[Bldg-sim] exhaust air liquid heat recovery loop

[Jim Dirkes]

Chris,
I don't think I understand the system....
That clearly means it's not something common for my portion of the world!
On the other hand, it sounds no different than energy recovery - can you clarify a bit, please?

… The world is having a crisis of reason. I don’t think the world is having a crisis of faith. If anything, there is plenty of faith around, in both good and bad things. In some ways, there is altogether too much faith, and too little reason.

Jim Dirkes 1631 Acacia Drive NW Grand Rapids, MI 616 450 8653

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, January 15, 2021 8:39 AM, Chris Yates via Bldg-sim <bldg-sim at lists.onebuilding.org> wrote:

> Hi all,
>
> I will resist the temptation to say “happy” new year. Perhaps, for 2021, the expression “moderately relieved” new year is more appropriate (it’s certainly more British). I hope as many of you as possible have avoided covid. I know there are some members of this list who have not been so fortunate. God speed your recovery.
>
> In IDA ICE, there is an option to model a liquid heat recovery loop in the exhaust of an air handling unit (image attached). In essence, this is just putting a cooling coil in the exhaust. Heating, including heat recovery, is after all as much a cooling process as it is a heating process. This cooling coil can then integrate with some form of heat recovery/ reversible chiller – a bit like a run-a-round coil heat recovery on steroids!
>
> This works in theory. However, I was just wondering how prevalent it is in practice. Would I be naïve to present this as an option to clients? I know I’ve not come across this in the UK. Is it just a Scandinavian thing?
>
> I’d be very grateful to hear of any projects that have successfully (or unsuccessfully!) integrated heat recovery via exhaust air liquid loops.
>
> It seems to me that the benefits could be manifold:
>
> - “decoupling”: Heat recovery potential increases as the building gets warm, but with traditional plate or thermal wheel heat recovery the demand for it simultaneously decreases. By buffering the heat to water, or re-directing it elsewhere (e.g. SHW) heat recovery becomes more general purpose.
> - A useful load for the chiller during periods of low chiller load. There are well understood problems with chillers cycling on/off during periods of low load – aka “low delta T syndrowm”. By dual purposing chiller equipment for heat recovery, it provides a stable baseload for chillers during these periods.
>
> Kind regards
>
> Chris
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