Correlation investigations into pollutant emission and the operational states of compression-ignition engines in dynamic tests

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1 Aticle citation info: CHŁOPEK, Z., LASOCKI, J. Coelation investigations into pollutant emission and the opeational states of compession-ignition engines in dynamic tests. Combustion Engines. 27, 69(2), DOI:.926/CE Zdzisław CHŁOPEK Jakub LASOCKI CE Coelation investigations into pollutant emission and the opeational states of compession-ignition engines in dynamic tests This study investigates the coelation dependences between pollutant emission intensity and the engine opeational states detemining these popeties, in vaious conditions, both in elation to measuements of engine opeational states and thei dynamic natue. The eseach was caied out in a vaiety of dynamic tests. Investigations into the coelations of pocesses occuing in combustion engines make it possible to assess the impact of one pocess on anothe and the elationship between the vaious pocesses. In geneal, it was found that simila dependencies occu fo cabon monoxide and hydocabons, but wee often substantially diffeent fo nitogen oxides. Key wods: combustion engines, pollutant emission, coelation analysis. Intoduction The objective of this study is to examine the coelation dependences between pollutant emission intensity and the intenal combustion (IC) engine opeational states detemining these popeties, in diffeent conditions, both in elation to the values of the states and thei dynamic natue. Divese woking conditions of IC engine ae applied duing engine testing, in a vaiety of dynamic tests. The opeational states of IC engines which detemine pollutant emission fom engines pe-heated to a stable tempeatue ae descibed in this study by the following measues: engine otational speed, engine toque and effective powe. Pollutant emission intensity depending on engine opeational states and the intensity of emission of individual pollutants elative to each othe have been subjected to coelation eseach. Due to the limited size of the aticle the published eseach uses only the Peason s linea coelation [4], and efeence is also made to the authos own unpublished esults using the non-paametic coelation theoies Speaman s ank coelation [6], Kuskal s gamma coelation [2], and Kendall s tau coelation []. Most of the publications concening coelation elationships between pocesses occuing in IC engines ae associated with engine steeing [5, ] and diagnostics [7]. These publications ae moe pactical than cognitive. Studies on coelation models of paticulate matte emission and the quantities chaacteising smoke opacity [7] can also be met. In the wok pesented in [8] the sensitivity of pollutant emission to the diffeent specifications of fuels in diffeent aeas of the static states of engine opeation was investigated. In publication [9] the esults of the analysis of paticulate matte emission in the conditions of actual bus opeation ae pesented. In that epot, the esults of investigations into the coelative effects of the paticulate matte emission on, inte alia, engine opeational states, have been published. The esults of coelation investigations into pollutant emission fom spak-ignition engines and compession-ignition engines have been pesented in aticles [4] and [3], espectively. Publication [2] deals with eseach into elationships between the intensity of pollutant emission fom compession-ignition engines and the states detemining the pollutant emission, caied out by employing the function of intecoelation between the pocesses unde investigation. This study deals with eseach into pollutant emission pocesses and engine opeational states detemining the pollutant emission, in dynamic tests chaacteising the woking conditions of compession-ignition engines in nonoad machines. 2. Reseach esults Tests wee caied out on a Cummins 6C8.3 engine. It is a fou-cylinde tubochaged compession-ignition engine with an 8.3 dm 3 capacity. This engine meets the emissionlevel equiements of Euo III. The tests wee caied out within the poject epoted in []. The engine was tested on a test stand equipped with a dynamomete bench that allows the testing of engines in dynamic conditions. Reseach was caied out using dynamic tests: (Non-Road Tansient Cycle), employed in typeappoval pocedues [8], (Bulldoze-Blade Dynamic Test) pepaed within the poject epoted in [], (Bulldoze-Rippe Dynamic Test) pepaed within the poject epoted in []. and tests wee developed in accodance with the pinciple of faithful simulations in eal time [3]. The esults of expeiments caied out on a testing gound in the blade and ippe opeating modes of a bulldoze wee used fo the synthesis of tests []. As fundamental citeia of similaity when developing the tests, the similaity of the aveage value and vaiance of the engine steeing and toque in tests, and unde empiical test conditions, wee assumed. Figues 6 show the time histoies of the engine speed and toque in the individual tests. Figues 7 9 epesent the set of IC engine opeational states within the coodinate system: engine speed toque, in individual tests. The points of coodinates of the aveage values of the engine speed and engine toque have also been maked on the gaph. Figue epesents the points of coodinates: the aveage values of the engine speed and engine toque in individual tests against the backgound of full-load toque vs. engine speed cuve. COMBUSTION ENGINES, 27, 69(2) 87

