All categories

4 years ago

What is the thermal efficiency of this reheat cycle in terms of enthalpies?

Engineering

1 answer:

schepotkina [342]4 years ago

5 0

Answer:

$\eta =\dfrac{\left (h_3-h_4\right )+(h_5-h_6)-(h_2-h_1)}{(h_3-h_2)+(h_5-h_4)}$

Explanation:

For close gas turbine:

Gas turbine works on Brayton cycle.Gas turbine have lots of applications like ,it is use in aircraft,in land applications etc.

Reheating is the method to improve the efficiency of the gas turbine.In reheating gas is expanding in two turbine instead of one turbine alone.Two turbine like high pressure turbine and low pressure turbine are used for expansion.

In the above diagram 1-2 is a compressor,2-3 heat addition,3-4 high pressure turbine,4-5 reheating of cycle 5-6 low pressure turbine,6-1 heat rejection,

We know that $\eta =\frac{W_{net}}{Q_{s}}$

Now take $h_{1},h_{2},,h_{3},h_{4},h_{5},h_{6}$ represent the enthalpy of point 1,2,3,4,5,6 in the cycle respectively.

So total heat supplied $Q_S$ =

$\left (h_3-h_2\right )+\left (h_5-h_4\right )$

Net work out put

$W_{net}$ = $\left (h_5-h_6\right )-\left (h_2-h_1\right )$

So efficiency $\eta =\frac{W_{net}}{Q_{s}}$

$\eta =\dfrac{\left (h_3-h_4\right )+(h_5-h_6)-(h_2-h_1)}{(h_3-h_2)+(h_5-h_4)}$

You might be interested in

(35-39) A student travels on a school bus in the middle of winter from home to school. The school bus temperature is 68.0° F. Th

arlik [135]

Answer:

The net energy transfer from the student's body during the 20-min ride to school is 139.164 BTU.

Explanation:

From Heat Transfer we determine that heat transfer rate due to electromagnetic radiation ( $\dot Q$ ), measured in BTU per hour, is represented by this formula:

$\dot Q = \epsilon\cdot A\cdot \sigma \cdot (T_{s}^{4}-T_{b}^{4})$ (1)

Where:

$\epsilon$ - Emissivity, dimensionless.

$A$ - Surface area of the student, measured in square feet.

$\sigma$ - Stefan-Boltzmann constant, measured in BTU per hour-square feet-quartic Rankine.

$T_{s}$ - Temperature of the student, measured in Rankine.

$T_{b}$ - Temperature of the bus, measured in Rankine.

If we know that $\epsilon = 0.90$ , $A = 16.188\,ft^{2}$ , $\sigma = 1.714\times 10^{-9}\,\frac{BTU}{h\cdot ft^{2}\cdot R^{4}}$ , $T_{s} = 554.07\,R$ and $T_{b} = 527.67\,R$ , then the heat transfer rate due to electromagnetic radiation is:

$\dot Q = (0.90)\cdot (16.188\,ft^{2})\cdot \left(1.714\times 10^{-9}\,\frac{BTU}{h\cdot ft^{2}\cdot R^{4}} \right)\cdot [(554.07\,R)^{4}-(527.67\,R)^{4}]$

$\dot Q = 417.492\,\frac{BTU}{h}$

Under the consideration of steady heat transfer we find that the net energy transfer from the student's body during the 20 min-ride to school is:

$Q = \dot Q \cdot \Delta t$ (2)

Where $\Delta t$ is the heat transfer time, measured in hours.

If we know that $\dot Q = 417.492\,\frac{BTU}{h}$ and $\Delta t = \frac{1}{3}\,h$ , then the net energy transfer is:

$Q = \left(417.492\,\frac{BTU}{h} \right)\cdot \left(\frac{1}{3}\,h \right)$

$Q = 139.164\,BTU$

The net energy transfer from the student's body during the 20-min ride to school is 139.164 BTU.

7 0

3 years ago

What type of car engine is best for cold weather.

Komok [63]

Answer:Antifreeze/coolant

Explanation: keeps your engine cool in warm weather and keeps it from freezing up in the winter. A 50-50 mix of full strength coolant and water generally protects to around -30 degrees Fahrenheit. Make sure you check with the supplier or your owner's manual for the correct formulation

5 0

3 years ago

This method will sell the seat in row i and column j unless it is already sold. A ticket is sold if the price of that seat in th

blsea [12.9K]

Answer:

The solution code is written in Java.

public class Movie {
private double [][] seats = new double[5][5];
private double totalSales;
public Movie(){
for(int i= 0; i < this.seats.length; i++){
for(int j = 0; j < this.seats[i].length; j++){
this.seats[i][j] = 12;
}
}
this.totalSales = 0;
}
public boolean bookSeat(int i, int j)
{
if(this.seats[i][j] != 0){
this.totalSales += this.seats[i][j];
this.seats[i][j] = 0;
return true;
}else{
return false;
}
}
}

Explanation:

The method, bookSeat(), as required by the question is presented from Line 16 - 26 as part of the public method in a class Movie. This method take row, i, and column, j, as input.

By presuming the seats is an two-dimensional array with all its elements are initialized 12 (Line 7 - 10). This means we presume the movie ticket price for all the seats are $12, for simplicity.

When the bookSeat() method is invoked, it will check if the current price of seats at row-i and column-i is 0. If not, the current price, will be added to the totalSales (Line 19) and then set the price to 0 (Line 20) and return true since the ticket is successfully sold (Line 21). If it has already been sold, return false (Line 23).

8 0

3 years ago

Why is a metal work enclosure dangerous?

dedylja [7]

Answer:

Why is a metal work enclosure dangerous? Metalworkers are not only exposed to pollutants from metal cut ting and polishing procedures, but they are also exposed to metalworking fluids (MWF).

8 0

2 years ago

Javier is well versed in computer-aided design and is adept at spatial reasoning. What other skill would be

snow_tiger [21]

Surveying and cartography

5 0

3 years ago

Read 2 more answers