喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請放心下載，，有疑問咨詢QQ:1064457796或者1304139763 ==================== 喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請放心下載，，有疑問咨詢QQ:1064457796或者1304139763 ==================== 題目：某輕型貨車鼓式制動器設(shè)計某輕型貨車鼓式制動器設(shè)計匯報內(nèi)容匯報內(nèi)容1.研究意義與國內(nèi)外發(fā)展概況研究意義與國內(nèi)外發(fā)展概況2.制動器的結(jié)構(gòu)選擇及方案分析制動器的結(jié)構(gòu)選擇及方案分析3.制動器的設(shè)計計算制動器的設(shè)計計算4.制動器主要零部件的結(jié)構(gòu)設(shè)計制動器主要零部件的結(jié)構(gòu)設(shè)計5.制動器主要零件的加工工藝制動器主要零件的加工工藝6.尺寸工藝鏈分析尺寸工藝鏈分析7.結(jié)論結(jié)論8.致謝致謝1.1 研究背景及意義研究背景及意義汽車使用越來越廣泛，對制動性能要求也越來越高，而制動系故障引起的交通事故與日增多，所以目前急需要一種不僅可以完全發(fā)揮鼓式制動器制動效能因數(shù)高的優(yōu)點，同時具有盤式制動器摩擦副壓力分布均勻、制動效能穩(wěn)定等優(yōu)點的制動器；制動器是制動系中最主要零部件之一,它的設(shè)計制造對制動系的制動性能和穩(wěn)定性有很大的影響；因此，本次設(shè)計是針對鼓式制動器來進(jìn)行設(shè)計。1.2國內(nèi)外現(xiàn)狀及發(fā)展國內(nèi)外現(xiàn)狀及發(fā)展目前很多發(fā)動機(jī)排量較小的中低檔車型，其制動系統(tǒng)大多采用“前盤后鼓式”，比如常見的大眾捷達(dá)、長安鈴木奧拓、東風(fēng)悅達(dá)起亞千里馬以及上海通用賽歐等。另外，鼓式制動器還用在一系列貨車上。所以，鼓式制動器的設(shè)計制造水平很重要。雖然領(lǐng)從蹄式制動器的效能及穩(wěn)定性在各式制動器中均處于中等水平，但由于其在汽車前進(jìn)和倒車時的制動性能不變，結(jié)構(gòu)簡單，造價較低，也便于附裝駐車制動機(jī)構(gòu)，易于調(diào)整蹄片與制動鼓之間的間隙。所以，本次設(shè)計選擇領(lǐng)從蹄式制動器。2.制動器的結(jié)構(gòu)選擇及方案分析制動器的結(jié)構(gòu)選擇及方案分析3.1.參考車型的參數(shù)：3.制動器的設(shè)計計算制動器的設(shè)計計算3.2 制動力與制動力分配系數(shù) 在 汽車進(jìn)行制動的時候，在踏板力相對來說比較小時，地面的制動力FB與制動器的制動力Ff是近似相同的，地面制動力最大只能和地面附著力一樣大，但是制動器的制動力只與踏板力有關(guān)，從理論上來說可以是無限大，因此當(dāng)踏板力達(dá)到一個定值后，即圖中的交點時，如繼續(xù)加大制動器制動力，接著踩踏板時，就會出現(xiàn)車輪不轉(zhuǎn)的情況，車輪就會出現(xiàn)抱死：（1）前輪先抱死，然后后輪再抱死；（2）后輪先抱死，然后前輪再抱死；（3）前、后輪同時抱死，這種情況的附著條件利用得最好。=3.3 同步附著系數(shù) 圖中實際前后制動器制動力分配線與I曲線交于B點，可求出B點處的附著系數(shù)，則交線處的附著系數(shù)為同步附著系數(shù)。所以，同步附著系數(shù)選取0.774。3.4 行車制動（制動距離）制動距離s=31.04m 由上表算得的制動距離，=36.60m 因為，算得的制動距離小于表格規(guī)定的最大制動離，所以該制動系的行車效能滿足要求。4.1 制動鼓 1.制動鼓直徑D 輪輞直徑為13英寸，貨車的D/Dr一般在0.70-0.83，所以取 D/Dr=0.73，得：Dr=13*25.4=330.2mm D=0.73*330.2=241.05mm 根據(jù)QC/T3091999制動鼓工作直徑及制動蹄片寬度尺寸系列的規(guī)定，制動鼓直徑等于240mm；2.本設(shè)計采用由鋼板沖壓成形的輻板與灰鑄鐵鼓筒部分鑄成一體的組合式制動鼓，制動鼓壁的厚度一般在13-18mm之間，選取13mm。4.制動器主要零件的結(jié)構(gòu)設(shè)計制動器主要零件的結(jié)構(gòu)設(shè)計4.2 制動蹄 1.本設(shè)計制動蹄采用熱軋鋼板沖壓焊接制成，腹板和翼緣的厚度貨車約為5-8mm,選取6mm；2.制動蹄的支承：采用偏心支承銷，可以使一個自由度的制動蹄的工作表面與制動鼓的工作表面同軸心；3.制動蹄支承點位置坐標(biāo)：k=0.2R=24mm，c=96mm。4.3 摩擦襯片 1.本次設(shè)計摩擦片采用著模壓材料，它是以石棉纖維為主并與樹脂粘結(jié)劑、調(diào)整摩擦性能的填充劑，摩擦系數(shù)f=0.3；2.摩擦片的包角 通常在90到120度之間選取，雖然包角減小有利于散熱，但單位壓力過高將加速磨損。實際上包角兩端處單位壓力最小，過大不僅不利于散熱，而且易使制動作用不平順，甚至可能發(fā)生自鎖。所以，選取 =95度，根據(jù)QC/T3091999制動鼓工作直徑及制動蹄片寬度尺寸系列，選取寬度 b=50mm，起始角 =42.5度；3.一個制動器的摩擦面積為198.87cm2。4.4 制動底板 制動底板是除制動鼓外制動器各零件安裝基本，應(yīng)保證各安裝零件相互間位置地正確，它承受著制動器工作時的制動反力矩，應(yīng)有足夠的剛度。因此，本設(shè)計制動底板采用熱軋鋼板沖壓成形，制動底板的厚度一般為2.6-5.8mm之間，選取5mm。4.5 制動輪缸 輪缸的缸體由灰鑄鐵HT250制成，其缸筒為通孔，采用兩個活塞推動。1.輪缸直徑：公式 =18.74mm，根據(jù) GB 752487標(biāo)準(zhǔn)規(guī)定的尺寸系列中，選取輪缸直徑為22mm；2.輪缸工作容積:=1519.76 3.輪缸活塞寬度22mm 4.缸筒壁厚6mm。4.6制動器間隙的調(diào)整機(jī)構(gòu) 在未制動的狀態(tài)下，制動鼓與摩擦襯片之間應(yīng)有工作間隙，以保證制動鼓能自由轉(zhuǎn)動。一般鼓式制動器的設(shè)定間隙為0.20.5mm?？紤]到在制動過程中摩擦副可能產(chǎn)生機(jī)械和熱變形，所以制動器在冷卻狀態(tài)下的間隙應(yīng)通過試驗來確定。另外，制動器在工作過程中會因為摩擦襯片的磨損而加大，因此制動器必須設(shè)有間隙調(diào)整機(jī)構(gòu)。5.制動器摩擦片的加工工藝制動器摩擦片的加工工藝摩擦片加工的標(biāo)準(zhǔn)：螺栓锪孔后的剩余厚度應(yīng)為摩擦片厚度的1/3，連合后的摩擦片貼合牢固，無裂損，不得有大于0.15的縫隙；光磨后的摩擦片螺栓頭應(yīng)低于摩擦片表面3以上，與制動鼓的接觸面積應(yīng)大于50，并保證兩端首先接觸；摩擦片的連接應(yīng)從摩擦片的中部依次向兩端擰緊螺栓，連接后的摩擦片與制動蹄應(yīng)全部貼合，連接牢固，連接后蹄架進(jìn)行油漆處理。摩擦片車削時要做到定位準(zhǔn)確，圓跳動符合要求，圓跳動大于1時就要檢查蹄片及定位情況，必要時更換蹄架；加工后，還應(yīng)檢查與制動鼓切合情況，保證摩擦片與制動鼓有較大的切合面積。檢查工藝：先在制動鼓上涂以白粉，將摩擦片貼合在制動鼓上來回移動，檢查切合情況，切合面積不小于摩擦片總面積的50%，且兩端向中間分布，兩端切合較重，中間較輕。6.尺寸工藝鏈分析尺寸工藝鏈分析圖中，A1為增環(huán)，A2,A3為減環(huán)，間隙A0為封閉環(huán)。