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Application of a range extender in an electric vehicle can reduce the battery bank size and extend the driving range on a need basis. A micro gas turbine offers high power density, fuel flexibility, a reliable thermal efficiency (with recuperation), and less raw exhaust gaseous emissions compared to an internal combustion engine. However, micro gas turbines also incur low component performances due to small-scale effects related to high viscous losses, heat transfer between hot and cold sections, and manufacturing and assembly constraints compared to their larger counterparts. In this paper, the micro gas turbine thermodynamic cycle has been designed in Gas Turbine Simulation Program (GSP) and evaluated in terms of the small-scale effects simultaneously with the battery bank energy and charging time analysis. The key objective is to demonstrate the effectiveness of a micro gas turbine in saving the weight of a range-extended electric vehicle while understanding the impact of small-scale effects on the battery bank energy and charging time. Results indicate that a relatively smaller 22-kWh battery bank can be utilized with prospects of cost-savings together with a 47-kW micro gas turbine range extender to achieve an average driving range of 100 km and a charging time of 30 min for the baseline electric vehicle. Furthermore, the compressor and turbine isentropic efficiencies are found to have a significant impact on the overall battery bank performance.
Adeel Javed; Hassan Abdullah Khalid; Syed Umer bin Arif; Muhammad Imran; Ahmed Rezk; Zafar Ali Khan. Micro Gas Turbine Small-Scale Effects in Range Extended Electric Vehicles. Journal of Energy Resources Technology 2021, 143, 1 -18.
AMA StyleAdeel Javed, Hassan Abdullah Khalid, Syed Umer bin Arif, Muhammad Imran, Ahmed Rezk, Zafar Ali Khan. Micro Gas Turbine Small-Scale Effects in Range Extended Electric Vehicles. Journal of Energy Resources Technology. 2021; 143 (12):1-18.
Chicago/Turabian StyleAdeel Javed; Hassan Abdullah Khalid; Syed Umer bin Arif; Muhammad Imran; Ahmed Rezk; Zafar Ali Khan. 2021. "Micro Gas Turbine Small-Scale Effects in Range Extended Electric Vehicles." Journal of Energy Resources Technology 143, no. 12: 1-18.
This study explores the effects of inter-farm wakes and proposes staggering schemes that are most suitable for optimization of existing wind farm arrays to mitigate the effects of compound wakes. The case study considers a total of 9 out of 33 most deteriorated wind turbine for a microscale numerical analysis using the steady-state actuator disk model coupled with the mesoscale boundary condition data. Furthermore, the convective atmospheric boundary layer has also been considered. For vertically staggered layouts, the effect of the inter-farm wakes appeared mild at 100 m, modest at 80 m, and high at 60 m; as the maximum velocity deficit observed under the influence of compound wakes is approximately 13.3%, 14.1%, and 15.2%, respectively. Onsite recorded power data has been used to validate the baseline predicted powers at 80 m hub height. Both vertical and horizontal staggering options have been assessed for partial repowering. By elevating the turbines to a 100 m hub height, the cumulative power generation from the 9 × turbines increased by approximately 13.5% while reducing the hub height to 60 m decreased the power output by approximately 11.5% of that of the baseline at 80 m hub height. Further increase in cumulative power of up to 23% compared to existing layout is achieved by applying a lateral repositioning of 3 × underperforming turbines now positioned at 100 m hub height. This paper hence presents an applied insight for partial repowering of onshore wind farms affected by inter-farm wakes.
Mehtab Ahmad Khan; Adeel Javed; Sehar Shakir; Abdul Haseeb Syed. Optimization of a wind farm by coupled actuator disk and mesoscale models to mitigate neighboring wind farm wake interference from repowering perspective. Applied Energy 2021, 298, 117229 .
AMA StyleMehtab Ahmad Khan, Adeel Javed, Sehar Shakir, Abdul Haseeb Syed. Optimization of a wind farm by coupled actuator disk and mesoscale models to mitigate neighboring wind farm wake interference from repowering perspective. Applied Energy. 2021; 298 ():117229.
Chicago/Turabian StyleMehtab Ahmad Khan; Adeel Javed; Sehar Shakir; Abdul Haseeb Syed. 2021. "Optimization of a wind farm by coupled actuator disk and mesoscale models to mitigate neighboring wind farm wake interference from repowering perspective." Applied Energy 298, no. : 117229.
