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Simulating the heat up of an autoclave and it's contents

Question asked by Rohan Kelkar on Jan 22, 2020

Greetings community,


I am trying to simulate an autoclave that is used for sterilization of the items that are loaded into it. Steam enters the chamber via two inlets on the top and drops down to the bottom of the chamber via gravity. There is a drain at the bottom of the chamber that is closed during the heating up of the chamber, and only opens at the end of the cycle to let the steam escape and allow for the chamber to depressurize. 


I know from real world data, the pressure & temperature of the chamber at the start of the heat up cycle, and the pressure & temperature of the chamber at the end.I also know that steam is being introduced through the two inlets at the top at a pressure of 26 psia. 


The question I'd like to ask is, what boundary conditions should I set to simulate flow of steam into a chamber (but not let out of the chamber, for the purposes of my study)?


I've tried applying 26 psia static pressure to the inlets, and I end up with the following flow trajectories:



Seems kind of odd, because I thought there would be a massive expansion of the steam into the chamber, and not what seems like a direct flow straight downwards to the floor of the chamber. 


In addition to the flow trajectories, I got a "Maximum Mach number exceeded" and a "Real Gas parameters T > Tmax" warning. The temperature seemed to spike up to 1448 K, MUCH greater than the inlet steam temperature of 394 K, which is what I had set it at. 


Anyone on here tried an autoclave simulation, or something similar like a pressure cooker?


Any assistance on what boundary conditions to apply would be greatly appreciated!