Diesel Turbos

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edignan Guru Join Date: Jun 2006 Location: Borrego Springs Posts: 2636 Good Answers: 62	Diesel Turbos 04/20/2009 8:37 AM
	I am something of a maniac for instrumentation, and have admired some other maniacs work, but have hit a puzzler in the EE forum. Fella is doing some diesel instrumentation, and has dual exhaust banks. The curious thing is they are already tapped for temperature both before the turbo (EGT) as well as AFTER the turbo (hunh)? I've tapped after the turbo for boost, but what information would post-turbo temp give me that an operator needs? __________________ "If you want to get somewhere else, you must run at least twice as fast as that!"
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Anonymous Poster	#1 Re: Diesel Turbos 04/20/2009 3:49 PM
	I work on engine test beds, mainly emmision testing for developing catalytic convertors. We place thermocouples in many postions in the exhaust stream on petrol and diesels engines for ideal positioning of catalysts.
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awelch Commentator Join Date: Sep 2008 Location: Vancouver, BC Posts: 68 Good Answers: 4	#2 Re: Diesel Turbos 04/21/2009 12:27 AM
	You can use these to calculate the temperature drop. Temperature drop across the turbine can allow you to observe how much energy is lost due to energy extraction by the effect of the turbine (which converts heat energy to mechanical energy). As well, some heat will be lost over the short path between the inlet and outlet of the turbine. Other than that, the exhaust temperature out is also of interest to modern truck engines with Diesel Particulate Filters (DPF) required to meet the new emission standards. Depending on the DPF and whether it has a catalytic coating, you need certain minimum temperatures to burn off the accumulated soot. This can occur passively (at high engine torque) and with assistance (post-injection of diesel).
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jjnyongesa Active Contributor Join Date: Jul 2008 Location: Mombasa, Kenya Posts: 24 Good Answers: 1	#3 Re: Diesel Turbos 04/21/2009 12:41 AM
	I have worked with engines running on Heavy fuel oil, one setback of which is fouling of the nozzle ring especially if run at low loads. An indication of this fouling would be increased turbo speed and less work done by the exhaust gas. If one does not have a speed pick up for the turbo speed, you would rely on the temperature difference before and after the turbo to gauge how efficient the turbo is. ΔT is a measure of the work done by the turbo. Less ΔT implies less work done, reduced performance of the turbo. Thermodynamics, I guess. I could be wrong, but I think that is why you have the two temperature sensors. I don't know about this on normal diesel engines, though. __________________ Curiosity has its reasons for existence - Albert Einstein
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