| 1. |
- Khan, Muhammad Ahsan Iqbal, et al.
(författare)
-
An Experimental and Comparative Performance Evaluation of a Hybrid Photovoltaic-Thermoelectric System
- 2021
-
Ingår i: Frontiers in Energy Research. - : FRONTIERS MEDIA SA. - 2296-598X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- The majority of incident solar irradiance causes thermalization in photovoltaic (PV) cells, attenuating their efficiency. In order to use solar energy on a large scale and reduce carbon emissions, their efficiency must be enhanced. Effective thermal management can be utilized to generate additional electrical power while simultaneously improving photovoltaic efficiency. In this work, an experimental model of a hybrid photovoltaic-thermoelectric generation (PV-TEG) system is developed. Ten bismuth telluride-based thermoelectric modules are attached to the rear side of a 10 W polycrystalline silicon-based photovoltaic module in order to recover and transform waste thermal energy to usable electrical energy, ultimately cooling the PV cells. The experiment was then carried out for 10 days in Lahore, Pakistan, on both a simple PV module and a hybrid PV-TEG system. The findings revealed that a hybrid system has boosted PV module output power and conversion efficiency. The operating temperature of the PV module in the hybrid system is reduced by 5.5%, from 55 degrees C to 52 degrees C. Due to a drop in temperature and the addition of some recovered energy by thermoelectric modules, the total output power and conversion efficiency of the system increased. The hybrid system's cumulative output power increased by 19% from 8.78 to 10.84 W, compared to the simple PV system. Also, the efficiency of the hybrid PV-TEG system increased from 11.6 to 14%, which is an increase of 17% overall. The results of this research could provide consideration for designing commercial hybrid PV-TEG systems.
|
|
| 2. |
- Irfan, Muhammad, 1986, et al.
(författare)
-
Constrained Lagrangian Formulation for Modelling and Analysis of Transmission Synchronizers
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An engineering model of a generic synchronizer is considered. The generic synchronizeris modeled consisting of the selector sleeve with engaging teeth and frictional cone, thesynchronizing ring with blocker and the gearwheel with engaging teeth. It is assumed thatfor the sleeve and synchronizing ring translational and rotational motions are feasible, forthe gearwheel only rotational motion is feasible. The motion of the generic synchronizer isperformed under the external and internal loads. The external loads comprise the vehicleresistance torque and the control force applied to the sleeve and the drag torque due to theclutch. The internal loads comprise the forces and torques arises due to interactionbetween the sleeve, the synchronizing ring, the gearwheel as well as oil splash during thesynchronization process. A feasible synchronization process of a generic synchronizer isdivided into four main phases: pre-synchronization, main synchronization, blockertransition (indexing for the ring), and engagement. Pre-synchronization and blockertransition are further divided into several sub-phases. The generic synchronizer is fullyparametrized and together with description of all phases constitutes kinematics ofsynchronization process in question.Due to the nature of synchronization process in transmission system a motion of asynchronizer mechanism is subjected to unilateral or/and bilateral constraints imposed ongeneralized coordinates or/and generalized velocities of the synchronizer. ConstrainedLagrangian Formalism (CLF) has been proposed as an approach for developingmathematical and computational models of a generic synchronizer dynamics. The CLFgives possibility to formulate direct dynamics, semi-inverse dynamics and inversedynamics problems for a generic synchronizer in unified and efficient way. It is shown thatCLF can be promising and useful for advanced dynamic analysis of the existingsynchronizer mechanisms and to design novel optimized ones.In the present report mathematical and computational models of a generic synchronizerwith five degrees of freedom have been developed using CLF. Application of CLF on themodelling of the synchronization process gives system of differential-algebraic equations(DAE). Analysis of the generic synchronizer performance diagrams has shown that the CLFbased model is able to predict the synchronization process characteristics reasonably well.The developed model has been validated by using measurement data from test rig at CVAB Scania. Performance of the generic synchronizer is also analyzed in case of drivelinevibrations. Sensitivity analysis of the synchronizer mechanism performance with respect tocone angle, coefficient of friction, maximum value of shift force and rate of applying shiftforce has been done.Next, the developed models will be used to get further insight into synchronizer design andits performance diagrams with aid of global sensitivity analysis and Pareto optimization.
|
|
| 3. |
- Irfan, Muhammad, 1986, et al.
