$3$: $(20$ pts$)$ Consider a fluid passing through a valve at a rate of $1k\frac{g}{s},$ going from $500$ kPa at the inlet to $100$ kPa at the outlet.

$($a$)$ If the fluid is saturated liquid water, at what rate is entropy produced in the process?

$($b$)$ If the fluid is Nitrogen, at what rate is entropy produced in the process? $($Assume Ideal Gas$)$