Energy Engineering - Internal Combustion Engines

Multiple choice test

19/01/22, 15:22 IC Engines - January 19, 2022. Part A (10 points) https://forms.office.com/Pages/ResponsePage.aspx?id=K3EXCvNtXUKAjjCd8ope64cHfHFJHqdBkPyq7vedZGJUODFZNUlBTTgzTkYxUUpGRV … 1/3 IC Engines - January 19, 2022. Part A (10 points)If the intake valve diameter is reduced, we expect that the volumetric efficiency: 1. A) will decrease mainly at high speeds B) will decrease mainly at low speeds C) will decrease in a similar way at all engine speeds D) will decrease mainly at low loads. The two-stroke engine is: 2. A) always more efficient than the four-stroke engine B) always less efficient than the four-stroke engine C) characterized by higher thermal and mechanical stresses than the four-stroke D) applied only in the case of very small displacement and effective power. Pulse turbocharging: 3. A) does not determine fluctuations of the turbine efficiency B) requires a double-entry compressor C) damps the pressure perturbations in a large volume exhaust manifold D) reduces the “turbo-lag” issue. The waste-gate valve in a turbocharged SI engine must be opened: 4. A) to allow the operation of high pressure EGR B) at high engine speeds, to control the turbine power C) at low engine speeds, to control the turbine power D) to increase the compressor boost pressure. 19/01/22, 15:22 IC Engines - January 19, 2022. Part A (10 points) https://forms.office.com/Pages/ResponsePage.aspx?id=K3EXCvNtXUKAjjCd8ope64cHfHFJHqdBkPyq7vedZGJUODFZNUlBTTgzTkYxUUpGRV … 2/3In a spark ignition engine, when the burnt gas has reached 50% of the chamber volume, the burnt mass fraction: 5. A) is equal to 20% B) is equal to 50% C) is equal to 75% D) is equal to 100% Knock is a form of abnormal combustion which, if not controlled, may occur: 6. A) during the expansion stroke of the cycle B) mainly in the CI engine with high compression ratio C) due to a high flame front velocity D) in both naturally aspirated and turbocharged SI engines. In a SI engine the minimum of unburnt HC formed during combustion is typically observed for: 7. A) slightly rich mixture B) slightly lean mixture C) stoichiometric mixture D) extremely lean mixture. The heat release curve [J/°] in a Diesel engine: 8. A) exhibits an initial negative tract due to fuel evaporation B) exhibits an initial negative tract due to premixed combustion C) exhibits an initial negative tract due to diffusive combustion D) is always positive. Downstream of a SCR an oxidizing device is present: 9. A) only if there is not an oxidizing element upstream of the SCR 19/01/22, 15:22 IC Engines - January 19, 2022. Part A (10 points) https://forms.office.com/Pages/ResponsePage.aspx?id=K3EXCvNtXUKAjjCd8ope64cHfHFJHqdBkPyq7vedZGJUODFZNUlBTTgzTkYxUUpGRV … 3/3 Questo contenuto è creato dal proprietario del modulo. I dati inoltrati verranno inviati al proprietario del modulo. Microsoft non è responsabile per la privacy o le procedure di sicurezza dei propri clienti, incluse quelle del proprietario di questo modulo. Non fornire mai la password. Con tecnologia Microsoft Forms | Privacy e cookie | Condizioni per l'utilizzoB) to increase the gas temperature C) to oxidized CO and HC D) to oxidize NH3. The NO conversion efficiency in a three-way catalytic converter for an equivalence ratio=0.7 is: 10. A) very high because of the corresponding CO concentration in the exhaust gases B) very low because of the corresponding CO concentration in the exhaust gases C) very high because of the corresponding Ce2O3 concentration in the exhaust gases D) very low because of the corresponding Ce2O3 concentration in the exhaust gases