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An Experimental Investigation of the...

Klinkert, Stefan.

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An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.

Record Type:	Electronic resources : Monograph/item
Title/Author:	An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap./
Author:	Klinkert, Stefan.
Description:	192 p.
Notes:	Source: Dissertation Abstracts International, Volume: 75-08(E), Section: B.
Contained By:	Dissertation Abstracts International75-08B(E).
Subject:	Mechanical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3619650
ISBN:	9781303890635

An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.
Klinkert, Stefan.

An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap. - 192 p.

Source: Dissertation Abstracts International, Volume: 75-08(E), Section: B.

Thesis (Ph.D.)--University of Michigan, 2014.

This item is not available from ProQuest Dissertations & Theses.

Use of homogeneous charge compression ignition (HCCI) combustion mode in engines offers the potential to simultaneously achieve high efficiency and low emissions. Implementation and practical use of HCCI combustion, however, remain a challenge due to the limited operating load range. Managing the timing and duration of the combustion event, so that it is neither too early nor too late, neither too fast nor too slow, causing knock or misfire respectively, is difficult and represents a major obstacle to achieving high loads.

ISBN: 9781303890635Subjects--Topical Terms:

649730
Mechanical engineering.

An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.
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020 $a 9781303890635
035 $a (MiAaPQ)AAI3619650
035 $a AAI3619650
040 $a MiAaPQ $c MiAaPQ
100 1 $a Klinkert, Stefan. $3 3175266
245 1 3 $a An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.
300 $a 192 p.
500 $a Source: Dissertation Abstracts International, Volume: 75-08(E), Section: B.
500 $a Advisers: Dionissios N. Assanis; Volker Sick.
502 $a Thesis (Ph.D.)--University of Michigan, 2014.
506 $a This item is not available from ProQuest Dissertations & Theses.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a Use of homogeneous charge compression ignition (HCCI) combustion mode in engines offers the potential to simultaneously achieve high efficiency and low emissions. Implementation and practical use of HCCI combustion, however, remain a challenge due to the limited operating load range. Managing the timing and duration of the combustion event, so that it is neither too early nor too late, neither too fast nor too slow, causing knock or misfire respectively, is difficult and represents a major obstacle to achieving high loads.
520 $a Most studies on high load extension of HCCI have been done on engines with conventional positive valve overlap (PVO) strategies, which use a heater to control intake temperature and adjust combustion timing. From a practical standpoint, however, this is not preferred, because of the additional energy required by the heater, slow response time and inadequate authority over combustion timing. Although there has been work on engines employing a more practical negative valve overlap (NVO) strategy, which controls charge temperature by varying the retained amount of hot internal residual gas, most of these studies were confined to a limited boost pressure range and/ or did not explore and isolate the effects of individual thermo-physical parameters on combustion and the maximum load limit.
520 $a This research work is unique in that a practical yet highly flexible NVO engine with fixed compression ratio, allowing for independent control of intake boost pressure, charge temperature and composition, thermal/ compositional stratification (NVO) and exhaust back-pressure, was used to independently investigate the effects of these variables on burn duration and combustion phasing limits. Results showed that maximum achievable loads for the NVO engine were less than those obtained by previous workers on a boosted PVO engine due to less efficient breathing, less stable combustion, which limits the achievable combustion phasing retard, and lower maximum allowable peak cylinder pressure. Lower engine speed enabled higher maximum load due to shorter crank-angle burn durations, facilitating later combustion phasing, and higher allowable peak pressure rise rates. Employing external EGR to partially replace air led to an increase in maximum load due to its retarding effect on ignition alleviating the constraint of limited cam-phasing authority. Similarly, lower intake temperature and exhaust back-pressure enabled higher maximum load.
520 $a Detailed studies of burn rates showed minimal effects of intake boost pressure and moderate effects of composition. In particular, replacing air with eEGR, thus decreasing in-cylinder oxygen concentration, led to a moderate increase of burn duration especially during the early heat release. Increase in boost pressure caused a minimal shortening of burn duration, but pressure rise rates and knock were unaffected.
520 $a Additional studies of knock and combustion stability limits showed that internal EGR has a negative effect on the combustion stability limit, because of increased cycle-to-cycle feedback, yet it had a positive effect on the knock limit by decreasing maximum pressure rise rates due to increased thermal stratification. Partially replacing air with external EGR led to an extension of the viable combustion phasing window, because of an increase in heat capacity moderately slowing down combustion rates. Boost pressure had no direct effect on either of the combustion phasing limits.
520 $a This research provides new insights into how boost pressure and other operating parameters in a NVO HCCI engine impact the maximum attainable load and combustion phasing limits. The results suggest that the maximum load is more dependent on the combustion stability limit and overall engine constraints, such as maximum allowable peak cylinder pressure and limited cam-phasing authority, than on burn rates.
590 $a School code: 0127.
650 4 $a Mechanical engineering. $3 649730
650 4 $a Automotive engineering. $3 2181195
690 $a 0548
690 $a 0540
710 2 $a University of Michigan. $b Mechanical Engineering. $3 2104815
773 0 $t Dissertation Abstracts International $g 75-08B(E).
790 $a 0127
791 $a Ph.D.
792 $a 2014
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3619650