Energy Conversion and Management-X最新文献

Applications for alternative energy sources range from very small scale to large scale grid-coupled hybrid energy systems. In addition, hybrid energy systems are safer to generate power and cheaper to produce than single-source energy systems. The main goal of this study is to determine whether renewable energy hybrid system with horizontal axis wind turbine (HAWT) or vertical axis wind turbine (VAWT) is more efficient and cost effective in terms of energy, economics, and environmental performance. The use of the Multi Objective Genetic Algorithm (MOGA) in MATLAB software for the sizing of hybrid sustainable energy system with wind turbine (horizontal and vertical axis), solar photovoltaic, and grid connection is evaluated in this study. The results revealed that the cost of energy, NPC and system total cost for the case where HRES consists of HAWT is $0.02 /kWh, $85,905, and $332,240, respectively, while for the case when VAWT is used, these values are $0.06 /kWh, $129,932 and $502,511, respectively. The renewable fraction and CO₂ emission saving are 80.5% and 73.2% for cases 1 and 2, respectively. The use of renewable energy sources will spread more widely and there will be less air pollution as a result of less reliance on grid electricity. The findings from both situations show that adopting HAWTS-based HRESs is more cost effective and efficient for electrifying rural areas. This study paves the way for researchers to focus on types of wind turbines while designing HRESs.

This study examines the performance, combustion, and emissions characteristics of a single-cylinder internal combustion diesel engine when fueled with a blend of diesel and biodiesel derived from muskmelon seeds. The kinematic viscosity of the extracted muskmelon seed oil was 6.1 cSt at 40 °C, which is higher than the kinematic viscosity of petroleum diesel of 2.6 cSt. Muskmelon biodiesel was further analyzed using thin-layer chromatography (TLC) and high-voltage separator tests. A comparison of the fuel properties of muskmelon biodiesel with conventional diesel fuel revealed that muskmelon biodiesel could be used alone or in a diesel–biodiesel blend to fuel compression diesel engines. In this study, muskmelon seed biodiesel was blended with diesel fuel at proportions of 10 %, 20 %, and 50 % (BD10, BD20, and BD50, respectively). At a relatively low rotational speed of 1200 rpm, the brake thermal efficiency (BTE) of the engine operated with BD10 and BD20 blends were 36.1 % and 36.0 %, respectively, while the brake-specific fuel consumption (BSFC) of the two blends were 0.260 kg/kWh, and 0.262 kg/kWh, respectively. These values closely resemble those typically observed in diesel fuel engines. Indeed, the average BTE of the BD20 blend was only 3.24 % less than the average BTE of diesel fuel. Diesel fuel generates less NO_x and SO₂ emissions compared to biodiesel blends: BD100 emitted the most NO_x pollution of all fuels tested. In addition, BD10 released significantly more SO₂ emissions compared to the other fuels tested. However, the BD20 blend outperformed all other blends in terms of CO, NO_x, and SO₂ emissions at high engine speeds. The only exception was H₂S emissions, which were higher than BD50 and BD100. BD20 also exhibited significantly reduced CO emissions compared to diesel fuel, while BD10 emitted significantly more CO emissions than the other biodiesel blends. Our findings revealed that BD20 exhibited the best engine performance and lower emissions among all fuels tested. In other words, BD20 is the ideal fuel blend for use in diesel engines and does not require any alterations to the engine. Muskmelon waste seeds represent a non-edible waste stream that can be exploited in the production of biodiesel fuel, allowing for the upcycling of a potentially problematic thermochemical conversion feedstock. This potentially valuable use for waste muskmelon seeds in the energy sector could address the wastefulness associated with this particular waste stream.

