Comments on: Taking the heat http://www.ret-monitor.com/articles/1998/taking-the-heat/ Specific mission-critical info for professionals Fri, 18 May 2012 09:30:03 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: Terry http://www.ret-monitor.com/articles/1998/taking-the-heat/comment-page-1/#comment-9984 Terry Fri, 30 Dec 2011 03:21:00 +0000 http://www.ret-monitor.com/articles/1998/taking-the-heat/#comment-9984 Heat transfer across the upper liner wall is indeed a critical issue, but not solely for the reasons discussed in the article. The most critical issue with cylinder liner heat transfer is the operating temperature of the bore surface. There must be adequate heat transfer across the liner wall thickness to the coolant to keep the bore surface temperature within the lube oil's capability. If not, the lube oil film will flash off and the rings will scuff. Regardless of how much coolant flows through the jacket, if the liner wall is too thick, or has a low material CTE, or is thermally isolated from the coolant flow, the bore surface will not be adequately cooled. Besides the measures described in the article for increasing local coolant heat transfer rates, there are other less extreme approaches. First, since heat transfer between the liner wall and coolant flow only takes place within a thin boundary layer, designing the jacket shape such that it forces as much coolant flow against the liner as possible would help. Ideally it would be a thin, high velocity flow. Second, a bit of surface texture on the liner would help, since it would trip up the coolant boundary layer flow and increase the local heat transfer rate. Heat transfer across the upper liner wall is indeed a critical issue, but not solely for the reasons discussed in the article. The most critical issue with cylinder liner heat transfer is the operating temperature of the bore surface. There must be adequate heat transfer across the liner wall thickness to the coolant to keep the bore surface temperature within the lube oil’s capability. If not, the lube oil film will flash off and the rings will scuff.

Regardless of how much coolant flows through the jacket, if the liner wall is too thick, or has a low material CTE, or is thermally isolated from the coolant flow, the bore surface will not be adequately cooled.

Besides the measures described in the article for increasing local coolant heat transfer rates, there are other less extreme approaches. First, since heat transfer between the liner wall and coolant flow only takes place within a thin boundary layer, designing the jacket shape such that it forces as much coolant flow against the liner as possible would help. Ideally it would be a thin, high velocity flow. Second, a bit of surface texture on the liner would help, since it would trip up the coolant boundary layer flow and increase the local heat transfer rate.

]]> By: Edmo http://www.ret-monitor.com/articles/1998/taking-the-heat/comment-page-1/#comment-9865 Edmo Mon, 19 Dec 2011 11:04:23 +0000 http://www.ret-monitor.com/articles/1998/taking-the-heat/#comment-9865 Hello John, do you see some correlation between the phenomena you described and tribocorrosion on TDC due to condensation of sulfur and acids from the combustion products? Hello John,
do you see some correlation between the phenomena you described and tribocorrosion on TDC due to condensation of sulfur and acids from the combustion products?

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