1驗證各環(huán)基本尺寸：A0=A1-(A2+A3）=120(110+10)=0mm 2求各組成環(huán)平均公差：Tav=T0/(n-1)=0.1 3.調(diào)整各組成環(huán)公差：選A3為協(xié)調(diào)環(huán)，調(diào)整A3公差 T1=0.040(mm),T2=0.035(mm)那么，T3=0.025，則A3的公差等級為IT8，這樣將容易通過切削加工來保證。7.結(jié)論結(jié)論1.通過對給定汽車制動系統(tǒng)的結(jié)構(gòu)分析與設(shè)計計算，認(rèn)識制動系各部分結(jié)構(gòu)的功能和作用，了解現(xiàn)階段使用狀況以及普遍存在的問題，提升了我對汽車制動系統(tǒng)更全面的認(rèn)識；2.制動系統(tǒng)是汽車中一個重要的總成，它既可以讓行駛中的汽車減速與制動，又能保證停車后的汽車能停駐原地。制動系統(tǒng)工作可靠、制動性能優(yōu)良的汽車能充分發(fā)揮出其高速行駛的動力性并保證行駛的安全性。這顯示出了制動系統(tǒng)是汽車非常重要的組成部分，從而對于汽車制動系統(tǒng)的設(shè)計也顯得非常的重要。謝辭謝辭請各位老師，同學(xué)批評指正請各位老師，同學(xué)批評指正Open Access Journal Journal of Power Technologies 92(1)(2012)5567journal homepage:papers.itc.pw.edu.plEffect of hydrogen-diesel quantity variation on brake thermal efficiency of adual fuelled diesel engineBiplab K.Debnath,Ujjwal K.Saha,Niranjan SahooDepartment of Mechanical Engineering,Indian Institute of Technology GuwahatiGuwahati-781039,Assam,IndiaAbstractThe twenty first century could well see the rise of hydrogen as a gaseous fuel,due to it being bothenvironment friendly and having a huge energy potential.In this paper,experiments are performedin a compression ignition diesel engine with dual fuel mode.Diesel and hydrogen are used as pilotliquid and primary gaseous fuel,respectively.The objective of this study is to find out the specificcomposition of diesel and hydrogen for maximum brake thermal efficiency at five different loadingconditions(20%,40%,60%,80%and 100%of full load)individually on the basis of maximum dieselsubstitution rate.At the same time,the effects on brake specific fuel consumption,brake specificenergy consumption,volumetric efficiency and exhaust gas temperature are also observed at variousliquid gaseous fuel compositions for all the five loadings.Furthermore,second law analysis is carriedout to optimize the dual fuel engine run.It is seen that a diesel engine can be run efficiently inhydrogen-diesel dual fuel mode if the diesel to hydrogen ratio is kept at 40:60.Keywords:Diesel Engine,Diesel Replacement Ratio,Hydrogen,Dual Fuel,Efficiency,Second Law1.IntroductionThe use of conventional fossil fuels has reacheda perceived crisis point.A number of reasons areresponsible for this,such as finite reserves of whatare non-renewable energy sources and the damagefossil fuels cause to the environment 1.There-fore,researchers around the world are exploringevery option to find suitable alternatives to re-place fossil fuels,whether partially or fully 2.Some of the alternative fuels that have been usedto replace petroleum-based fuels include vegetableCorresponding authorEmail addresses:d.biplabiitg.ernet.in(BiplabK.Debnath),sahaiiitg.ernet.in(Ujjwal K.Saha),shockiitg.ernet.in(Niranjan Sahoo)oils,alcohols,liquefied petroleum gas(LPG),liq-uefied natural gas(LNG),compressed natural gas(CNG),bio gas,producer gas,hydrogen etc.Inthis context,hydrogen(H2),a non-carboniferousand non-toxic gaseous fuel,has attracted greatinterest and has huge potential.H2is only oneof many possible alternative fuels that can be de-rived from various natural resources.Others in-clude:coal,oil shale and uranium or renewableresources based on solar energy.H2can be com-mercially formed from electrolysis of water andby coal gasification;thermo-chemical decompo-sition of water and solar photo-electrolysis,al-though these are still in the developmental stageat present 3.The energy required to ignite H2is very low and thus its usage in spark