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Oliver Johnson & Sam Wilding Heat Transfer Me 340-2 Winter Semester, 2010.

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Presentation on theme: "Oliver Johnson & Sam Wilding Heat Transfer Me 340-2 Winter Semester, 2010."— Presentation transcript:

1 Oliver Johnson & Sam Wilding Heat Transfer Me Winter Semester, 2010

2 Using inputs like fluid type, internal or external flow, and parameters given in the problem, this program will automatically select the applicable Nusselt Number equation(s) and return the Nusselt Number(s)

3 if config == 2; % External Flow % Find fluid properties at film temperature Tf = (Tinf+Ts)/2; [rho,mu,nu,Pr] = props(fluid,Tf,quality); % Fixed Surface Temperature if geometry == 3; % Flat Plate, Parallel Flow Re = v*D/nu; xcritical = 5e5*nu/v; if isnan(qs) && isnan(Xi); if D <= 1.05*xcritical % Laminar if Pr >= 0.6 Nu{1,1} = 0.332*Re^(1/2)*Pr^(1/3); %Eq Nu{1,2} = 'Eq. 7.23'; if Re < 5.3e5 Nu{2,1} = 0.664*Re^(1/2)*Pr^(1/3); %Eq Nu{2,2} = 'Eq. 7.30'; end % Liquid Metals if isequal('hg',fluid) && Pr = 100 Nu{3,1} = 0.565*(Re*Pr)^(1/2); %Eq Nu{3,2} = 'Eq. 7.32'; end % Churchill-Ozoe if Pr*Re >= 100 Nu{4,1} = *Re^(1/2)*Pr^(1/3)/(1+(0.0468/Pr)^(2/3))^(1/4); %Eq Nu{4,2} = 'Eq (Churchill-Ozoe)'; if Re < 5.3e5 Nu{5,1} = 2*Nu; Nu{5,2} = 'Nu_ave '; end elseif D > 1.05*xcritical && D < 20*xcritical % Mixed Laminar/Turbulent if Pr > 0.6 && Pr < 60 Nu{6,1} = (0.037*Re^(4/5)-871)*Pr^(1/3); %Eq Nu{6,2} = 'Eq. 7.38'; end elseif D >= 20*xcritical % Fully Turbulent if Pr > 0.6 && Pr < 60 Nu{7,1} = *Re^(4/5)*Pr^(1/3); %Eq Nu{7,2} = 'Eq. 7.36'; end if Re > 10^8 Nu{8,1} = 0.037*Re^(4/5)*Pr^(1/3); %Eq Nu{8,2} = 'Eq. 7.38'; end % Unheated Starting Length elseif isnan(qs) && ~isnan(Xi) if Re < 5e5 %Laminar Nu{9,1} = 0.332*Re^(1/2)*Pr^(1/3)/(1-(Xi/D)^(3/4))^(1/3); %Eq Nu{9,2} = 'Eq. 7.42'; else %Turbulent Nu{10,1} = *Re^(1/2)*Pr^(1/3)/(1-(Xi/D)^(3/4))^(1/3); %Eq Nu{10,2} = 'Eq. 7.43'; end % Fixed Heat Flux elseif isnan(Ts) && isnan(Xi) if Re = 0.6 Nu{11,1} = 0.453*Re^(1/2)*Pr^(1/3); %Eq Nu{11,2} = 'Eq. 7.45'; elseif Re > 5e5 && Pr > 0.6 && Pr < 60 Nu{12,1} = *Re^(4/5)*Pr^(1/3); %Eq Nu{12,2} = 'Eq. 7.46'; end elseif geometry == 4; % Cylinder Re = v*D/nu; % Hilpert if Re > 0.4 && Re = 0.6 if Re >= 0.4 && Re < 4 C = 0.989; m = 0.330; elseif Re >= 4 && Re < 40 C = 0.911; m = 0.385; elseif Re >= 40 && Re < 4000 C = 0.683; m = 0.466; elseif Re >= 4000 && Re < C = 0.193; m = 0.618; elseif Re >=40000 && Re <= C = 0.027; m = 0.805; end Nu{13,1} = C*Re^m*Pr^(1/3); %Eq Nu{13,2} = 'Eq (Hilpert)'; end % Churchill if Re*Pr >= 0.2 Nu{14,1} = *Re^(1/2)*Pr^(1/3)*(1+(Re/282000)^(5/8))^(4/5)/(1+(0.4/Pr)^(2/3))^(1/4); %Eq Nu{14,2} = 'Eq (Churchill)'; end % Zhukauskas [rhoinf,muinf,nuinf,Prinf] = props(fluid,Tinf,quality); [rhos,mus,nus,Prs] = props(fluid,Ts,quality); Reinf = v*D/nuinf; if Prinf > 0.7 && Prinf 1 && Reinf < 10^6 if Reinf >= 1 && Reinf < 40 C = 0.75; m = 0.4; elseif Reinf >= 40 && Reinf < 1000 C = 0.51; m = 0.5; elseif Reinf >= 10^3 && Reinf < 2e5 C = 0.26; m = 0.6; elseif Reinf >= 2e5 && Reinf < 1e6 C = 0.076; m = 0.7; end if Prinf <= 10 n = 0.37; else n = 0.36; end Nu{15,1} = C*Reinf^m*Prinf^n*(Prinf/Prs)^(1/4); %Eq Nu{15,2} = 'Eq (Zhukauskas)'; end % Sphere elseif geometry == 5; % Whitaker [rhoinf,muinf,nuinf,Prinf] = props(fluid,Tinf,quality); [rhos,mus,nus,Prs] = props(fluid,Ts,quality); Reinf = v*D/nuinf; muratio = muinf/mus; if ffld == 0; if Prinf > 0.71 && Prinf 3.5 && Reinf 1 && muratio < 3.2 Nu{16,1} = 2+(0.4*Reinf^(1/2)+0.06*Reinf^(2/3))*Prinf^(0.4)*(muratio)^(1/4); %Eq Nu{16,2} = 'Eq (Whitaker)'; end % Ranz and Marshall for freely falling liquid drops elseif ffld == 1; Nu{17,1} = 2+0.6*Reinf^(1/2)*Pr^(1/3); %Eq Nu{17,2} = 'Eq (Ranz and Marshall)'; end elseif config == 1; % Internal Flow if geometry == 1; % Circular Pipe Tmave = (Tmi+Tmo)/2; [rho,mu,nu,Pr] = props(fluid,Tmave,quality); [rhos,mus,nus,Prs] = props(fluid,Ts,quality); if isnan(mdot); Re = rho*v*D/mu; elseif isnan(v); Re = 4*mdot/(pi*mu*D); end muratio=mu/mus; f Re < 2300 % Laminar xhydro = D*0.05*Re; xthermal = xhydro*Pr; xratio = xthermal/xhydro; S = (Re*Pr/(L/D))^(1/3)*(muratio)^0.14; if S >= 2 if xratio >= 0.5 && xratio 0.48 && Pr && muratio < 9.75 Nu{18,1} = 1.86*S; %Eq Nu{18,2} = 'Eq. 8.57'; elseif xratio > 1.5 Nu{19,1} = (0.0668*(D/L)*Re*Pr)/(1+0.04*((D/L)*Re*Pr)^(2/3)); %Eq Nu{19,2} = 'Eq. 8.56'; end elseif S < 2 if ~isnan(qs) Nu{20,1} = 4.36; %Eq Nu{20,2} = 'Eq. 8.53'; Nu{21,1} = Nu{20,1}; Nu{21,2} = 'Nu_ave'; elseif ~isnan(Ts) Nu{22,1} = 3.66; %Eq Nu{22,2} = 'Eq. 8.55'; Nu{23,1} = Nu{22,1}; Nu{23,2} = 'Nu_ave'; else disp('Error: Cannot have Ts == const and qs == const simultaneously.') return end elseif Re > 2300 % Turbulent if L < 60*D % Short Pipe L = 60*D*1.01; % This is here to calculate a fully developed Nu needed to find the % Nu for a short pipe is 101% of fully developed length shortpipe = 1; end if ~isequal('hg',fluid) if isnan(qs) && isnan(f) % Dittus if Pr > 0.7 && Pr && L > 60*D if Ts > Tmave n = 0.4; elseif Ts < Tmave n = 0.3; end Nu{24,1} = 0.023*Re^(4/5)*Pr^n; %Eq Nu{24,2} = 'Eq. 8.60'; Nuave = Nu{24,1}; end elseif ~isnan(qs) || ~isnan(Ts) if isnan(f) % Sieder if Pr > 0.7 && Pr && L > 60*D Nu{25,1} = 0.027*Re^(4/5)*Pr^(1/3)*(muratio)^0.14; %Eq Nu{25,2} = 'Eq (Sieder)'; Nuave = Nu{25,1}; end elseif ~isnan(qs) || ~isnan(Ts) && ~isnan(f) % Gnielinski if Pr > 0.5 && Pr 3000 && Re 60*D Nu{26,1} = (f/8)*(Re-1000)*Pr/(1+12.7*(f/8)^(1/2)*(Pr^(2/3)-1)); %Eq Nu{26,2} = 'Eq (Gnielinski)'; Nuave = Nu{26,1}; end elseif isequal('hg',fluid) % Liquid Metals Pe = Pr*Re; if isnan(Ts) && ~isnan(qs) if Pe > 100 && Pe 3.63e3 && Re < 9.05e6 Nu{27,1} = *(Pe)^0.287; %Eq Nu{27,2} = 'Eq. 8.64'; Nuave = Nu{27,1}; end elseif isnan(qs) && ~isnan(Ts) if Pe >= 100 Nu{28,1} = *Pe^0.8; %Eq Nu{28,2} = 'Eq. 8.65'; Nuave = Nu{28,1}; end if shortpipe == 1; C = ; m = 0.676; Nu{29,1} = Nuave*(1+C/(L/D)^m); %Eq Nu{29,2} = 'Eq (Short Tubes)'; end elseif geometry == 2; % Non-Circular Cross Section Tmave = (Tmi+Tmo)/2; [rho,mu,nu,Pr] = props(fluid,Tmave,quality); [rhos,mus,nus,Prs] = props(fluid,Ts,quality); muratio=mu/mus; Dh = 4*Ac/P; if isnan(mdot); Reh = rho*v*Dh/mu; elseif isnan(v); Reh = 4*mdot/(pi*mu*Dh); end if Reh < 2300 Nu{30,1} = 'See Table 8.1'; Nu{30,2} = ''; elseif Reh > 2300 % Sieder if Pr > 0.7 && Pr if L > 60*Dh Nu{31,1} = 0.027*Reh^(4/5)*Pr^(1/3)*(muratio)^0.14; %Eq Nu{31,2} = 'Eq (Sieder - Non-Circular Cross Section)'; elseif L <= 60*Dh % Short Pipe L = 60*Dh*1.01; % This is here to calculate a fully developed % Nu needed to find the Nu for a short pipe is 101% of fully developed length Nuave = 0.027*Reh^(4/5)*Pr^(1/3)*(muratio)^0.14; %Eq C = ; m = 0.676; Nu{29,1} = Nuave*(1+C/(L/Dh)^m); %Eq Nu{29,2} = 'Eq (Short Tubes)'; end


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