This paper presents a simulation-based study to evaluate three potential benefits of fuelsaving technologies implemented in spark-ignition (SI) engines for a passenger car over actual urban driving cycles. These technologies include cylinder deactivation (CDA), stop-start system, and engine downsizing (≈20% degree of downsizing). The aim of the work is to evaluate individual benefits of each system in terms of fuel consumption. GT-Power engine simulation tool is utilised to model engines which employ each of the mentioned technologies; each of the engines has identical full-load torque characteristics. Each engine model is instructed to run over a transient, part-load, torque driven operations based on actual road test measurements, and the cycle-averaged fuel consumption was evaluated. From the analysis, the contribution of each technology in terms of fuel economy can be assessed based on an actual part-load transient operation, which can be beneficial to developers to optimise the operation of SI engines. The results revealed stopstart system to be the most promising technology for the driving cycle at hand with 27.5% fuel consumption improvement over the baseline engine. CDA engine allows for 12.6% fuel economy improvement. On the other hand, the downsized turbocharged engine has caused increasing cycle fuel consumption by 7.5%. These findings are expected to be valid for typical urban driving cycles as far as they conform to the operating load residency points over the transient torque profile.
There are limited studies on improving the piston expander performance for a wider operating range by adopting the variable valve timing method. This study uses a simple conversion technique to develop a single-piston expander (SPE) from a small two-stroke engine. The SPE is being tested at different operating conditions to study the feasibility of the SPE operating under different intake pressure and valve timing conditions. By fixing the exhaust valve timing, the SPE was tested at four intake pressure; 3, 4, 5, and 6 bar, while the intake valve closing varied from 30° to 110°. From the study, the highest power produced by the SPE was only 64 Watt when tested at 6 bar, with the intake valve opening at TDC and closed at 70°. The results show that the converted SPE is feasible in terms of functionality, but it is not performance-wise because much power has been lost through the recompression process. The study also observed that the intake valve timing could significantly affect the SPE power output, besides the intake pressure alone.
An electronic valve timing control unit has been developed mainly for the internal combustion engine operation. This study aims to implement a similar technology into a single-piston expander (SPE) with readily available and low-cost microcontrollers. The study used an Arduino Mega 2560 and ESP32-WROOM microcontrollers to control the valve timing with the rotational input signal obtained from an absolute encoder. The SPE has been expected to run at the rotational speed of up to 2000 rpm. This setup was prepared to simulate the actual SPE operation using a direct current motor to drive the spindle connected to the encoder shaft to create a similar hardware testing and controlled environment. The study aims to identify the efficiency of the microcontroller’s performance with a variation of the valve’s opening and closing time. Results have shown that the clock rate of the microcontroller affects the performance of valve timing response. By increasing the clock rate, the microcontroller can control the valve at a higher speed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.