ignitionJournal of Power Technologies 92(1)(2012)5567(SI)engines is not suitable.Again,in compres-sion ignition(CI)engines,H2will not auto ignitedue to its high auto ignition temperature(858 K).Therefore the dual fuel mode appears the bestway to utilize H2in internal combustion(IC)en-gines 4.The dual fuel environment can be cre-ated by initially using a small amount of diesel(as pilot fuel)to launch the combustion and thensupplying H2(as primary fuel)to deliver the restamount of energy to run the cycle.Regardingpower output,hydrogen enhances the mixturesenergy density at lean conditions during a dualfuel run by increasing the hydrogen-to-carbon ra-tio,and thereby improves torque at the wide openthrottle condition 5.H2can be supplied in theengine by carburation,manifold or port injectionor by cylinder injection 6,7.However,the injec-tion of H2in the intake manifold or port requires aminor modification in the engine and offers a bet-ter power output than carburetion 810.Theexperimental works of Yi et al.11 establishedthat intake port injection delivers higher efficiencythan in-cylinder injection at different equivalenceratios too.Varde and Frame figured out that the brakethermal efficiency(bth)of H2diesel dual fuel modeis primarily dependent upon the amount of H2added.The larger the amount of H2,the higherthe value of bthis 3,12.It has been seen in H2diesel dual fuel mode that 90%enriched H2giveshigher efficiency than 30%at 70%load,but can-not complete the load range beyond that due toknocking problems 3.However,bthwas foundto drop when the amount of H2is less than orequal to 5%.In their analysis,an extremely leanair H2mixture restricts the flame to propagatefaster,which lowers H2combustion efficiency 12.However,experimental works done later,with H2diesel dual fuel mode,do not prove this drop inbthwith H2addition as mentioned above 13.According to Shudo et al.hydrogen combus-tion causes higher cooling loss to the combustionchamber wall than hydrocarbon combustion,be-cause of its higher burning velocity and shorterquenching distance 14.A study performed byWang and Zhang indicates that the introductionof hydrogen into the diesel engine causes the en-ergy release rate to increase at the early stagesof combustion,which increases the indicated effi-ciency 15.This is also the reason for the low-ered exhaust temperature.According to them,for fixed H2supply at 50%,75%and 100%load,H2replaces 13.4%,10.1%and 8.4%energy respec-tively with high diffusive speed and high energyrelease rate.The practice of normal and heavy exhaust gasrecirculation(EGR)in H2diesel dual fuel modeis found to lower power production and fuel con-sumption 16.Increases in compression ratio(CR)for H2fuelled diesel engine improves power,efficiency,peak pressure,peak heat release rateand emission of oxides of carbon,but increasesNOxemission 17.A study of injection timingvariation shown that advancing injection timingalthough provides favorable emission reduction,but makes engine operation more inefficient andunstable 18.Sahoo et al.performed an experi-mental study on syngas diesel dual fuel mode forH2:CO ratio of 100:0 at 20%,40%,60%,80%and100%of full load at maximum possible supply ofhydrogen until knocking 19.The study revealsthat at 80%load,the engine offers a maximum19.75%brake thermal efficiency at a maximum72.3%diesel replacement ratio.A few researchers4,20 have studied the variation of H2-dieselquantity for