Tag Archives: thermodynamics

Prettying Up the 3D Graph Output

Posted on May 26, 2016 by R.P. Churchill

Here I’ve prettied the graph up so the lines change color every 100 degrees F, and I’ve added a legend. I suppose I could choose consecutive colors with a bit more contrast.

Posted in Tools and methods | Tagged animation, canvas, matrix solution techniques, simulation, sim_presentation_series, thermodynamics | Leave a comment

Graphing the Matrix Output

Posted on May 25, 2016 by R.P. Churchill

Here I continually run the heating routine for a piece with an initial temperature of 70 degrees in a furnace set to 2300 degrees. The temperature scale, expressed vertically, runs from 0-2500 degrees. The bottom of the piece, which sits … Continue reading →

Posted in Tools and methods | Tagged animation, canvas, matrix solution techniques, simulation, sim_presentation_series, thermodynamics | Leave a comment

Finally Solving the Matrix

Posted on May 19, 2016 by R.P. Churchill

Once we get all the parameters calculated and the matrix loaded, then we can finally solve the thing. Here’s how the code looks:

    function loadMatrix(index,fceTemp)
    {
      var i; var j; var k;
      var tsa; var tfa; var ts3; var tf4;

      tfa = arrayTfce[index] + Tabs;
      tf4 = tfa * tfa * tfa * tfa;

      for (k = 0; k <= sizeNodes; k++)
      {
        ZSRCE[k] = 0.0;
        ZAUX[k] = 0.0;
        for (i = 0; i <= sizeBandWidth; i++)
          ZMATX[k][i] = 0.0;
      }

      k = 0;
      for (j = 0; j < nodesHigh; j++)
        for (i = 0; i < nodesWide; i++)
        {
          k++;

          //nodal energy
          ZMATX[k][1] += arrayRho[i][j] * arrayCp[i][j];
          ZSRCE[k] += arrayRho[i][j] * arrayCp[i][j] * arrayT[i][j];

          //conduction to right
          if (arrayKright[i][j] > 0.0)
          {
            ZMATX[k][1] += arrayKright[i][j];
            ZMATX[k][2] -= arrayKright[i][j];
            ZMATX[k+1][1] += arrayKright[i][j];
          }

          //conduction up
          if (arrayKup[i][j] > 0.0)
          {
            ZMATX[k][1] += arrayKup[i][j];
            ZMATX[k][1+nodesWide] -= arrayKup[i][j];
            ZMATX[k+nodesWide][1] += arrayKup[i][j];
          }

          //radiation
          if (arrayRad[i][j] > 0.0)
          {
            tsa = arrayT[i][j];
            ts3 = tsa * tsa * tsa;
            ZMATX[k][1] += arrayRad[i][j] * ts3;
            ZSRCE[k] += arrayRad[i][j] * tf4;
          }

        }
    }     //loadMatrix

    function oneCalc(index) {
      calcParams(index);

      for (var i=0; i<nodesWide; i++) {
        for (var j=0; j<nodesHigh; j++) {
          arrayT[i][j] = arrayTpieces[index][i][j] + Tabs;
        }
      }
      
      loadMatrix(index);
      calcMatrix();
      
      k = 0;
      for (var j=0; j<nodesHigh; j++) {
        for (var i=0; i<nodesWide; i++) {
          k++;
          arrayTpieces[index][i][j] = ZSRCE[k] - Tabs;
        }
      }
    }  //oneCalc

    var loopCount = 0;
    
    var s="Temperatures after "+loopCount+" time steps<br />";
    for (var j=nodesHigh-1; j>=0; j--) {
      for (var i=0; i<=nodesWide-1; i++) {
        s += arrayTpieces[0][i][j].toPrecision(7) + ", ";
      }
      s += "<br />";
    }
    document.getElementById("stuff").innerHTML = s;

    function runOneTime() {
      if (loopCount == 0) {
        for (var i=0; i< pieceCount; i++) {
          for (var j=0; j<nodesWide; j++) {
            for (var k=0; k<nodesHigh; k++) {
              arrayTpieces[i][j][k] = 70.0;
            }
          }
        }
      } else {
        oneCalc(0);
      }
      var s="Temperatures after "+loopCount+" time steps<br />";
      for (var j=nodesHigh-1; j>=0; j--) {
        for (var i=0; i<=nodesWide-1; i++) {
          s += arrayTpieces[0][i][j].toPrecision(7) + ", ";
        }
        s += "<br />";
      }
      document.getElementById("stuff").innerHTML = s;
      loopCount++;
      if (loopCount > 20) {
        loopCount = 0;
      }
    }

    var intervalID = setInterval(runOneTime, 1000);

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function loadMatrix(index,fceTemp)

{

var i; var j; var k;

var tsa; var tfa; var ts3; var tf4;

tfa = arrayTfce[index] + Tabs;

tf4 = tfa * tfa * tfa * tfa;

for (k = 0; k <= sizeNodes; k++)

{

ZSRCE[k] = 0.0;

ZAUX[k] = 0.0;

for (i = 0; i <= sizeBandWidth; i++)

ZMATX[k][i] = 0.0;

}

k = 0;

for (j = 0; j < nodesHigh; j++)

for (i = 0; i < nodesWide; i++)

{

k++;

//nodal energy

ZMATX[k][1] += arrayRho[i][j] * arrayCp[i][j];

ZSRCE[k] += arrayRho[i][j] * arrayCp[i][j] * arrayT[i][j];

//conduction to right

if (arrayKright[i][j] > 0.0)

{

ZMATX[k][1] += arrayKright[i][j];

