Outline and problems of modeling of Diesel combustion, mainly phenomenological modeling were described as virtual engine design engineering. Because of verification of a new combustion system and new technology, the role of modeling (virtual engine design) is very large and useful. Compared to actual Engine tests, modeling (virtual engine design) can accurately predict engine performance that may be difficult to valuate through engine experiments at low cost and in short time.
Three-dimensional numerical simulations were carried out on dense gas-solid flows for the purpose of investigating the effect of ship rolling motion on circulating fluidized beds (CFBs). Because our research was intended for numerically modeling of realistic CFBs, instead of using a Eulerian-Lagrangian model, a two-fluid model and its sub-models based on the kinetic theory of granular flows were employed for the present gas-solid system in order to reduce computational time. From the numerical results, it was found that the fluidized states under the rolling conditions were obviously different from those in the upright CFBs. Under rolling cases, in comparison to an upright CFB, the amount of solids accumulating at the lower part of a riser increased and solid circulation fluxes markedly decreased. These results qualitatively agreed with experimental observations. To find out the relationship between fluidized states and rolling motion, we examined the external forces, especially drag force, acting on the solid phase per unit mass. In the case of the upright CFB, the horizontal direction components of the drag force were much smaller than that in the vertical direction. On the other hand, it was found that there was significant drag force acting on the solid phase not only in the direction of the riser axis but also in the rolling direction at the lower part of the riser in the rolling CFB. Therefore, it may be inferred that the drag force component in the rolling direction influences the decrease of solid circulation fluxes.
Ever stricter emission legislation and fuel economies are placing ever greater demands on engine design. Therefore it is important to optimize aspects of the whole engine, including after treatment and some mechanisms variables. One-dimensional engine simulation tools have been developed to predict the performance of the whole engine system. These help to understand physical phenomenon within the engine system and help us to study the differences of engine configurations. We show the features of a one-dimensional engine simulation code, and introduce some examples.
Droplet collision in a diesel spray has been studied through observation of binary collision of two equivalent droplets of the same kind. In a direct water injection (DWI) system, a two-needle injector may produce considerable collisions between fuel and water droplets, and because of the near co-axial nozzle hole layout. In this study, the empirical criteria were directly adopted into KIVA3 code. This was divided into bounce, coalescence and separations after the collision of two droplets of any kind. The effective entrainment of water into fuel spray was numerically captured in the DWI system of the two-needle injector. The results were partially confirmed through observation of the actual DWI spray in a constant volume bomb.
Paint is typically applied to metal surfaces as a coating to cover up any surface irregularities and to prevent such surfaces from being eaten away by rust and marine organisms. In our study, we examined how harsh environmental conditions might affect two different kinds of paint: a typically used white paint and Mighty CF-CP, a product which has recently begun to attract attention as an anti-corrosion paint on steel. We coated one iron plate with the white paint and one with Mighty CF-CP and then immersed both plates in the sea (at a depth of about one meter) for a period of nine months. The sea was chosen because we thought it provided us with the harshest environmental conditions. We discovered that although the film of both of these types of paint, as well as the surface of the iron plates changed with the passage of time, the degree in which they changed was remarkably different. Mighty CF-CP paint was much more resistant to effects of rust and marine organisms. In this paper, we will discuss in detail our findings.
The Offshore Cargo Operation (OCO) in the Port of Kobe is a unique cargo transfer style for naked chemical substances including flammable dangerous goods, palm and tallow oil, etc. We examined imported and exported chemical substances between 1989 and 2007. We also investigated which countries were the majors exporting to Japan, and which were the principle discharge ports in Japan. This, after they were transferred by way of OCO in 1995 and 2007, and vice versa was examined. As a result, the export and import of pure chemicals to and from foreign countries has reduced gradually since 1995. The value in 2007 showed 307,000 and 440,000 M/T, respectively. These values correspond to 42.0% and 50.8% to those of 1995. The United States of America was the major country to export chemicals to Japan in 1995 and in 2007. It became obvious that the OCO still plays an important role for our local chemical industries located near the smaller ports, such as Himeji, Tokuyama, and Yokkaichi, etc. This is because the domestic shipping can supply large amounts to the chemical industries located at the waterfront and/or carry out from them to export by way of OCO.
We studied cavitation erosion of pure titanium (TB270H, TB340C, TB480H), titanium alloy (Ti-6Al-4V) and stainless steel (SUS316) by using a cavitating jet apparatus in seawater and in tap water. The obtained data were compared with those from similar experiments previously carried out in 3% salt water and also de-ionized water. A rotating disk was used. And a vibration test was made using apparatus for pure titanium, titanium alloy (Ti-6Al-4V, Ti-15V-3Cr-3Sn-3Al) and stainless steel (SUS316, SUS316L). The erosion resistance of pure titanium and the stainless steel in tap water was excellent. Whilst the erosion rates in seawater were higher than those in tap water. This suggests that it is necessary to reduce the inspection interval when those materials are used in a seawater pump impeller. Corrosion current density behavior was similar to that of cavitation erosion rate. The corrosion current density of the eroded pure titanium was 1.2 μA/cm2]. This was 2.4 times higher than that of the stainless steel. Relative erosion resistance of these metals was obtained with a cavitating jet, a rotating disk and a vibratory apparatus, which exhibits a good linear relationship against the Vickers hardness value on the logarithmic graph paper.
