Ok another way. Maybe I was asking wrong way. I'm using nitrogen as inert gas. In that case I'm heating Monopropylen glycol (MPG). Because, when I'm heating it, with no pressure (atmopspehric pressure), I'm will get only 120°C. Then the heating curve will stop at this temperature 120°C But when I'll add some more pressure, let's say 400kPa I can get to 160°C and than it will stop again at this temperature. So is it possible, that this amount of pressure will increase the absorption of MW irradiation into MPG?