A clear understanding of the flow characteristics in the older generation of industrial gas turbines operating with silo combustors is important for potential upgrades. Non-uniformities in the form of circumferential and radial variations in internal flow properties can have a significant impact on the gas turbine stage performance and durability. This paper presents a comprehensive study of the underlying internal flow features involved in the advent of non-uniformities from twin-silo combustors and their propagation through a single axial turbine stage of the Siemens v94.2 industrial gas turbine. Results indicate the formation of strong vortical structures alongside large temperature, pressure, velocity, and flow angle deviations that are mostly located in the top and bottom sections of the turbine stage caused by the excessive flow turning in the upstream tandem silo combustors. A favorable validation of the simulated exhaust gas temperature (EGT) profile is also achieved via comparison with the measured data. A drop in isentropic efficiency and power output equivalent to 2.28% points and 2.1 MW, respectively is observed at baseload compared to an ideal straight hot gas path reference case. Furthermore, the analysis of internal flow topography identifies the underperforming turbine blading due to the upstream non-uniformities. The findings not only have implications for the turbine aerothermodynamic design, but also the combustor layout from a repowering perspective.
Hafiz M Hassan; Adeel Javed; Asif H Khoja; Majid Ali; Muhammad B Sajid. Numerical investigation of non-uniform flow in twin-silo combustors and impact on axial turbine stage performance. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 2021, 1 .
AMA StyleHafiz M Hassan, Adeel Javed, Asif H Khoja, Majid Ali, Muhammad B Sajid. Numerical investigation of non-uniform flow in twin-silo combustors and impact on axial turbine stage performance. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy. 2021; ():1.
Chicago/Turabian StyleHafiz M Hassan; Adeel Javed; Asif H Khoja; Majid Ali; Muhammad B Sajid. 2021. "Numerical investigation of non-uniform flow in twin-silo combustors and impact on axial turbine stage performance." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy , no. : 1.
The integration of commercial onshore large-scale wind farms into a national grid comes with several technical issues that predominately ensure power quality in accordance with respective grid codes. The resulting impacts are complemented with the absorption of larger amounts of reactive power by wind generators. In addition, seasonal variations and inter-farm wake effects further deteriorate the overall system performance and restrict the optimal use of available wind resources. This paper presented an assessment framework to address the power quality issues that have arisen after integrating large-scale wind farms into weak transmission grids, especially considering inter-farm wake effect, seasonal variations, reactive power depletion, and compensation with a variety of voltage-ampere reactive (Var) devices. Herein, we also proposed a recovery of significant active power deficits caused by the wake effect via increasing hub height of wind turbines. For large-scale wind energy penetration, a real case study was considered for three wind farms with a cumulative capacity of 154.4 MW integrated at a Nooriabad Grid in Pakistan to analyze their overall impacts. An actual test system was modeled in MATLAB Simulink for a composite analysis. Simulations were performed for various scenarios to consider wind intermittency, seasonal variations across four seasons, and wake effect. The capacitor banks and various flexible alternating current transmission systems (FACTS) devices were employed for a comparative analysis with and without considering the inter-farm wake effect. The power system parameters along with active and reactive power deficits were considered for comprehensive analysis. Unified power flow controller (UPFC) was found to be the best compensation device through comparative analysis, as it maintained voltage at nearly 1.002 pu, suppressed frequency transient in a range of 49.88–50.17 Hz, and avoided any resonance while maintaining power factors in an allowable range. Moreover, it also enhanced the power handling capability of the power system. The 20 m increase in hub height assisted the recovery of the active power deficit to 48%, which thus minimized the influence of the wake effect.
Shah Rukh Abbas; Syed Ali Abbas Kazmi; Muhammad Naqvi; Adeel Javed; Salman Raza Naqvi; Kafait Ullah; Tauseef-Ur-Rehman Khan; Dong Ryeol Shin. Impact Analysis of Large-Scale Wind Farms Integration in Weak Transmission Grid from Technical Perspectives. Energies 2020, 13, 5513 .
AMA StyleShah Rukh Abbas, Syed Ali Abbas Kazmi, Muhammad Naqvi, Adeel Javed, Salman Raza Naqvi, Kafait Ullah, Tauseef-Ur-Rehman Khan, Dong Ryeol Shin. Impact Analysis of Large-Scale Wind Farms Integration in Weak Transmission Grid from Technical Perspectives. Energies. 2020; 13 (20):5513.