constant diesel supply at each loadto improve the brake power(BP).The increasein the supply of H2in inlet manifold causes a re-duction in the air flow to the engine.As a result,the volumetric efficiency(vol)and consequentlythe bthof the engine reduces.Therefore,thereis scope to study and understand engine perfor-mance by varying both H2and diesel supply whilemaintaining constant BP at each load condition.In light of this fact,the objective of the presentstudy is to determine the best composition of H2-diesel for maximum bthby varying the quantity offuel(pilot and primary)and maintaining constantspeed and BP at each of the five load conditionscorrespondingly.Some of the important physicaland thermodynamic properties of diesel and H2are shown in Table 1.The load conditions selectedare 20%,40%,60%,80%and 100%of full load.As reported by Sahoo et al.19,the maximum 56 Journal of Power Technologies 92(1)(2012)5567Table 1:Properties of H2and diesel 19PropertiesDieselHydrogenChemical compositionC12H26H2Density?kgm3?8500.085Calorific value?MJkg?42119.81Cetane number4555Auto-ignition temperature(K)553858Stoichiometric air fuel ratio14.9234.3Energy density?MJNm3?2.822.87diesel replacement ratios during a dual fuel runare considered as 26%,42%,58%,72%and 44%atthe aforementioned loads respectively.Other per-formance parameters studied alongside are brakespecific fuel consumption(BSFC),brake specificenergy consumption(BSEC),voland exhaust gastemperature(EGT).In order to endorse the ex-perimental results and analysis,the Second Lawanalysis is performed to provide histograms of cal-culated availability of fuel,cooling water,exhaustgas,availability destruction and exergy efficiency.In this way,the present experimental and analyt-ical studies will establish the optimized quantityof H2-diesel composition for best efficiency at con-stant power at each load.2.Experimental setupThe experiments are carried out in a KirloskarTV1 CI diesel engine installed at the Centrefor Energy of the Indian Institute of Technol-ogy(IIT),Guwahati,India.Figure 1 shows aschematic diagram of the engine test bed.Theoriginal engine specifications are shown in Table 2.The engine loading is performed by an eddy cur-rent type dynamometer.The liquid fuel is sup-plied to the engine from the fuel tank through afuel pump and injector.The fuel injection sys-tem of the engine consists of an injection nozzlewith three holes of 0.3 mm diameter with a 120spray angle.A U-tube type manometer is used toquantity the head difference of air flow to the en-gine,while allowing the intake air to pass throughan orifice meter.The engine block and cylinderhead are surrounded by a cooling jacket throughwhich water flows to cool the engine.To mea-sure the specific heat of exhaust gas,a calorime-ter of counter flow pipe-in pipe heat exchanger isalso provided.Temperature measurement is per-formed by K-type thermocouples,which are fittedat relevant positions 21.In order to convert the diesel engine test bedinto dual fuel mode,some additional equipmentis installed in the setup.These include:hydro-gen gas cylinder with regulator,coriolis mass flowmeter,flame trap with fine tuning regulator,nonreturn valve(NRV)and gas carburetor.The cori-olis mass flow meter measures the mass flow rateof hydrogen;while the flame trap and the NRV areused to prevent fire hazards due to accidental en-gine backfire.In the dual fuel mode H2is suppliedto the