Dizel araçlarda yol eğimi bilgisinin dizel partikül filtresi rejenerasyonuna etkisi
Effects of road slope information on diesel particulate filter regeneration in diesel vehicles
Yazar: NAZLI ECEM ÇOKER
Danışman: PROF. DR. HALUK EROL
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Makine Dinamiği, Titreşimi ve Akustiği Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Dizel egzoz gazlarının içinde bulunan yanmamış hidrokarbonlar (HC), karbonmonoksit (CO), nitrojenoksitler  (NOx) ve partikül maddeler (PM) çevre kirletici maddelerdir. Dünya üzerinde bu kirletici maddelerin etkilerini indirgemek amacıyla emisyon düzenlemeleri yapılmıştır. Geliştirilen emisyon sınırları gün geçtikçe daralmakta ve otomotiv sektörü bu standartlara uyabilmek için yeni geliştirmeler yapmaktadır. Euro 6 emisyon standartlarını sağlamak için yapılan geliştirmelerden biri de Dizel Partikül Filtre (DPF) adı verilen parçanın kullanılmaya başlanmasıdır. Bu parça dizel motorlarda yanma sonucunda oluşan partikül maddelerin tutulmasını sağlamaktadır. 
DPF kullanımının beraberinde getirdiği en büyük problemlerden biri, tutulan kurumların birikmesi ve filtreyi kullanılmaz hale getirmesidir. Bunu bu problemi çözmek için araç üzerinde egzoz sıcaklıkları yaklaşık 600 derece seviyelerine yükseltilerek DPF içerisinde biriken kurumların yakılması sağlanır. Bu işlem rejenerasyon işlemi olarak adlandırılır. Rejenerasyon işleminin ne zaman, hangi sıklıklıkla ve hangi koşullarda gerçekleşmesi gerektiği konuları da DPF'in beraberinde getirdiği konulardan biri olmuştur. 
Doğru zamanda yapılmayan rejenerasyon işlemleri DPF'in hasar görmesine, tıkanarak araç çalışmasını engellemesine, rejenerasyonun doğru şekilde tamamlanamamasına, fazla yakıt tüketimine ve yağ kirlenmesi problemlerine sebep olabilmektedir. Bu nedenle rejenerasyon stratejisi üzerinde yapılacak bir iyileştirmenin birçok konuda etkisi olacağı söylenebilmektedir. 
Günümüzde rejenerasyon stratejilerinde navisgasyon sistemleri kullanılması pek çok firma tarafından düşünülmektedir. Navigasyon sisteminden alınan trafik ve yol bilgisine göre rejenerasyon kararı alınmasıyla ilgili kaynaklar bulunmaktadır. Bu tez kapsamında GPS verileri üzerinden elde edilen yol eğimi bilgisinin rejenerasyon üzerindeki etkisi incelenmiştir. Çalışmanın ilk kısmında egzoz sıcaklıklarının hangi eğim noktalarında ne kadar değiştiği araştırılmıştır. Bu araştırma ticari bir araçla, yükseltisi bilinen İstanbul/Sancaktepe – Eskişehir/İnönü rotası üzerinde yapılmıştır.
Çalışmanın ikinci kısmında, ilk kısımda elde edilen bilgiler doğrultusunda DPF rejenerasyon işlemini öteleyecek ya da erkenden gerçekleşmesini sağlayacak eğime bağlı rejenerasyon kuralları yazılmıştır. Yazılan kurallar Matlab Simulink programında kurulan DPF Rejenerasyon Karar modeli üzerinde doğrulanmıştır.

Abstract:
The unburned hydrocarbons (HC), carbon monoxides (CO), nitrogen oxides (NOx) and particulate matters (PM) are environmental pollutants which caused by diesel engines. Emission standards are placed to control these harmful pollutants.  The emission limits are getting narrower and the automotive sector is making new improvements to meet these standards. One of the improvements made to meet Euro 6 emission standards is the usage of the so-called Diesel Particulate Filter (DPF). This component ensures that particulate matter is generated by combustion in diesel engines.
One of the biggest problems associated with the use of DPF is the increasing of soot load and making the filter unusable. In order to solve this problem, exhaust temperatures are increased to about 600 degrees on the vehicle and the stored soot on DPF are burned. This process is called the regeneration process. One of the topics that the regeneration process bring about is when, how often and in which conditions to regenerate the filter.
Regeneration processes that are not performed at the right time can cause damage to DPF, inhibit the operation of the vehicle by clogging, failure to complete the regeneration correctly, excessive fuel consumption and oil dilution problems. Therefore, it can be said that an improvement on the regeneration strategy will have an effect on many issues.
Today, the use of navigation systems in regeneration strategies is considered by many companies. There are many sources related to the regeneration decision that according to the traffic and road information received from the navigation system. In this thesis, the effect of road slope information obtained from GPS data on regeneration has been investigated. In the first part of the study, it is investigated how far the exhaust temperatures change at the slope points. This research was carried out with a commercial vehicle on the Istanbul / Sancaktepe - Eskişehir / İnönü route.
As a GPS, predictive cruise control module on vehicle is used. Predictive cruise control module produces elevation information of route. In this thesis this information used to determine route slope information.
