Chapter 7, Problem 7.49P

Interpretation Introduction

(a)

Interpretation:

The temperature of the superheated steam is to be calculated immediately after the rapid adiabatic expansion.

Concept introduction:

A flowchart is the complete representation of a process through boxes or other shapes which represents process units and arrows that represents the input and output of the process. The flowchart must be fully labelled to infer important data about the process involved.

In a system, a conserved quantity (total mass, mass of a particular species, energy or momentum) is balanced and can be written as:

$\mathrm{input}+generation-output-consumpumtion=accumulation$

Here, ‘input’ is the stream which enters the system. ‘Generation’ is the term used for the quantity that is produced within the system. ‘Output’ is the stream which leaves the system. ‘Consumption’ is the term used for the quantity that is consumed within the system. ‘Accumulation’ is used for the quantity which is builds up within the system.

All the equations which are formed are then solved simultaneously to calculate the values of the unknown variables.

The equation for energy balance is:

$\Delta \dot{H}+\Delta {\dot{E}}_{\text{k}}+\Delta {\dot{E}}_{\text{p}}=\dot{Q}-{\dot{W}}_{\text{s}}$   ....... (1)

Here, $\Delta \dot{H}$ is the rate of change in the enthalpy of the system, $\Delta {\dot{E}}_{\text{k}}$ is the rate of kinetic energy change of the system, $\Delta {\dot{E}}_{\text{p}}$ is the rate of potential energy change of the system, $\dot{Q}$ is the net rate at which energy is transferred to a system and ${\dot{W}}_{\text{s}}$ is the rate at which energy is transferred as shaft work.

Interpretation Introduction

(b)

Interpretation:

The observation about the formation of the white plume and the estimated temperature at this point is to be determined.

Concept introduction:

Saturated steam is the steam vaporized with little heat at its boiling point. Above this saturation temperature, the steam becomes superheated.

When steam at higher temperature is cooled rapidly in contact with a surface then the formation of tiny water droplets takes place on that surface which is called mist.