If ignited, which of the listed materials would be a class "B" fire？A.MagnesiumB.PaperC.Wo

A.Magnesium

B.Paper

C.Wood

D.Diesel Oil

Whenever a combustible solid or liquid is heated to a sufficiently high temperature (flashpoint), it will produce a vapour that is capable of being ignited by a flame, spark or hot surface which has the required concentration and duration of thermal energy.

Which statement is TRUE concerning the flash point of a substance ________．

A.It is lower than the ignition temperature

B.It is the temperature at which a substance will spontaneously ignite

C.It is the temperature at which a substance，when ignited，will continue to burn

D.It is the temperature at which the released vapors will fall within the explosive range

The（auto）ignition temperature is that temperature at which ______．

A.No spark or flame is required to ignite gas or vapor

B.A fuel begins to give off explosive vapors

C.A fuel if ignited will continue to burn

D.A 1% mixture of the fuel with air will explode

A sample of D-ribose（C₅H₁₀O₅) with mass 0. 727 g was weighed into a calor

A sample of D-ribose(C₅H₁₀O₅) with mass 0. 727 g was weighed into a calorimeter and then ignited in presence of excess oxygen. The temperature rose by 0.910 K when the sample was combusted. In another separated experiment in the same calorimeter the combustion of 0. 825 g of benzoic acid,for which the Δ_cU^Θ_m= 3251 kJ·mol^-1,gave a temperature rise of 1.940 K. Calculate the Δ_rU^Θ_mand Δ_rH^Θ_mof D-ribose combusted.

A.indigenous

B.ignited

C.indignant

D.indefinite

n the cylinder has more air than is needed for complete combustion. Lean combustion reduces peak temperatures and therefore NOx emissions. Efficiency is increased and higher output is reached while avoiding knocking. Combustion of the lean air-fuel mixture is initiated by injecting a small amount of LFO (pilot fuel) into the cylinder. The pilot fuel is ignited in a conventional diesel process, providing a high-energy ignition source for the main engine. To obtain the best efficiency and lowest emissions, every cylinder is individually controlled to ensure operation at the correct air-fuel ratio and with the correct amount and timing of pilot fuel rejection. Wartsila has developed a special electronic control system to cope with the demanding task of controlling the combustion in each cylinder, and to ensure optimal performance in terms of efficiency and emissions under all conditions by keeping each cylinder within the operating window. Stable and well-controlled combustion also contributes to less mechanical and thermal load on the engine components. Current stringent emission regulations demand the reduction of NOx emissions. In an internal combustion engine this means controlling peak temperature and residence time, which are the main parameters governing NOx formations. In the Wartsila 50DF engine, the air-fuel ratio is very high (typically 2.2). Since the same specific heat quantity released by combustion is used to heat up a larger mass of air, the maximum temperature and consequently NOx formation are lower. The mixture is uniform. throughout the cylinder since the fuel and air are premixed before introduction into the cylinders, which helps to avoid local NOx formation points within the cylinder. Benefiting from this unique feature, NOx emissions from the Wartsila 50DF are extremely and comply with the most stringent existing legislation.

What is the combustion feature of the Wartsila 50DF？

A.Lean air in the cylinder

B.Excessive fuel in the cylinder

C.Excessive air in the cylinder

D.Spark ignition

A.indignant

B.indigenous

C.indefinite

D.ignited

A.isgraceful

B.graceful

C.ignited

D.indignant