HT1 Recit - HT1 Recita+on Data processing Power ...

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Unformatted text preview: HT1 Recita+on Data processing Power distribu+on Air pollu+on Communica+ons focus: report- level organiza+on wri+ng an abstract formaAng of plots Assignment Data processing Power Distribu+on Power distribu+on The main goal of the lab is to quan+fy this: Pw |Po| |Pa|+|Pe| Lth Lc |Pp| Pni |Pp| Lth Lc Lth Lc Pgi Pf (not to scale) Obtain some quan++es from direct measurements: Which direct measurements yield the red boxes? Pw |Po| |Pa|+|Pe| Lth Lc |Pp| Pni |Pp| Lth Lc Lth Lc Pgi Pf (not to scale) Which quan++es can be obtained by difference of directly measured quan++es? Data processing: Indicated work and power Pw |Po| |Pa|+|Pe| Lth Lc |Pp| Pni |Pp| Lth Lc Lth Lc Pgi Pf (not to scale) Integra4on of P- V Data for Work 0.0009 V 0.0008 0.0007 0.0006 0.0005 Series1 0.0004 0.0003 0.0002 0.0001 0 - 200 - 100 0 100 200 300 400 500 600 700 7 6 p 5 4 3 Series1 2 1 0 - 200 - 100 Note: convert voltage signal to bar, then to pascal. - 1 - 2 0 100 200 300 400 500 600 700 MAE 4272 HT1 Sample Indicator Diagram 25 Pressure, bar 20 15 Series1 10 5 0 0 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 - 5 Volume, m3 0.0007 0.0008 0.0009 MAE 4272 HT1 Sample Indicator Diagram, close- up 5 Pressure, bar 4 3 Series1 2 1 0 0 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 - 1 Volume, m3 0.0007 0.0008 0.0009 Data processing: fuel power and combus+on losses Pw |Po| |Pa|+|Pe| Lth Lc |Pp| Pni |Pp| Lth Lc Lth Lc Pgi Pf (not to scale) Fuel power Pf = m f QHV Fuel power equa+on uses QHV, hea+ng value of the fuel (gasoline) QHV represents the maximum thermal enthalpy that can be released during combus+on, per mass fuel. For const- P adiaba+c processes, ΔH = 0 For combus+on, it’s convenient to write this as: ΔH chem + ΔH thermal = 0 Define | Δ H chem | , when combus+on is complete, i.e. Q HV = all C becomes CO2; m f all H becomes H2O You can look up the value of hea+ng value (MJ/kg) for specific fuels. See end of lab manual for some values. Combus+on Loss This loss is basically the fuel power of the exhaust stream. We need to account for two fuel components: CO and unburned hydrocarbons (which we will assume has the same hea+ng value as gasoline) c CO ,exh HV ,CO HC ,exh HV , HC Use measured fuel inlet mass flowrate and stoichiometric A/F ra+o to obtain exhaust mass flowrate. (A slightly more accurate value can be obtained using the measured lambda rather than assuming a stoichiometric mixture.) Then use measured mole frac+ons of CO and unburned hydrocarbons in the exhaust to obtain mass flowrates of CO and HC in the exhaust. Details follog on next page. Cau+on: generally, HC composi+on in the exhaust is not the same as in the fuel. However, we will use the hea+ng value of gasoline here too. L =m Q +m Q Conversion of mole frac+on CO in dry exhaust to mass flowrate CO in exhaust •  Instrument measures moles CO/ mole dry exhaust (i.e. exhaust aher H2O is condensed out and removed). •  Find mole frac+on CO in wet exhaust by mul+plying dry- exhaust value by 0.88 (based on balanced combus+on reac+on for C8H15 with a reasonable value of lambda) •  Convert mole frac+on to mass frac+on using molecular weight CO and average molecular weight of combus+on products. •  Mul+ply mass frac+on in wet exhaust by total mass flowrate exhaust to find mass flowrate CO in exhaust. •  Process is basically the same for HC, but with a different molecular weight. In that case the conversion from mole frac+on to mass frac+on is significant! Data processing: dis+nguishing between losses in transmission vs aux power and engine fric+on losses Pw |Po| |Pa|+|Pe| Lth Lc |Pp| Pni |Pp| Lth Lc Lth Lc Pgi Pf (not to scale) Role of data point taken in neutral •  Data point taken in neutral has no transmission fric+on losses. So use its measured net indicated power, along with the wheel power, to obtain |Pa|+|Pe|, for a given engine speed. •  We have no way of separa+ng |Pa| from |Pe| Possible pilalls •  Units for p- V (bar, m3; convert to Pa, m3) •  Integra+on of p- V diagram over wrong range of crank angles for pumping work vs gross indicated work •  Sign of losses vs powers •  Conversion from one cylinder to full engine (indicated work for one cylinder to indicated power for whole engine) •  Conversion from work to power: note that one CYCLE takes two REVOLUTIONS of the crankshah. •  Conversions from mole frac+ons (ppm) to mass frac+ons needed to obtain mass flowrates CO andHC in exhaust Data processing Exhaust emissions Catalyst efficiency •  Straighlorward calcula+on based on mole frac+ons of a given