Chapter 9, Problem 9.39P

Interpretation Introduction

(a)

Interpretation:

The number of tenants in office buildings for the given conditions should be determined.

Concept introduction:

The concept of unitary methods in mathematics is used for calculating the number of tenants. Based on the given data of items with respect to the power consumption per unit. The quantities of specific items are multiplying with its power consumption.

For calculation of the number of tenants, total power consumed per unit along with total power supplied by the solid oxide fuel cell is being considered.

Interpretation Introduction

(b)

Interpretation:

The amount of heat loss in kW should be determined for the thermal efficiency of $\text{60}\text{\%}$.

Concept introduction:

Thermal efficiency is defined as the ratio of energy output with energy input defined as,

$n=\frac{\text{Energy}\text{output}}{\text{Energy}\text{input}}$

Where,

Energy input is defined as the amount of energy fed to the reactor.

Energy output is defined as the total amount of energy produced by the reactor.

The amount of heat transferred is

$\begin{array}{l}Q\text{}=\sum _{out}n{\hat{H}}_i-\sum _{in}n{\hat{H}}_i\\ \end{array}$

$\sum _{out}n{\hat{H}}_i$ is the heat of formation of product.

$\sum _{in}n{\hat{H}}_i$ is the heat of formation of reactant.

The enthalpies of reactants and products depends on the heat capacity and temperature.

Interpretation Introduction

(c)

Interpretation:

The value of molar flow rate of fuel for the given conditions of fractional conversion should be determined.

Concept introduction:

Fractional conversion of components is defined as the ratio of moles fed to the reactor with respect to the moles of output obtained at the exit of reactor.

$f\text{=}\frac{{\left(n_a\right)}_{\text{feed}}}{{\left(n_a\right)}_{\text{output}}}$

Where,

Number of moles fed to the reactor = ${\left(n_a\right)}_{\text{feed}}$.

Number of moles obtained at the output = ${\left(n_a\right)}_{\text{output}}$.

Percent excess air is the ratio of difference between the number of moles of air fed and moles of air theoretically required to number of moles theoretically required.

$\%Excessair=\left(\frac{{\left(n_{air}\right)}_{feed}-{\left(n_{air}\right)}_{theoritical}}{{\left(n_{air}\right)}_{theoritical}}\right)$.

Molar flow rate is defined as the ratio of mole with time,

$\text{M}\text{=}\frac{\text{n}}{\text{time}}$

Where,

M is the molar flow rate.

n be the number of moles.

Time is taken in hours.

Interpretation Introduction

(d)

Interpretation:

The molar flow rate for input after business hour should be calculated.

Concept introduction:

Fractional conversion of components is defined as the ratio of moles fed to the reactor with respect to the moles of output obtained at the exit of reactor.

$f\text{=}\frac{{\left(n_a\right)}_{\text{feed}}}{{\left(n_a\right)}_{\text{output}}}$

Where,

Number of moles fed to the reactor = ${\left(n_a\right)}_{\text{feed}}$.

Number of moles obtained at the output = ${\left(n_a\right)}_{\text{output}}$.

Percent excess air is the ratio of difference between the number of moles of air fed and moles of air theoretically required to number of moles theoretically required.

$\%\text{Excess}\text{air}=\left(\frac{{\left(n_{air}\right)}_{\text{feed}}-{\left(n_{\text{air}}\right)}_{\text{theoritical}}}{{\left(n_{\text{air}}\right)}_{\text{theoritical}}}\right)$.

Molar flow rate is defined as the ratio of mole with time,

$\text{M}\text{=}\frac{\text{n}}{\text{time}}$

Where,

M is the molar flow rate.

n be the number of moles.

Time is taken in hours.