Chapter 7, Problem 7.41P

Interpretation Introduction

(a)

Interpretation:

The amount of heat transferred to the tank is to be calculated.

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:

$input+generation-output-consumpumtion=accumulation$

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:

$\Delta U+\Delta E_{\text{k}}+\Delta E_{\text{p}}=Q-W_{\text{s}}$   ....... (1)

Here, $\Delta U$ is the rate of change in the internal energy of the system, $\Delta E_{\text{k}}$ is the rate of kinetic energy change of the system, $\Delta E_{\text{p}}$ is the rate of potential energy change of the system, $Q$ is the net rate at which energy is transferred to a system and $W_{\text{s}}$ is the rate at which energy is transferred as shaft work.

Mass $\left(m\right)$ is calculated from volume $\left(V\right)$ and specific volume $\left(\hat{V}\right)$ a substance as:

$m=\frac{V}{\hat{V}}$   ....... (2)

Interpretation Introduction

(b)

Interpretation:

The final temperature of the contents of the tank is to be calculated.

Concept introduction:

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

Interpretation Introduction

(c)

Interpretation:

The amount of steam which is condensed is to be calculated.

Concept introduction:

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

At this saturation temperature at a particular pressure, steam is present along with some condensed steam when cooled.

The total mass of the system is conserved for the system before and after the cooling takes place.