namespace path   {::tcl::mathop ::tcl::mathfunc} 
set Nu_combined [ - [ + 0.40 0.32 ]  [* 0.40 0.32 ]  ]
answer% 0.592 for measured efficiencies
set carnotefficiency_gas_turbine [ carnotthermic 1700 900]
answer% 0.4705 or 47 percent
set novikovefficiency_gas_turbine [ endothermic 1700  900]
answer% 0.272
set carnotefficiency_steam [ carnotthermic  900 400]
answer% 0.555
set novikovefficiency_steam [ endothermic  900 400]
answer% 0.33
set Nu_combined_Novikov [ - [ + 0.272 0.33 ]  [* 0.272 0.33 ]  ]
answer% 0.512 for Novikov estimated efficiencies

    namespace path {::tcl::mathop ::tcl::mathfunc}
    set Nu_Carnot  [ - 1.  [/ 300. 900. ] ]
    set Nu_Carnot  [ - 1.  [/ 300. 1200. ] ]
    set Nu_Carnot  [ - 1.  [/ 300. 1400. ] ]
    set Nu_Carnot  [ - 1.  [/ 300. 700. ] ]
    set Nu_Endoreversable  [ - 1.  [sqrt [/ 300. 900. ] ]]
    set Nu_Endoreversable  [ - 1.  [sqrt [/ 300. 1200. ] ]]
    set Nu_Endoreversable  [ - 1.  [sqrt [/ 300. 1400. ] ]]
    set Nu_Endoreversable  [ - 1.  [sqrt [/ 300. 700. ] ]]

    set Nu_Carnot  [ - 1.  [/ 32. 96.5 ] ]
    set Nu_Carnot  [ - 1.  [/ 24.5 95.5 ] ]
    set Nu_Carnot  [ - 1.  [/ 24. 96.5 ] ]
    set Nu_Novikov  [ - 1.  [sqrt [/ 32. 96.5 ] ]]
    set Nu_Novikov  [ - 1.  [sqrt [/ 24.5 95.5 ] ]]
    set Nu_Novikov  [ - 1.  [sqrt [/ 24.5 96.5 ] ]]

    set Nu_Carnot  [ - 1.  [/ 300. 1370. ] ]
    set Nu_Carnot  [ - 1.  [/ 300. 1400. ] ]
    set Nu_Novikov  [ - 1.  [sqrt [/ 300. 1370. ] ]]
    set Nu_Novikov  [ - 1.  [sqrt [/ 300. 1400. ] ]]

 set current   4.5E5 
 R=    delta T/ power or(1200K-300K)        /4.68E5 watts  
 delta 1200K-300K = 900K (SUM of delta T’s of each R)
 set R_overall [/   900 4.65e5]
  SUM R =0.00190 OR 1.9e-3
 R2 is largest component of SUM R
 For each R step,    R=    delta T/ power
 R1 is  delta 100K / 4.5E5 =0.000222
 R2 is  delta 700K / 4.5E5 =0.001555
 R3 is  delta 50K / 4.5E5 =0.0001111 
 R4 is  delta 50K / 4.5E5 =0.0001111
 2% set R1 [/  100 4.5E5]
 0.000222
 3% set R2 [/  700 4.5E5]
 0.001555
 4% set R3 [/  50 4.5E5]
 0.001111
 5% set R4 [/  50 4.5E5]
 0.001111
 6% set sumR [+ 0.000222 0.001555 0.000111  0.000111 ]
 0.00199
 P=VOLTS*CURRENT>> (T1-T2)*I
 set R2_power [* [- 800 100] 500]
 350000
 set efficiency [/ 3.5E5 4.5E5 ]
 0.77777
 set process_heat [/  [* [- 100 50] 500] 4.5E5 ]
 0.0555 or 5.55 percent.
 Only small portion of heat cooks pizza