Chicago/Turabian StyleShah Rukh Abbas; Syed Ali Abbas Kazmi; Muhammad Naqvi; Adeel Javed; Salman Raza Naqvi; Kafait Ullah; Tauseef-Ur-Rehman Khan; Dong Ryeol Shin. 2020. "Impact Analysis of Large-Scale Wind Farms Integration in Weak Transmission Grid from Technical Perspectives." Energies 13, no. 20: 5513.
Forecasting skills for a wind farm would significantly degrade if the complex wake effects of the upstream wind farms are excluded, especially when they are spatially close to each other. In this study, the Weather Research and Forecasting (WRF) model has been used to predict wind speed and power for a wind farm in Pakistan in the presence of wake interference from neighboring wind farms for two different seasons. Forecasting is done for two different cases i.e. without and with inter-farm wake effects, and different statistical error parameters were evaluated based on the real observations. A significant reduction in errors was observed in the latter case. For instance, the mean absolute errors in wind speed prediction were reduced by 7.7% and 14% in June (summer) and January (winter) respectively, by the inclusion of inter-farm wake effects. Similarly, an improved forecast of power output was obtained by incorporating the interaction of upstream wind farms i.e. a reduction of 15% and 26% in the normalized mean absolute error in power output values was observed for June and January, respectively. However, the prediction accuracy of power output substantially deteriorated in the winter season.
Raja M. Asim Feroz; Adeel Javed; Abdul Haseeb Syed; Syed Ali Abbas Kazmi; Emad Uddin. Wind speed and power forecasting of a utility-scale wind farm with inter-farm wake interference and seasonal variation. Sustainable Energy Technologies and Assessments 2020, 42, 100882 .
AMA StyleRaja M. Asim Feroz, Adeel Javed, Abdul Haseeb Syed, Syed Ali Abbas Kazmi, Emad Uddin. Wind speed and power forecasting of a utility-scale wind farm with inter-farm wake interference and seasonal variation. Sustainable Energy Technologies and Assessments. 2020; 42 ():100882.
Chicago/Turabian StyleRaja M. Asim Feroz; Adeel Javed; Abdul Haseeb Syed; Syed Ali Abbas Kazmi; Emad Uddin. 2020. "Wind speed and power forecasting of a utility-scale wind farm with inter-farm wake interference and seasonal variation." Sustainable Energy Technologies and Assessments 42, no. : 100882.
This paper explores passive flow control via leading-edge (LE) slats to reduce the dynamic stall (DS) phenomenon and related blade-wake interaction in an H-Darrieus type vertical axis wind turbine (VAWT) operating under low wind speed conditions. A comprehensive 2D unsteady computational fluid dynamics (CFD) assessment has been carried out for the non-slatted baseline rotor and the advance slatted rotor (ASR) configurations. The unsteady Reynolds-averaged Navier-Stokes (URANS) approach with k-ω shear stress transport (SST) turbulence model and sliding mesh technique have been applied in Ansys Fluent. Optimum slat deflection angle δ has been evaluated using the single-blade oscillatory case with and without the LE slats. Results indicate a reduction in optimum δ from 16° at rated wind speed of 10 ms−1 to 12° for low wind speed operation at 5 ms−1. A significant increase in the maximum coefficient of lift CL,max by approximately 32% and a delay in stall angle of attack αmax by 3° is obtained with ASR configuration compared to the baseline. Further assessment of the ASR configuration on the three-blade rotatory case demonstrates an increase in the power coefficient CP by approximately 15% at the rated tip-speed ratio λ compared to the baseline.
Tariq Ullah; Adeel Javed; Ali Abdullah; Majid Ali; Emad Uddin. Computational evaluation of an optimum leading-edge slat deflection angle for dynamic stall control in a novel urban-scale vertical axis wind turbine for low wind speed operation. Sustainable Energy Technologies and Assessments 2020, 40, 100748 .
AMA StyleTariq Ullah, Adeel Javed, Ali Abdullah, Majid Ali, Emad Uddin. Computational evaluation of an optimum leading-edge slat deflection angle for dynamic stall control in a novel urban-scale vertical axis wind turbine for low wind speed operation. Sustainable Energy Technologies and Assessments. 2020; 40 ():100748.