(författare)
-
Dynamics and Pareto Optimization of a Generic Synchronizer Mechanism
- 2016
-
Ingår i: Conference Proceedings of the Society for Experimental Mechanics Series. - Cham : Springer International Publishing. - 2191-5644 .- 2191-5652. - 9783319300849 ; 8, s. 417-425
-
Konferensbidrag (refereegranskat)abstract
- Transmission systems for passenger cars and trucks are equipped with synchronizer mechanism. It has a great impact on driving comfort and transmission efficiency. A synchronizer mechanism as a key component of a transmission system must be able to prevent gears from shocking and reduce the noise. Gear shifting improvement with respect to smooth, quick and energy efficient synchronizer's performance is still an important issue for automotive industry. This contribution studies the kinematics and dynamics of a generic synchronizer consisting of sleeve, blocker ring and gearwheel constituting a mechanical system with a set of time-varying constraints describing frictional contacts between system's components. The dynamic response is modelled using constrained Lagrangian formalism. Pareto optimization problem is stated and optimized the rate of the applied sleeve force, coefficient of friction and cone angle are found to attain a minimal synchronization time as well as speed difference between sleeve and gearwheel. One outcome of the study is that the obtained Pareto solution is characterized by the minimal admissible value of the cone angle of the synchronizer.
|
|
| 4. |
- Irfan, Muhammad, 1986, et al.
(författare)
-
Failure modes and optimal performance of a generic synchronizer
- 2018
-
Ingår i: The 5th Joint International Conference on Multibody System Dynamics. ; , s. 1-22
-
Konferensbidrag (refereegranskat)abstract
- The gear shifting mechanism is a crucial part of the gearbox which transmits the torque from engine to wheels with different transmission ratio. For smooth and comfortable gear changing the gear shifting mechanism is still a challenge for the engineers to adapt the different driving situations. In case of heavy vehicles particularly under certain circumstances optimized performance by avoiding failure modes of the gear shifting mechanism is also a challenge. In this paper failure modes and optimized values of the system parameters are identified to contribute for this challenge. A model of the gear shifting mechanism is developed in GT-Suite software. Failure modes are identified via sensitivity analysis. Four system response characteristics are plotted against the time and used to identify the failure modes. Optimization routine of the GT-Suite is applied on the model by taking seven parameters into account as independent variables and synchronization time as an objective function. Percentage changes of the variables from their initial values are calculated and analyzed. Finding of optimal values of parameters of the gear shifting mechanism is valuable contribution to design reliable and efficient transmission system for automotive industry especially for heavy vehicles.
|
|
| 5. |
- Irfan, Muhammad, 1986
(författare)
-
Meta Modeling of Transmission Error for Spur, Helical and Planetary Gears for Wind Turbine Application
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detailed analysis of drive train dynamics requires accounting for the transmission error that arises in gears. However, the direct computation of the transmission error requires a 3-dimensional contact analysis with correct gear geometry, which is impractically computationally intense. Therefore, a simplified representation of the transmission error is desired, a so-called meta-model, is developed. The model is based on response surface method, and the coefficients of the angle-dependent transmission error are dependent on shaft eccentricity (parallel misalignment), shaft bending (angular misalignment), torque and speed. Parallel spur gear, helical gear and planetary gear are studied, with parameters for wind turbine applications is considered and Abaqus 6.12-1 is used for the development of the meta-models. Upon evaluating the results, it is concluded that meta-modeling technique can be an efficient way of predicting the transmission error.
|
|
| 6. |
- Irfan, Muhammad, 1986, et al.
(författare)
-
Minimizing synchronization time of a gear shifting mechanism by optimizing its structural design parameters
- 2020
-
Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 234:2-3, s. 488-504
-
Tidskriftsartikel (refereegranskat)abstract
- A gear shifting mechanism is modeled in GT-Suite software. The mechanism has three main bodies: sleeve, ring, and gear. Results obtained from the simulation show that GT-Suite model can predict gear shifting process. Synchronization processes for three conditions of nominal, road grade, and vibrational motion of the master are studied in six cases by considering the sleeve and the gear as a master alternatively. The optimization based on the GT-Suite model is performed for each case to find the minimum gear shifting time based on variations of 17 structural design parameters. Minimum synchronization time is found almost same in all cases. It is concluded from closeness of the optimization results that average of the parameter values can be considered as optimized values for all cases. At the end, robustness of the optimized structural design parameters are analyzed with respect to the road grade, amplitude, and frequency of oscillatory excitation of rotational motion of the master.