2 Coelation investigations into pollutant emission and the opeational states of compession-ignition engines in dynamic tests Fig.. Engine speed n vs. time t cuve, ecoded in the test Fig. 5. Engine speed n vs. time t cuve, ecoded duing the test M e [N m] 4 3 M e [N m] Fig. 2. Engine toque M e vs. time t cuve, ecoded in the test Fig. 6. Engine toque M e vs. time t cuve, ecoded in the test 3 8 (AV[n], AV[M e ]) Fig. 3. Engine speed n vs. time t cuve, ecoded in the test Fig. 7. The set of engine opeational states: engine speed n, toque M e in the test; (AV[n], AV[M e]) the coodinates of the aveage values of the engine speed and engine toque (AV[n], AV[M e ]) M e [N m] Fig. 4. Engine toque M e vs. time t cuve, ecoded in the test Fig. 8. The set of engine opeational states: engine speed n, toque M e in the test; (AV[n], AV[M e]) the coodinates of the aveage values of the engine speed and engine toque 88 COMBUSTION ENGINES, 27, 69(2)

3 Coelation investigations into pollutant emission and the opeational states of compession-ignition engines in dynamic tests 8 6 (AV[n], AV[M e ]),2,5 4 E CO [g/s], 2, Fig. 9. The set of engine opeational states engine speed n, toque M e in the test; (AV[n], AV[M e]) the coodinates of the aveage values of the engine speed and engine toque 7 Fig.. Couses of the cabon monoxide emission intensity E CO in tests,, E HC [g/s],6,4, Fig. 2. Couses of the hydocabons emission intensity E HC in tests Fig.. Points of coodinates: the aveage value of the engine speed n, the aveage value of the engine toque M e in tests against the backgound of full-load toque vs. speed cuve A big diffeence is clealy visible in the positions of the points of the coodinates: the aveage values of the engine speed and the engine toque, in individual tests. The and tests in espect of the static states of engine opeation accoding to the citeion of thei aveage values ae close to each othe. These tests ae chaacteised by high speed and high loads. The ecoded signals of engine speed, engine toque and pollutant emission intensity wee synchonised with taking into account the exhaust-gas tap-off location in the engineexhaust system the delays in individual signals, elated to the exhaust-gas analysis, wee taken into account. The measuement sampling fequency was Hz. The signals wee digitally pocessed to eliminate goss eos and to educe the influence of high-fequency intefeence. The goss eos wee identified by continuously analysing the vaiance of measuement esults. To educe the effects of high-fequency noise on the signals, a Golay-Savitzky lowpass filte [5] was used, with both-side appoximation fom 5 data points on each side to a polynomial of degee 2 being applied. The gaphs shown in Figues 3 epesent in aggegate fom the time histoies of pollutant emission intensity in the tests. Figue 4 shows the aveage values of pollutant emission intensity in individual tests. E NOx [g/s],35,3,25,2,5,, Fig. 3. Couses of the nitogen oxides emission intensity E NOx in tests,4,2,,8 AV[E],6,4,2 Fig. 4. The aveage value AV[E] of pollutant emission intensity in individual tests ECO EHC ENOx COMBUSTION ENGINES, 27, 69(2) 89

4 Coelation investigations into pollutant emission and the opeational states of compession-ignition engines in dynamic tests Thee is a clea diffeentiation between the aveage values of the pollutant emission intensity in the vaious tests. Tests with a lage engine load involve lage values of aveage pollutant emission intensity; paticulaly lage diffeences occus in the case of nitogen oxides. The aveage values of the emission intensities of individual pollutants in and tests ae close to each othe. Figs. 5, 6 and 7 show, espectively, the coefficient of Peason s linea coelation between pollutant emission intensity and engine speed, toque and effective powe.,8 ejected is below., even fo thei lowest values. This can be explained by a vey lage size of the sets unde investigation [6], which consist of about 2, elements fo the test and 6,4 fo the and tests. The values of the coefficient of coelation between the engine speed and the pollutant emission intensity ae the highest in test, and the lowest in the test. Fo toque and effective powe the patten is diffeent: the and tests have simila coelation coefficient values, while the test has consideably lowe coelation coefficient values. Figs. 8 2 pesent the coefficient of the coelation between the emission intensity of individual pollutants and engine speed, toque and effective powe.,6,4,8,2,6 n - ECO n - EHC n - ENOx,4 Fig. 5. The coefficient of Peason s linea coelation between engine speed and pollutant emission intensity in individual tests,2,8 n - ECO Me - ECO Ne - ECO Fig. 8. The coefficient of Peason s linea coelation of cabon monoxide emission intensity with engine speed, toque and effective powe,6,4,8,2,6 Me - ECO Me - EHC Me - ENOx,4 Fig. 6. The coefficient of Peason s linea coelation between engine toque and pollutant emission intensity in individual tests,2,8 n - EHC Me - EHC Ne - EHC Fig. 9. The coefficient of Peason s linea coelation of hydocabons emission intensity with engine speed, toque and effective powe,6,4,8,2,6 Ne - ECO Ne - EHC Ne - ENOx,4 Fig. 7. The coefficient of Peason s linea coelation between engine effective powe and pollutant emission intensity in individual test Although the coelation coefficient values ae widely divese (they ange fom.3 to.95), the pobability that the hypothesis of the absence of a coelation would not be,2 n - ENOx Me - ENOx Ne - ENOx Fig. 2. The coefficient of Peason s linea coelation of nitogen oxide emission intensity with engine speed, toque and effective powe 9 COMBUSTION ENGINES, 27, 69(2)

