Stainless Steel vs. Plastic Tubing heat loss calculations
Stainless Steel vs. Plastic Tubing heat loss calculations
(OP)
Will plastic tubing retain heat better than stainless steel? I assume that answer is a yes (thermal conductivity of plastic tubing is ~ .17 W/m K vs. 16 W/m K). If I want to compare how stainless steel will lose heat vs. plastic tubing on a 5 ft line (there are various line lengths but 5 ft. is the max length we'll have) where do I incorporate the different k-values? I will be insulating the line with Armacell NH foam tube insulation (k = .045 W/m K).
I have used the relationship of qin-qout=qstor to find my outlet temperature (where qstor = mdot *cp*(tin-tout)) using k=.045 but I don't see where I would place the k value for the tubing.
I work for a cosmetic lab and it is critical that the tube temperature not fluctuate more than a degree or two over that 5 ft. run. If so, the product begins to separate/solidify/discolor.
The advantage of plastic over steel is cost/flexibility/maintenance. We have to disassemble this line and clean it on a regular basis (weekly). The advantage of SS is that we could place a nozzle heater in-line to overcome the heat loss to the environment.
• Ambient temp is usually 18-20 C
• Fluid temp max is 80 C
• Volumetric flow rate ~ .000095 m^3/s - .000238 m^3/s
Thanks in advance
I have used the relationship of qin-qout=qstor to find my outlet temperature (where qstor = mdot *cp*(tin-tout)) using k=.045 but I don't see where I would place the k value for the tubing.
I work for a cosmetic lab and it is critical that the tube temperature not fluctuate more than a degree or two over that 5 ft. run. If so, the product begins to separate/solidify/discolor.
The advantage of plastic over steel is cost/flexibility/maintenance. We have to disassemble this line and clean it on a regular basis (weekly). The advantage of SS is that we could place a nozzle heater in-line to overcome the heat loss to the environment.
• Ambient temp is usually 18-20 C
• Fluid temp max is 80 C
• Volumetric flow rate ~ .000095 m^3/s - .000238 m^3/s
Thanks in advance





RE: Stainless Steel vs. Plastic Tubing heat loss calculations
I suggest using a resistance method. (R_conv_in, R_pipe, R_conv_out)
Fe
RE: Stainless Steel vs. Plastic Tubing heat loss calculations
Hi natem84
Have a look at the site below the first link gets you to the main door the second gets you to heat conduction across a tube wall,you don't need the Cp when dealing with this problem.
desertfox
http://www.freestudy.co.uk/home.htm
http:
RE: Stainless Steel vs. Plastic Tubing heat loss calculations
Now the total resistance of the insulation will presumably be way much larger than that of the wall (lower conductivity, higher thickness), so the contribution of k in the tube wall will be negligible. A lower conductivity may be of help in the transition regions (e.g. joints in the insulation), but for an insulation correctly installed the effect should also be negligible. However, as you disassemble the line frequently, the insulation could show up some defects with time.
My gut feeling is that you can choose the material for the tube on the basis of the other criteria, the heat loss won't change appreciably, even with your tight specs.
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes for fun rides
http://www.levitans.com : Air bearing pads
RE: Stainless Steel vs. Plastic Tubing heat loss calculations
RE: Stainless Steel vs. Plastic Tubing heat loss calculations
RE: Stainless Steel vs. Plastic Tubing heat loss calculations