|
|
| 7. |
- Irfan, Muhammad, 1986
(författare)
-
Modelling and optimization of gear shifting mechanism, Application to heavy vehicles transmission systems
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Without an efficient transmission system the idea of an efficient vehicle is incomplete. During running of the vehicle especially in case of heavy vehicles the transmission system has to face different situations during which the system possibly can lose its efficiency. Definitely variations in efficiency of the transmission system demand from engine to vary its power to maintain the system efficiency to regulate speed of the vehicle. Gear shifting mechanism of the transmission system is one of the responsible agents for losing rotational speed of the system. The engine needs to increase its power to compensate such kind of losses by injecting the more fuel. Ultimately there will be more emissions on exhaust side. In this scenario the conducted research is concentrated on the gear shifting mechanism. To start with the well-defined aim a generic cone synchronizer mechanism modelled by a mechanical system with five degrees of freedom and comprising three rigid bodies is studied to understand the gear shifting process. To resolve complexity of the complete gear shifting processes detailed kinematic description of the phases and sub-phases gives an opportunity to capture the nature of bodies’ interaction and forces arise during their interaction. In the project a mathematical model to represent the whole gear shifting process is developed based on Constrained Lagrangian Formalism. The developed model went through validation test by using experimental data. Because the developed mathematical model is flexible to adopt other relevant models, the friction model is applied to the developed mathematical model and analyzed the differences in the results. The next step is to optimize the gear shifting process based on the input parameters. Using the developed model the analysis is performed in two steps; in first step the sensitivity analysis is considered to study the effect of variations of individual parameter on the system performance and in second step effects of a set of synchronizer mechanism's parameters which vary simultaneously are studied by using the optimization technique. Time duration of the gear shifting and speed difference at end of the main phase of synchronization process are chosen as objective functions of the system. Parameters estimated quickness and smoothness (comfort) of synchronization processes are cone angle, cone coefficient of friction, applied shift force, blocker angle, blocker coefficient of friction, cone radius, gear moment of inertia and ring moment of inertia. Eight cases of the synchronizer mechanism performance are studied under different scenarios of master/slave and different operating conditions. Further analysis on results obtained from the Pareto optimization clarifies the degree of influence of the input parameters. It was found that optimal performance of the system can be obtained by tuning few of the system parameters which have higher degree of influence instead of changing all the parameters together. For example in the case where the sleeve is considered as a master at nominal condition optimal performance of the synchronizer can be obtained by paying attention to applied shift force, cones angle, cones coefficient of friction, blocker angle and blocker coefficient of friction instead of taking all eight input parameters. At the end a graphical user interface is developed to obtain the synchronization performance diagram.
|
|
| 8. |
- Irfan, Muhammad, 1986
(författare)
-
Modelling, failure modes prediction and optimization of gear shifting mechanism, Application to heavy vehicle transmission systems
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The transmission system has a key role to drive a vehicle transmitting power from engine to rotational motion at wheels. Gear shifting mechanism inside the gearbox is a crucial part of the transmission system. Particularly in case of heavy vehicles gear shifting needs to be more frequent and quick for the low energy consuming and high performing vehicles. In addition to this, highly growing change of technology from fuel consuming vehicles to electric vehicles puts a higher demand on the gear shifting mechanism. Development process of new design of the gear shifting mechanism must be fast to meet the future demands. In this regard two models of the gear shifting mechanism are developed. Sensitivity analysis and failure modes prediction are studied. The gear shifting process is optimized based upon the developed models by using genetic algorithm. A generic synchronizer modelled with five degrees of freedom and comprising three rigid bodies is studied to understand the gear shifting process. To get insight into the complete gear shifting process, detailed kinematic description of the phases and sub-phases is given. Nature of bodies’ interaction is studied. A mathematical model is developed based on Constrained Lagrangian Formalism. The developed model is validated against test rig data. After sensitivity analysis, optimization is performed based upon the developed model. Synchronization time and speed difference at end of the main phase of synchronization process are chosen as objective functions. Parameters are cone angle, cone coefficient of friction, applied shift force, blocker angle, blocker coefficient of friction, cone radius, gear moment of inertia and ring moment of inertia. Several cases of the synchronization process are studied under different scenarios of master/slave and different operating conditions. Further analysis of results obtained from Pareto optimization clarifies the degree of influence of the input parameters. To identify the failure modes, the gear shifting mechanism is modelled on GT-Suite software. System response characteristics are chosen to observe the failure modes. At failure modes occurrence limits of values of design parameters are identified. With these limits genetic algorithm based routine is applied to the optimization. The synchronization time is selected as an objective function to be minimized. At first step seven parameters are considered as varying parameters for optimization. At second step seventeen design parameters are optimized for six cases at master/slave settings with conditions of nominal, road grade and driveline excitation. Because of the minor differences between the optimization results average values of the parameters are taken as optimal values for all cases. It is shown that the obtained optimized values of design parameters are robust with respect to different driving conditions.
|
|
| 9. |
- Irfan, Muhammad, 1986, et al.
