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

Re-purposing heat exchanger coil in thermal store

Re-purposing heat exchanger coil in thermal store

Re-purposing heat exchanger coil in thermal store


I hope this post finds fertile ground and someone here can help a relative layman with a very simple, real-world project.

I have a domestic water filled thermal store. I want to add an air-source heat pump to the energy sources feeding into the store. There is a simple coiled tube heat exchanger coil in the lower portion of the store, originally intended to connect to some form of solar hot water system. I have some guide spec's for the heat exchanger, but no graphs or anything to show me how it performs over a range of conditions.

The simplistic data I have states that the coil is rated at 14.6kw based on a flow rate in the coil of 18 litres / min at 80 deg C. The lower parts of the store in which the coil sits would typically be between 20 and 40 deg C. The water in the store could have minimal turbulance (the store quite readily stratifies) or have quite a lot of turbulance when recuirculating pumps are running.

It it possible to get any meaningful indication of the possible performance of the heat exchanger by working backwards from those figures, and adding in some real-world knowledge of how these systems often behave in reality? My approach will have to be to build a test rig and try it out for real (because that's what I can do, and all that matters if if it will do what I want or not) but it would be a huge help if someone could tell me if I'm even in the right ball park or not.

My objective is to have a heat pump that can deliver between 4 and 6 kw into the store. Less than that and it's not really worth the trouble. The heat pump I am looking at has a flow rate of around 2 cubic metres per hour and delivers water / glycol at 35 to 60 deg C.

Thanks for any guidance.

RE: Re-purposing heat exchanger coil in thermal store

What is the coil made of?
You want to at or near the 18 lpm flow. Do you have a pressure drop at that flow?
You would need that in order to make sure that it sizes with your pump.
As the temp difference goes down so will the heat transfer.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

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


White Paper - Reshoring Prototyping and Production
In this whitepaper, we'll provide insight into why and when it makes sense for U.S. manufacturers to reshore prototyping and production, and how companies can leverage the benefits of working with local design, prototype, and manufacturing partners during the pandemic and beyond. Download Now
Engineering Report - Top 10 Defect Types in Production
This 22-page report from Instrumental identifies the most common production defect types discovered in 2020, showcases trends from 2019 to 2020, and provides insights on how to prevent potential downtime in 2021. Unlike other methods, Instrumental drives correlations between a variety of data sources to help engineers find and fix root causes. Download Now
White Paper - Addressing Tooling and Casting Requirements at the Design Stage
Several of the tooling and casting requirements of a part can be addressed at the design stage. If these requirements are not addressed at the design stage, lot of time is spent in design iteration when the design reaches the die caster. These design issues lead to increase in time and cost of production leading to delay in time to market and reduced profits for the organization. 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