t0 = 4;
tk = 80;
tp = 105;
cvody = 4186;
Δ = tk  -  t0;
m = 200*100;
Q = 
        m*cvody*(Δ/(24*60*60)) // 
          N;
Print["Q= ", Q, "  W"]

Δ1 = tp - t0;
Δ2 = tp - tk;
Solve[
        Q == 
          kS*((Δ1 - Δ2)/Log)[Δ(1/Δ)2]];
\(Print["kS= ", 
      kS /. %[\([1]\)], \*""  W.\!\(K\^\(-1\)\)""]\)

mpivo  =  0.5;
Qpullitr  =  
        cvody*mpivo*(tk - t0);
Print[Qpullitr/10^9 GJ]

Print[(Qpullitr*700)/10^9  "Kč/pullitr"]

Print[Qpullitr/3600000 "kWh/pullitr"]

Print[2*Qpullitr/3600000 "Kč/pullitr"]

0.1*200*100

λFe = 14;
ntrubek = 10;
QV = ((200*100*(10^(-3)))/(3600*24. ));
\(Print["QV= ", 
      QV, \*"" \!\(m\^3\).\!\(s\^\(-1\)\)""]\)
mm = 0.001;
tsteny = 1  mm;
Din = 10  mm;
S1trubka = Pi*((Din^2)/4);
Scelkem = ntrubek*S1trubka;
vpivo = (QV/Scelkem);
\(Print["vpivo= ", vpivo, \*"" m.\!\(s\^\(-1\)\)""]\)

Tdef = 0.25*(2  tp + t0 + tk);
Print["Tdef= ", Tdef, " K"]
ν = (10^(-6)) Fit[{{70, 0.413}, {80, 0.365}}, {1, T}, T] /. 
          T -> Tdef;
\(Print["ν= ", ν, \*"" (m^2).(s^(-1))""]\)

Rey = ((vpivo*Din)/ν);
Print["Re= ", Rey, " -"]

Pr = 
        Fit[{{60, 2.98}, {80, 2.22}}, {1, T}, T] /. 
          T -> Tdef;
Print["Pr= ", Pr, " -"]

λ = 
        Fit[{{50, 0.645}, {80, 0.670}}, {1, T}, T] /. 
          T -> Tdef;
\(Print["λ= ", λ, \*"" W.(m^(-1)).(K^(-1))""]\)