engine by the induction method.In thismethod,H2mixes with the intake air in the inletmanifold outside the cylinder.A gas carburetor16 is fixed in the intake manifold of the engineto provide the H2supply.The liquid fuel supplyis controlled through a fuel cut offvalve for vari-ous diesel fuel replacement ratios by a lever-armarrangement,as shown in Fig.2.3.Experimental procedureTable 3 illustrates the designed experimental ma-trix of the H2-diesel test at different loads.Ini-tially,the engine is allowed to run on diesel atno load condition for a few minutes to attaina steady state.The cooling water supplies forthe engine and calorimeter are set to 270 and 57 Journal of Power Technologies 92(1)(2012)5567Table 2:Diesel engine specification 21ParameterSpecificationEngine typeKirloskar TV1General detailsSingle cylinder,four stroke diesel,water cooled,compression ignitionBore and stroke87.5110 mmCompression ratio17.5:1Rated output5.2 kW(7 BHP)1500 rpmAir boxWith orifice meter and manometerDynamometerEddy current loading unit,016 kgFuel injection opening205 bar 23BTDC staticCalorimeter typePipe in pipe arrangementRotameterFor water flow measurementTable 3:The experimental matrixLoadDiesel replacement ratioEngine operation20%10,20,26Speed:40%10,20,30,40,42150050 RPM60%10,20,30,40,50,58Injection timing:80%10,20,30,40,50,60,70,7223BTDC100%10,20,30,40,44Figure 1:Schematic diagram of the setup80 liters per hour,as per the engine provider in-structions.Thereafter,the load is gradually in-creased to 3.2 kg(20%load)and the engine is al-lowed to run until it reaches a steady state.Then,the inlet and outlet temperatures of engine cool-ing water,calorimeter cooling water and exhaustgas are measured.Water head difference,dieselFigure 2:Adjustable lever arm arrangementflow rate and engine speed are also recorded.Theadjustable lever arm is then rotated to press thefuel cut offvalve,which will reduce the fuel supplyand speed.The lever arm is then fixed at a point wherediesel supply is reduced by 10%.At this pointH2(99.99%purity)is allowed to flow from thehigh pressure cylinder to the flame trap,throughthe coriolis mass flow meter.At the outlet of theflame trap,one fine tuning regulator is connectedto control H2flow accurately and is delivered tothe intake manifold through the NRV and gas car-58 Journal of Power Technologies 92(1)(2012)5567buretor.The added supply of chemical energy inthe form of H2in the cylinder is converted into me-chanical energy after combustion.This increasesthe speed and BP of the engine.The quantity ofH2is adjusted precisely to return the engine speedand BP to its previous value,recorded during thepure diesel run.The pressure of the H2outlet isnot allowed to exceed 1.2 bar.After the enginereaches a steady state,the values of temperatures,water manometer head and mass flow of H2fromcoriolis flow meter are recorded.The H2supply isthen stopped and the adjustable lever depressedfurther to reduce the diesel fuel supply by 20%.At this point,H2supply is initiated and the pro-cedure is repeated.Once the data of all the fuel replacement ratiosare recorded,the engine is restored to its dieselmode.The load is increased by the eddy currentdynamometer,and the measurement procedurefor all the diesel replacement ratios are repeatedat that load.The maximum fuel replacement ra-tios(shown in Table 3)for five loading conditions(20%,40%,60%,80%and 100%of full load)aretaken from the