Comparing Heat transfer through metals
Comparing Heat transfer through metals
(OP)
Hey everyone,
This is my first time posting and am unsure of how things work here. I am new to the engineering world and would like some help in solving two problems. I am comparing to separate parts; one made with Stainless steel (304) and one made with Cast Iron (Grade:65-45-12). My problem isn't real complicated but for some reason I am struggling.
Problem:
1.) The main difference between these two parts is the geometry I can machine the cast part a hair smaller but it is still roughly twice the thickness of the Stainless steel. I am looking ad placing an RTD sensor on one of the two but would like to know how to find out which will give me a more accurate reading of the fluid flowing in the pipe.
2.) same situation except I would like to know how to specify a heater (such as a band heater) to heat the fluid inside the pipe to 400 Deg. F.
Again any help would be great some dimensions are bellow.
Thickness SS - 13.5cm
CI - 26 cm
Length SS - 100cm
CI - 84 cm
Thanks for any help.
I will be looking in my old textbooks this weekend but thought this couldn't hurt.
This is my first time posting and am unsure of how things work here. I am new to the engineering world and would like some help in solving two problems. I am comparing to separate parts; one made with Stainless steel (304) and one made with Cast Iron (Grade:65-45-12). My problem isn't real complicated but for some reason I am struggling.
Problem:
1.) The main difference between these two parts is the geometry I can machine the cast part a hair smaller but it is still roughly twice the thickness of the Stainless steel. I am looking ad placing an RTD sensor on one of the two but would like to know how to find out which will give me a more accurate reading of the fluid flowing in the pipe.
2.) same situation except I would like to know how to specify a heater (such as a band heater) to heat the fluid inside the pipe to 400 Deg. F.
Again any help would be great some dimensions are bellow.
Thickness SS - 13.5cm
CI - 26 cm
Length SS - 100cm
CI - 84 cm
Thanks for any help.
I will be looking in my old textbooks this weekend but thought this couldn't hurt.





RE: Comparing Heat transfer through metals
Diameter SS - 76 mm
CI - 100 mm
RE: Comparing Heat transfer through metals
RE: Comparing Heat transfer through metals
RE: Comparing Heat transfer through metals
RE: Comparing Heat transfer through metals
The thermal conductivity (k) for
304 ss at 200 deg C is 18 W/m.K
for CI
40 W/m.K
You will need to know the fluid density, density of ss is
7900 kg/m3 and for CI is 7272 kg/m3
You will need the heat capacity of the fluid, ss and CI
for ss 477 J/kg.K and for CI 420 J/kg.K
Thermal diffusivity
304 ss is 4 x 10^-6 m2/s
CI is 1.7 x 10 ^-5
Have fun
RE: Comparing Heat transfer through metals
400 degree heat tracing is very challenging. After rereading your posts it almost sounds like you are working on a plasics extruder.
RE: Comparing Heat transfer through metals
There are several big caveats in defrosting lines especially at your specified temperature of 400F. You have to control the direction of the applied heat in defrosting the line, or simply you cannot start in the middle. You have to be careful about overshoot if your product is heat sensitive.
If the line is any size the process fluid will have to have a good thermal conductivity.
Can you comeback with the material in the line and some sizes of your piping sizes?
What are you going to use for heating media, electric,thermal fluids?
http://
RE: Comparing Heat transfer through metals
There is a really big difference between a solid and a stagnant liquid.
Which do you have?
RE: Comparing Heat transfer through metals
Currently we are using 2 - 750 watt band heaters on the outside of some cast iron, which is roughly 100mm in diameter and on average 21 in thick.
And RTD is placed on another part away from the heaters to measure the temperature. (poor design and looking to improve) It sits on a stainless steel part that is 70mm in dia. and 10.5 mm thick.
At the moment my ideas to increase the time to heat the fluid is to:
A. seal the top of the enclosure as to not create a bouyancy effect with the air around the heaters and pipe
and
B. to add insulating tape around the heaters and RTD