In this study, a wear test was carried out to clarify the effects of the experimental potentials on tribocharacteristics of metals against alumina(Al2O3) in 3% NaCl solution and under different potentials. We used an oscillatory type, and a cylinder-on-disk type test apparatus. As the results show [phosphor bronze(PBB2)] a generally higher wear resistance and lower coefficient of friction than with either carbon steel(S45C) or stainless steel(SUS304). But it does show a lower wear resistance under corrosion potential (COP(+250mV)) than with them. SUS304 shows a generally lower wear resistance and a higher coefficient of friction than with either S45C or PBB2, though it shows a higher wear resistance under corrosion potential (COP(+250mV)). The wear resistance of S45C is easier to receive the effect of the experimental potentials in PBB2 and over SUS304.
Palm oil is being seriously looked at as one of the alternative fuels to fossil fuels, this being due to the aspect of vegetable oils and the so called carbon neutral state. However, at room temperature, the viscosity of palm oil is too high to apply as a fuel for the internal combustion engine. In this study, pure palm oil is mixed with fossil fuels, this in order to reduce the viscosity. In the experiment palm oil was blended with gas oil and then marine diesel oil, by weight ratio, and the kinematic viscosity of the mixed fuels were measured. In the cases of 20% palm oil used, and 50%, was found to be useable without any heating of the fuels. Engine performances, such as cylinder pressure histories and exhaust emissions, were examined with a pre-combustion chamber type diesel engine. We discovered that a palm oil blended fuel shows earlier ignition and shorter combustion period than gas oil or marine diesel oil. NOx emissions show a lower concentration for all palm blended cases, and the reduction ratio is proportional to the palm mixing amount. From these results, we can suggest that palm oil could be used for the diesel engine by mixing with the fossil fuels without heating the fuels.
Critical heat flux (CHF) and flow boiling characteristics in parallel flow boiling channels simulating soot burning were experimentally investigated. This, for the purpose of prevention of a soot-fire on an exhaust gas economizer. Heat load by exhaust gas was simulated by uniformly heating parallel heated tubes through electrodes from two direct current power sources, respectively. Soot burning was simulated by non-uniformly heating only the other heated tube. Three gas burners were used or by increasing only the electric power. The inside diameter and length of the heated tubes were 4.35 and 1,000 mm, respectively. The main results are as follows: CHF in the soot burning tube first occurs near the heated tube exit. The point of sharp rise in tube wall temperature shifts on the upstream side with increasing time and / or heat flux. Flow rate in each heated tube, the pressure drop between pressure heads, or the total circulating flow rate monitoring system, is effective in order to early detect soot burning from the point of view of flow boiling characteristics.
Pathogenic and fecal bacteria, such as Vibrio cholerae and Escherichia coli, possibly invade via seawater. This may expose marine engineers to an intrinsic risk of infection when they carry out routine maintenance. We therefore investigated, following the voyage, the seawater taken into a ship's engine-room. As for the populations, they varied from 102.9 to 105.9 colony-forming units (cfu) ml-1. A correlation coefficient between the population and the in situ seawater temperature was 0.71, 0.30, and 0.068 for the samples taken from calls facing to the ocean (n = 6), the Inland Sea (n = 12), and the coastal area around the Pacific Ocean (n = 16), respectively. An occupational ratio of Vibrio sp. population increases when the seawater was retained for more than three months in the condensers for the air conditioner and the drain cooler. Although three strains were detected from the drain cooler, those of which had ability to make yellow-colored colonies on a selective plate at 37°C and left for 6 months. It was identified as to be Aerococcus viridans. In that species, the lobster pathogen is included, but nothing human. So far examined is pathogenic V. cholerae, which was not detected in all the samples taken from the engine-room. These results indicate that the possibility of infection of marine engineers to be quite low when they do the maintenance on board in the coastal area and the Inland Sea of Japan
Further improvement in the purification performance of exhaust gas is required for the three-way catalyzers (TWC) to purify gasoline engine exhaust gas. Therefore it is necessary to investigate the purification characteristics, in detail, and improve the catalyzer geometry, etc. In this study the conversion efficiencies of exhaust gas components; CO, HC and NO in the TWC were estimated by three-dimensional calculation with the authors' GTT code, in which a catalytic reaction model was incorporated in order to analyze the thermo-fluid flow with chemical reaction in the TWC. The effects of the shapes of exhaust pipe and diffuser in the upstream part of the monolith catalyzer on conversion efficiency were investigated. It has been found that both exhaust pipe and diffuser shapes considerably affect the conversion efficiency of catalyzer, especially in the range of catlyzer activation temperature, i.e., from about 400 K to 520 K.