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snow_tiger [21]
3 years ago
8

A flat-plate solar collector is used to heat water by having water flow through tubes attached at the back of the thin solar abs

orber plate. The absorber plate has a surface area of 2 m2 with emissivity and absorptivity of 0.9. The surface temperature of the absorber is 35°C, and solar radiation is incident on the absorber at 500 W/m2 with a surrounding temperature of 0°C. Convection heat transfer coefficient at the absorber surface is 5 W/m2 ∙K, while the ambient temperature is 25°C. Net heat rate absorbed by the solar collector heats the water from an inlet temperature (Tin) to an outlet temperature (Tout). If the water flow rate is 5 g/s with a specific heat of 4.2 kJ/kg∙K, determine the temperature rise of the water.
Engineering
1 answer:
-BARSIC- [3]3 years ago
3 0

Answer:

dT = 21.35 C

Explanation:

Given:

- Area of the absorber plate A = 2 m^2

- e= a = 0.9

- T_s = 35 C

- q''_solar = 500 W/m^2

- T_surr = 0 C

- h = 5 W/m^2 K

- T_amb = 25 C

- flow(m) = 5 g/s

- c_p = 4.2 KJ/kgK

Find:

- The temperature rise of water.

Solution:

- Using Energy balance on the plate:

                                   E_in - E_out = q_in

- Find E_in and E_out:

                                   E_in = a*q''_solar

                            E_out = q"_convec + q"_rad

                   E_out = h*(T_s - T_amb) + e*σ*(T_s^4 - T_surr^4)

- Compute E_in and E_out:

                            E_in = 0.9*(500) = 450 W/m^2

         E_out = 5*(35 - 25) + 0.9*5.67*10^-8*(308^4 - 273^4)

                                E_out = 225.778 W/m^2

- Hence,

                                  E_in - E_out = q_in

                                 450 - 225.778 = q_in

                                  q_in = 224 W/m^2

- Assuming thickness of plate and pipe through which water flows as negligible, then:

                                flow(m)*c_p*(dT) = q_in*A

                                dT = q_in*A / flow(m)*c_p

- plug values in:

                                    dT = 224*2 / 5*4.2

                                    dT = 21.35 C

                     

                 

                             

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//Function Declarations

void add();

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//Main Code Displays Menu And Take User Input

int main()

{

  int choice;

  cout << "\nMenu";

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void add()

{

  int rows1,cols1,i,j,rows2,cols2;

 

  cout << "\nmatrix1 # of rows: ";

  cin >> rows1;

 

  cout << "\nmatrix1 # of columns: ";

  cin >> cols1;

 

   int m1[rows1][cols1];

 

  //Taking First Matrix

  for(i=0;i<rows1;i++)

      for(j=0;j<cols1;j++)

      {

          cout << "\nEnter element (" << i << "," << j << "): ";

          cin >> m1[i][j];

          cout << "\n";

      }

  //Printing 1st Matrix

  for(i=0;i<rows1;i++)

  {

      for(j=0;j<cols1;j++)

          cout << m1[i][j] << " ";

      cout << "\n";

  }

     

  cout << "\nmatrix2 # of rows: ";

  cin >> rows2;

 

  cout << "\nmatrix2 # of columns: ";

  cin >> cols2;

 

  int m2[rows2][cols2];

  //Taking Second Matrix

  for(i=0;i<rows2;i++)

      for(j=0;j<cols2;j++)

      {

          cout << "\nEnter element (" << i << "," << j << "): ";

          cin >> m2[i][j];

          cout << "\n";

      }

  //Displaying second Matrix

  cout << "\n";

  for(i=0;i<rows2;i++)

  {

      for(j=0;j<cols2;j++)

          cout << m2[i][j] << " ";

      cout << "\n";

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  if(rows1 == rows2 && cols1 == cols2)

  {

      cout << "\n";

      for(i=0;i<rows1;i++)

      {

          for(j=0;j<cols1;j++)

              cout << m1[i][j]+m2[i][j] << " ";

          cout << "\n";  

      }

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  main();

 

}

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  int rows1,cols1,i,j,k,rows2,cols2;

  cout << "\nmatrix1 # of rows: ";

  cin >> rows1;

 

  cout << "\nmatrix1 # of columns: ";

  cin >> cols1;

 

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      for(j=0;j<cols1;j++)

      {

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  cout << "\nmatrix2 # of columns: ";

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  if(rows1 == rows2 && cols1 == cols2)

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  else

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}

void mul()

{

  int rows1,cols1,i,j,k,rows2,cols2,mul[10][10];

  cout << "\nmatrix1 # of rows: ";

  cin >> rows1;

 

  cout << "\nmatrix1 # of columns: ";

  cin >> cols1;

 

   int m1[rows1][cols1];

 

  for(i=0;i<rows1;i++)

      for(j=0;j<cols1;j++)

      {

          cout << "\nEnter element (" << i << "," << j << "): ";

          cin >> m1[i][j];

          cout << "\n";

      }

  cout << "\n";

  for(i=0;i<rows1;i++)

  {

      for(j=0;j<cols1;j++)

          cout << m1[i][j] << " ";

      cout << "\n";

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  cout << "\nmatrix2 # of rows: ";

  cin >> rows2;

 

  cout << "\nmatrix2 # of columns: ";

  cin >> cols2;

 

  int m2[rows2][cols2];

 

  for(i=0;i<rows2;i++)

      for(j=0;j<cols2;j++)

      {

          cout << "\nEnter element (" << i << "," << j << "): ";

          cin >> m2[i][j];

          cout << "\n";

      }

  cout << "\n";

  //Displaying Matrix 2

  for(i=0;i<rows2;i++)

  {

      for(j=0;j<cols2;j++)

          cout << m2[i][j] << " ";

      cout << "\n";

  }

     

  if(cols1!=rows2)

      cout << "operation is not supported";

  else

  {

      //Initializing results as 0

      for(i = 0; i < rows1; ++i)

  for(j = 0; j < cols2; ++j)

  mul[i][j]=0;

// Multiplying matrix m1 and m2 and storing in array mul.

  for(i = 0; i < rows1; i++)

  for(j = 0; j < cols2; j++)

  for(k = 0; k < cols1; k++)

  mul[i][j] += m1[i][k] * m2[k][j];

// Displaying the result.

  cout << "\n";

  for(i = 0; i < rows1; ++i)

      for(j = 0; j < cols2; ++j)

      {

      cout << " " << mul[i][j];

      if(j == cols2-1)

      cout << endl;

      }

      }  

  main();

 }

5 0
3 years ago
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