Experimental facility and methodology for systematic studies of cold startability in direct injection Diesel engines

Abstract

Cold start at low temperatures in current direct injection (DI) Diesel engines is a problem which has not yet been properly solved and it becomes particularly critical with the current trend to reduce the engine compression ratio. Although it is clear that there are some key factors whose control leads to a proper cold start process, their individual relevance and relationships are not clearly understood. Thus, efforts on optimization of the cold start process are mainly based on a trial-and-error procedure in climatic chambers at low ambient temperature, with serious limitations in terms of measurement reliability during such a transient process, low repeatability and experimental cost. This paper presents a novel approach for an experimental facility capable of simulating real engine cold start, at room temperature and under well-controlled low speed and low temperature conditions. It is based on an optical single cylinder engine adapted to reproduce in-cylinder conditions representative of those of a real engine during start at cold ambient temperatures (of the order of −20 °C). Such conditions must be realistic, controlled and repeatable in order to perform systematic studies in the borderline between ignition success and misfiring. An analysis methodology, combining optical techniques and heat release analysis of individual cycles, has been applied.

Gasoline effects on spray characteristics, mixing and auto-ignition processes in a CI engine under Partially Premixed Combustion conditions

“…The most relevant specifications of this engine are presented in Table 2. Figure 2 shows a complete scheme of the facility, and more details about it can be found in [12].…”

Ignition and combustion development for high speed direct injection diesel engines under low temperature cold start conditions

“…A more detailed explanation about the facility adaptation and its capabilities has already been presented in [13].…”

“…The study will be performed in a single-cylinder optical engine that has been adapted to simulate in-cylinder conditions similar to those of a real engine operating at low temperature cold start [13]. After this introduction, the experimental and calculation tools and methodology used for the study are presented.…”

Influence of spray-glow plug configuration on cold start combustion for high-speed direct injection diesel engines

“…The main contribution of this work is that they show that glow plug configuration and disposition parameters have an effect only on pilot injection and they also add the glow plug temperature as another possible influence parameter. But, a larger statistical sample would be necessary in order to account with cycle to cycle dispersion, which is typical under such conditions [16] In a previous work presented by the authors [17], a description of the mechanisms that lead to pilot ignition was presented as a basis to understand further parametric variations. In that paper, the importance of the glow plug surface as the only possible ignition spot is confirmed.…”

“…A complete description of this experimental facility and methodol-ogy has been previously reported in [16]. This sub-section only shows a brief summary of the main contents.…”