×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Calculations for Flex Heater

Calculations for Flex Heater

Calculations for Flex Heater

(OP)
I am working on integrating a flexible heater into a design that currently houses Pyrex test tubes.  The idea is to pre-heat the samples before they enter the measurement chamber.

I have carried out the Overall Heat Transfer Coefficient calcs to determine what that would be.  Now I am kind of stuck.  What do I need to do to be able to determine what the correct sizing would be for the heater (they are being rated as X W/in^s) and how long it will take to raise the sample from room temp to 70 deg C?

thanks for any help

Jay

RE: Calculations for Flex Heater

You need to know the amount of Joule heat required, i.e., thermal_mass * delta_temp, and the actual heat flow, which you claimed to have done.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: Calculations for Flex Heater

(OP)
thanks,  I now have the Joule heat required and the heat flow of the system.

I'm sure there is a calculation relating heat required and heat flow I just can't seem to remember/find it.

Can I just multiply the heat flow by time and have the output be how much heat has been transferred to the system in that time frame?  I could then set Q = (heat flow)*(time) to determine how long it will take to get up to temp.

 

RE: Calculations for Flex Heater

Joule_heat/heat_flow = time

This gives you the absolute minimum possible time to achieve the end result.  However, for any bulk process, there are thermal conductivities not accounted for here.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources