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Gasoline and diesel, the two fuels with very different characteristics and with wide availability for conventional engine use, were blended as a HCCI engine fuel. Gasoline, with high volatility, easy vaporization and mixture formation, is used to form the homogeneous charge. Diesel fuel which has good ignitability and fast combustion at the conditions predominating in the HCCI environment, is used to dominate the auto-ignition and restrain the knocking combustion. It is expected that these two different fuels with opposite but complementary properties can be used to reach a good compromise in HCCI combustion. Experiments, conducted with moderate compression ratios (CR) and using two modes of HCCI control, i.e. intake heating with CR 15.0 and negative valve overlap (NVO) with CR 10.4, yielded results that prove this expectation.

The detection of needle displacement within a Common Rail injector is a crucial step to suitably characterize the behaviour of an injector. The needle motion is traditionally measured by means of an eddy current sensor. Apart from its high cost, scientific literature highlights its drawbacks, such as the introduction of mechanical weakness on the control piston as well as the electromagnetic disturbance affecting data acquisition. In order to provide an improved quality of signal, other solutions have been developed, which require a large number of components, leading to increased layout complexity. This layout can create a packing issue while mounting the sensor on the test rig. A novel sensor (UK Patent Application No.1819731.9) using fibre optic cable has been designed and built to overcome the limitations typically associated with needle displacement transducers.