Search

The conventional Diesel cycles engine is now approaching the practical limits of efficiency. The recuperated split cycle engine is an alternative cycle with the potential to achieve higher efficiencies than could be achieved using a conventional engine cycle. In a split cycle engine, the compression and combustion strokes are performed in separate chambers. This enables direct cooling of the compression cylinder reducing compression work, intra cycle heat recovery and low heat rejection expansion. Previously reported analysis has shown that brake efficiencies approaching 60% are attainable, representing a 33% improvement over current advanced heavy duty diesel engine. However, the achievement of complete, stable, compression ignited combustion has remained elusive to date. The challenge is to induct hot high pressure charge air close to top dead centre into the combustion cylinder and then inject and burn the fuel before the piston has travelled significantly down the expansion stroke. In this paper, we report results from a single cylinder split cycle combustion research engine. Stable, rapid combustion was achieved at 800 rpm and 1200 rpm at the retarded timings required for a split cycle engine. The calculated rate of heat release was more rapid than typically observed on conventional compression ignition engine suggesting good mixing of the fuel and air during induction. One dimensional cycle analysis was used to calculate the implications of the test results on the full engine cycle which indicated class leading brake efficiencies approaching and possibly exceeding, 60% are possible from a split cycle engine.

Randomized clinical trials (RCTs) are the gold standard for building evidence. However, the strength of evidence in cardiovascular disease guidelines is not keeping pace with the number of emerging recommendations,1 perhaps reflecting the growing difficulties in developing adequately powered RCTs. In the context of secondary prevention after acute coronary syndromes (ACS), the increase in sample size needed to establish benefit, the rising costs, and the growing complexity of the regulatory environment and study logistics are challenging the development of new therapies. In response to these concerns, the European Society of Cardiology (ESC) convened an ad hoc meeting in May 2009. This paper summarizes the discussions and offers suggestions for improvement ( Table 1 ), which may complement previous proposals.2 [Note: the ideas presented are those of the individual participants (listed in the Appendix) and do not reflect the ideas of the participating bodies]. View this table: Table 1 Strategies to improve research on secondary prevention after acute coronary syndromes In spite of major advances, our understanding of the pathophysiology of coronary atherosclerosis progression and triggers of recurrent thrombotic events after ACS remains limited. To enhance therapeutic development, a clearer picture of coronary atherothrombosis is required. For that, large collaborative consortia between Pharma and acadaemia focused on pathophysiology, genetic epidemiology, new biomarkers, and other intermediate measurements, as well as clinical research on traditional outcomes are needed to better understand the natural history of coronary artery disease. The identification of new pathways and therapeutic targets, as well as the genetic, phenotypic, or behavioural causes underlying the wide individual variations in responses to therapies, particularly antithrombotic treatments should be prioritized. Traditional and new ways of research will be essential to achieve these objectives ( Table 1 ).3 Better ways are also needed to identify patients at high risk for coronary or other vascular recurrences as well as the …

As part of an ongoing investigation, the influence of in-cylinder charge density, and injector nozzle geometry on the behavior of diesel sprays were examined using high-speed imaging. Both liquid and vapor penetration profiles were investigated in operating conditions representative of a modern turbocharged after-cooled HSDI diesel engine. These conditions were achieved in an optical rapid compression machine fitted with a common-rail fuel injection system. Differences in spray liquid and vapor penetrations were observed for different nozzle geometries and in-cylinder conditions over a range of injection fuelling representative of those in a typical engine map. Investigation into the differences in spray structure formed by multi-hole and single-hole injections were also undertaken. The results of the spray penetration profiles from the experiments were compared to empirical correlations in the literature and differences observed were attributed to flow structures within the nozzle, which are not taken into account by these correlations.