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Article
Publication date: 20 August 2019

B. Saleh, Ayman A. Aly, M. Alsehli, M.M. Bassuoni and A. Elfasakhany

This paper aims to investigate the performance and working fluids screening for an ejector refrigeration cycle (ERC) activated by solar energy. Several common and new…

158

Abstract

Purpose

This paper aims to investigate the performance and working fluids screening for an ejector refrigeration cycle (ERC) activated by solar energy. Several common and new hydrofluorocarbons, hydrocarbons, hydrofluoroolefins and hydrofluoroethers are proposed as refrigerants for the ERC to determine the most appropriate one.

Design/methodology/approach

The ejector performance is characterized by the ejector area ratio (EAR) and entrainment ratio (ω), while the cycle performance is described by the coefficient of performance (COP). The influences of many working parameters like the evaporator, condenser and generator temperatures on the ejector and cycle performances are investigated for all candidates as well.

Findings

The results indicate that the best ejector and cycle performances are attained with the highest critical temperature dry refrigerant, i.e. R601 under all studied working conditions. From the perspective of energy efficiency and environmental issues, R601 can be considered the most appropriate working fluid amongst all candidates. However, extra attention should be considered against its flammability. The maximum COP, the corresponding ω and the necessary EAR using R601 are 0.743, 1.02 and 15.5, respectively, with 25 ºC condenser temperature and the typical values for the rest operating conditions.

Originality/value

Many common and new hydrofluorocarbons, hydrocarbons, hydrofluoroolefins and hydrofluoroethers are suggested as working fluids for the ERC to determine the most appropriate one. The mixing process inside the ejector constant-area section is assumed constant-pressure process.

Details

World Journal of Engineering, vol. 16 no. 5
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 23 September 2022

Dinesh R., Stanly Jones Retnam, Dev Anand M. and Edwin Raja Dhas J.

The demand for energy is increasing massively due to urbanization and industrialization. Due to the massive usage of diesel engines in the transportation sector, global warming is…

92

Abstract

Purpose

The demand for energy is increasing massively due to urbanization and industrialization. Due to the massive usage of diesel engines in the transportation sector, global warming is increasing rapidly. The purpose of this paper is to use hydrogen as the potential alternative for diesel engine.

Design/methodology/approach

A series of tests conducted in the twin cylinder four stroke diesel engine at various engine speeds. In addition to the hydrogen, the ultrasonication is applied to add the nanoparticles to the neat diesel. The role of nanoparticles on engine performance is effective owing to its physicochemical properties. Here, neat diesel mixed 30% of biodiesel along with the hydrogen at the concentration of 10%, 20% and 30% and 50 ppm of graphite oxide to form the blends DNH10, DNH20 and DNH30.

Findings

Inclusion of both hydrogen and nanoparticles increases the brake power and brake thermal efficiency (BTE) of the engine with relatively less fuel consumption. Compared to all blends, the maximum BTE of 33.3% has been reported by 30% hydrogen-based fuel. On the contrary, the production of the pollutants also reduces as the hydrogen concentration increases.

Originality/value

Majority of the pollutants such as carbon monoxide, carbon dioxide and hydrocarbon were dropped massively compared to diesel. On the contrary, there is no reduction in nitrogen of oxides (NOx). Highest production of NOx was witnessed for 30% hydrogen fuel due to the premixed combustion phase and cylinder temperatures.

Details

Aircraft Engineering and Aerospace Technology, vol. 96 no. 8
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 13 September 2024

A.M. Obalalu, E.O. Fatunmbi, J.K. Madhukesh, S.H.A.M. Shah, Umair Khan, Anuar Ishak and Taseer Muhammad

Recent advancements in technology have led to the exploration of solar-based thermal radiation and nanotechnology in the field of fluid dynamics. Solar energy is captured through…

46

Abstract

Purpose

Recent advancements in technology have led to the exploration of solar-based thermal radiation and nanotechnology in the field of fluid dynamics. Solar energy is captured through sunlight absorption, acting as the primary source of heat. Various solar technologies, such as solar water heating and photovoltaic cells, rely on solar energy for heat generation. This study focuses on investigating heat transfer mechanisms by utilizing a hybrid nanofluid within a parabolic trough solar collector (PTSC) to advance research in solar ship technology. The model incorporates multiple effects that are detailed in the formulation.

