algorithm was validated for various scenarios with different fault types at various locations, different fault incident angles, fault impedances, sampling frequencies, hybrid line consisting of overhead (OH) line and underground (UG) cable sections, different types of transformer windings and the presence of noise. Two phase faults with and without the involvement of ground were differentiated using the ground fault index based on the zero sequence current. This study was performed on the IEEE-13 nodes test network to which a solar PV plant with a capacity of 1 MW was integrated. The performance of the algorithm was also tested on the western part of utility grid in the Rajasthan State in India where solar PV energy integration is high. The performance of the algorithm was effectively established by comparing it with the discrete Wavelet transform (DWT), Wavelet packet transform (WPT) and Stockwell transform-based methods.

It is widely discussed that GDP growth has a vague impact on environmental pollution due to carbon dioxide emissions from fossil fuels consumed in production, transportation, and power generation. The main purpose of this study is to investigate the relationships between economic growth, fossil fuel consumption, mortality (from cardiovascular disease (CVD), diabetes mellitus (DM), cancer, and chronic respiratory disease (CRD), and environmental pollution since environmental pollution can be a reason for societal mortality rate increases. This study uses the generalized method of moments (GMM) estimation technique for the Commonwealth of Independent States (CIS) members for the period from 1993–2018. The major results revealed that the highest variability of mortality could be explained by CO2 variability. Regarding fossil fuel consumption, the estimation proved that this variable positively affects mortality from CVD, DM, cancer, and CRD. Additionally, any improvements in the human development index (HDI) have a negative effect on mortality increases from CVD, DM, cancer, and CRD in the CIS region. It is recommended that the CIS members implement different policies to improve energy transitions, indicating movement from fossil fuel energy sources to renewable sources. Moreover, we recommend the CIS members enhance various policies for easy access to electricity from green sources and increase the renewable supply through improved technologies, sustainable economic growth, and increase the use of green sources in daily social life.

Carbon dioxide emission, which acts as one of the major agents of greenhouse gases (GHG), has significant effects on global warming. Nowadays, there is a considerable global tendency toward decreasing the amount of GHG emissions to the atmosphere. In the present study, a simulated power plant flue gas (Be’sat, Power Plant, Tehran) with a constant injection rate of 21.41 cm3 s−1, including 10% CO2, 7% O2 and 83% N2 , was injected to the Synechococcus elongatus culture under two different light–dark (L/D) cycles: 24-0 and 16-8. Additionally, the biomass productivity and the CO2 biofixation rate by microorganisms were investigated. The highest biomass productivities were recorded as 0.68 and 0.52 g L−1 d−1 for 24-0 and 16-8 L/D cycles, respectively. Furthermore, the maximum rate of the CO2 biofixation was 1.26 g L−1 d−1 for the 24-0 L/D cycle and 0.98 g L−1 d−1 for the 16-8 L/D cycle during the cultivation.

Palm kernel shell biochars (PKSB) ejected as residues from a gasifier have been used for solid fuel briquette production. With this approach, palm kernel shells can be used for energy production twice: first, by producing rich syngas during gasification; second, by compacting the leftover residues from gasification into high calorific value briquettes. Herein, the process parameters for the manufacture of PKSB biomass briquettes via compaction are optimized. Two possible optimum process scenarios are considered. In the first, the compaction speed is increased from 0.5 to 10 mm/s, the compaction pressure is decreased from 80 Pa to 40 MPa, the retention time is reduced from 10 s to zero, and the starch binder content of the briquette is halved from 0.1 to 0.05 kg/kg. With these adjustments, the briquette production rate increases by more than 20-fold; hence capital and operational costs can be reduced and the service life of compaction equipment can be increased. The resulting product satisfactorily passes tensile (compressive) crushing strength and impact resistance tests. The second scenario involves reducing the starch weight content to 0.03 kg/kg, while reducing the compaction pressure to a value no lower than 60 MPa. Overall, in both cases, the PKSB biomass briquettes show excellent potential as a solid fuel with calorific values on par with good-quality coal.CHNS: carbon, hydrogen, nitrogen, sulfur; FFB: fresh fruit bunch(es); HHV: higher heating value [J/kg]; LHV: lower heating value [J/kg]; PKS: palm kernel shell(s); PKSB: palm kernel shell biochar(s); POME: palm oil mill effluent; RDF: refuse-derived fuel; TGA: thermogravimetric analysis.

The environmental impacts of the ammonia production process are because of the discharge of harmful chemicals as well as the high energy demand. One way to control its environmental impacts in the electricity transition phase, is the natural gas/biomass-based scenarios. This life cycle assessment (LCA) study, which has used ReCiPe and cumulative exergy demand (CExD), proves that natural gas is not right option for this specific case because the natural gas-based scenarios have more burdens than the residual fuel oil-based scenarios especially regarding fossil depletion (0.72%), human toxicity (14%), freshwater ecotoxicity (23%), particulate matter formation (33%), marine ecotoxicity (37%), and terrestrial acidification (40%). Moreover, this study shows that it is possible to reduce the environmental impacts without retrofitting the heart of process technology using the biomass-based scenarios. This paves the way for a sustainable ammonia process under the energy transition scenarios where retrofitting the process heart is not desired.