( a ) Under what conditions would an equal-percentage valve be used instead of a linear valve? ( b ) What are some reasons to use a valve positioner? For the heat exchanger described in Example 20.1,...

( a ) Under what conditions would an equal-percentage valve be used instead of a linear valve?

( b ) What are some reasons to use a valve positioner?

For the heat exchanger described in Example 20.1, determine the output response for a 10°F change in both steam temperature and inlet temperature.