This work investigates the effect of blending biodiesel with diesel on the combustion of an isolated fuel droplet. Biodiesel blends substituting diesel oil in different concentrations on volumetric basis, in addition to neat diesel and biodiesel, were studied. High-speed Schlieren and backlighting imaging techniques have been used to track droplet combustion. The results showed that partial substitution of diesel oil by biodiesel at the test conditions led to increasing secondary atomization from the droplet, compared to neat diesel or biodiesel fuel droplets. This in turn enhances evaporation, mixing, and then combustion. Additionally, the results showed that biodiesel has a higher burning rate compared to diesel, and that increasing biodiesel in the blend increases the burning rate of the blend. Nucleation has also been traced to take place inside the droplets of the blends. Moreover, flame size (height and width) has been reduced by increasing biodiesel concentration in the blend.

Droplet impingement on solid surfaces takes place in a variety of industrial and environmental applications. However, there are still some areas that are not fully comprehended; emulsion droplet impact on a heated surface is one of these areas that require further comprehension. Hence, the present work represents an experimental exploration for spread characteristics of diesel-in-water (DW) emulsion droplet impacting a heated flat plate. Three different emulsions in which water concentration is set to 10%, 20%, and 30% of the overall emulsion content by volume have been tested in addition to the neat diesel. The temperature of the flat plate is varied over the range 20, 40, 60, and 80 degrees C respectively. Magnified high speed direct imaging and shadowgraphy have been used simultaneously for tracking droplet spread over the heated surface post impact. Droplet spread rate. maximum diameter, rebound height and velocity represent the main evaluated parameters. The results show that the maximum spread diameter is proportional while spread rate is inversely proportional to the increase in plate temperature for all diesel concentrations including the neat diesel. Whereas. droplet rebound height and velocity are found to be more responsive to the variation in diesel concentration than the variation in plate temperature, so they are both minimum in the case of neat diesel and are increasing by the decrease of diesel concentration in the emulsions.

One of the major problems in the contemporary world is pollution. The major contribution in this area comes from automobile emissions and industries. Diesel being one of the major fuels is also a major contributor in adding harmful pollutants into the atmosphere. In order to meet the stringent emission norms, the polluting components in the fuels need considerable reduction. Fuel characteristics play a major role in engine efficiency and engine emissions directly or indirectly. In the present work, an experimental investigation of the effect of adding methanol to the diesel-biodiesel blends on the performance and combustion characteristics of the diesel engine has been performed. Three different concentrations of methanol are used; namely 5%, 7%, and 10% of the overall mixture volume, while, biodiesel concentration has been fixed to eliminate its effect on the results. The results revealed that using methanol as an additive to the diesel-biodiesel blends prominently improved brake power, decreased brake specific fuel consumption (BSFC) and increased brake thermal efficiency (BTE) of the engine. CO, HC, and NOx emissions have shown a slight decrease compared to the corresponding neat diesel and diesel-biodiesel at the same loading and engine speed conditions.

يعد اضطراب التدفق أحد الأساليب الأكثر استخدامًا لتحسين نقل الحرارة. استخدمت هذه الدراسة المحاكاة العددية والاختبارات التجريبية لفحص تأثير المضطربات الكروية على خصائص احتكاك السوائل وانتقال الحرارة في أنبوب دائري. باستخدام طريقة الحجم المحدود، تم إجراء المحاكاة العددية بواسطة برنامج Ansys Fluent 19 R3. قسم الاختبار، وهو عبارة عن أنبوب نحاسي بطول 1 متر وقطر داخلي 24 مم، يعمل كأحد المكونات الأكثر أهمية لجهاز الاختبار التجريبي. يتم إدخال محركات كروية بأقطار مختلفة 10 و 15 و 20 ملم وأطوال فاصلة 20 سم في الأنابيب الدائرية. أصبحت نسبة قطر الكرة إلى قطر مسار التدفق الداخلي للأنبوب، نسبة اضطراب الكرة (BTR) = 0.41 و0.62 و0.83. تم استخدام الماء كسائل عمل برقم رينولدز من 3500 إلى 11500. تظهر النتائج اتفاقًا ممتازًا مع انحرافات أقل من 11٪. بلغ معامل الأداء الحراري الأقصى حوالي 1.18 و 1.24 و 1.4 للـ 0.41BTR و 0.62 و 0.83 على التوالي. تنتج المراوح الكروية زيادة في عامل الاحتكاك، وهذه الزيادة في النتائج التجريبية هي 52، 65 و 78% عند 0.41، 0.62 و 0.83 على التوالي. ويرتفع عامل الاحتكاك فجأة عند تجاوز BTR 0.62. كما يلاحظ أن هناك انخفاض تدريجي في الأداء الحراري عندما يكون نطاق أرقام رينولدز أعلى من 7500.