Chicago/Turabian StyleTariq Ullah; Adeel Javed; Ali Abdullah; Majid Ali; Emad Uddin. 2020. "Computational evaluation of an optimum leading-edge slat deflection angle for dynamic stall control in a novel urban-scale vertical axis wind turbine for low wind speed operation." Sustainable Energy Technologies and Assessments 40, no. : 100748.
The excess emission of greenhouse gases (GHGs) such as CO2 and CH4 is posing an acute threat to the environment, and efficient ways are being sought to utilize GHGs to produce syngas (H2, CO) and lighter hydrocarbons (HCs). In this study, the dry reforming of methane (DRM) has been carried out at 700 °C using La2O3 co-supported Ni/MgAl2O4 nano-catalyst in a fixed bed thermal reactor. The catalyst is characterized using various techniques such as XRD, FESEM, EDX-mapping, CO2-TPD, H2-TPR and TGA. The modified MgAl2O4 shows the flake type structure after the addition of La2O3. The TPR and TPD analysis shows the highly dispersed metal and strong basic nature of the catalyst consequently enhances the conversion of CO2 and CH4. The highest conversion for CH4 is 87.3% while CO2 conversion is nearly 89.5% in 20 h of operation time. The selectivity of H2 and CO approached 50% making the H2/CO ratio above unity. In the longer time-on-stream (TOS) test, the catalyst shows elevated potential for longer runs showcasing better catalytic activity. The stability of the catalyst is indicated via a proposed reaction mechanism for DRM in operating conditions. Moreover, TGA indicates the lower weight loss of spent catalyst which ascribed the lower formation of carbon during TOS 20 h.
Asif Hussain Khoja; Mustafa Anwar; Sehar Shakir; Muhammad Taqi Mehran; Arslan Mazhar; Adeel Javed; Nor Aishah Saidina Amin. Thermal dry reforming of methane over La2O3 co-supported Ni/MgAl2O4 catalyst for hydrogen-rich syngas production. Research on Chemical Intermediates 2020, 46, 3817 -3833.
AMA StyleAsif Hussain Khoja, Mustafa Anwar, Sehar Shakir, Muhammad Taqi Mehran, Arslan Mazhar, Adeel Javed, Nor Aishah Saidina Amin. Thermal dry reforming of methane over La2O3 co-supported Ni/MgAl2O4 catalyst for hydrogen-rich syngas production. Research on Chemical Intermediates. 2020; 46 (8):3817-3833.
Chicago/Turabian StyleAsif Hussain Khoja; Mustafa Anwar; Sehar Shakir; Muhammad Taqi Mehran; Arslan Mazhar; Adeel Javed; Nor Aishah Saidina Amin. 2020. "Thermal dry reforming of methane over La2O3 co-supported Ni/MgAl2O4 catalyst for hydrogen-rich syngas production." Research on Chemical Intermediates 46, no. 8: 3817-3833.
Performance of solar absorption cooling systems (SACS) is the focus of contemporary studies for decreasing the electrical energy consumption of buildings as the conventional cooling system of buildings is the main consumer of electrical energy during the summer season in hot–humid climates. In this study, the performance analysis of SACS by manipulating different flow schemes to the heat transfer fluid between different components of the system was performed. TRNSYS model of SACS in an education building located at the city of Peshawar (34.00 N, 71.54 E), Pakistan to encounter the peak cooling load of 108 kW (during operating hours of the building i.e., 09 a.m. to 05 p.m.) is developed and all possible flow schemes of heat transfer fluid between the system’s components were compared. In Scheme-1 (S-1), a conventional flow pattern is used in which the hot water exiting from the chiller unit flows directly toward the stratified thermal storage unit. In Scheme-2 (S-2), the modified flow pattern of hot water exiting from the chiller unit will divert towards the auxiliary unit, if its temperature exceeds the temperature at the hot side outlet of the tank. Another modified flow pattern is Scheme-3 (S-3) in which the hot water leaving the chiller to keep diverting towards the auxiliary unit unless the outlet temperature from the hotter side of the tank would reach the minimum driving temperature (109 °C) of the chiller’s operation. Simulations in TRNSYS evaluates the SACS’s performance of all the schemes (conventional and modified) for the whole summer season and for each month. In general, S-3 with evacuated tube solar collector results in better primary energy saving with the smallest collector area per kilowatt for achieving 50% primary energy saving for the whole summer season.
