Automotive Science and Engineering

Performance evaluation of PEM fuel cells; impact of relative humidity, pressure and temperature of inlet species on the current density of the PEMFCs

Golamreza Molaeimanesh

Due to the increasing level of air pollution and the reduction of fossil fuels, the need for new technologies and alternative fuels is felt more than ever. Proton exchange membrane fuel cells (PEMFCs) are one of these technologies, which have been of great interest to the researchers due to the benefits of non-contamination, high efficiency, fast start-up, and high power density. The proper functioning of the fuel cell requires thermal management and water management within the cells. To this end, in this work, the effect of different parameters on the performance of PEM fuel cell was investigated. The results demonstrated that the performance of the cell increases with increasing the pressure in the low current densities, while in the high current density, performance decreases with increasing the pressure of the cell. Also, the study of the effect of relative humidity shows that increasing the relative humidity of the cathode does not have much effect on the performance of the cell while increasing the relative humidity of the anode improves the performance of the cell.

Extracting Tehran Refuse Collection Truck Driving Cycle and Estimating the Braking Energy

Sohrab Pakdel Bonab

Driving cycle is used to assess fuel consumption, pollutant emissions and performance of the vehicle. The aim of this paper is to extract the driving cycle for refuse collection truck and estimate its braking energy. For this purpose, after selecting the target truck and geographic area, the equipment needed to measure the required variables were prepared and mounted on the truck. Then, the actual data were collected from the performance of the target Truck while performing its mission. Since the amount of braking energy depends on the speed, truck mass and road grade, the speed of the vehicle is measured simultaneously with the truck mass and road grade. The collected data are then processed and subdivided into micro-trips. The micro-trips are clustered according to the number of state spaces using the K-Means algorithm. Next, the representative micro trips are selected from within the clusters and the final driving cycle is generated. The representative driving cycle shows that the truck speed is zero at 47% of the working time. Finally, the amount of braking power and accumulative braking energy in the driving cycle is calculated.

Design of an Adaptive Fuzzy Controller for Antilock Brake Systems

Farzan Rashidi

The control of Antilock Braking Systems (ABS) is a difficult problem, because of their nonlinearities and uncertainties appearing in their dynamics and parameters. To overcome these issues, this paper proposes a new adaptive controller for the next generation of ABS. After considering a complex vehicle dynamic, a triple adaptive fuzzy control system is presented. Important parameters of the vehicle dynamic include two separated brake torques for front ands rear wheels, as well as longitudinal weight transfer which is caused by the acceleration or deceleration. Because of the nonlinearity of the vehicle dynamic model, three fuzzy-estimators have been suggested to eliminate nonlinear terms of the front and rear wheels’ dynamic. Since the vehicle model parameters change due to variations of road conditions, an adaptive law of the controller is derived based on Lyapunov theory to adapt the fuzzy-estimators and stabilize the entire system. The performance of the proposed controller is evaluated by some simulations on the ABS system. The results demonstrate the effectiveness of the proposed method for ABS under different road conditions.

The study of entrance port shape effect on current rotation rate and observation of combustion behavioral changes in sparking ignition engine with natural gas

Yasin Babajanpour

Use of natural gas has been proposed as one of the solutions to reduce fossil fuel consumption such as petrol and gasoline, which emit more pollutants. In this regard, more attention has been directed toward use of natural gas due to its high calorific value and low pollution. This paper studies the effect of different fluid rotation coefficients in parallel form with a surface of a piston bowl (Swirl). And, it attempts to explore the changing effects of this indicator on power and major pollutants of sparking ignition gas engines. Three-dimensional computational fluid dynamics are employed to simulate the procedure. Open-cycle engine, the moment between air-intake-valve opens and the exhaust-valve opens, is simulated through applying combustion equations of turbulence and emissions. First, the results are validated based on experimental data. Then, an analysis of different rotation coefficients is used to compare the temperature and pressure inside the cylinder, productivity, and the amount of generated pollution. The results demonstrate that changing the shape of entrance port, which leads to concomitant change in the fluid rotation rate in the chamber, causes a slight change in the output power. But, the change has a significant impact on the production of pollutants.

Redesigning and non-linear parametric and free-size optimization of an Mg alloy automotive seat frame

Alireza Sadeghi

Application of Mg alloy parts in automotive industry is increasing to reduce weight and fuel consumption. One of the high potential parts for application of Mg alloys is the front seat frame. However, change of material is accompanied by change of manufacturing process and change of design for the seat frame. In the present research while keeping the reference overall ergonomic outline, a new substitute Mg alloy design was proposed, featuring a simple easy to manufacture Z profile. Next, a two-stage optimization technique (size and shape) is proposed for the Mg seat frame based on the stress and displacement criteria of standard test plans. The final optimized design is close to fully-stressed state and is 70% lighter than the reference steel backrest.

Heat Transfer and Pressure Drop of Al2O3-Ethylene Glycol-water Nanofluid as the Coolant in an Automotive Radiator

mohammad fakhari

In this experimental study, heat transfer and pressure drop, ΔP, of a coolant nanofluid, obtained by adding alumina nanoparticles to Ethylene Glycol-water mixture (60:40 by mass), in a automotive radiator have been investigated. For this purpose, an experimental setup has been designed and constructed. The experiments have been performed for base fluid and nanofluid with different volume fractions of 0.003, 0.006, 0.009 and 0.012 and under laminar regime with various coolant flow rates of 9, 11 and 13 lit/min and two air velocities of 3.75 and 2.85 m/s. The thermophysical properties have been calculated using the recently presented temperature dependent models. According to the results, the heat transfer and ΔP increase with increasing the coolant flow and nanoparticles volume fraction. Increasing the air velocity causes enhancement of heat transfer. Although Nusselt number decreases when nanofluid is utilized, it enhances as the nanoparticles volume fraction increases. The performance evaluation using nanofluid in the car radiator shows remarkable enhancement in radiator thermal efficiency. However, the ratio of heat transfer rate to the needed pumping power (Merit parameter) decreases.