Recent content by onno

Hello Tom Thanks http://coimbra.ucsd.edu/publications/papers/2019c_Orosco_Coimbra.pdf That clears up the issue. Detailed but convincing. Pt keeps being a bad emitter (emissivity 0.1 to 0.2) up to high temperatures 1800 K. Thanks that was very helpful Onno

Hello Hutchphd You say: "So when hot enough they emit well" We are designing an oven using a current driven, very thin Pt filament. I have data on filament temperature as function of the heating current. If I compare the measured temperature with some heat transfer simulations I come to the...

I am looking for data on the total hemispherical emissivitie from a Platinum surface at high temperature 1400 - 2000 K. In this temperature range the Platnium surface will color from red, orange to white. I learned that, practically, the bove mentioned emissivity will approach to one in this...

My latest post did not adress the original question of this thread, How can phase transitions be physical equilibriums?, as well as the post of the moderator concerning the exact definitions of the different sytems. So, here I go Suppose I am interested in studying phase transitions of water...

That is of course a most usefull addition, to add mass transfer. I also quite like the Wikipedia definition of a closed system where they speak, maybe in even more general terms, of "transfer in and out" of the system. A closed system is a physical system that does not allow certain types of...

A closed system is always in equilibrium because no energy moves in or out of it. That is a definition and we use it as such. An open system may change its energy state because it interacts with its surroundings. The hot water kettle is an open system. You use heat to reach a higher temperature...

Suppose there is liquid water. You will have to put the kettle on (heat it) to convert the water into its gas phase. That is a practicality of everyday life. The hot water kettle however is not a closed system. You will loose some water vapor in the boiling process and that signifies an...

Hallo Maybe it helps to define the vacuum better. At the vacuum end of the tube filled with mercury there is a pressure: the vapor pressure of mercury at the tube temperature. The force that this presurre exerts is very small compared with the atmspheric pressure at the other, open end of the...