The built environment is a significant contributor to global energy demand, particularly in the Gulf Cooperation Council (GCC) countries, where it accounts for roughly two-thirds of total energy consumption. The GCC region is known for its high per capita energy consumption, and addressing the building sector’s excessive energy use is crucial for a sustainable future. Despite efforts by GCC governments to encourage the adoption of building energy efficiency (BEE) measures, numerous barriers hinder their implementation and diffusion. This paper provides a comprehensive exploration of the barriers to BEE adoption in the GCC, identifying and categorizing 46 such barriers into six distinct clusters: governmental and institutional, economic and financial, technical and technological, capacity and awareness, social and cultural, and market and industry barriers. The study employs a qualitative methodology, utilizing content analysis to identify common themes and patterns in the data collected from various sources, including academic literature, government publications, and international agency reports. The findings underscore that while GCC states have the financial capacity to augment energy efficiency measures through a state-driven approach, they have yet to fully embrace these initiatives, largely due to low energy tariffs and the political dynamics of rentier states. To effectively address these barriers, the study argues for a holistic, interconnected approach that recognizes the government’s role in promoting energy efficiency and sustainability. The implications of this study are crucial for stakeholders, offering insights to facilitate the enhancement of BEE measures in the GCC’s existing and new buildings. By identifying and understanding the complex interplay of factors hindering BEE adoption, policymakers and organizations can develop targeted strategies and policies to overcome these barriers and foster a more sustainable built environment in the GCC region.

Elastocaloric cooling has been considered a promising solid-state technology for cooling and heat pumping among the alternatives to vapor compression, at room temperature range. The technology is based on elastocaloric effect that is a thermophysical phenomenon occurring in materials like Shape Memory Alloys (SMA). The effect is detectable as a temperature change in the material if adiabatically subjected to a forcing field of mechanical nature. The latter provokes to the materials a stress that can derive from tension, compression, bending, torsion solicitations. As a result, the SMA experiments a structural phase change from austenite to martensite (coupled with heat addition) and temperature rise. Dually when the stress is removed, the SMA releases heat with a temperature decrease. In this paper the SUSSTAIN-EL rotary elastocaloric heat pump has been deeply investigated to test the energy performances while it works on open loop and closed loop, through a 2D numerical model based on the finite element method, for cooling and heating operation modes. The device employs a binary NiTi SMA as elastocaloric refrigerant and air as heat transfer medium. A wide set of working conditions has been considered like variable inlet mass flow rate, rotation frequency and thermal loads. The acquired results demonstrate that, both in open and closed loop, the prototype’s energy performances are promising and highly favourable for the intended macroscale collocation of the device.

The aviation industry faces an urgent need to adopt sustainable aviation fuels for significant decarbonization. Power-to-Liquid (PtL) fuel is considered a potential game changer, but questions remain about the wider economic impacts of introducing PtL fuel in the aviation sector. This paper examines the economic impacts of introducing PtL fuel blending quotas along with a price policy consisting of a kerosene tax and PtL fuel subsidies for the case of Germany. Based on a detailed supply chain analysis, we apply a social accounting matrix and a computable general equilibrium model to take into account both, the production and utilization perspectives of PtL jet fuel. Our results show that the influence of low blending quotas is mainly limited to the aviation sector, with a 10 % blending quota increasing consumer prices by 7.9 % and reducing aviation industry output by 3.1 %. When quota levels increase, however, the effects go beyond the air transport system. On inter-sectoral level, we identify three main patterns: First, industries that substantially contribute to the PtL fuel supply chain, such as metal products and electrical equipment, see increasing levels in both, domestic production, and imports. Second, aviation upstream industries like transport infrastructure and aircraft production see reduced domestic production and imports. Third, aviation downstream industries, such as delivery services and travel agencies, see substitution effects, where imports partly replace domestic output. Macroeconomic indicators are affected negatively by the quota scenarios, but the relative impact is low as the maximum decrease in the gross domestic product (GDP) does not exceed 0.35 %. PtL fuel production subsidies can largely mitigate the decrease in aviation demand but come at the cost of a stronger reduction in the GDP and government income. Moreover, the sensitivity analysis emphasizes that various assumptions and parameters, such as the cost projections of PtL fuel, import options, and elasticities of demand, affect the intensity of economic consequences. Our analysis implies the trade-offs of policymaking between sectoral and macroeconomic interests in the context of sustainable fuels. The main contribution of this study is the investigation of the broader economic effects resulting from the adoption of PtL fuels in aviation. In particular, the production as well as the utilization perspective are considered simultaneously in this study.

