I have a doubt regarding hot air ovens. I want to find out how much time it takes for a body in oven to reach a prescribed temperature. I know final temperature to be attained by the body and it's initial temperature, material properties etc., For the oven air is preheated before sending towards object using some heat source. Once the body attains the required final temperature, air will be pumped out.
So, how to simulate this kind of problem using commerical software like fluent. How to approach this problem to solve. Any relevant help in the form of suggestions or references will be appreciated.
Thanks for your time ...🙂
Indeed, you can start without outlet boundary conditions. If you are asking for the procedures, there are too many tutorials available in YouTube.
This is a transient heat transfer problem. I suggest the following two steps:
(1) Start by solving the problem using lump capacitance method or the approximate method (depending on Biot number that you need to calculate). This will give you a rough idea about the time needed to reach your temperature.
(2) If you have to solve it using FLUENT, then you need to run transient simulation for which you need appropriate initial and boundary conditions. Simplify the domain. For example, let the flow of air inlet be specified and its exit, the temperatures, properties, so on. When you reach the desired temperature of the object, stop the simulation.
If I am correct, you are sending hot air through an inlet of the oven to heat an object inside the oven domain. Ask yourself two questions:
1) Is the air forced into the oven getting accumulated (compressed) ? If no then air is being pushed out simultaneously through the inlet.
2) What about the conservation of energy ? If the boundary conditions do not satisfy energy conservation then temperature inside the oven would continue to rise and there shall be no convergence.
I hope it helps.
Thanks Ahmad Khalaf Sleiti for your suggestion.
I have proceeded in the same way in beginning. I need to use a heater to preheat the air. So in this heating procedure, I have to find the max temperature reached by air before it enters the chamber, to use it in calculation.
In the attached image, I have taken free stream temperature as an assumed value. My doubt is how to find this value.
For this I want to do a simulation with no outlet and heater in the middle, so max temperature attained by fluid can be calculated.
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