Background
So I am working on a project to where I am trying to heat up air within a 2 inch tube, with high air flow. I am using 2 inch tri clamp stainless steel tubes where I basically have a fan on one end and am trying to get an inline heater so that the result is a high flow rate and high temperature (around 400F - 500F).
What I have tried so far
I have had some decent success by buying a cheapo heat gun from Harbor Freight and taking the nickel chromium array out of it, suspending it inside a 2 inch tube. I was able to get to about 400 F but after some time (an hour or so) the element seems to burn out and die. I seem to be so close to being able to achieve this goal but was hoping there is a more reliable method to heat the air without having to replace the element that often. I would like to stay to electric heat sources if possible and it would need to be 120V, below 15A (standard house breakers in a kitchen).
Question
So I am not asking for a particular product, but rather what electric heater types out there might work for my application?
The closest thing I could find was something like this:
This one fits inside a 2 inch tri clamp tube but seems it needs to be in a liquid, not just with air flow around it? Would this more than likely just burn up too?