Finished methane conductivity; closes #631

Added a few tests
CoolProp · Apr 29, 2015 · b51465b · b51465b
1 parent 2da100b
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diff --git a/src/Backends/Helmholtz/TransportRoutines.cpp b/src/Backends/Helmholtz/TransportRoutines.cpp
@@ -982,7 +982,7 @@ CoolPropDbl TransportRoutines::conductivity_hardcoded_methane(HelmholtzEOSMixtur
     for (int i = 1; i <= 6; ++i){
         summer += jl[i]*pow(delta, rl[i])*pow(tau, sl[i]);
     }
-    double delta_sigma_star = 1.0;
+    double delta_sigma_star = 1.0; // Looks like a typo in Friend - should be 1 instead of 11
     if (HEOS.T() < HEOS.T_critical() && HEOS.rhomolar() < HEOS.rhomolar_critical()){ 
         delta_sigma_star = HEOS.saturation_ancillary(iDmolar, 1, iT, HEOS.T())/HEOS.keyed_output(CoolProp::irhomolar_critical);
     }
@@ -992,7 +992,33 @@ CoolPropDbl TransportRoutines::conductivity_hardcoded_methane(HelmholtzEOSMixtur
     double rhostar = 1-delta;
     double F_T = 2.646, F_rho = 2.678, F_A = -0.637;
     double F = exp(-F_T*sqrt(std::abs(Tstar)) - F_rho*POW2(rhostar) - F_A*rhostar);
-    double CHI_T_star = 0.28631*delta*tau/(1+2*delta*HEOS.dalphar_dDelta() + POW2(delta)*HEOS.d2alphar_dDelta2());
+    double CHI_T_star;
+    if (std::abs(Tstar) < 0.03){
+        if (std::abs(rhostar) < 1e-16){
+            // Equation 26
+            const double LAMBDA = 0.0801, gamma = 1.190;
+            CHI_T_star = LAMBDA*pow(std::abs(Tstar), -gamma);
+        }
+        else if (std::abs(rhostar) < 0.03){
+            // Equation 23
+            const double beta = 0.355, W = -1.401,S = -6.098, E = 0.287, a = 3.352, b = 0.732, R = 0.535, Q = 0.1133;
+            double OMEGA = W*Tstar*pow(std::abs(rhostar), -1/beta);
+            double theta = 1;
+            if (Tstar < -pow(std::abs(rhostar), -1/beta)/S){
+                theta = 1+E*pow(1+S*Tstar*pow(std::abs(rhostar), -1/beta), 2*beta);
+            }
+            CHI_T_star = Q*pow(std::abs(rhostar),-a)*pow(theta, b)/(theta + OMEGA*(theta + R));
+        }
+        else{
+            // Equation 19a
+            CHI_T_star = 0.28631*delta*tau/(1+2*delta*HEOS.dalphar_dDelta() + POW2(delta)*HEOS.d2alphar_dDelta2());
+        }
+    }
+    else{
+        // Equation 19a
+        CHI_T_star = 0.28631*delta*tau/(1+2*delta*HEOS.dalphar_dDelta() + POW2(delta)*HEOS.d2alphar_dDelta2());
+    }
+
     lambda_critical = 91.855/(eta*POW2(tau))*POW2(1+delta*HEOS.dalphar_dDelta() - delta*tau*HEOS.d2alphar_dDelta_dTau())*pow(CHI_T_star, 0.4681)*F ; //[mW/m/K]
     return (lambda_dilute + lambda_residual + lambda_critical)*0.001;
 }

diff --git a/src/Tests/CoolProp-Tests.cpp b/src/Tests/CoolProp-Tests.cpp
@@ -507,6 +507,12 @@ vel("p-Xylene", "T", 600, "D", 1e-12, "L", 41.73e-3 , 1e-3),
 vel("EthylBenzene", "T", 300, "D", 1e-12, "L", 9.71e-3, 1e-3),
 vel("EthylBenzene", "T", 600, "D", 1e-12, "L", 41.14e-3, 1e-3),
 
+// Friend, JPCRD, 1989
+vel("Methane", "T", 100, "D", 1e-12, "L", 9.83e-3, 1e-3),
+vel("Methane", "T", 400, "D", 1e-12, "L", 49.96e-3, 1e-3),
+vel("Methane", "T", 182, "Q", 0, "L", 82.5e-3, 5e-3),
+vel("Methane", "T", 100, "Dmolar", 28.8e3, "L", 234e-3, 1e-2),
+
 };
 
 TEST_CASE_METHOD(TransportValidationFixture, "Compare thermal conductivities against published data", "[conductivity],[transport]")