×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

The power required for heating a circulating fluid

The power required for heating a circulating fluid

The power required for heating a circulating fluid

(OP)
the equation to use to work out the power required for heating a circulating fluid:
Pch = (Qm × Cp ×(t2 − t1) × 1,2) ÷ 860
-Heating power : Pch (kW)
– Mass flow rate : Qm (kg/h)
– Specific heat of fluid : Cp (kcal/kg × °C)
– Inlet temperature : t1 (°C)
– Required outlet temperature : t2 (°C)
– 1,2 : Safety coefficient linked to our manufacturing tolerances and variations in network power

however the system im using is a closed loop so whatever leaves t2 will come back into t1 therefore my t1 temperature will always be changing so how would i calculate it with the constant change ?

any ideas will be helpful

RE: The power required for heating a circulating fluid

Your delta T should be the average temperature of your fluid vs. the average temperature of the ambient to which it loses heat. THAT is the steady state case.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The power required for heating a circulating fluid

Well power in watts ( joules /second) needs a mass flow rate in hour to be divided by 3600, not 860

If you're talking about heating up then you need to use a transient program or do this in a series of small steps.

As noted in your previous post Cp changes with temperature.

This is a transient event with many things changing as the temperature rises (including any heat losses in your circuit). It is not possible to find a simple equation which can calculate this.

If you do the bulk energy method and then divide by a factor of 1.5 you won't be far away providing you heat losses aren't too big.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: The power required for heating a circulating fluid

(OP)
ok thank you
why would i need to divide the bulk energy by a factor of 1.5?

Also when calculating a object heating up time do i factor in the heat loss which will increase the time or would i put a tolerence of +/- a suitable number to make up for the heat loss ?

RE: The power required for heating a circulating fluid

The 860 is because they have kCal/kgC for the specific heat but power is in kW. 3600 / 4.184 = 860.

"Also when calculating a object heating up time do i factor in the heat loss which will increase the time or would i put a tolerence of +/- a suitable number to make up for the heat loss ?
"

If you are heating it up to ambient? Heat loss will be quite small. Heating it up to 500 degC? A lot more heat loss to ambient...

RE: The power required for heating a circulating fluid

You should be able to design the system so that a pump is not needed, and you would use gravity to cause the heated fluid to circulate "naturally". You would need to know how the fluid's density changes with temperature, and the other physical properties needed to calculate the fluid friction etc.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close