Merge pull request #315 from CoolProp/develop

Added surface tension for HFC fluids.  Closes https://github.com/CoolProp/CoolProp/issues/306

CoolPropBibTeXLibrary.bib

@@ -1088,6 +1088,18 @@
   timestamp = {2013.04.10}
 }
 
+@ARTICLE{Okada-IJT-1999,
+  author = {M. Okada and T. Shibata and Y. Sato and Y. Higashi},
+  title = {{Surface Tension of HFC Refrigerant Mixtures}},
+  journal = {International Journal of Thermophysics},
+  year = {1999},
+  volume = {20},
+  pages = {119-127},
+  number = {1},
+  owner = {Belli},
+  timestamp = {2014.12.08}
+}
+
 @ARTICLE{Olchowy-IJT-1989,
   author = {G. A. Olchowy and J. V. Sengers},
   title = {{A Simplified Representation for the Thermal Conductivity of Fluids

dev/fluids/R404A.json

@@ -186,6 +186,17 @@
       "max_abs_error": 0.8960338468479963, 
       "max_abs_error_units": "J/mol/K", 
       "type": "rational_polynomial"
+    }, 
+    "surface_tension": {
+      "BibTeX": "Okada-IJT-1999", 
+      "Tc": 345.18, 
+      "a": [
+        0.0536
+      ], 
+      "description": "sigma = sum(a_i*(1-T/Tc)^n_i)", 
+      "n": [
+        1.249
+      ]
     }
   }, 
   "CAS": "R404A.PPF", 

dev/fluids/R407C.json

@@ -186,6 +186,17 @@
       "max_abs_error": 1.1362542557756523, 
       "max_abs_error_units": "J/mol/K", 
       "type": "rational_polynomial"
+    }, 
+    "surface_tension": {
+      "BibTeX": "Okada-IJT-1999", 
+      "Tc": 359.23, 
+      "a": [
+        0.05877
+      ], 
+      "description": "sigma = sum(a_i*(1-T/Tc)^n_i)", 
+      "n": [
+        1.229
+      ]
     }
   }, 
   "CAS": "R407C.PPF", 

dev/fluids/R410A.json

@@ -186,6 +186,17 @@
       "max_abs_error": 4.484588321318679, 
       "max_abs_error_units": "J/mol/K", 
       "type": "rational_polynomial"
+    }, 
+    "surface_tension": {
+      "BibTeX": "Okada-IJT-1999", 
+      "Tc": 344.56, 
+      "a": [
+        0.06238
+      ], 
+      "description": "sigma = sum(a_i*(1-T/Tc)^n_i)", 
+      "n": [
+        1.246
+      ]
     }
   }, 
   "CAS": "R410A.PPF", 

dev/fluids/R507A.json

@@ -186,6 +186,17 @@
       "max_abs_error": 1.511103834455641, 
       "max_abs_error_units": "J/mol/K", 
       "type": "rational_polynomial"
+    }, 
+    "surface_tension": {
+      "BibTeX": "Okada-IJT-1999", 
+      "Tc": 343.76, 
+      "a": [
+        0.05344
+      ], 
+      "description": "sigma = sum(a_i*(1-T/Tc)^n_i)", 
+      "n": [
+        1.25
+      ]
     }
   }, 
   "CAS": "R507A.PPF",