Iftikhar Bashir Butt; Jinwang Tan; Adeel Waqas; Majid Ali; Adeel Javed; Asfand Yar Ali. Effect of Modified Flow Schemes of Heat Transfer Fluid on the Performance of a Solar Absorption–Cooling System for an Educational Building in Pakistan. Applied Sciences 2020, 10, 3327 .
AMA StyleIftikhar Bashir Butt, Jinwang Tan, Adeel Waqas, Majid Ali, Adeel Javed, Asfand Yar Ali. Effect of Modified Flow Schemes of Heat Transfer Fluid on the Performance of a Solar Absorption–Cooling System for an Educational Building in Pakistan. Applied Sciences. 2020; 10 (9):3327.
Chicago/Turabian StyleIftikhar Bashir Butt; Jinwang Tan; Adeel Waqas; Majid Ali; Adeel Javed; Asfand Yar Ali. 2020. "Effect of Modified Flow Schemes of Heat Transfer Fluid on the Performance of a Solar Absorption–Cooling System for an Educational Building in Pakistan." Applied Sciences 10, no. 9: 3327.
Repowering augments the power generation capacity of a wind farm in order to enhance the exploitation of the high mean wind speed regions. In this study, a partial repowering strategy has been discussed for an onshore commercial-scale wind farm with deteriorated performance under the influence of wakes originating from upstream wind farms. The mesoscale Weather Research and Forecasting (WRF) model with Wind Farm Parameterization has been employed to evaluate the wind speed and power deficit observed by the individual wind turbine generators. Wakes induced by the upstream wind farms are observed to cause a reduction in wind speed and power output by up to 15% and 35%, respectively. The predicted power was also validated by the observed data for each turbine generator. The hub heights of selected wind turbines with the highest power deficit are varied to alleviate the influence of upstream wind farm wake interference. Power output and wind shear profiles have been evaluated at new hub heights of 61.5 m and 100 m, and results are compared with the existing hub height turbine generators at 80 m. Power output reduced by up to 12% at the lower hub height of 61.5 m as compared to the default case, while an increase of about 13.6% is observed for the 100 m hub height case. A mean increase of 7.5% is estimated in the total wind power generation from the wind farm under evaluation. This paper presents a theoretical and engineering platform for partial repowering of wind farms with depleted generation due to inter-farm wake interaction.
Abdul Haseeb Syed; Adeel Javed; Raja M. Asim Feroz; Ronald Calhoun. Partial repowering analysis of a wind farm by turbine hub height variation to mitigate neighboring wind farm wake interference using mesoscale simulations. Applied Energy 2020, 268, 115050 .
AMA StyleAbdul Haseeb Syed, Adeel Javed, Raja M. Asim Feroz, Ronald Calhoun. Partial repowering analysis of a wind farm by turbine hub height variation to mitigate neighboring wind farm wake interference using mesoscale simulations. Applied Energy. 2020; 268 ():115050.
Chicago/Turabian StyleAbdul Haseeb Syed; Adeel Javed; Raja M. Asim Feroz; Ronald Calhoun. 2020. "Partial repowering analysis of a wind farm by turbine hub height variation to mitigate neighboring wind farm wake interference using mesoscale simulations." Applied Energy 268, no. : 115050.
A kinetic study on dry reforming of methane (DRM) in hybrid dielectric barrier discharge (DBD) plasma reactor over La2O3 co-supported Ni/MgAl2O4 catalyst has been investigated. Three different parametric effects namely specific input energy (SIE), discharge volume (VD) and feed flow rate corresponding to GHSV (h−1) are studied using the modified power-law model. The developed kinetic model indicates instantaneous conversions of CH4 and CO2 are functions of SIE, VD and GHSV. Increasing SIE linearly enhances the conversion of CH4 and CO2, while VD displays a non-linear relation with conversion and selectivity. GHSV also shows a linear relation with instantaneous CH4 and CO2 conversion and selectivity of H2 and CO. The rate constants ( kCH4, kCO2), determined using the proposed kinetic model and various process parameters, are compared with DRM experimental results for validation. The apparent activation energy (Ea), calculated for CH4 and CO2 using modified Arrhenius equation, are = 32.6 kJ mol−1 (CH4) and Ea = 35.2 kJ mol−1 (CO2), respectively. The modified power-law model is a good preliminary description for future understanding of the overall performance of a hybrid catalytic DBD plasma reactor for DRM.