work reported by Sahoo et al.19.Finally,the H2supply is stopped completely,andthe engine is allowed to run at“no load condition”prior to complete shutdown.4.Analysis procedureAfter collecting the data sets at each diesel re-placement ratio and for each load,the dependentparameters are calculated according to the follow-ing equations 22,23.The diesel replacement ratio(Z)is given byZ=md mpd md 100%(1)The brake power can be written asBP=2 3.142 N W r60000(2)The brake thermal efficiency for diesel mode ismeasured as(bth)diesel=BP md LHVd 100%(3)The brake thermal efficiency for dual fuel modeis given by(bth)dual=BP mpd LHVpd+mh LHVh 100%(4)The brake specific fuel consumption for dualfuel mode is computed fromBSFC=mpd+mhBP!3600(5)The brake specific energy consumption for dualfuel mode is given byBSEC=mpd LHVpd+mh LHVhBP(6)The volumetric efficiency can be computedfromvol=ma?kgs?3600?3.1424?D2 L Nn 60 K a 100%(7)5.Thermodynamic analysisThe results of the hydrogen-diesel dual-fuel ex-periment are analyzed using the Law of Ther-modynamics.It provides significant informationregarding the appropriate distribution of energysupplied by fuel in different parts of the engine24.Also,the energy that is utilized or destroyedis quantified through availability analysis.Thisanalysis,finally,gives the exact amount of hy-drogen and diesel composition which should bemaintained to extract the maximum amount ofenergy from the fuel energy supplied.Hence,the“First Law(Energy)”along with the“Second Law(Exergy)”study of the engine is described in thefollowing section with correct equations.5.1.Energy analysisAccording to the First Law of thermodynamics,the energy supplied in a system is conserved inits different processes and components 25.In aCI engine,the fuel energy supplied(Qi)is trans-ferred in its different processes,viz.Shaft power(Ps),Energy in cooling water(Qc),Energy in ex-haust gas(Qe)and Uncounted energy losses(Qu)59 Journal of Power Technologies 92(1)(2012)5567in the form of friction,radiation,heat transfer tothe surroundings,operating auxiliary equipments,etc.These different forms of energies are calcu-lated according to the following analytical expres-sions 26.The fuel energy supplied,i.e.,the energy inputcan be calculated as follows:(Qi)diesel=md3600 LHVd(8)(Qi)dual=mpd3600 LHVpd+mh3600 LHVh(9)The energy transferred into the shaft can bemeasured asPs=Brake power of the engine(10)The energy transferred into cooling water canbe computed asQC=mpd3600!Cpw(Two Twi)(11)The energy flow through exhaust gas can beestimated asQe=?me3600?Cpe(Tei Teo)(12)For a more precise thermodynamic analysis,thespecific heat of exhaust gas is calculated from theenergy balance of the exhaust gas calorimeter.Fi-nally,from the energy balance,the uncounted en-ergy losses can be estimated asQu=Qi(Ps+Qc+Qe)(13)5.2.Exergy analysisThe availability can be described as the abil-ity of the supplied energy to perform a usefulamount of work 27.In the CI engine the chem-ical availability of fuel(Ai)supplied is convertedinto different types of exergy,viz.,Shaft availabil-ity(As),Cooling water availability(Ac),Exhaustgas availability(Ae)and Destructed availability(Ad)in the form of friction,radiation,heat trans-fer to the surroundings,operating auxiliary equip-ments,etc.These forms of energies are calculatedaccording to the following analytical expressionsas described in the literature 2830.The chemical availability of the fuel supplied isgiven by(Ai)diesel=1.0338 md3600 LHVd(14)(Ai)dual=1.0338 mpd3600 LHVpd(15)+0.985 mh3600 LHVhThe availability transferred through the shaftis recorded asAs=Brake power of the engine(16)The cooling water availability can be measuredasAC=QC?mw3600?Cpw ln TwoTwi!