        # TCL source code follows
        # pretty print from autoindent and ased editor
        # heat engine combustion calculator V2
        # written on Windows XP on TCL
        # working under TCL version 8.6
        # gold on TCL Club, 12Dec2018
        package require Tk
        package require math::numtheory
        namespace path {::tcl::mathop ::tcl::mathfunc math::numtheory }
        set tcl_precision 17
        frame .frame -relief flat -bg aquamarine4
        pack .frame -side top -fill y -anchor center
        set names {{} {combustion chamber diameter meters:} }
        lappend names {combustion chamber height meters:}
        lappend names {heat source temperature input: }
        lappend names {heat sink temperature input: }
        lappend names {optional:}
        lappend names {answers: volume cubic meters: }
        lappend names {total heat units, megajoules: }
        lappend names {endo process, applied/total energy: }
        foreach i {1 2 3 4 5 6 7 8} {
            label .frame.label$i -text [lindex $names $i] -anchor e
            entry .frame.entry$i -width 35 -textvariable side$i
            grid .frame.label$i .frame.entry$i -sticky ew -pady 2 -padx 1 }
        proc about {} {
            set msg "Calculator for Heat Engine Combustion Calculator V2
            from TCL Club
            # gold on TCL Club, 12Dec2018 "
            tk_messageBox -title "About" -message $msg }
        proc self_help {} {
            set msg " Heat Engine Combustion Calculator V2
            from TCL ,
            # self help listing
            # problem, Heat Engine Combustion Calculator V2
            # 1 given follows.
            1) combustion chamber diameter meters:
            2) combustion chamber height meters:
            3) heat source temperature input:
            4) heat sink temperature input:
            # Recommended procedure is push testcase and fill frame,
            # change first three entries etc, push solve,
            # and then push report. Report allows copy and paste
            # from console to conventional texteditor. For testcases
            # testcase number is internal to the calculator and
            # will not be printed until the report button is pushed
            # for the current result numbers.
            # >>> copyright notice <<<
            # This posting, screenshots, and TCL source code is
            # copyrighted under the TCL/TK license terms.
            # Editorial rights and disclaimers
            # retained under the TCL/TK license terms
            # and will be defended as necessary in court.
            Conventional text editor formulas or  grabbed from internet
            screens can be pasted into green console.
            # gold on  TCL Club, 12Dec2018 "
            tk_messageBox -title "Self_Help" -message $msg }
        proc pi {} {expr acos(-1)}
        proc pistonvolumex { d h } {
            set  pistonvolumexxx [* .25 [pi] $d $d $h ]
            return $pistonvolumexxx
        }
        proc heatx { vol density } {
            set fuel_mass [* $vol $density]
            set total_heat [* $fuel_mass 40.1]
            return $total_heat
        }
        proc endothermic { theatsource tlow  } {
            set endo [expr { 1.-sqrt($tlow)/sqrt($theatsource)} ]
            return $endo
        }
        proc carnotthermic { theatsource tlow  } {
            set theatsource [* 1. $theatsource]
            set tlow  [* 1. $tlow]
            set carnot [- 1. [/ $tlow $theatsource]]
            return $carnot
        }
        proc endoprocess { theatsource tlow  } {
            set theatsource [* 1. $theatsource]
            set tlow  [* 1. $tlow]
            set endoprocess [* .25 [- 1. [/ $tlow $theatsource]]]
            return $endoprocess
        }
        proc firebox { total_heat burn_time cross_section temp_ambient temp_flame} {
            set d $cross_section
            set firing_temp 1
            set heat_flux [/ $total_heat $burn_time]
            set heat_flux_persec [/ $heat_flux $burn_time]
            set cross_section [ / [* [pi] $d $d ] 4.]
            set item 25
            set temp_ambient 25
            set temp_flame 1488.
            set tx  $temp_ambient
            set taxx $temp_flame
            set t 25
            set h [/ $heat_flux_persec $cross_section]
            while {$item <= 4000} {
                incr item
                set t [+ $t 1 ]
                set term1 [* 1. $t $t $t $t]
                set term2 [* 1. $tx $tx $tx $tx]
                set term1 [* .000000000056703 [ - $term1 $term2]]
                set term2 [* $h  1.1 [/ [- $taxx $t]  [ - $taxx $tx ]]]
                set difference  [abs [- $term1 $term2]]
                if {$difference < 2.} { set temp_answer $t }
            }
            return $temp_answer
        }
        proc calculate {     } {
            global answer2
            global side1 side2 side3 side4 side5
            global side6 side7 side8
            global testcase_number
            incr testcase_number
            global piston_volume piston_temperature_exp
            global workdays total_heat massfromvolume
            global total_heat firebox_temp heatsourcetemp2
            global carnotefficiency novikovefficiency
            global idealappliedovertotal piston_firing_time
            global heatsinktemp1
            set side1 [* $side1 1. ]
            set side2 [* $side2 1. ]
            set side3 [* $side3 1. ]
            set side4 [* $side4 1. ]
            set side5 [* $side5 1. ]
            set side6 [* $side6 1. ]
            set side7 [* $side7 1. ]
            set side8 [* $side8 1. ]
            incr testcase_number
            set piston_diameter $side1
            set piston_height $side2
            set piston_firing_time [* 2 60 10]
            set heatsourcetemp2 $side3
            set heatsinktemp1 $side4
            set piston_volume 1
            set piston_volume [pistonvolumex $piston_diameter $piston_height]
            set fuel_density 850
            set massfromvolume [* $piston_volume $fuel_density]
            set fuel [* [ /  8.2 60.   ] $massfromvolume]
            set total_heat [* 13.5 $fuel]
            set temp_amb 25.
            set temp_flame 1488.
            set piston_temperature_exp $temp_flame
            set total_heat_joules [* $total_heat 1.0E6]
            set firebox_temp [firebox $total_heat_joules $piston_firing_time $piston_diameter $temp_amb $temp_flame]
            if  {$piston_temperature_exp > 1200.} {set piston_temperature_exp 1200}
            set workdays [/ $piston_volume 3. ]
            set carnotefficiency [ carnotthermic $heatsourcetemp2 $heatsinktemp1]
            set novikovefficiency [ endothermic $heatsourcetemp2 $heatsinktemp1]
            set idealappliedovertotal [ endoprocess $heatsourcetemp2 $heatsinktemp1]
            set fractionwork [ endoprocess $heatsourcetemp2 $heatsinktemp1]
            set side6 $piston_volume
            set side7 $total_heat
            set side8 $fractionwork
        }
        proc fillup {aa bb cc dd ee ff gg hh} {
            .frame.entry1 insert 0 "$aa"
            .frame.entry2 insert 0 "$bb"
            .frame.entry3 insert 0 "$cc"
            .frame.entry4 insert 0 "$dd"
            .frame.entry5 insert 0 "$ee"
            .frame.entry6 insert 0 "$ff"
            .frame.entry7 insert 0 "$gg"
            .frame.entry8 insert 0 "$hh"
        }
        proc clearx {} {
            foreach i {1 2 3 4 5 6 7 8 } {
                .frame.entry$i delete 0 end } }
        proc reportx {} {
            global answer2
            global side1 side2 side3 side4 side5
            global side6 side7 side8
            global testcase_number
            global piston_volume piston_temperature_exp
            global workdays total_heat massfromvolume
            global total_heat firebox_temp heatsourcetemp2
            global carnotefficiency novikovefficiency
            global idealappliedovertotal piston_firing_time
            global heatsinktemp1
            console eval {.console config -bg palegreen}
            console eval {.console config -font {fixed 20 bold}}
            console eval {wm geometry . 40x20}
            console eval {wm title . " Heat Engine Combustion Report V2, screen grab and paste from console 2 to texteditor"}
            console eval {. configure -background orange -highlightcolor brown -relief raised -border 30}
            console show;
            puts "%|table $testcase_number |printed in| tcl format|% "
            puts "&| quantity| value| comment, if any|& "
            puts "&| $testcase_number :|testcase_number | |&"
            puts "&| $side1 :|combustion chamber diameter meters:  |   |&"
            puts "&| $side2 :|combustion chamber height meters:   | |& "
            puts "&| $side3 :|heat source temperature input: | |& "
            puts "&| $side4 :|heat sink temperature input: | |&"
            puts "&| $side5 :|optional:  | |&"
            puts "&| $side6 :|answers: volume cubic meters |  |&"
            puts "&| $side7 :|total heat units, megajoules: |  |&"
            puts "&| $side8 :|endo process, applied/total energy: |  |&"
        }
        frame .buttons -bg aquamarine4
        ::ttk::button .calculator -text "Solve" -command { set side8 0 ; calculate   }
        ::ttk::button .test2 -text "Testcase1" -command {clearx;fillup .5 .5 900. 300. 0. 0.0981  153.9 .166 }
        ::ttk::button .test3 -text "Testcase2" -command {clearx;fillup 1.5 1.5 1200. 300. 0. 2.65  4156. .1875 }
        ::ttk::button .test4 -text "Testcase3" -command {clearx;fillup 2. 2. 1400. 300. 0. 6.28  9853. .196 }
        ::ttk::button .clearallx -text clear -command {clearx }
        ::ttk::button .about -text about -command {about}
        ::ttk::button .self_help -text self_help -command { self_help }
        ::ttk::button .cons -text report -command { reportx }
        ::ttk::button .exit -text exit -command {exit}
        pack .calculator  -in .buttons -side top -padx 10 -pady 5
        pack  .clearallx .cons  .self_help .about .exit .test4 .test3 .test2   -side bottom -in .buttons
        grid .frame .buttons -sticky ns -pady {0 10}
        . configure -background aquamarine4 -highlightcolor brown -relief raised -border 30
        wm title . "Heat Engine Combustion Calculator V2"    

