Journal of King Saud University: Engineering Sciences (Jan 2021)
A study of the environmental qualities of diesel engines and their efficiency when a portion of their cylinders are deactivated in small-load modes
Abstract
A significant jump in the development of machine building technologies requires the adjustment of environmental indicators. The main sources of air pollution are vehicles with internal combustion engines. According to research data, the main share of toxic emissions is accounted for by the engine idle mode and constant load mode. Studies carried out to improve fuel efficiency of diesel engines which have been in operation for some time show the potential for increasing the efficiency by deactivating a portion of the cylinders. At the same time, the improvement of efficiency indicators varies within a wide range - from 4 to 30%. The larger the number of deactivated cylinders, the higher the fuel economy effect, but as the effective power increases, it is advisable to reduce their number. The potential for increasing efficiency by deactivating a portion of the cylinders is incorporated in all diesel engines in operation. The efficiency of cylinder deactivation is confirmed by experimental data obtained on various types of engines, including automobile, tractor, diesel locomotive, and ship engines. This method is known in engine building primarily as a means of increasing the efficiency of diesel engines at idle speed and small loads. It has been established that there is a decrease in the hourly fuel consumption to 33% of the rated effective power when engine cylinders are deactivated compared to operation without cylinder deactivation. A diesel engine was tested on a running-brake stand fitted with the necessary measuring and recording equipment and instruments, allowing for a maximum torque of 363 N·m at the crankshaft speed within 1200–3000 min−1. Our studies covered three engine operation options. It has been established experimentally that the specific indicator fuel consumption in the second mode, as compared to the first mode, decreases to 9% due to a decrease in the hourly fuel consumption at the speeds from 1600 min−1 to 2350 min−1. In the third mode, fuel economy at idle speed with a shutdown of the fuel supply and the drive of the gas distribution mechanism of the 2nd and 3rd cylinders was about 24% at the engine shaft speed in the range from 1200 min−1 to 2350 min−1. Upgrading the diesel engine using an electromagnetic fuel valve will pay itself off in about a year. A comparison of the experimental and theoretical data shows that their discrepancy in the whole range of the engine crankshaft speeds does not exceed 7%.
