Comparative Study between Curved and Straight Pipe Heat Exchanger Using Solid Works

 هذا البحث يركزعلى زيادة فعالية مبادل حراري مزدوج مستقيم الشكل عن طريق حني الانبوب بزاوية 1800. تم استخدام برنامج Solid works لرسم وبناء الشكل. تعرض نموذج المبادل الحراري المقترح دراسته على ظروف تشغيل مختلفه مشتمله على درجة حرارة الانبوب الداخلي ومعدل جريان المائع بالاضافه الى درجة الحراره الداخلة للقشرة. لقد اظهرت نتائج النمذجة ان كفاءة المبادل الحراري ذو الانبوب المنحني اعلى من كفاءة المبادل الحراري المستقيم  وذلك لان الانحناء في الانبوب  تعطي وقت اطول للتبادل الحراري بين السائل الحار والبارد. عند ثبوت معدل جريان المائع ودرجه حراره الدخول للقشره لوحظت زياده في كفاءة المبادل الحراري المنحني بنسبة 14.86% بالمقارنه مع المبادل الحراري المستقيم عند درجه حرارة 357 كلفن.لقد وصلت اعظم كفاءة الى 13.75%عند 363 كلفن للمبادل الحراري المنحني عند معدل جريان 0.22 كغم/ثا ودرجه حرارة ثابته للقشره في حين كانت بنسبة  12.15% عند 363 كلفن بالنسبه للمبادل الحراري المزدوج ذو الانبوب المستقيم.This work focuses on an increase in the effectiveness for straight double pipe heat exchanger through curving the pipe through 180o. The geometry, mesh and boundary conditions are built up using solid works program. The proposed model of the curved pipe heat exchanger is subjected to different boundary conditions, according to inlet tube mass flow rate and inlet shell temperature. The simulated results confirmed that the effectiveness of the curved pipe heat exchanger is higher than straight pipe heat exchanger because the curvature of the pipe gives a longer time to exchange heat between hot and cold fluids. For fixed inlet tube mass flow rate and inlet shell temperature, the increase in the effectiveness of curved pipe is 14.86% compared to straight pipe at 357 K. The maximum effectiveness reached 13.75% at 363 K for curved heat exchanger with 0.22 kg/s inlet tube mass flow rate and fixed inlet shell temperature while it was 12.15% at 363 K for the straight pipe heat exchanger

Dual Mode NOx Sensor: Measuring Both the Accumulated Amount and Instantaneous Level at Low Concentrations

The accumulating-type (or integrating-type) NOx sensor principle offers two operation modes to measure low levels of NOx: The direct signal gives the total amount dosed over a time interval and its derivative the instantaneous concentration. With a linear sensor response, no baseline drift, and both response times and recovery times in the range of the gas exchange time of the test bench (5 to 7 s), the integrating sensor is well suited to reliably detect low levels of NOx. Experimental results are presented demonstrating the sensor’s integrating properties for the total amount detection and its sensitivity to both NO and to NO2. We also show the correlation between the derivative of the sensor signal and the known gas concentration. The long-term detection of NOx in the sub-ppm range (e.g., for air quality measurements) is discussed. Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed

Determination of the NOx Loading of an Automotive Lean NOx Trap by Directly Monitoring the Electrical Properties of the Catalyst Material Itself

Recently, it has been shown that the degree of loading of several types of automotive exhaust aftertreatment devices can be directly monitored in situ and in a contactless way by a microwave-based method. The goal of this study was to clarify whether this method can also be applied to NOx storage and reduction catalysts (lean NOx traps) in order to obtain further knowledge about the reactions occurring in the catalyst and to compare the results with those obtained by wirebound NOx loading sensors. It is shown that both methods are able to detect the different catalyst loading states. However, the sensitivity of the microwave-based method turned out to be small compared to that previously observed for other exhaust aftertreatment devices. This may limit the practical applicability of the microwave-based NOx loading detection in lean NOx traps

Studies of NOx Storage Catalysts - Preparation, Characterization, Sulfur Deactivation and Micro Kinetic Modelling