Asif Hussain Khoja; Muhammad Tahir; Nor Aishah Saidina Amin; Adeel Javed; Muhammad Taqi Mehran. Kinetic study of dry reforming of methane using hybrid DBD plasma reactor over La2O3 co-supported Ni/MgAl2O4 catalyst. International Journal of Hydrogen Energy 2020, 45, 12256 -12271.
AMA StyleAsif Hussain Khoja, Muhammad Tahir, Nor Aishah Saidina Amin, Adeel Javed, Muhammad Taqi Mehran. Kinetic study of dry reforming of methane using hybrid DBD plasma reactor over La2O3 co-supported Ni/MgAl2O4 catalyst. International Journal of Hydrogen Energy. 2020; 45 (22):12256-12271.
Chicago/Turabian StyleAsif Hussain Khoja; Muhammad Tahir; Nor Aishah Saidina Amin; Adeel Javed; Muhammad Taqi Mehran. 2020. "Kinetic study of dry reforming of methane using hybrid DBD plasma reactor over La2O3 co-supported Ni/MgAl2O4 catalyst." International Journal of Hydrogen Energy 45, no. 22: 12256-12271.
CO2 capture at high temperature through calcium looping is a capable technology for the implementation of carbon capture and storage (CCS). The major drawback of this process is the rapid deactivation of calcium-based sorbent due to sintering and attrition. To reduce these drawbacks, an environmentally friendly and low-cost approach is highly appreciated by researchers. Efforts were made to introduce a cost-effective and eco-friendly method to reduce sintering and enhance capacity by adding fly ash from coal-fired plants, into Ca-based sorbents with acetic acid through sonochemical and ball milling methods. Four different methods of mixing were used i.e. dry, wet, sonochemical and ball milling methods. The sorbents were characterized by SEM-EDS, XRD, TGA, and XRF. Hydration under acidic conditions with Ca-based sorbent using fly ash showed improved capacity and stability rather than under basic conditions. The sonochemical method achieved the highest CaO conversion of 100% in the first two cycles followed by the ball milling method with 99.8% also maintaining stability through the cycles as compared to other methods. Ball Milling method achieved higher improvement not only to proper mixing of fly ash and CaO but also a reduction in sizes improved conversion and stability, thus it can be considered as a green technology for scaled-up CO2 capture.
Azra Nawar; Majid Ali; Adeel Waqas; Adeel Javed; Naseem Iqbal; Rashid Khan. Effect of Different Activation Processes on CaO/Fly Ash Mixture for CO2 Capture. Energy & Fuels 2019, 34, 2035 -2044.
AMA StyleAzra Nawar, Majid Ali, Adeel Waqas, Adeel Javed, Naseem Iqbal, Rashid Khan. Effect of Different Activation Processes on CaO/Fly Ash Mixture for CO2 Capture. Energy & Fuels. 2019; 34 (2):2035-2044.
Chicago/Turabian StyleAzra Nawar; Majid Ali; Adeel Waqas; Adeel Javed; Naseem Iqbal; Rashid Khan. 2019. "Effect of Different Activation Processes on CaO/Fly Ash Mixture for CO2 Capture." Energy & Fuels 34, no. 2: 2035-2044.
Performance of a vertical axis wind turbines (VAWTs) is a major focus of research these days. The present research focuses on numerical investigate the performance of a VAWT in the presence of upstream bluff bodies and investigate the impact of vortices shed on the VAWT performance. Designing of wind turbine is performed using Multiple Stream Tube Model which uses turbine power, number of turbine blades, aspect ratio and wind speed as parameter. Simulations are done using Reynolds averaged Navier-Stokes equation. Furthermore, VAWT equipped with three NACA 0018 airfoils is used. In this study, single and two upstream bluff bodies are used and the distance of the VAWT relative to a bluff body is changed to 1D, 2D and 3D (where D is the length and width of bluff body) both along and perpendicular to flow direction in order to find an optimal location for maximum power. This study shows that the deflected wind from the bluff body possess high wind velocity which is 12% higher for single bluff body and 25% higher for two bluff bodies than the free stream wind velocity. Moreover the VAWTs can be deployed downstream of tall urban structures for enhancement of wind turbine power generation.
Ammar Naseem; Emad Uddin; Zaib Ali; Jawad Aslam; Samiur Rehman Shah; Muhammad Sajid; Ali Abbas Zaidi; Adeel Javed; Muhammad Yamin Younis. Effect of vortices on power output of vertical axis wind turbine (VAWT). Sustainable Energy Technologies and Assessments 2019, 37, 100586 .
