Thermal conductivity of nanofluid
 

In this article, on pg 6 http://www.sciencedirect.com/science...4960360400134X

kr=4.97phi^2+2.72phi+1 has been derived from Hamilton Crosser model (1962), when I tried I am getting kr=1.0737phi^2 + 0.9795phi + 1


Any idea how to derive this kr=4.97phi^2+2.72phi+1