For the protection of the global environment, it is essential to decrease the emissions of CO2 which is a green house gas. Lean-burn and diesel engines offer relatively low CO2 emissions and good fuel economy. However, in oxygen excess, the conversion of NOx is low, since the reducing agents in the exhaust are more favorably oxidized by oxygen than by NOx. The NOx storage and reduction technique solves this problem by trapping NOx for a relatively long period of time (min) in lean conditions, where catalytic conversion of NOx to N2 is unfavorable. The engine is then for a short time (s) tuned to a rich mixture, which causes a release and reduction of the stored NOx. A typical NOx storage catalyst consists of one or more noble metal(s), such as Pt, Rh and Pd, a NOx storage compound, commonly BaO, and a support material like γ-Al2O3. One major problem with NOx storage catalysts is sulfur poisoning, through which the NOx storage capacity and the reduction properties are strongly suppressed. Sulfur comes from sulfur in the fuel and lubricating oils. The main objective of this work was to improve the understanding of the effect of noble metal and storage material dispersion on the catalytic activity for NOx storage and reduction, in the presence and absence of sulfur. The capacity for NOx storage and reduction in Pt/BaO/Al2O3 NOx storage catalysts can be enhanced by enhancing the dispersion of both Pt and BaO. The Pt dispersion can be enhanced by choosing a Pt precursor with chemical properties suitable for a proper interaction with the support. We prepared Pt/BaO/Al2O3 catalysts from different precursors and found that catalysts prepared using platinum nitrate are most active for NOx storage and reduction. In order to understand how sulfur interacts with Pt and NOx storage sites, Pt/BaO/Al2O3 and BaO/Al2O3 samples were treated with SO2, SO2 + O2 or SO2 + H2 prior to performing NOx storage and thermal regeneration cycles. The NOx storage capacity declined for all samples at all sulfur exposure conditions. For the Pt-containing samples, the deactivation was fastest with SO2 + H2 treatment, while all three sulfur exposure conditions had a similar effect on the BaO/Al2O3 samples. Quantitative sulfur analysis showed that more sulfur was trapped in a SO2 + O2-treated Pt/ BaO/Al2O3 sample, compared to a corresponding SO2 + H2-treated sample. No sulfur was found in the BaO/Al2O3 samples, indicating that the sulfur was weakly bound to these samples and desorbed with time. To describe these results with kinetic modelling, we assumed that NOx is stored only on surface storage sites, while sulfur is stored on both surface and bulk sites. The model was able to describe the experimental results fairly well. To attempt to improve the sulfur tolerance of Pt/BaO/Al2O3 catalysts, we studied the effect of metal oxide additives on the NO and SO2 oxidation capacity of metal oxide-promoted Pt/Al2O3 catalysts. We found that the addition of MoO3 to Pt/Al2O3 enhances the oxidation of NO to NO2, while suppressing the oxidation of SO2 to SO3. However, the NOx storage performance of the MoO3 modified Pt/BaO/Al2O3 catalyst declined more rapidly than the performance of the unmodified Pt/BaO/Al2O3 catalyst, due to faster deterioration during the regeneration (rich) periods

The circumvention of taxation of forbidden loans through tax planning using foreign holding companies