5 Coelation investigations into pollutant emission and the opeational states of compession-ignition engines in dynamic tests Simila tends exist fo toque and effective powe. It is chaacteistic that the dominant facto detemining the emission intensity of hydocabons, and less clealy of cabon monoxide, is engine speed, wheeas of nitogen oxides toque and effective powe. Figue 2 shows the coelation coefficient between the pollutant emission intensity in individual tests.,8,6,4,2 EHC - ECO ENOx - ECO EHC - ENOx Fig. 2. The coefficient of Peason s linea coelation between the pollutant emission intensity in individual tests It was found that majo diffeences exist in the values of the coelation coefficient between the pollutant emission intensity in individual tests. Also in this case, the pobability that the hypothesis of the absence of a coelation would not be ejected is below. in all pais of sets analysed. The coelation coefficient has the highest value fo the hydocabons emission intensity and the cabon monoxide emission intensity in the test, while the lowest was in the same test fo the cabon monoxide emission intensity and the nitogen oxide emission intensity. In all othe cases, the diffeences between the values of the coelation coefficient ae lowe. In geneal thee is a cetain similaity because of the value of the coelation coefficient in the and tests. 3. Summay The eseach wok having been caied out may be ecapitulated by fomulating the following conclusions:. Wide diffeences between the values of the coelation coefficient fo the examined quantities in the ange of.3 to.95 wee found. Nevetheless, even fo the smallest values, the pobability that the hypothesis of the absence of a coelation would not be ejected is below., which can be explained by the vey lage size of the sets unde investigation. 2. The values of the coelation coefficient between the engine speed and the pollutant emission intensity ae the highest in test, and the lowest in the test. 3. The and tests have the highest values of the coelation coefficient of toque and effective powe with pollutant emission intensity, while the test has consideably lowe coelation coefficient values. 4. The dominant facto detemining the emission intensity of hydocabons and less clealy of cabon monoxide, is engine speed, wheeas of nitogen oxides toque and effective powe. 5. It was found that majo diffeences exist in the values of the coelation coefficient between the pollutant emission intensity in individual tests: the coelation coefficient has the highest value fo the hydocabon emission intensity and the cabon monoxide emission intensity in the test, while the lowest in the same test fo the cabon monoxide emission intensity and the nitogen oxide emission intensity. This pape pesents the esults of eseach using Peason s linea coelation coefficient. Simila esults can also be obtained fo the coefficients of Speaman s ank coelation, Kuskal s gamma coelation, and Kendall s tau coelation. Investigations into the coelations between the pocesses occuing in IC engines make it possible to assess the impact of one pocess on anothe and the elationships between the vaious pocesses. It is symptomatic of combustion engines that dynamic opeating states affect in diffeent ways the phenomenon of the emission of vaious pollutants. Geneally, simila dependencies occu fo cabon monoxide and hydocabons, but they ae often substantially diffeent fo nitogen oxides. The eseach was pefomed in thee tests simulating the woking conditions of IC engine in non-oad machines. The authos own wok shows that simila tends apply in the case of othe woking conditions of IC engines. Nomenclatue AV E E CO E HC E NOx aveage value Bulldoze-Blade Dynamic Test Bulldoze-Rippe Dynamic Test emission intensity cabon monoxide emission intensity hydocabons emission intensity nitogen oxides emission intensity IC M e n t intenal combustion engine toque engine otational speed non-oad tansient cycle the coefficient of Peason s linea coelation time Bibliogaphy [] BUDNY, E., CHŁOPEK, Z., CHŁOSTA, M. Ocena skuteczności zasilania silnika spalinowego gazem ziemnym w celu oganiczenie emisji zanieczyszczeń w waunkach użytkowania silnika w maszynie do obót ziemnych ciągniku gąsienicowym (The evaluation of the effectiveness of supplying of combustion engine with natual gas to educe pollutant emission in the conditions of the engine used in an eath move cawle tacto). Repot of eseach COMBUSTION ENGINES, 27, 69(2) 9

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