pollutant entering and exi+ng the catalyst. •  You will obtain three different catalyst efficiencies for the three different categories of pollutants, for selected data points. •  3- way catalysts require near- stoichiometric opera+on for high efficiencies; expect efficiencies of about 90% or higher. Trends with load •  Uncontrolled emissions would tend to have higher NOx at higher load (because NO forma+on is strongly dependent on T, and there is less dilu+on of F/A mixture at high load). •  EGR counters this trend. Note when it switches on. •  Principle of EGR: lower peak cylinder T by mixing in combus+on products from the exhaust manifold. This lowers NO emissions at the cost of power output. (Surprisingly, it actually improves efficiency.) Wri+ng: Report- level organiza+on Short lab report assignment •  Some sec+ons of the tradi+onal lab report (introduc+on, method, conclusion) are omiqed. •  Other parts of the report should be wriqen as if the missing parts were there. So abstract needs to summarize the missing sec+ons as well as the sec+ons that you write Tradi+onal lab report sec+ons Read p. 20 of lab manual! •  •  •  •  •  •  •  Abstract Introduc+on Apparatus and Method Results Discussion Conclusions Appendices •  Technical wri+ng is meant to be accessed non- sequen+ally! On the job, people do not expect to read an en+re report from start to finish. They need to find the par+cular informa+on of interest to them. •  The tradi+onal lab report format (similar to scien+fic paper format) allows efficient retrieval of useful informa+on. Wri+ng: Wri+ng an abstract •  The abstract is a +me- saving summary for the reader. •  Word limit; take it seriously! •  Two kinds of abstract –  Descrip(ve. This kind tells you what kind of results are in the report, but does not say what they are. –  Informa(ve. We will use this kind, at least in HT labs. This kind actually contains the important content of the report. •  Write an abstract for “Fuel Efficiency of Vehicles on US Roads, 1923- 2006” Figures and tables exercise •  Cri+que these various versions of plots. What is good and bad about a given plot? •  Ask them to bring laptops and ploAng programs to class so that they can create their own, beqer version? Op+on A Grams CO per kilometer year Japan EU 2002 158 2004 148 Australia S. Korea 168 210 210 160 188 200 US California 152 2006 China 259 200 254 2007 251 2008 249.5 2009 247 257 245 239 228 212 216 189 2013 205 187 2014 193 182 182 175 171 170 2010 183 2011 2012 2015 201 125 130 2016 2020 93 Op+on B 300 Grams CO2 per kilometer 250 200 Japan EU China 150 Australia S. Korea 100 US California 50 0 2000 2002 2004 2006 2008 2010 2012 Year 2014 2016 2018 2020 2022 Op+on C Grams CO per kilometer 300 250 200 Japan EU China 150 Australia S. Korea 100 US California 50 0 1 2 3 4 5 6 7 8 9 Number of years aQer 2001 10 11 12 13 14 Op+on D Grams CO per kilometer year Japan EU 2002 158 2004 148 Australia S. Korea 168 210 210 160 188 200 US California 152 2006 China 259 200 254 2007 251 2008 249.5 2009 247 257 245 239 228 212 216 189 2013 205 187 2014 193 182 182 175 171 170 2010 183 2011 2012 2015 201 125 130 2016 2020 93 Op+on E Grams CO2 per kilometer 300 250 Japan 200 EU China 150 Australia 100 S. Korea US 50 0 2000 California 2005 2010 2015 Year 2020 2025 Op+on F 280 USA Grams CO2 per kilometer 260 240 S. Korea 220 Australia 200 180 140 120 California China 160 Japan EU 100 80 2001 2003 2005 2007 2009 2011 Year 2013 2015 2017 2019 2021 Op+on G 280 Grams CO2 per kilometer 260 240 220 Japan 200 EU 180 China 160 Australia 140 S. Korea 120 US 100 California 80 2001 2006 2011 Year 2016 2021 Op+on H Grams CO2 per kilometer 280 240 Japan EU 200 China Australia 160 S. Korea US 120 California 80 2001 2006 2011 Year 2016 2021 Op+on I Grams CO2 per kilometer 280 USA Australia S. Korea California China Japan EU 80 2001 2003 2005 2007 2009 2011 Year 2013 2015 2017 2019 2021 Op+on J Grams CO2 per kilometer 250 200 Japan EU 150 China Australia 100 S. Korea US 50 California 0 2001 2006 2011 Year 2016 2021 Op+on K Grams CO2 per kilometer 250.00 200.00 Japan EU 150.00 China Australia 100.00 S. Korea US 50.00 California 0.00 2001 2006 2011 Year 2016 2021 Assignment Due date Teamwork and responsibili+es Content Appendices. Note that we expect that data referred to in the text should appear in the main text as well as in the appendix. •  Answer ques+ons •  •  •  •  ...
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This note was uploaded on 12/13/2011 for the course MAE 2943 taught by Professor Walter during the Spring '11 term at Southern Vermont.

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