  puts " %| testcase $testcase_number | value| units |comment |%"
  puts " &| volume| $volume| cubic meters |based on length $side1 and width $side2   |&"  

        # pretty print from autoindent and ased editor
        # Novikov efficiency of small gas stoves
        # written on Windows XP on eTCL
        # working under TCL version 8.5.6 and eTCL 1.0.1
        # gold on TCL WIKI , 8aug2013
        package require Tk
        namespace path {::tcl::mathop ::tcl::mathfunc}
        console show
       proc novikov { theatsource tlow  } {
            set endo [expr { 1.-sqrt($tlow)/sqrt                        ($theatsource)} ]
            return $endo
            }
        proc carnot { theatsource tlow  } {
            set theatsource [* 1. $theatsource]
            set tlow  [* 1. $tlow]
            set carnot [- 1. [/ $tlow $theatsource]]
            return $carnot
            }
        proc k { temperature  } { 
             set temperature [+ $temperature 273. ]  
             return $temperature
             }
  puts "%|name|water boiled|measured Nu|Novikov Nu|Carnot Nu |%"
  puts "&|stove a|1 l|49.4|[* 100 [novikov 96.5 32.]]|[* 100. [carnot 96.5 32.]]|&"
  puts "&|stove b|1 l|43.8|[* 100. [novikov 95.5 24.5]] |[* 100. [carnot 95.5 24.5]] |&"
  puts "&|stove c|0.5 l|32.4|[* 100. [novikov 96.5 24.]] |[carnot 96.5 24.]|&"