Question

In a gasoline engine, fuel vapors are ignited by a spark. In a diesel engine, a fuel-air mixture is drawn in, then rapidly compressed to as little as 1/20 the original volume, in the process increasing the temperature enough to ignite the fuel-air mixture.

Part A

Explain why the temperature rises during the compression.

Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

increases

escapes

doesn't escape

decreases

The piston does work on the gas which _____________ the thermal energy; and it does so quickly enough that heat ______________ the system fast enough to keep the gas below ignition temperature.

Answer 1

the temperature rises because it is an adiabatic compression.

Step-by-step explanation:

The process in an internal combustion engine has several stages in the compression stage the embolus rises rapidly and the gas is compressed, in an almost adiabatic environment, the loss of heat through the walls is small, so the temperature must rise, by the first law of thermodynamics

Q = W - DU

As it is almost adiabatic Q = 0

W = DU

The temperature rise of almost equal to the work done on the gas by the piston, this work is positive

In short, the temperature rises because it is an adiabatic compression.

The word order for the blanks is

Increase, do not escape