The air conditioning demand of the world is largely fulfilled by vapor compression systems; however, these systems are also responsible for depleting ozone layer due to the nature of refrigerants. Desiccant cooling systems integrated with solar thermal energy technologies could be an attractive alternative with some performance enhancement techniques. In this study, transient seasonal performance investigation is performed for an innovative solar integrated desiccant cooling system that uses regenerative evaporative cooler known as solar assisted desiccant integrated Maisotsenko cycle cooler for better cooling performance. Furthermore, transient annual performance analysis of solar system for meeting thermal energy requirement for regenerating the desiccant wheel in summer season and handling heating load of the building in winter season is also carried out with three different solar thermal collector technologies for finding out more efficient technology. The key performance indicators in this study are useful energy gain, solar source efficiency, auxiliary energy sharing, coefficient of performance, and solar fraction. The results of the key performance parameters are reported as monthly average values. The proposed integrated system resulted to be very efficient with a maximum COP value of 1.13 in April when latent cooling loads are low and 0.78 in August when latent cooling loads are higher. The system’s maximum cooling capacity is 24 kW in April corresponding to a sensible heat factor of 0.720. Furthermore, the regeneration temperature requirements ranged from 50 °C to 78 °C, respectively that makes it favorable to use low grade thermal energy through non concentrating solar thermal collectors. The regeneration thermal energy requirement for desiccant wheel fluctuates throughout the year, maximizing in August due to higher dehumidification requirements. The study also revealed that the evacuated tube collector technology is most suitable with average annual efficiency of around 36 %.

In recent times, there has been a notable surge in interest regarding the utilization of microalgae for biodiesel production through wastewater treatment. This can be attributed to the versatile nature of microalgae to thrive in various water systems, including wastewater systems, and their ability to show a high rate of photosynthesis. This research aims to assess the viability of utilizing Scenedesmus parvus microalgae, commonly used in the treatment of wastewater, as a potential source of oil feedstock for biofuel production. To extract oil from microalgae, a Soxhlet extraction technique was employed, using methanol for both extraction and separation processes. The extraction process was carried out under differing experimental conditions, including variable extraction temperatures (40–80 °C), extraction period (3–12 h), and algae to solvent ratios (S/L) (1:05–1:10). The microalgae exhibited a maximum oil yield of about 24% when subjected to the extraction conditions of an 8-hour extraction period, an extraction temperature of 70 °C, and a methanol to algae ratio of 1:10. The extraction process of algae oil using the Soxhlet method was analyzed for its thermodynamic and kinetic properties using a second-order equation and Eyring's theory, respectively. In this process, biodiesel was successfully produced with an efficiency of approximately 92.2 ± 0.8% through an alkaline transesterification reaction. This reaction was conducted at a temperature of 65 °C, using a catalyst concentration of 1 wt% (KOH), with the ratio of algae oil to methanol set at 1:9, for 3 h. The biodiesel obtained from microalgae in this research conformed to the global biodiesel standards, specifically ASTM D6751 and EN 14214. The findings emphasize the viability of Scenedesmus parvus microalgae as a valuable resource for biodiesel production.

