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Increasing the efficiency of high-pressure systems in aerospace through 3D metal printing

2020-11-17
Heat exchangers are a prolific application found in all things that concern fluid and power; they are mission-critical applications that affect overall performance in aircraft of all sizes. Yet, for years, heat exchangers have been constrained, by traditional manufacturing, in terms of limited geometric freedom and lengthy lead times. Consider the following • Heat exchangers are commonly fabricated with stainless steel and then gold brazed, which can be extremely costly • Each weld joint costs $100; in traditionally manufactured fuel and high-pressure systems, there could be hundreds of welds • There can be a lack of integration with other systems like electrical motors or conformal cooling with batteries. Assembly integration, testing, and validation are lengthy and difficult. Additive manufacturing (aka 3D printing) has opened new possibilities for thermal conductivity and heat-exchanger design that enable end users to push the limits of what is possible.
Technical Paper

Wall Heat Flux on Impinging Diesel Spray Flame: Effect of Hole Size and Rail Pressure under Similar Injection Rate Condition

2020-10-30
2020-32-2313
The fuel economy of recent small size DI diesel engines has become more and more efficient. However, heat loss is still one of the major factors contributing to a substantial amount of energy loss in engines. In order to a full understanding of the heat loss mechanism from combustion gas to cylinder wall, the effect of hole size and rail pressure under similar injection rate conditions on transient heat flux to the wall were investigated. Using a constant volume vessel with a fixed impingement wall, the study measured the surface heat flux of the wall at the locations of spray flame impingement using three thin-film thermocouple heat-flux sensors. The results showed that the characteristic of local heat flux and soot distribution was almost similar by controlling similar injection rate except for the small nozzle hole size with increasing injection pressure.
Technical Paper

Investigations on NOx and Smoke Emissions Reduction Potential through Diesel-Water Emulsion and Water Fumigation in a Small Bore Diesel Engine

2020-10-30
2020-32-2312
In the present work, a relative comparison of addition of water to diesel through emulsion and fumigation methods is explored for reducing oxides of nitrogen (NOx) and smoke emissions in a production small bore diesel engine. The water to diesel ratio was kept the same in both the methods at a lower concentration of 3% by mass to avoid any adverse effects on the engine system components. The experiments were conducted at a rated engine speed of 1500 rpm under varying load conditions. A stable water-diesel emulsion was prepared using a combination of equal proportions (1:1 by volume) of Span 80 and Tween 80. The mixture of Span 80 in diesel and Tween 80 in water was homogenized using an IKA Ultra Turrax homogenizer with tip stator diameter 18mm at 5000 rpm for 2 minutes. The water-in-diesel emulsions thus formulated were kinetically stable and appeared translucent. No phase separation was observed on storage for approximately 105 days.
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