Design/methodology/approach

The mathematical model is transformed using suitable similarity transformations into a system of higher-order nonlinear differential equations. The model was solved by implementing a numerical procedure based on the Wavelets and Chebyshev wavelet method for simulating the outcome.

Findings

The velocity profile is reduced by Deborah's number and velocity slip parameter. The Ag-EG nanoparticles mixture demonstrates less smooth fluid flow compared to the significantly smoother fluid flow of the Ag-Fe3O4/EG hybrid nanofluids (HNFs). Additionally, the Ag-Ethylene Glycol nanofluids (NFs) exhibit higher radiative performance compared to the Ag-Fe3O4/Ethylene Glycol hybrid nanofluids (HNFs).

Practical implications

Additionally, the Oldroyd-B hybrid nanofluid demonstrates improved thermal conductivity compared to traditional fluids, making it suitable for use in cooling systems and energy applications in the maritime industry.

Originality/value

The originality of the study lies in the exploration of the thermal transport enhancement in sun-powered energy ships through the incorporation of silver-magnetite hybrid nanoparticles within the heat transfer fluid circulating in parabolic trough solar collectors. This particular aspect has not been thoroughly researched previously. The findings have been validated and provide a highly positive comparison with the research papers.

Details

Multidiscipline Modeling in Materials and Structures, vol. 20 no. 6
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 11 November 2024

Taghreed H. Alarabi and Nasser S. Elgazery

Try to find a way to treat wastewater and achieve its purification from suspended waste, which was removed by examining the magneto-Williamson fluid on a horizontal cylindrical…

8

Abstract

Purpose

Try to find a way to treat wastewater and achieve its purification from suspended waste, which was removed by examining the magneto-Williamson fluid on a horizontal cylindrical tube while taking advantage of solar radiation and nanotechnology.

Design/methodology/approach

The effect of Cattaneo–Christoph law of heat transfer, solar radiation, oblique magnetic field, porosity and internal heat generation on the flow was studied. The control system was solved by the numerical technique of Chebyshev pseudospectrum (CPS) with the help of the program MATHEMATICA 12. The tables comparing the published data results with the existing numerical calculation match exactly.

Findings

The tables comparing the published data results with the existing numerical calculation match exactly. The current simulation results indicate that when using variable viscosity, the Nusselt number and surface friction decrease significantly compared to their value in the case of constant viscosity, and variable viscosity has a significant effect on flow, which reduces speed. Curves and increasing temperature profiles.

Originality/value

Developing a theoretical framework for the problem of sewage turbidity in a healthier and less costly way, by studying the flow of Williamson fluid with variable viscosity (to describe the intensity of sewage turbidity) on a horizontal cylindrical tube, and taking advantage of nanotechnology, solar radiation, Christoph’s thermal law and internal heat generation to reach water free of impurities. Inclined magnetic force and porous force were used, both of which played an effective role in the purification process.

Details

Multidiscipline Modeling in Materials and Structures, vol. 21 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 7 June 2024

Salem H. Abdelgader, Marzena Kurpinska, Hakim Salem Abdelgader, Farzam Omidi Moaf and Mugahed Amran

The research investigates the impact of concrete design methods on performance, emphasizing environmental sustainability. The study compares the modified Bolomey method and…

36

Abstract

Purpose

The research investigates the impact of concrete design methods on performance, emphasizing environmental sustainability. The study compares the modified Bolomey method and Abrams’ law in designing concretes. Significant differences in cement consumption and subsequent CO2 emissions are revealed. The research advocates for a comprehensive life cycle assessment, considering factors like compressive strength, carbonation resistance, CO2 emissions, and cost. The analysis underscores the importance of evaluating concrete not solely based on strength but also environmental impact. The study concludes that a multicriteria approach, considering the entire life cycle, is essential for sustainable concrete design, addressing durability, environmental concerns, and economic factors.

Design/methodology/approach

The study employed a comprehensive design and methodology approach, involving the formulation and testing of 20 mixed concretes with strengths ranging from 25 MPa to 45 MPa. Two distinct design methods, the modified Bolomey method (three equations method) and Abrams’ law, were utilized to calculate concrete compositions. Laboratory experiments were conducted to validate the computational models, and subsequent analyses focused on assessing differences in cement consumption, compressive strength, CO2 emissions, and concrete resistance to carbonation. The research adopted a multidisciplinary perspective, integrating theoretical analysis, laboratory testing, and life cycle assessment to evaluate concrete performance and sustainability.