AMA StyleAmmar Naseem, Emad Uddin, Zaib Ali, Jawad Aslam, Samiur Rehman Shah, Muhammad Sajid, Ali Abbas Zaidi, Adeel Javed, Muhammad Yamin Younis. Effect of vortices on power output of vertical axis wind turbine (VAWT). Sustainable Energy Technologies and Assessments. 2019; 37 ():100586.
Chicago/Turabian StyleAmmar Naseem; Emad Uddin; Zaib Ali; Jawad Aslam; Samiur Rehman Shah; Muhammad Sajid; Ali Abbas Zaidi; Adeel Javed; Muhammad Yamin Younis. 2019. "Effect of vortices on power output of vertical axis wind turbine (VAWT)." Sustainable Energy Technologies and Assessments 37, no. : 100586.
Despite the use of composite materials, timber is still widely used in the wind energy industry and especially in small wind turbine blades. Four species of timber namely alder, ash, beech and hornbeam which are grown in Iran were tested for their suitability for use in small blades. A solid blade is easiest to manufacture and is interesting from the structural aspect but its high inertia could delay starting since small turbines have no pitch mechanism to optimize the blade angles of attack during starting. We describe the design and optimization of solid and hollow blades for a small horizontal axis turbine via genetic algorithms. In order to maximize the power coefficient and minimize the starting time, the optimization algorithm tries to find the external/internal geometry of the blades while the resultant stresses do not exceed the allowable stress of the timbers. Regardless of the type of timbers, the optimization results show that the power coefficient of all the optimal blades is sufficiently high but the starting performance requires choosing an appropriate timber. More specifically, the alder solid blade would be better than the beech, hornbeam and ash. For the hollow blades, the alder and beech timbers could be used for windy areas and all four timbers are very promising for operation in low wind speed regions where starting behavior is more important.
Abolfazl Pourrajabian; Maziar Dehghan; Adeel Javed; David Wood. Choosing an appropriate timber for a small wind turbine blade: A comparative study. Renewable and Sustainable Energy Reviews 2018, 100, 1 -8.
AMA StyleAbolfazl Pourrajabian, Maziar Dehghan, Adeel Javed, David Wood. Choosing an appropriate timber for a small wind turbine blade: A comparative study. Renewable and Sustainable Energy Reviews. 2018; 100 ():1-8.
Chicago/Turabian StyleAbolfazl Pourrajabian; Maziar Dehghan; Adeel Javed; David Wood. 2018. "Choosing an appropriate timber for a small wind turbine blade: A comparative study." Renewable and Sustainable Energy Reviews 100, no. : 1-8.
The following are the highlights of the paper titled ‘Small-Scale Turbocompressors for Wide-Range Operation with Large Tip-Clearances for a Two-Stage Heat Pump Concept’ submitted to the International Journal of Refrigeration: • We describe a detailed design review and methodology for miniature oil-free turbocompressors for a heat pump application. • A decentralized 6.5 kW two-stage heat pump concept with multiple heat sources is presented. • The compressors are designed to satisfy different operational and, manufacturing and assembly constraints. • The compressors achieve high stage efficiencies and wide operating range theoretically. • The impeller blades are designed to minimize secondary and tip-leakage flows. Two mechanically driven small-scale turbocompressors running on gas lubricated bearings have been theoretically designed for a 6.5 kW two-stage heat pump functioning under variable operating conditions. The novelty in the heat pump system lies in the application of oil-free turbocompressor technology and the introduction of unused heat from various secondary heat sources. Managing the heat pump operational deviations with the secondary heat is difficult for the turbocompressors. The turbocompressors can potentially exceed their operating range defined by the surge, choke and maximum rotational speed margins. Furthermore, regulating the tip-leakage flow caused by large tip-clearances in small-scale turbomachinery is challenging. This paper will guide the readers through different stages of the design process of small-scale turbocompressors subjected to different operational and design constraints. The design review and the presented methodology will help the designers to make suitable parameter selections for achieving high efficiency and wide compressor operating range.
Adeel Javed; Cordin Arpagaus; Stefan Bertsch; Jürg Schiffmann. Small-scale turbocompressors for wide-range operation with large tip-clearances for a two-stage heat pump concept. International Journal of Refrigeration 2016, 69, 285 -302.
