نشریه تحقیقات موتور
پیاپی 65 (Winter 2022)

Performance evaluation of Internal Combustion Engines (ICEs) and setting different emission standards has manifested the importance of pollution reduction as well as the optimal fuel consumption of these engines. Accordingly, the Engine Management Systems (EMS) are utilized which resulted in optimizing the power alongside the decrease in pollutant emission, through preparing the appropriate air-fuel mixture. Engine management systems are nowadays able to provide an accurate air-fuel mixture. However, the performance of Port Fuel Injection (PFI) engines is also highly dependent on the time of fueling operation which is called the fuel injection phase. There are several methods to achieve the fuel injection phase, the most common of which is using the camshaft position sensor. Nevertheless, this issue is still considered as one of the challenges, devoting much of the researchers’ work, in that using camshaft position sensors and similar ones result in increased production costs as well as some complexities in after-sales services. Therefore, this study aimed to design a control algorithm and determine the fuel injection phase as well as identify the moment of inlet valve closure by evaluation of manifold pressure sensor signal of a single-cylinder engine. In the next step, this feature was added to the engine management system and the engine performance was assessed. The results indicated that it is perfectly possible to determine the injection phase through this method. Moreover, to define the effect of this algorithm on emission reduction, the ECE-R40 emission test was held and its results were compared with the emissions level when the engine management system was not equipped with this algorithm. This comparison shows, by using the phase-detection algorithm, the mean carbon monoxide, unburned hydrocarbons, and nitrogen oxides reduced each by 5.9%, 9.4%, and 2.6%, respectively.

In the present paper, the effect of using Different Orifice Geometries & Needle Lifts on transient heat-mass transfer and Combustion Indicated Quantities & Air Pollutant Species has been investigated in Marine Propulsion System Fuel Injectors using AVL-Fire CFD code. The effect of each of the proposed geometry and needle movement profiles (triangular, trapezius & boot) with the help of a three-dimensional moving mesh by numerical model in AVL Fire software, which has been validated with experimental data in each part, on the performance & Air Pollutant Species of the Marine Propulsion System has been investigated by ANALYSER module. Numerical results show that converged conical with trapezius needle lift profile has better engine performance, efficiencies and lower NO pollution. Although, diverged conical with trapezius needle lift profile has lower CO pollution. Fuel consumption decreases by 18.5% and its power and torque increase 64%. Also in this case, carbon monoxide pollutants decrease by 14% and nitrogen oxide pollutants decreasing by 10% for optimum status. In these case, indicated and mechanical efficiencies are increasing 22% and 41.5%, respectively.

This paper details a new method for model-based discrete sliding mode control of a spark ignition (S.I.) engine cold start considering nonlinear dynamic effects, modeling uncertainty and multiple switched dynamic configurations. Control algorithm deals with stabilization and tracking problems that correspond to crank-shaft velocity, air-to-fuel ratio (AFR) and catalyst temperature in cold start operating mode. To this end, an individual sliding function is assigned to each tracking problem which is subsequently used in construction of associated Lyapunov function. Crank-shaft velocity is regulated using air mass flow rate into intake manifold considering associated dynamic equations describing air mass flow. To ensure precise AFR control, the sliding control model is constructed considering the previously calculated air mass flow rate which leads to nonlinear expressions that are subsequently employed in calculation of appropriate fuel mass flow rate. Stabilization of catalyst temperature is conducted through definition of a virtual control input corresponding to spark angle. As catalyst temperature is described using logarithmic mathematical expressions, additional steps have to be considered to ensure feasibility of control algorithm in various operating conditions. The designed control was numerically applied to validated mathematical model of Toyota 2AZ-FE engine so as to render efficiency and precision of feedback performance.

The aim of this study is to evaluate the effect of hydrogen addition on a heavy-duty diesel engine performance and emission under RCCI combustion fueled with natural gas and diesel fuel. For this purpose, a single-cylinder heavy-duty diesel engine is used to operate at a low-load range from 5.6 to 7.7 bar gross IMEP, constant engine speed, and a fixed amount of diesel fuel. Furthermore, in order to reduce hydrocarbon fuels consumption, hydrogen is gradually added to natural gas while the total fuel energy content is kept to be constant. The results show that by adding hydrogen to natural gas in the RCCI engine at 5.6, 6.3, and 7.7 bar gross IMEP, the hydrogen energy share would be enhanced up to 35.7%, 23.70%, and 9.93%, respectively. And also, the overall hydrocarbon fuels consumption per cycle can be reduced up to 45.23%, 29.26%, and 12.07%, respectively. Although CO and UHC emissions decrease drastically, NOx increases significantly with the addition of hydrogen compared to RCCI combustion fueled with natural gas and diesel fuel.

Not only are Fuel cell vehicles one of the significant options to replace gasoline engines, but they also come with a multitude number of benefits; For instance, fuel cell efficiency is more than about three times the efficiency of engines with internal combustion. According to the specific complexities of modeling the behavior of PEMFC, determining the performance of this system in case of its structural characteristics is considered as one of the parameters needed to better know of behavior the PEMFC. The present study attempts to find and examine a polymer membrane fuel cell for utilizing in a vehicle. To examine the performance of fuel cells, the modeling process was done by addressing diverse production-consumption heat in the anode and cathode positions and waterflood conditions. Using quadratic method, the flow channels were meshed and based on the finite difference method the mathematical equations were numerically discretized in the steady-state. Based on the simulation results, all heat values decrease over the channel of flow. By evaluating the relative humidity effect, it was obvious that the cathode relative humidity didn’t change considerably along the channel of flow and at the same time, the relative humidity of the anode decreased along the channel of flow. There was a significantly low membrane layer velocity given the fact that this layer had a lower permeability coefficient in comparison with reactant layers and gas diffusion (Average Reynolds number: 612).

This paper presents a machine vision approach to detect the installation error of conrod bearing in four-cylinder engines. Since there are always human errors in engine production lines that would reduce the quality of the final product, it is vital to establish the intelligent machine vision systems in order to track the process of assembling parts and prevent installation errors. The proposed method is such that by taking an engine block image, it produces a binary image that the whole image is black and only the places where conrod bearings exist are white, and also it announces which bearings are present and which ones are not installed. To this end, firstly the images of 16 different bearing installation cases were captured by camera. Then, all images were analyzed with a combination of image processing methods including Gaussian filtering, image thresholding and segmentation, and morphological techniques including erosion and dilation. Finally, with applying if-then rules on the characteristics of the objects created in the image, its condition was decided. The results showed that the best threshold range for separating the bearing from other parts of image was between 110 and 245. Also a disk-shaped structuring element with the radius of 60 provided the best morphological tool to detect the bearings. In addition, the results demonstrated that the regions belonged to conrod bearings had an area between 30,000 and about 80,000 pixels. With using if-then rule, the different bearing installation cases in all images were successfully detected with 100% accuracy. The total time for analyzing each image was about 1 s. So the results showed that the proposed machine vision system provided a non-error and fast tool for detecting the existence of conrod bearings which can be served as a Poka-Yoke system in the engine production line.