The pursuit of renewable fuels for the transportation sector, particularly for combustion engines like diesel, is crucial in reducing greenhouse gas emissions. This study introduces an innovative strategy for biodiesel production utilizing marine macroalgae Ulva lactuca as the primary feedstock, emphasizing sustainability and resource efficiency. Lipids were extracted from the macroalgae via a Soxhlet process and characterized using GC–MS and FTIR to ascertain fatty acid composition and functional groups. The Cu–BTC@AC catalyst, synthesized from the lipid-extracted algae residue via pyrolysis and hydrothermal treatment, underwent characterization using SEM–EDS, XRD, and FTIR techniques. Subsequently, the Cu–BTC@AC catalyst was employed in the transesterification process to efficiently convert the extracted algal lipids into biodiesel, achieving a high yield of 92.56 % under RSM-optimized conditions: 65 °C temperature, 3.96 wt% catalyst amount, 15:1 methanol-to-lipid ratio, and 140 min reaction time. Kinetic and thermodynamic parameters for biodiesel production were calculated as follows: E_a = 33.20 kJ mol⁻¹, ΔH^# = 30.39 kJ mol⁻¹, ΔS^# = –165.86 J mol⁻¹ K⁻¹, and ΔG^# = 86.48 kJ mol⁻¹. GC–MS analysis identified a significant FAME content in the biodiesel, comprising 98.12 % of its composition. Notably, the Cu–BTC@AC catalyst exhibited excellent reusability, maintaining 80.21 % biodiesel yield after the third cycle. Moreover, physicochemical analysis of the biodiesel confirmed its compliance with ASTM D6751 specifications, underscoring its potential as a viable alternative fuel for the transportation sector.

The pursuit of sustainable hydrogen production through the conversion of methane (CH₄) and carbon dioxide (CO₂), two prevalent greenhouse gases, is advanced by utilizing cost-effective Ni-supported catalysts within the framework of methane dry reforming. Utilizing crystalline porous zeolite, specifically ZSM-5, enhances the dispersion of nickel (Ni) across the catalyst surface and within its pore channels, hence increasing catalytic efficiency. Herein, we investigate the impact of incorporating various promoters (Ce, Cs, Cu, Fe, Sr) into the 5Ni/ZSM-5 catalyst, systematically examining how these modifications influence the reducibility, basicity, and crystallinity of the catalyst’s active sites, thereby affecting its hydrogen yield potential.

Our findings reveal that the inferior activity of Cu-promoted catalysts is due to the depletion of basic sites and larger NiO crystallite size (than rest-promoted catalysts). The introduction of Fe results in a highly dispersed Ni with a stable NiFe phase, but dilution of active sites results in low hydrogen yield. Conversely, Sr promotion enhances the basicity and accessibility of NiO active sites both on the surface and within the pore channels of the zeolite, leading to a notable hydrogen yield of 28 % at 700℃ after 300 min. Furthermore, the addition of 2 wt% ceria significantly optimizes Ni dispersion within the pore channels and surges the maximum population of basic sites (including the presence of very strong basic sites), achieving 35 % hydrogen yield at 700 °C and ∼ 70 % at 800℃. This investigation underscores the critical role of promoter-induced modifications in enhancing catalyst performance for hydrogen production, contributing to the development of more efficient and sustainable energy conversion technologies.

Driven by a rapid surge in cooling demand in buildings, the energy consumption dedicated to cooling has experienced remarkable growth. To address this challenge, the adoption of latent heat thermal energy storage utilizing phase change materials (PCM) has gained significant momentum in recent years. This paper presents the design and evaluation of an integrated latent heat thermal energy storage (ILHTES) system tailored for residential buildings. This system integrates a PCM-to-air heat exchanger (PAHX) with an air conditioning unit. Modelica language is utilized to develop a numerical model for the ILHTES system. The heat transfer model of the PAHX is developed and validated using existing literature data. To simulate the dynamic behavior and energy consumption of the residential building, the open-source library AixLib is adopted. The developed ILHTES system model is used for the optimization of key design variables, including the PCM slab thickness and air flow rate, based on the results of long-term simulations covering the entire cooling season. Evaluation of the energy saving potential of the optimized ILHTES systems is carried out in comparison to conventional air conditioning systems, considering various climatic conditions in five European cities. The results highlight the profound impact of PCM types on the Energy Saving Ratio (ESR) throughout the entire cooling season. Among the four commercially available PCMs examined—RT27, RT25, RT20, and RT18—RT25 consistently outperforms the others. Across all five cities investigated, using RT25 leads to a minimum ESR of 16% in Catania and a maximum ESR of 44.7% in Stockholm for the entire cooling season.