(17)Exhaust gas availability can be calculated asAe=Qe+?mw3600?(18)To(Cpw ln ToTei!Re ln PoPe!)The exhaust gas constant(Re)is estimatedfrom the energy balance of the exhaust gascalorimeter and the products of complete com-bustion of the diesel fuel.The uncounted availability destruction is deter-mined from the availability balance asAd=Ai(As+Ace+Ae)(19)Therefore,the exergy efficiency(II)can be es-timated asII=1 DestructedavailabilityFuelavailability=1 AdAi(20)6.Results and discussionThe results and discussion part of this H2-dieseldual fuel experiment work is divided into two sec-tions;viz.,performance analysis and Second Lawanalysis.The performance analysis discusses bth 60 Journal of Power Technologies 92(1)(2012)5567 05101520251020304050607080Diesel Replacement(%)20%Load40%Load60%Load80%Load100%LoadFigure 3:Variation of brake thermal efficiency with dieselreplacement 0.20.40.60.81.01.21.41020304050607080Diesel Replacement(%)20%Load40%Load60%Load80%Load100%LoadFigure 4:Variation of brake specific fuel consumption withdiesel replacement,BSFC,BSEC,vol,EGT and a comparison ofmaximum brake thermal efficiencies for diesel anddual fuel modes.Later on,the Second Law anal-ysis shows the availabilities of fuel,cooling waterand exhaust gas,destroyed availability and exergyefficiency.6.1.Performance analysisThe effect of variation of H2-diesel quantity onbthfor the five loading conditions is shown inFig 3.Except for the 20%load,all other load-ing conditions show that an increase in H2quan-tity increases bth,but only up to a certain limit.This indicates that in the lower load region,H2cannot burn properly with diesel and results inpoor combustion efficiency.However,this con-dition improves with the increase in load.Themaximum value of bthobtained is around 20%at 0.640.660.680.700.721020304050607080Diesel Replacement(%)20%Load40%Load60%Load80%Load100%LoadFigure 5:Variation of volumetric efficiency with diesel re-placement 481216201020304050607080Diesel Replacement(%)20%Load40%Load60%Load80%Load100%LoadFigure 6:Variation of brake specific energy consumptionwith diesel replacement80%load condition for both 50%and 60%dieselreplacement ratio.Along with the increase in thebththere is also a reduction in BSFC encounteredwith the increase in load and H2substitution rate(except for the 20%load)which is exemplifiedin Fig.4.This is because with the increase inH2,the quantity of energy supply rate into thecylinder increases.Therefore,the total amountof fuel needed for the same BP is alleviated asfar as energy supply is concerned.However,af-ter a certain point of H2replacement,the enginemay not run more efficiently,resulting in a reduc-tion in bth.This is because of the large reductionin volumetric efficiency caused by a reduction ofair(or more precisely oxygen)accessibility insidethe cylinder.This can be clearly understood fromFig.5.The reduction in BSEC with the increase 61 Journal of Power Technologies 92(1)(2012)5567 1002003004005006007008009001020304050607080Diesel Replacement(%)20%Load40%Load60%Load80%Load100%LoadFigure 7:Variation of exhaust temperature with dieselreplacement 051015202520406080100Eng