Examinatal Study on Common Rail Diesel Engine for Multi-injection Strategies
Based on diesel engine equipped with common rail, the multi-injection strategies common rail diesel engine test bed is established with NI test system. In this test bed, the influences of optimized multi-injection strategies to diesel engine performances are studied. The test results show that by using multi-injection strategies, the diesel engine exhaust temperature can reduce 50???, and noises can reduce 15dB, and emission improve obviously.
Effect of Multi-Injection Strategy on Cavitation Development in Diesel Injector Nozzle Holes
The effect of multiple-injection strategy on nozzle hole cavitation has been investigated both experimentally and numerically. A common-rail Diesel injection system, used by Toyota in passenger car engines, has been employed together with a double-shutter CCD camera in order to visualise cavitation inside a submerged and optically accessible (in one out of the six holes) real-size VCO nozzle. Initially the cavitation development was investigated in single injection events followed by flow images obtained during multiple injections consisting of a pilot and a main injection pulse. In order to identify the effect of pilot injection on cavitation development during the main injection, the dwell time between the injection events was varied between 1.5-5ms for different pilot injection quantities. The extensive test matrix included injection pressures of 400 and 800bar and back pressures ranging from 2.4 up to 41 bar. The results have confirmed that cavitation patterns in the pilot are very similar to those of the main injection, while the effect of the dwell time was present through the variation of the actual injection pressure caused by the pressure wave dynamics within the injection system. The flow inside the VCO nozzle was also simulated using a recently developed cavitation CFD model which takes into account the movement of the needle. Simulations have shown that cavitation inception is very fast and synchronous for both the pilot and the main injection events while its intensity in the sense of spatial extent appears to peak at relatively low needle lifts.
Ocean thermal energy conversion: The promise of a clean future
Due to the world's heavy dependence on fossil fuels for electricity, pollution and global warming is on the rise. However, numerous countries are still relying on diesel generators as their main source of energy. There is a lack of practical alternative energy source that can meet the global energy demand without posing any threat to the natural environment. Ocean Thermal Energy Conversion (OTEC) is a concept that has the potential to address this growing issue. It is basically a mechanism that exploits the temperature difference between warm surface seawater and cold deep ocean water, to produce electricity. Although OTEC has a low energy density, the thermal energy in the ocean is vastly abundant. OTEC development has been dormant for a long time since it was first proposed in 1881. However, it has now regained recognition worldwide as a realistic solution to our world energy issue. Instead of having a great potential for power generation, it also carries the ability to produce high value products from the large volume of Deep Sea Water (DSW) that can be released as byproducts of OTEC plant operation. These products can hold a very profitable place in industries such as pharmaceutical, food, cosmetics and mineral water production. Further research on ocean current and DSW properties can someday lead to the commercial used of OTEC. This paper is a review of the basic concept, present status and future prospects of OTEC around the world.