Findings

Conclusion from the study includes substantial variations (56%–112%) in cement content, depending on the calculation method. Abrams' law proves optimal for compressive strength (30 MPa–45 MPa), while the three equations method yields higher actual strength (30%–51%). Abrams' law demonstrates optimal cement use, but concrete designed with the three equations method exhibits superior resistance to aggressive environments. Cement content exceeding 450 kg/m³ is undesirable. Concrete designed with Abrams' law is economically favorable (12%–30% lower costs). The three equations method results in higher CO2 emissions (38–83%), emphasizing the need for life cycle assessment.

Originality/value

This study’s originality lies in its holistic evaluation of concrete design methods, considering environmental impact, compressive strength, and cost across a comprehensive life cycle. The comparison of the traditional Abrams' law and the three equations method, along with detailed laboratory tests, contributes novel insights into optimal cement use and concrete performance. The findings underscore the importance of a multicriteria approach, emphasizing sustainability and economic viability. The research provides valuable guidance for engineers and policymakers seeking environmentally conscious and economically efficient concrete design strategies, addressing a critical gap in the field of construction materials and contributing to sustainable infrastructure development.

Details

International Journal of Building Pathology and Adaptation, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2398-4708

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Article
Publication date: 1 November 2024

Fuad Baba, Jihad Awad, Yazan Elkahlout and Mohammed Sherzad

This paper aims to compare the impacts of adaptive daily and seasonal cooling setpoints on cooling energy consumption and overheating hours to determine which approach is more…

22

Abstract

Purpose

This paper aims to compare the impacts of adaptive daily and seasonal cooling setpoints on cooling energy consumption and overheating hours to determine which approach is more effective in a desert climate, develop a methodology that effectively integrates passive strategies with adaptive daily and seasonal cooling setpoint strategies and assess how future climate conditions will impact these strategies in the medium and long term.

Design/methodology/approach

(1) Integrate adaptive thermal comfort principles into mechanical cooling systems to find the optimized cooling setpoint. (2) Evaluating the optimized cooling setpoints using a mixed-mode operation: In this step, the natural ventilation is activated by opening 40% of the window area when the indoor temperature is higher than 23°C and the outdoor temperature. Both the adaptive seasonal and daily setpoint strategies are evaluated. (3) If overheating hours exceed acceptable limits gradually add mitigation measures (e.g. exterior shading, cool roofs and green roofs). (4) If necessary, further reduce the cooling setpoint until acceptable limits are met. (5) Generate extreme future climate scenarios and evaluate the optimized model. (6) Implement additional measures and setpoint adjustments to maintain acceptable overheating hours in future conditions.

Findings

Although the building complies with the Dubai Green Code and uses external shading, its cooling energy consumption was 92 kWh/m² in 2021 with a 24°C setpoint. Using the adaptive seasonal setpoint combined with a cool roof, night cooling and cross-ventilation reduces cooling energy consumption by 52, 48 and 35% in 2020, 2050 and 2090, respectively, with overheating hours not exceeding 40 h annually. Using an adaptive daily setpoint strategy with the same mitigation measures is similarly effective; it achieved a 57, 42 and 34% reduction in cooling energy consumption in 2020, 2050 and 2090, respectively, while eliminating overheating hours.

Originality/value

The originality and value of this study lie in optimizing cooling setpoints without the effect of overheating hours in desert climates. Using the adaptive seasonal setpoint combined with a cool roof, night cooling and cross-ventilation reduces cooling energy consumption by 52, 48 and 35% in 2020, 2050 and 2090, respectively, with overheating hours not exceeding 40 h annually. Using an adaptive daily setpoint strategy with the same mitigation measures is similarly effective; it achieved a 57, 42 and 34% reduction in cooling energy consumption in 2020, 2050 and 2090, respectively, while eliminating overheating hours.