AMA StyleAdeel Javed, Cordin Arpagaus, Stefan Bertsch, Jürg Schiffmann. Small-scale turbocompressors for wide-range operation with large tip-clearances for a two-stage heat pump concept. International Journal of Refrigeration. 2016; 69 ():285-302.
Chicago/Turabian StyleAdeel Javed; Cordin Arpagaus; Stefan Bertsch; Jürg Schiffmann. 2016. "Small-scale turbocompressors for wide-range operation with large tip-clearances for a two-stage heat pump concept." International Journal of Refrigeration 69, no. : 285-302.
Compressor impellers for mass-market turbochargers are die-casted and machined with an aim to achieve high dimensional accuracy and acquire specific performance. However, manufacturing uncertainties result in dimensional deviations causing incompatible operational performance and assembly errors. Process capability limitations of the manufacturer can cause an increase in part rejections, resulting in high production cost. This paper presents a study on a centrifugal impeller with focus on the conceptual design phase to obtain a turbomachine that is robust to manufacturing uncertainties. The impeller has been parameterized and evaluated using a commercial computational fluid dynamics (CFDs) solver. Considering the computational cost of CFD, a surrogate model has been prepared for the impeller by response surface methodology (RSM) using space-filling Latin hypercube designs. A sensitivity analysis has been performed initially to identify the critical geometric parameters which influence the performance mainly. Sensitivity analysis is followed by the uncertainty propagation and quantification using the surrogate model based Monte Carlo simulation. Finally, a robust design optimization has been carried out using a stochastic optimization algorithm leading to a robust impeller design for which the performance is relatively insensitive to variability in geometry without reducing the sources of inherent variation, i.e., the manufacturing noise.
Adeel Javed; R. Pecnik; J. P. Van Buijtenen. Optimization of a Centrifugal Compressor Impeller for Robustness to Manufacturing Uncertainties. Journal of Engineering for Gas Turbines and Power 2016, 138, 112101 .
AMA StyleAdeel Javed, R. Pecnik, J. P. Van Buijtenen. Optimization of a Centrifugal Compressor Impeller for Robustness to Manufacturing Uncertainties. Journal of Engineering for Gas Turbines and Power. 2016; 138 (11):112101.
Chicago/Turabian StyleAdeel Javed; R. Pecnik; J. P. Van Buijtenen. 2016. "Optimization of a Centrifugal Compressor Impeller for Robustness to Manufacturing Uncertainties." Journal of Engineering for Gas Turbines and Power 138, no. 11: 112101.
This paper presents a study on a small centrifugal impeller for microturbine application from a manufacturing perspective. The aim is to analyze the impact of geometric deviations on part performance using adequate performance modeling tools and statistical methods. A one-dimensional (1D) performance analysis tool has been developed in-house derived from the meanline and two-zone modeling methods. The 1D model has proved to be a simple and computationally inexpensive tool for having a quick performance analysis of the impeller using basic geometric information extracted from part drawings. For the sensitivity analysis, a total of eight input geometric parameters including radii, tip-clearance and blade angles have been varied individually within specific limits in the 1D tool for classifying their influence on the output performance. Since the 1D model is a simplified version of a much complex three-dimensional (3D) model, a commercial computational fluid dynamics (CFD) tool has been used to provide a comparison with the 1D model and scrutinize the effects of such deviations on the fluid behavior inside the impeller passage at a detailed level. For uncertainty quantification, Monte Carlo simulation has been performed using the 1D model to assess the variability of overall impeller output performance to simultaneous random deviations in the input geometric parameters. The study is useful to evaluate the possibility of designing gas turbine parts for manufacturability and superior production cost-effectiveness.
A. Javed; R. Pecnik; M. Olivero; J. P. Van Buijtenen. Effects of Manufacturing Noise on Microturbine Centrifugal Impeller Performance. Volume 7: Structures and Dynamics, Parts A and B 2012, 847 -857.
AMA StyleA. Javed, R. Pecnik, M. Olivero, J. P. Van Buijtenen. Effects of Manufacturing Noise on Microturbine Centrifugal Impeller Performance. Volume 7: Structures and Dynamics, Parts A and B. 2012; ():847-857.
Chicago/Turabian StyleA. Javed; R. Pecnik; M. Olivero; J. P. Van Buijtenen. 2012. "Effects of Manufacturing Noise on Microturbine Centrifugal Impeller Performance." Volume 7: Structures and Dynamics, Parts A and B , no. : 847-857.