“…To resolve this problem, advanced combustion modes have been proposed such as homogeneous charge-compression ignition (HCCI) and premixed charge-compression ignition (PCCI) [2,3]. Early injection is a key technology that can extend the mixing time of liquid fuel and air to achieve a homogeneous mixture and a high efficient combustion.…”
Abstract:The effect of wall roughness with different lubricant film thicknesses on the characteristics of adhered fuel films of diesel-n-butanol blending fuels after spray impingement has been investigated. Four steel plates with different types of roughness (root mean square height-Sq) that were coated with different lubricant film thicknesses (h l ) were used as impinged walls. The experimental conditions included dry walls (h l = 0), semi-wetted walls (SWW) with different thin oil films (0 < h l /Sq < 1), and fully wetted walls (FWW) with a thick lubricant film (h l > Sq). The results indicate that the adhered fuel mass ratio (ε) of blended fuel with 25% n-butanol (B25) was higher than that of blended fuel with 15% n-butanol (B15) under the same conditions. ε increased with an increase in Sq on the dry walls, but, under SWW conditions, it decreased with an increase in oil film thickness. The fuel film morphology was almost unaffected by the change in Sq, but the results implied that the roughness parameter-Skewness (Ssk) exerted a greater impact. The mean thickness h a and accumulated diameter D l of the adhered fuel film increased with an increase in h l , but, under FWW conditions, the effect of the roughness on the adhered film's features was insignificant.
“…To resolve this problem, advanced combustion modes have been proposed such as homogeneous charge-compression ignition (HCCI) and premixed charge-compression ignition (PCCI) [2,3]. Early injection is a key technology that can extend the mixing time of liquid fuel and air to achieve a homogeneous mixture and a high efficient combustion.…”
Abstract:The effect of wall roughness with different lubricant film thicknesses on the characteristics of adhered fuel films of diesel-n-butanol blending fuels after spray impingement has been investigated. Four steel plates with different types of roughness (root mean square height-Sq) that were coated with different lubricant film thicknesses (h l ) were used as impinged walls. The experimental conditions included dry walls (h l = 0), semi-wetted walls (SWW) with different thin oil films (0 < h l /Sq < 1), and fully wetted walls (FWW) with a thick lubricant film (h l > Sq). The results indicate that the adhered fuel mass ratio (ε) of blended fuel with 25% n-butanol (B25) was higher than that of blended fuel with 15% n-butanol (B15) under the same conditions. ε increased with an increase in Sq on the dry walls, but, under SWW conditions, it decreased with an increase in oil film thickness. The fuel film morphology was almost unaffected by the change in Sq, but the results implied that the roughness parameter-Skewness (Ssk) exerted a greater impact. The mean thickness h a and accumulated diameter D l of the adhered fuel film increased with an increase in h l , but, under FWW conditions, the effect of the roughness on the adhered film's features was insignificant.
“…Some previous research studies have been performed to demonstrate its ability to generate stable and repeatable HCCI combustion. Most of these studies have focused on numerical simulations to study the effects of fuel chemistry on HCCI engine performance [16][17][18]. These studies used the computational fluid dynamic (CFD) model to explore the combustion process of the HCCI engine.…”
Establishing the homogeneous charge compression ignition (HCCI) process in a diesel engine, in order to improve exhaust emission quality while extending the HCCI regime, is one of the challenges in applying HCCI in worldwide applications. This can be done by decreasing the compression ratio, and controlling the exhaust gas recirculation (EGR) rate and charging temperature. In this paper, an original single cylinder diesel engine was converted to n-heptane-fueled HCCI with the fuel injected into the intake manifold. At the designed compression ratio of 20:1, the HCCI engine could operate stably at low speed (from 1600 rpm to 2000 rpm) and low load (10% to 20% load). In addition, reducing the compression ratio from 20:1 to 14.87:1 by changing the thickness of the cylinder head gasket and with no EGR applied extended the operating range to 50% load and 3200 rpm speed.
“…Today, engine advancements are designed via technological platforms for better and accurate results. The HCCI combustion engine offers potential advancement for engine designs due to high efficiency, low particulate matter emissions, and low nitrogen oxide [15,16]. Numerical simulations are commonly used today to achieve greater flexibility in engine designs with lower cost.…”
Homogenous charge compression ignition (HCCI) combines the advantages of spark ignition (SI) and compression ignition (CI) engines to improve fuel consumption and emission levels. HCCI engines have the advantage of relatively higher engine efficiency than SI engines while maintaining lower emissions levels than CI engines. Combustion in HCCI engines occurs spontaneously at any location once the fuel-air mixture reaches its chemical activation energy. Pistons have a major effect on controlling the combustion inside the combustion chamber of an HCCI engine. Many researchers have studied various designs for pistons to improve HCCI engines. The aim of this study is to explore these different types of pistons and their designs in terms of improving the performance of HCCI engines fuelled with gasoline. The most common pistons used in HCCI are twostroke pistons, bowl types, specialised pistons, and dome-shaped pistons; each offers distinct advantages and disadvantages. Software simulation is the latest way of determining the best piston to be used for HCCI engines, as it is more cost effective and less time consuming than experiments. Overall, bowl type pistons offer reduced fuel consumption and a higher load capacity when used in an HCCI engine.
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