Highlights

  • (1)

    A methodology is developed to find the optimal cooling setpoints

  • (2)

    Adaptive thermal comfort concept is extended for integration with a cooling system

  • (3)

    Validation simulation model is used using certain building information

  • (4)

    Climate change effect is studied using current and future warmer typical years

  • (5)

    Effective passive summer mitigation measures are studied

A methodology is developed to find the optimal cooling setpoints

Adaptive thermal comfort concept is extended for integration with a cooling system

Validation simulation model is used using certain building information

Climate change effect is studied using current and future warmer typical years

Effective passive summer mitigation measures are studied

Details

Smart and Sustainable Built Environment, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2046-6099

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Article
Publication date: 16 August 2023

Taraprasad Mohapatra, Sudhansu Sekhar Mishra, Mukesh Bathre and Sudhansu Sekhar Sahoo

The study aims to determine the the optimal value of output parameters of a variable compression ratio (CR) diesel engine are investigated at different loads, CR and fuel modes of…

414

Abstract

Purpose

The study aims to determine the the optimal value of output parameters of a variable compression ratio (CR) diesel engine are investigated at different loads, CR and fuel modes of operation experimentally. The output parameters of a variable compression ratio (CR) diesel engine are investigated at different loads, CR and fuel modes of operation experimentally. The performance parameters like brake thermal efficiency (BTE) and brake specific energy consumption (BSEC), whereas CO emission, HC emission, CO2 emission, NOx emission, exhaust gas temperature (EGT) and opacity are the emission parameters measured during the test. Tests are conducted for 2, 6 and 10 kg of load, 16.5 and 17.5 of CR.

Design/methodology/approach

In this investigation, the first engine was fueled with 100% diesel and 100% Calophyllum inophyllum oil in single-fuel mode. Then Calophyllum inophyllum oil with producer gas was fed to the engine. Calophyllum inophyllum oil offers lower BTE, CO and HC emissions, opacity and higher EGT, BSEC, CO2 emission and NOx emissions compared to diesel fuel in both fuel modes of operation observed. The performance optimization using the Taguchi approach is carried out to determine the optimal input parameters for maximum performance and minimum emissions for the test engine. The optimized value of the input parameters is then fed into the prediction techniques, such as the artificial neural network (ANN).

Findings

From multiple response optimization, the minimum emissions of 0.58% of CO, 42% of HC, 191 ppm NOx and maximum BTE of 21.56% for 16.5 CR, 10 kg load and dual fuel mode of operation are determined. Based on generated errors, the ANN is also ranked for precision. The proposed ANN model provides better prediction with minimum experimental data sets. The values of the R2 correlation coefficient are 1, 0.95552, 0.94367 and 0.97789 for training, validation, testing and all, respectively. The said biodiesel may be used as a substitute for conventional diesel fuel.

Originality/value

The blend of Calophyllum inophyllum oil-producer gas is used to run the diesel engine. Performance and emission analysis has been carried out, compared, optimized and validated.

Details

World Journal of Engineering, vol. 21 no. 5
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 7 March 2023

Miral Sabry AlAshry

The purpose of this study is to investigate the extent of digital surveillance by Arab authorities, which face risks and threats of surveillance, and how journalists seek to press…

361

Abstract

Purpose

The purpose of this study is to investigate the extent of digital surveillance by Arab authorities, which face risks and threats of surveillance, and how journalists seek to press freedom by using tools and techniques to communicate securely.

Design/methodology/approach

The study used focus group discussions with 14 journalists from Syria, Saudi Arabia, Libya, Yemen, Oman, Jordan and Egypt. While in Egypt, questionnaires were distributed to 199 journalists from both independent and semi-governmental outlets to investigate how Egyptian journalists interpret the new data protection law and its implications for press freedom.

Findings

The study indicated that journalists from these countries revealed severe censorship by their respective governments, an element inconsistent with the Arab Constitution. The recommendation of the study encourages media organisations to play a more active role in setting policies that make it easier for journalists to adopt and use digital security tools, while Egyptian journalists see the law as a barrier to media independence because it allows the government to exercise greater information control through digital policy and imposes regulatory rules on journalists.

Practical implications

The study identifies practical and theoretical issues in Arab legislation and may reveal practices of interest to scientists researching the balance between data protection, the right of access to information and media research as an example of contemporary government indirect or “soft” censorship methods.

Originality/value

To the best of the authors’ knowledge, this paper is one of the first research contributions to analyse the relationships between Arab authoritarians who used surveillance to restrict freedom of the press after the Arab Spring revolutions of 2011 to keep themselves in power as long as they could. In addition, Egypt's use of surveillance under new laws allowed the regimes to install software on the journalists’ phones that enabled them to read the files and emails and track their locations; accordingly, journalists can be targeted by the cyberattack and can be arrested.

Details

Digital Policy, Regulation and Governance, vol. 25 no. 3
Type: Research Article
ISSN: 2398-5038

Keywords

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