Influence of excessive air coefficient during combustion on intensity of two-stroke diesel engine operation in wide range of modes

The article describes the specific features of the forced diesel engines operating on a helical characteristic. One of them is a decreasing coefficient of excessive air during combustion with a decreasing power. Reducing the air charge of the cylinder and its available work require a greater cyclic supply of fuel to provide a given power, which affects the engine efficiency. It is possible to increase the boost pressure and the mass of the air charge of the cylinder by acting on the adjustable nozzle apparatus of a turbo-charging unit. In this case, gas parameters significantly change over the diesel cycle, which leads to changes in the indicators of thermal and mechanical tension. There have been presented the results of theoretical studies of indicators and criteria of thermal and mechanical tension of a marine two-stroke internal combustion engine operating in a wide range of modes with a constant coefficient of excessive air during combustion. Direct control of air flow at shared load modes was performed by turning the blades of an adjustable nozzle apparatus of a turbo-charging unit. The study of a diesel engine was carried out theoretically for two options: the original version (without adjustable nozzle unit) and under direct control of the air flow using an adjustable nozzle unit; the results were processed depending on the relative power of the diesel fractional load modes. There have been illustrated the graphs of dependence of the blade rotation angle of the nozzle apparatus of a turbocharging unit, relative change of the gas temperature behind the cylinder, cycle average temperature of the working fluid, average heat flux, relative change in the heat stress criterion of the piston, heat stress criterion for the cylinder, change in the pressure cycle of the working fluid, degree of increase working fluid during combustion, maximum rate of pressure rise depending on the load of the diesel engine.

Gradient Hydrogel Construct Based on an Improved Cell Assembling System

In this study, a two-step crosslinking method derived from commercial rapid prototyping equipment was used to fabricate a gradient hydrogel scaffold in vitro. This system contained two types of nozzles; one was double-nozzle unit, used for relatively simple gradient hydrogel scaffold composed of two nonmiscible hydrogel materials. The other was single nozzle that was used for mixing a gradient hydrogel scaffold composed of two types of hydrogel materials. Different types of scaffolds were formed by modifying the gradient in one of the relevant nozzles. To improve the extrusion controlling effect, accessorial parameters were introduced. A 3D gradient construct containing neuron cells and Schwann cells was fabricated and cultured for 7 days. This construct was helpful in designing a gradient mode to observe the relationship between different cells in vitro. This work has improved tissue-engineering techniques for later manufacturing of very complicated organ analogs.

Study on CO2 Releasing Nozzle for CO2 Ocean Storage

Ocean storage of CO2 is one of greenhouse gas control technologies, where CO2 captured from flue gas of fossil fuels is injected into deep sea below 3500m depth to be sequestered from the atmosphere. A CO2 sending method, COSMOS, was proposed as a method of ocean storage, which enables CO2 drops released in mid-depth water to descend to deep sea floor below the depth of 3500m. Then, the authors have worked for development and evaluation of COSMOS. In the first phase of the COSMOS project, the concept of COSMOS was demonstrated by in situ experiments of small-scale CO2 releasing at mid-depth water in Monterey Bay, U.S.A. Three models of CO2 releasing nozzle unit were developed for the experiments. The first model of nozzle unit released liquid CO2 as one mass; however, it was immediately broken into small droplets and soon turned to ascend. The second and third models were designed to have thermal insulator enough to keep low temperature so that both models successfully released liquid CO2 with dry ice, which continued descending for a few minutes. Based on these results, COSMOS was improved, where injection of a mixture of liquid CO2 and dry ice, CO2 slurry, is expected to enable small CO2 drops to descend to deep sea floor below 3500m depth. Then, in the second phase of the COSMOS project, the authors started an investigation on the effect of the aspects of releasing nozzle on the behavior of released slurry drops, and obtained a few results from lab experiment of CO2 slurry releasing from two types of nozzle head.