While the adaptive cruise control does not give the slope information, it is needed to calculate slope of route points. Regression method is used to calculate these slope informations. 
Exhaust gas temperature values recorded all way long then investigated. There were four different areas which could be said related to slope change. Common characteristics of these four regions were; similar average velocity, no big change on vehicle speed, no behaviour change on engine. Although having no change on given characteristics it is discovered that exhaust gas temperatures icreased or dicreased with respect to change of elevation. 
First district is detected with 185 degree Celcius tempereature decrease on DPF inlet temperature between 31 and 36 kilometers of the route. There was no other factor to effect exhaust gas temperatures except slope of the road. Then slope is calculated between the points of starting and end of the exhaust temperature change with regression method. It is considered that to trust regression method R-squared value must be greather than 0,92. In the end slope value calculated as -34 and R-squared value calculated as 0,97. The second area is detected with 179 degree Celcius tempereature increase on DPF inlet temperature between 65 and 67 kilometers of the route. There was no other factor to effect exhaust gas temperatures except slope of the road. The slope value calculated as +50 and R-squared value calculated as 0,92. The third area is detected with 227 degree Celcius tempereature decrease on DPF inlet temperature between 72 and 76 kilometers of the route. There was no other factor to effect exhaust gas temperatures except slope of the road. The slope value calculated as -41 and R-squared value calculated as 0,93. The last district is detected with 207 degree Celcius tempereature increase on DPF inlet temperature between 217 and 225 kilometers of the route. There was also no other factor to effect exhaust gas temperatures except slope of the road. The slope value calculated as +28 and R-squared value calculated as 0,95. 
In the end of the exhaust gas and slope releation investigation it is detected that all the districts have slope around ±20 and R squared values greather than 0,90 which means reliable information. Although the behaviours of areas were similar, slope calculation ranges are different. To determine the proper slope calculation change, slope values are recalculated for all four district with two, four and six kilometer mileage. Than it decidet to continue with four kilometer slope calculation range due to the effortless calculation advantage for powertrain control module of the vehicle
In the second part of the study, according to the information obtained in the first section, the regeneration decision rules related to the slope were written which would either delay the DPF regeneration process or enable it to take place early. The rules are validated on the DPF Regeneration Decision model established in the Matlab Simulink program.
The areas which have negative slope values would couse exhaust gas temperature decrease on vehicle. It would couse more post injection on engine to keep the exhaust warm. This much post injection would couse oil dilution on engine. To prevent this penalities vehicle should be inhibited to do regeneration. The regeneration permission block which is in the vehicle software is used to execute that inhibitation. There could be a possible critical problem about regeneration inhibit. If the soot load level of DPF is at the critial level it might couse DPF blockage. This problem is told to be the worst problem about DPF. To optimize this it is considered to use soot load level as a input of nwe regeneration rule. If the DPF soot load level is not at critical level which would couse DPF blockage and the calculated slope for coming four kilometers smaller than 20 with R-squared value bigger than 0,9 the regeneration delayed for upcoming 4 kilometer range. 
The areas which have positive slope values would couse exhaust gas temperature increase on vehicle. It would couse less post injection on engine to keep the exhaust warm. This less post injection would decrease the oil dilution on engine. To take advantage of these factors vehicle should do regeneration as soon as possible. The regeneration activation rule block which is in the vehicle software is used to execute that opportunistic regeneration event. The crutial point of this could be again the soot level of DPF. All the effects must be considered to decide at which soot load level opportunistic regeneration start. It is decided to start regeneration, If the soot load level is aroud 75% and the calculated slope for coming four kilometers grather than 20 with R-squared value bigger than 0,9.
Exhaust gas temperatures are generally around 300 degree Celcius in normal conditions. But to regenerate DPF exhaust temperatures must be around 600 degree Celcius. To keep exhaust warm engine produce post injections. These post injection not only work for keep exhaust warm but also increase the temperature level up to 600 degree. Also these post injection just used for regeneration. Which means regenation is responsible for fuel penalty coused by post injection.
In the thesis, it is also investigated that the regeneration and slope effects on fuel consumption. A constant named regeneration fuel rate is used for this investigation. This constant is the value of total post injection in regeneration divided by the total injection in the regeneration. This constant will give the information about how much of the total fuel consumed for regeneration. This constant is calculated for all the mesurement points in regen event. Than the mean value of the regeneration fuel rate for 600 minutes also calculated. While exhaust temperatures are narrower, it is expected that fuel consumption in regeneration should be higher in negative slope regions. In contrast, while exhaust gas temperatures expected to be higher in positive slope regions the fuel consumption due to the regeneration will be lower. Two different negative slope region, one positive slope region and one region with nearly zero slope are investigated. Mean regeneration fuel rate at negative regions are calculated as 0,3017 and 0,3213. The reference area which could be said without slope has 0,24 mean regeneration fule rate ratio and positive slope area has 0,2073 mean regeneration fule rate ratio.
In the end, it is detected that at the negative slope regions, mean regeneration fuel rates are greater than the mean regeneration fuel rate at positive slope regions as expected.