Final answer:
The air pressure builds up from 80 to 100 PSI within 45 seconds in a diesel engine's dual system, relying on compression of air to ignite the fuel without spark plugs, with a significant volume ratio V₁/V₂ impacting engine efficiency.
Step-by-step explanation:
Understanding Air Pressure in Diesel Engines
When the engine is at operating RPMs, the air pressure is built up from 80 to 100 PSI within 45 seconds in a dual system. This air pressure is essential for the proper functioning of a diesel engine, as the fuel is ignited without a spark plug. Instead, the diesel engine relies on the compression of air to increase its temperature above the fuel's ignition temperature. This process entails taking air at an ambient temperature of 20°C, compressing it adiabatically to a much higher temperature, and then injecting the fuel at the point of maximum compression for ignition.
An important concept in this process is the ratio of the volumes before and after compression, given the adiabatic condition and a constant (y) value of 1.4. The volume ratio V₁/V₂ is significant because it relates to the change in temperature and pressure within the cylinder, which directly impacts engine efficiency and performance.