variable &

i simulation reactor steam reforming . The heat transfer coefficients have been entered into the : k_CO2 ((3.69*(TS[1/K])^(-0.3838))/(1+(964/TS[1/K])+(1860000/(TS[1/K])^2)))[W/(m*K)] Thermal conductivity

Messages will unknown function: ^
All quantities for example :
Thermal conductivity;Heat Capacity;viscosity and reat reaction have a function ^
plz help me
how to expansion equation ?