Uppsatsens syfte är att mot bakgrund av införandet av 53 kap. IL och den s.k. X och Y- domen, analysera när ett lån från ett utländskt holdingbolag, kan omklassificeras till utdelning genom en tillämpning av principen om rättshandlingars verkliga innebörd. EU-domstolens dom i X och Y-målet föranledde att reglerna i 53 kap. IL ändrades och gjorde det möjligt för svenska privatpersoner att överlåta aktier till underpris till egna bolag i utlandet utan några omedelbara beskattningskonsekvenser. De nya reglerna öppnade upp för en omfattande skatteplanering genom upplägg med utländska holdingbolag. Genom att låna medel från ett holdingbolag som etablerats i utlandet, har svenska privatpersoner kunnat kringgå låneförbudsreglerna i ABL och därmed undvika beskattning. Under 2009 ändrades reglerna för beskattning av förbjudna lån. De nya reglerna tillämpades från den 13 februari 2009 och innebär att lån från utländska juridiska personer numera ska beskattas. Skatteverket har dock fortsatt att angripa lånetransaktioner som har företagits före denna tidpunkt och hävdat att lånen egentligen utgör skattepliktig utdelning. Principen om rättshandlingars verkliga innebörd innebär att domstolarna kan omklassificera en felaktigt betecknad rättshandling och låta den verkliga innebörden ligga till grund för beskattningen. En omklassificering kan endast göras om en rättshandlings beteckning inte stämmer överens med den verkliga innebörden. Ett lån från ett utländskt holdingbolag borde därför kunna omklassificeras till utdelning endast om lånet kan an-ses utgöra förtäckt utdelning enligt ABL. En samlad bedömning måste göras av samtli-ga omständigheter i det enskilda fallet. Frågan har dock inte prövats i högre instans och rättsläget är fortfarande oklart.The purpose of this thesis is to analyse when, in the light of the X and Y case and chapter 53 IL, a loan from a holding company could be classified as a dividend by applying the principle of substance over form. The ruling of the Court of Justice in the X and Y-case, led to a change of the rules in chapter 53 IL. The new rules made it possible for natural persons to transfer shares in companies at undervalue to foreign legal persons owned by them, without immediate taxation. The new rules resulted in wide tax planning with foreign holding companies. By taking a loan from a holding company established abroad, natural persons could circumvent the ban on credit rules in ABL, and thereby avoid taxation. In 2009 the tax rules concerning forbidden loans where changed. The new rules were applicable from the 13th of February 2009 and imply that loans taken from foreign legal persons should be taxed. However, the tax authorities continue to inspect transactions carried out before this date, claiming that the loans constitute taxable dividends. According to the principle of substance over form, courts are free to reclassify a legal act that is not labeled correctly. Thus, a legal act should be taxed due to its actual substance independent of what form or label it has. A reclassification can only be made when the label of the legal act does not correspond with its real meaning. Hence, a loan from a holding company should only be reclassified to a dividend, if the loan is considered to constitute such disguised dividend according to ABL. All facts need to be considered in the evaluation. The particular question has not been tried by a higher court and therefore the legal position is still unclear

Effect of Nano Fuel Additives on the Characteristics of Diesel Engine Fed with Biodiesel Blended Fuel

في هذا العمل تم اجراء تحليل عددي لتأثير تركيزات مختلفة من جزيئات النانو المخلوطة مع وقود الديزل الحيوي على خصائص محرك الديزل. تم استخدام برنامج المحاكاة Diesel-rk في هذا العمل. تم استخدام وقود الديزل الحيوي استر ميثيل الخروع (CME) والذي يتم تحضيره من زيت الخروع عن طريق عملية الاسترة. تم دراسة تأثير جزيئات النانو باستخدام ثلاثة تراكيز50 ,25) ، 100 جزء في المليون)   من الالومينا  ممزوجة بـ  B20%CME والتي تم تأكيدها من الدراسات السابقة باعتبارها أفضل نسبة معتمدة. عمومًا ، وجد أنه مع استخدام جزيئات النانو إلى جانب وقود الديزل الحيوي ، ينخفض ​​ضغط الأسطوانة وفترة التأخير ودرجة حرارة الاحتراق. ادرجت تحسينات ملحوظة في الكفاءة الحرارية المكبحية ومعدل استهلاك الوقود. أظهرت النتائج انخفاضا كبيرا في قيم الدخان وانبعاثات أكاسيد النيتروجين وكذلك المادة الجسيمية (PM)، لذا يمكن اعتبارها طريقه لمحاربة التناقض بين (PM-NOx). أظهرت النتائج أن أفضل تركيز لجزيئات النانو كان 25 جزء في المليون حيث لم يسجل أي تغير ملحوظ عند تجاوز هذا التركيز. تم التحقق من صحة النتائج العددية مع نتائج تجريبية أخرى في نفس ظروف التشغيل.A Numerical analysis for the effect of different Nano particles concentrations on the diesel engine characteristics fired with biodiesel blended fuel is investigated in the work. The simulation software Diesel-rk has been used in this work. The biodiesel under focus is castor methyl ester (CME) which is derived from castor oil via transesterification process. The impact of Nano particles is studied by using three doses of Al2O3 (25, 50, 100 ppm) mixed with B20% CME which is confirmed from previous studies as the best compromise ratio. Generally it's found that with use of Nano particles along with biodiesel fuel, the cylinder pressure, delay period, combustion temperature decreases. Noticeable enhancements in the brake thermal efficiency and fuel consumption have been recorded.  The results reported dramatic reductions in smoke values, NOx emissions as well as Particulate matter (PM), hence this way can fight trade-off relation (PM-NOx). The findings showed, best concentration of Nano particles was 25 ppm as no dramatic effect was observed beyond this dose. The validity of the numerical results is checked out with other experimental results at the same condition of operation