(författare)
-
Modelling of Heavy Vehicle Transmission Synchronizer using Constrained Lagrangian Formalism
- 2015
-
Ingår i: In Proc. of the International Conference on Engineering Vibration, Ljubljana, 7 - 10 September ; [editors Miha Boltežar, Janko Slavič, Marian Wiercigroch]. - EBook. - Ljubljana: Faculty for Mechanical Engineering, 2015. - 9789616536974 ; , s. 28-37
-
Konferensbidrag (refereegranskat)abstract
- Robust and efficient synchronizers are keys elements to ensure good gear shift in heavy vehicles. In order to improve existing as well as develop new synchronizers, efficient simulation tools are needed. In this contribution, a mechanical system with 5 degrees of freedom modelling a generic synchronizer consisting of engaging sleeve, synchronizer ring and gearwheel are considered.Due to the design of the different components and their interactions the synchronizing process is described in terms of different steps or phases; presynchronization, main synchronization, blocker transition and engagement. The four main phases are further divided into sub-phases.To study the whole process in a unified manner, Constrained Lagrangian Formalism (CLF) turns out to be a suitable method in which the interactions between components (sleeve,synchronizer ring and gearwheel) are described by unilateral or/and bilateral constraints imposed on generalized coordinates of the system during different phases. Using CLF a mathematical model of a generic synchronizer is developed and represented by the system of differential-algebraic equations. Kinematics and kinetics of the generic synchronizer are modelled for each sub-phase. The sleeve is considered as a master and thegearwheel is considered as a slave. The statement of the dynamics problem for a generic synchronizer is given and the numerical algorithm is implemented in Matlab for solving the differential-algebraic equations resulting from CLF. The generic synchronizer computational model is adapted to available experimental setup and validated using obtained measurement data. Sensitivity of the synchronization time is studied varying the cone angle, coefficient of dry friction and sleeve force. Effect of driveline vibrations on synchronization performance isalso studied.
|
|
| 10. |
- Irfan, Muhammad, 1986, et al.
(författare)
-
Performance improvement of a transmission synchronizer via sensitivity analysis and Pareto optimization
- 2018
-
Ingår i: Cogent Engineering. - : Informa UK Limited. - 2331-1916. ; 5:1, s. 1-46
-
Tidskriftsartikel (refereegranskat)abstract
- Gear-shifting mechanism has a key role in transmission system of a vehicle. During gear shifting, there is a risk of losing the engine optimal speed that will ultimately lead to more emission from the vehicle. It is demanded for optimal performance of transmission systems to increase quality of synchronizer used for gear shifting. Especially in the case of heavy vehicles, the synchronizer performance needs to be robust more even during different operating scenarios. Synchronization process varies by changing its parameters values. So one of the ways to improve performance of the synchronizer is to optimizing its parameters. In the paper, a generic synchronizer mechanism (GSM) is considered. Mathematical model of GSM is presented based on constrained Lagrangian formalism (CLF) and detailed kinematics of synchronization process in transmission system. Speed difference at the end of the main synchronization phase and synchronization time are chosen as two objectives. The following eight parameters of the synchronizer have taken as input parameters: cone angle, cone coefficient of friction, cone radius, rate of shift force, blocker angle, blocker coefficient of friction, gear moment of inertia, and ring moment of inertia. Influence of the parameters on objectives is studied. The values of the objective functions decrease with increasing some of the parameters and increase with increasing others. Not only the objective functions have opposite behavior between the parameters but also have opposite behavior with variation of the same parameters. For example, the synchronization time decreases but the speed difference increases with increasing cone coefficient of friction. The Matlab routine of multi-objective optimization is applied to obtain the optimized parameter values of the generic synchronizer at different operating conditions. In the first case, the sleeve is considered as a master, in the second case the gear is considered as master, and in the third case both sleeve and gear are considered as slaves. In each case, three different operating conditions are studied which are nominal, transmission vibrations, and road grade. The obtained results of biobjective optimization (Pareto fronts, Pareto sets, and corresponding performance diagrams) are analyzed and the most influencing synchronizer parameters have been identified.
|
|
| 11. |
- Irfan, Muhammad, 1986, et al.
(författare)
-
VERIFICATION OF A TRANSMISSION SYNCHRONIZATION MODEL
- 2017
-
Ingår i: Svenska Mekanikdagarna, Uppsala, 12-13 juni 2017. ; , s. 48-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A computational model of the gearshiftingmechanism may speed up the development of anew gearboxes. However, such model should beverified against other models as well as validatedagainst experiments to ensure reasonableaccuracy. In this contribution, results from the previousdeveloped mathematical model of a genericsynchronizer (gearshifting mechanism) againstthe model developed at Scania is presented. The mathematicalmodel is based on constrained Lagrangianformalism (CLF) and the generic synchronizer isconsist of engaging sleeve, synchronizer ring andthe gearwheel with dimensions relevant to that ofa heavy truck.
|
|
