Consider the coolant circuit in a standard automotive engine that produces a power output of 100 kw. the liquid coolant (which is usually a 50%-50% mixture of ethylene glycol and water) has a specific heat of 3.3 kj/kg-k. if the coolant inlet temperature is 70°c and heat transferred to the coolant at the maximum power operating condition is 28% of the power output, find the minimum mass flow rate of coolant required to keep the coolant exit temperature at or below 90°c.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.