ZMATX[k][2] -= arrayKright[i][j];

ZMATX[k+1][1] += arrayKright[i][j];

}

//conduction up

if (arrayKup[i][j] > 0.0)

{

ZMATX[k][1] += arrayKup[i][j];

ZMATX[k][1+nodesWide] -= arrayKup[i][j];

ZMATX[k+nodesWide][1] += arrayKup[i][j];

}

//radiation

if (arrayRad[i][j] > 0.0)

{

tsa = arrayT[i][j];

ts3 = tsa * tsa * tsa;

ZMATX[k][1] += arrayRad[i][j] * ts3;

ZSRCE[k] += arrayRad[i][j] * tf4;

}

} //loadMatrix

function oneCalc(index) {

calcParams(index);

for (var i=0; i<nodesWide; i++) {

for (var j=0; j<nodesHigh; j++) {

arrayT[i][j] = arrayTpieces[index][i][j] + Tabs;

}

loadMatrix(index);

calcMatrix();

k = 0;

for (var j=0; j<nodesHigh; j++) {

for (var i=0; i<nodesWide; i++) {

k++;

arrayTpieces[index][i][j] = ZSRCE[k] - Tabs;

}

} //oneCalc

var loopCount = 0;

var s="Temperatures after "+loopCount+" time steps<br />";

for (var j=nodesHigh-1; j>=0; j--) {

for (var i=0; i<=nodesWide-1; i++) {

s += arrayTpieces[0][i][j].toPrecision(7) + ", ";

}

s += "<br />";

}

document.getElementById("stuff").innerHTML = s;

function runOneTime() {

if (loopCount == 0) {

for (var i=0; i< pieceCount; i++) {

for (var j=0; j<nodesWide; j++) {

for (var k=0; k<nodesHigh; k++) {

arrayTpieces[i][j][k] = 70.0;

}

} else {

oneCalc(0);

}

var s="Temperatures after "+loopCount+" time steps<br />";

for (var j=nodesHigh-1; j>=0; j--) {

for (var i=0; i<=nodesWide-1; i++) {

s += arrayTpieces[0][i][j].toPrecision(7) + ", ";

}

s += "<br />";

}

document.getElementById("stuff").innerHTML = s;

loopCount++;

if (loopCount > 20) {

loopCount = 0;

}

var intervalID = setInterval(runOneTime, 1000);

We start with a 7×7-node workpiece where the interior nodes are two inches wide and two … Continue reading →

Posted in Tools and methods | Tagged matrix solution techniques, sim_presentation_series, thermodynamics | Leave a comment

Dimensions and Other Considerations Before We Solve the Matrix

Posted on May 18, 2016 by R.P. Churchill

Yesterday’s post showed how some of the constants and parameters are initialized or calculated. Today we’ll describe a few more. This exercise defines a cross-section of a steel billet that is 8 inches by 8 inches and divided into five … Continue reading →

Posted in Tools and methods | Tagged matrix solution techniques, sim_presentation_series, thermodynamics | Leave a comment

Static and Dynamic Coefficients in Matrix Thermal Solutions

Posted on May 17, 2016 by R.P. Churchill

Recalling yesterday’s initial heat balance equation for each node: it should be noted that the values of both the specific heat and the thermal conductivity of steel are themselves functions of temperature. That means that these values need to be … Continue reading →

Posted in Tools and methods | Tagged matrix solution techniques, simulation, sim_presentation_series, thermodynamics | Leave a comment

A Specific Example of Equations To Be Solved By Matrix

Posted on May 16, 2016 by R.P. Churchill

Dividing a cross-section of a steel billet into nodes, we can start by looking at the energy balance for each node: All this equation is saying is that the change in the quantity of energy in a given node per … Continue reading →

Posted in Tools and methods | Tagged matrix solution techniques, sim_presentation_series, thermodynamics | Leave a comment

The Steam Table Form… Finally!

Posted on April 25, 2016 by R.P. Churchill

About two months ago I started making a web form that allowed a user to calculate thermodynamic values for saturated water as functions of either temperature and pressure. I got sidetracked for quite a while working on the graphing capability … Continue reading →

Posted in Tools and methods | Tagged curve fitting, jQuery, thermodynamics, user entry forms | Leave a comment

Extending the Thermodynamic Functions To Their Full Range: Functions vs. Pressure

Posted on April 21, 2016 by R.P. Churchill

While finishing up the process of generating the plots of the thermodynamic functions vs. pressure I found an issue with how plots are drawn on the x-axis when the x-axis has a logarithmic scale. I calculated numeric values for every … Continue reading →

Posted in Tools and methods | Tagged curve fitting, graph project, thermodynamics | Leave a comment

Extending the Thermodynamic Functions To Their Full Range

Posted on April 20, 2016 by R.P. Churchill

Today I extended all 24 functions to their full range, 0-705.44 °F and 0.08866-3203.6 psi. I’ve shown the functions vs. temperature; the functions vs. pressure are generally derived from the same lines in the steam tables so the only difference … Continue reading →

Posted in Tools and methods | Tagged curve fitting, graph project, thermodynamics | Leave a comment

Fixing the Thermodynamic Functions for Saturated Water As A Function of Temperature

Posted on April 19, 2016 by R.P. Churchill

I’ve updated five of the thermodynamic property functions vs. temperature. Note that most of these define properties only up to a bit above 600 °F and, more importantly, to 1800 psi. The values for saturated water are defined up to … Continue reading →

Posted in Tools and methods | Tagged curve fitting, thermodynamics | Leave a comment

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