Chapter 3.8, Problem 6E

(A)

Interpretation Introduction

Interpretation:

The difference in specific enthalpy between entering and existing streams.

Concept Introduction:

The difference in specific enthalpy $\left(\Delta \widehat{H}\right)$.

$\Delta \widehat{H}={\widehat{H}}^V-{\widehat{H}}^L$

Here, specific enthalpy of saturated liquid phase is ${\widehat{H}}^L$ and specific enthalpy of vapor phase is ${\widehat{H}}^V$.

(B)

Interpretation Introduction

Interpretation:

The rate at which heat is added to the steam in the heat exchanger.

Concept Introduction:

Write the steady state energy balance equation.

$0={\dot{m}}_{\text{in}}\left({\widehat{H}}^L{}_{\text{in}}+\frac{v_{\text{in}}^2}{2}+g{h}_{\text{in}}\right)-{\dot{m}}_{\text{out}}\left({\widehat{H}}^V{}_{\text{out}}+\frac{v_{\text{out}}^2}{2}+g{h}_{\text{out}}\right)+\dot{Q}$

Here, entry and exit height are $h_{\text{in}}\text{and}{h}_{\text{out}}$, entry and exit mass flow rate are ${\dot{m}}_{\text{in}}\text{and}{\dot{m}}_{\text{out}}$, entry and exit linear velocity are $v_{\text{in}}\text{and}{v}_{\text{out}}$, rate of heat addition is $\dot{Q}$, and acceleration due to gravity is g.