The circumvention of taxation of forbidden loans through tax planning using foreign holding companies

Uppsatsens syfte är att mot bakgrund av införandet av 53 kap. IL och den s.k. X och Y- domen, analysera när ett lån från ett utländskt holdingbolag, kan omklassificeras till utdelning genom en tillämpning av principen om rättshandlingars verkliga innebörd. EU-domstolens dom i X och Y-målet föranledde att reglerna i 53 kap. IL ändrades och gjorde det möjligt för svenska privatpersoner att överlåta aktier till underpris till egna bolag i utlandet utan några omedelbara beskattningskonsekvenser. De nya reglerna öppnade upp för en omfattande skatteplanering genom upplägg med utländska holdingbolag. Genom att låna medel från ett holdingbolag som etablerats i utlandet, har svenska privatpersoner kunnat kringgå låneförbudsreglerna i ABL och därmed undvika beskattning. Under 2009 ändrades reglerna för beskattning av förbjudna lån. De nya reglerna tillämpades från den 13 februari 2009 och innebär att lån från utländska juridiska personer numera ska beskattas. Skatteverket har dock fortsatt att angripa lånetransaktioner som har företagits före denna tidpunkt och hävdat att lånen egentligen utgör skattepliktig utdelning. Principen om rättshandlingars verkliga innebörd innebär att domstolarna kan omklassificera en felaktigt betecknad rättshandling och låta den verkliga innebörden ligga till grund för beskattningen. En omklassificering kan endast göras om en rättshandlings beteckning inte stämmer överens med den verkliga innebörden. Ett lån från ett utländskt holdingbolag borde därför kunna omklassificeras till utdelning endast om lånet kan an-ses utgöra förtäckt utdelning enligt ABL. En samlad bedömning måste göras av samtli-ga omständigheter i det enskilda fallet. Frågan har dock inte prövats i högre instans och rättsläget är fortfarande oklart.The purpose of this thesis is to analyse when, in the light of the X and Y case and chapter 53 IL, a loan from a holding company could be classified as a dividend by applying the principle of substance over form. The ruling of the Court of Justice in the X and Y-case, led to a change of the rules in chapter 53 IL. The new rules made it possible for natural persons to transfer shares in companies at undervalue to foreign legal persons owned by them, without immediate taxation. The new rules resulted in wide tax planning with foreign holding companies. By taking a loan from a holding company established abroad, natural persons could circumvent the ban on credit rules in ABL, and thereby avoid taxation. In 2009 the tax rules concerning forbidden loans where changed. The new rules were applicable from the 13th of February 2009 and imply that loans taken from foreign legal persons should be taxed. However, the tax authorities continue to inspect transactions carried out before this date, claiming that the loans constitute taxable dividends. According to the principle of substance over form, courts are free to reclassify a legal act that is not labeled correctly. Thus, a legal act should be taxed due to its actual substance independent of what form or label it has. A reclassification can only be made when the label of the legal act does not correspond with its real meaning. Hence, a loan from a holding company should only be reclassified to a dividend, if the loan is considered to constitute such disguised dividend according to ABL. All facts need to be considered in the evaluation. The particular question has not been tried by a higher court and therefore the legal position is still unclear