T。D。C (11° A。T。D。C) compared to CB10 and CB20 atall

C。R。 As discussed earlier, higher fuel viscosity and lower calorific value of the higher biodiesel blends results in slower mixing and poor atomization during the initial stages of combustion。 This results in lower cylinder peak pressure。论文网

Variation of the hydrocarbon(HC)emissionswith load at all C。R is shown in Fig。 5。 Results show that HC emissions from CB10 and CB20 are comparatively less than diesel fuel by 14 % on an average。 In P-θ diagram, attainmentofpeakcylinderpressurefurthernearto

T。D。C in expansion stroke for CB10 and CB20 results in improved combustion process due to less overmixing of fuel and air and contributes to the decrease in HC emis- sions。 HC emissions decreased with increase in com- pression ratio。 On anaverageHCemissions decreased by 37。84, 42。83, 41。17 and 31。8 % for diesel, CB10, CB20

and CB40 respectively, when C。R is increased from 15 to 18。 The result of high temperature due to increase in

C。R and the presence of additional oxygen content in biodiesel improves the combustion process resulting in greater decrease in the emissions for biodiesel blends with increase in C。R。 For the same reason, similar phe- nomenon of carbon monoxide (CO) emissions variation with load for biodiesel blends is observed at all C。R and shown in Fig。 6。 An average decrease in CO emissions for diesel, CB10, CB20 and CB40 are 21。9, 22。54, 24。46 and

20。22 % respectively when C。R is increased from 15 to 18。 As a result ofimprovedcombustiondueto presence of additional oxygen content in biodiesel, carbon dioxide

(CO2) emissions increased for crude rice bran biodiesel blends。 Variation of CO2 emissions with load at all C。R is shown in Fig。 7。 Highest CO2 emission is observed for CB20 at all C。R。 CO2 emissions increased with increase in engine load and compression ratio。 An average increase of

11。73, 16。9, 24。16 and 16。9 % in CO2 emissions for diesel, CB10, CB20 and CB40 respectively, is recorded when C。R is increased from 15 to 18。 Improved combustion inside the combustion chamber increases the temperature。 Attainment of higher peak pressure near to T。D。C in the expansion stroke for CB10 and CB20 compared to diesel

and CB40 results in higher combustion chamber tem- perature leading to increase in NOx formation The same can be observed in the variation of oxides of nitrogen as NOx with load at all C。R in Fig。 8。 Increase in compression ratio increases the combustion temperature which tends to increase NOx formation。 NOx emissions increased by an average of 16。11, 24。71, 31。96 and 18。26 % for diesel, CB10, CB20 and CB40 respectively, when C。R is increased from 15 to 18。 CB40 has the lowest NOx emission due to its lower cylinder pressure resulting in lower temperature in combustion chamber compared to other fuelblends。

Emissions from oxides of nitrogen (NOx) can be con- trolled by two methods (Teng et al。 2007):

1。Treating the exhaust NOx with a reduction catalyst converter (either selective catalyst reduction or lean NOx trap)。

2。Operatingtheenginewithhighrateof cooled

exhaust gas recirculation (EGR) in order to lower the charge temperature at the start of combustion, as for the full range of engine operations the average NOx-

reduction efficiency is less than 80 %。

Conclusion Conclusions summarized from the above study and experimental investigations are as follows:摘要生物柴油作为石油衍生柴油的替代品，是一种具有可再生和环境友好的能源。对于石油进口国，在领土内的生物柴油生产原料的选择是一个重要的影响因素。用于生产生物柴油，米糠油的发现是良好的和可行的原料。对含有高游离脂肪酸粗米糠油进行了二步酯化反应。可变压缩比柴油机混合10、20和40%的粗米糠生物柴油进行测试，得到的压缩比有15、16、17和18。发动机性能和废气排放参数检查。绘制气缸压力曲轴转角变化。从15到18的压缩比的增加导致了特定的燃料消平均增加了18。6%，制动消耗平均减少14。66%。当压缩比增大时，气缸压力增加15%。当压缩比从15增加到18，一氧化碳的排放量平均减少了22。27%，碳氢化合物平均减少了38。4%，二氧化碳平均增加了17。43%，氮氧化物排放量平均增加了22。76%。与增加柴油机压缩比相比，混合粗米糠油的生物柴油的效果更好。 可变压缩比柴油发动机英文文献和中文翻译(6):http://www.youerw.com/fanyi/lunwen_100249.html