Engine Lab Report

Engine Lab Report

Diesel Engine
Load/N |Fuel Time/s |dH/mmH2O |Speed/r.p.m |Temp/℃ |Air consumption/kg/H |Fuel consumption/kg/H |Air-fuel ratio |Power/kw |Efficiency/ ％ | |40 |121.6 |17.5 |3018 |26.6 |130.16 |2.47 |52.7 |4.5 |0.019 | |80 |94.72 |17.5 |3009 |26.7 |130.14 |3.17 |41.05 |8.97 |0.059 | |125 |72.76 |17 |3009 |26.8 |128.25 |4.12 |31.13 |14.02 |0.111 | |171 |56.95 |17 |3000 |26.9 |128.23 |5.72 |24.33 |19.12 |0.161 | |212 |46.06 |16.5 |3006 |27.1 |126.28 |6.51 |19.40 |23.76 |0.202 | |232 |41.20 |17 |3010 |27.2 |128.16 |7.28 |17.60 |26.03 |0.216 | |
Petrol Engine
Load/N |Fuel Time/s |dH/mmH2O |Speed/r.p.m |Temp/℃ |Air consumption/kg/H |Fuel consumption/kg/H |Air-fuel ratio |Power/kw |Efficiency/ ％ | |40 |285 |2 |3000 |26.8 | 42.50 | 3.19 | 13.32 | 4.47 |0.014 | |109 |191 |7 |3000 |27.4 | 79.44 | 4.77 | 6.65 |12.19 |0.072 | |160 |160 |8 |2950 |28.2 | 84.81 | 5.69 | 14.91 |17.60 |0.125 | |248 |110.5 |14 |3000 |28.2 | 112.2 | 8.24 | 13.62 |27.74 |0.215 | |313 |93.56 |20 |3000 |28.3 | 145.4 | 9.73 | 14.94 |35.01 |0.290 | |374 |71.81 |27 |3000 |28.4 | 168.9 | 12.68 | 13.32 |41.83 |0.317 | |
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Fig 1

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Fig 2

From Fig 1, we know that air-fuel ratio of the petrol engine is not changing much as the brake power increases, however for the diesel engine, the air-fuel ratio drops as the power increases.

This is because the throttle which is situated in the air intake duct of the petrol engine. For the petrol engine, the combustion takes place in the whole cylinder, so the air-fuel ratio should be maintained to make sure the combustion to take place rapidly enough all the time. The throttle will adjust the air-fuel ratio. For the diesel engine, the combustion takes place around individual droplets of the fuel spray, therefore the output is related to the amount of fuel injected, and the air flow is not controlled.

Fig 2 shows that the efficiency increases with the power for both engines, however