[Bldg-sim] exhaust air liquid heat recovery loop

Chris Yates chris.malcolm.yates at gmail.com
Thu Jan 21 15:09:28 PST 2021


David

I was considering how the exhaust may be dual proposed for heat rejection,
but the idea was having a hard enough time gaining traction. I also
(rightly or wrongly) have a dislike of "changeover modes", preferring
things to work in a much more continuous manner.

Thanks

Chris

On Thu, 21 Jan 2021, 22:15 , <david at 360-analytics.com> wrote:

> There are a number of buildings here in WA State/Seattle that are
> incorporating a central HR chiller and/or heat pumps, and incorporating
> this exhaust air heat recovery coil as part of that design. Primarily
> hospitals and labs, but we have even seen this strategy used in an office
> building that uses a large DOAS. In that case, the coil satisfies our code
> requirement that DOAS systems have energy recovery. That particular
> building also has the ability to change over flow from the chilled water to
> hot water, and reject heat to the exhaust air, expanding the number of
> hours that the HR chiller can be used meet all of the building loads.
>
>
>
> In these cases, we have always just modeled the building in eQUEST or
> EnergyPlus, taken the hourly loads on the loop, and modeled the plant
> outside the program using a big spreadsheet.
>
>
>
> As of 2/1/21, this strategy will be required by in the  WA state energy
> code
> <https://sbcc.wa.gov/sites/default/files/2020-04/2018%20WSEC_C%202nd%20print.pdf>,
> primarily targeted at hospitals (see below a snipet of section the WA
> amendment C403.9.2.4).
>
>
>
>
>
>
>
>
>
>
>
>
>
> *David Reddy P.E.* *he/him/his*
>
> Building Performance Principal
>
>
>
> Tel 206-621-8626 x201
> Cell 206-406-9856
>
> Fax 206-621-8649
>
> O’Brien360 <https://obrien360.com/>⎜710 Second Ave., Suite 925
>
> Seattle, WA 98104
>
> david at obrien360.com
>
>
>
>
>
>
>
>
>
> *From:* Bldg-sim <bldg-sim-bounces at lists.onebuilding.org> *On Behalf Of *Chris
> Yates via Bldg-sim
> *Sent:* Thursday, January 21, 2021 1:27 PM
> *To:* 'Aaron Smith' <asmith at mreng.ca>; 'Fred Betz' <fbetz at aeieng.com>
> *Cc:* bldg-sim at onebuilding.org
> *Subject:* Re: [Bldg-sim] exhaust air liquid heat recovery loop
>
>
>
> Aaron, Fred
>
>
>
> Thanks. This is very helpful. Found the AJ article here:
> https://anthraciteashrae.weebly.com/uploads/2/2/8/5/22852420/hydronic_heat_recovery_in_health_care.pdf
>
>
>
> Cheers
>
>
>
> Chris
>
>
>
> *From:* Aaron Smith <asmith at mreng.ca>
> *Sent:* 21 January 2021 12:18
> *To:* Fred Betz <fbetz at aeieng.com>
> *Cc:* chris.malcolm.yates at gmail.com; David Eldridge <
> DEldridge at grummanbutkus.com>; Jim Dirkes <jvdirkes2 at protonmail.com>;
> bldg-sim at onebuilding.org
> *Subject:* Re: [Bldg-sim] exhaust air liquid heat recovery loop
>
>
>
> Hi Chris,
>
>
>
> I believe the system you you are describing has been utilized in North
> American hospitals. There was an article in the June 2014 edition of ASHRAE
> Journal - Hydronic Heat Recovery in Healthcare - which describes this type
> of system. Refer to the attached schematic from the article. It is also
> mentioned in ASHRAE’s 50% Savings Advanced Energy Design Guide for Large
> Hospitals. I’ve read about it being integrated into a few hospital projects
> since then (subsequent ASHRAE articles) and we are working on some
> ourselves now.
>
>
>
> There is a Canadian AHU manufacturer (AIR) providing this type of system
> as part of a packaged AHU but it loses one of the major benefits of taking
> a larger systems approach which the article describes - where you to
> recover heat from the building exhaust stream (from lights, equipment,
> people, etc) and use that for the largest energy use in a (North American)
> hospital - reheat. The heat recovery chiller should achieve a COP of ~4.0
> year around which is a pretty economical heating source with the side
> benefit of “free” chilled water. I think it provides over 90% of the annual
> heating in the hospital described in the article.
>
>
>
> Hope this helps,
>
> Aaron
>
>
>
>
>
> Aaron Smith, P.Eng
>
> Sent from my mobile
>
>
>
> On Jan 20, 2021, at 11:34, Fred Betz <fbetz at aeieng.com> wrote:
>
> 
>
> Chris,
>
>
>
> This is a similar product that we used in a hospital in Germany that I’m
> told are very common.
>
>
> https://www.flaktgroup.com/en/solutions/maintaining-hygienic-conditions/econot-product-solution/
>
>
> http://resources.flaktwoods.com/Perfion/File.aspx?id=7b7e19a7-0862-4a74-a9cf-97dbe9a120e8
>
>
>
> It’s worth noting in Germany hospitals are 100% outside so they are more
> laboratory like, but in general move less total air than US hospitals.
>
>
>
> I don’t think the FW product is quite as efficient as the Konvekta
> solution, but it’s cheaper.
>
>
>
> [Doing this from memory from ~4 years ago] Per regulations in Germany I
> believe air-side heat recovery effectiveness needs to be above 60% or 65%
> so a standard run around loop won’t achieve that. There’s also regulations
> regarding heat recovered per unit fan energy used so you’re not chewing up
> all your savings with static pressure.
>
>
>
> Not sure how uniform Europeans are on their energy code from country to
> country.
>
>
>
>
>
> AEI has done the system you’re describing in laboratories several years
> back with a field built solution tying in the condenser or evaporator side
> of the heat pump into the run around loop depending on climate and load
> profile. It was pretty effective in places like San Francisco, Washington
> DC, etc. [not extremely hot or cold] so you get more run hours out the RAL
> due to better approach temperatures and can support process cooling or
> reheat. I modeled this in TRNSYS as eQUEST doesn’t bend that way. We
> weren’t really using e+ back then so I didn’t try this configuration in
> that software.
>
>
>
> Getting the controls to work in the field was another matter so there’s a
> lot of benefit to a packaged solution like the ones identified in this
> thread. You can then integrate the heat pump anywhere in the chilled/hot
> water loops (assuming appropriate temperatures) and the heat recovery
> controller will dispatch according to what’s best for the RAL while loading
> the heat pump or heat recovery chiller as needed.
>
>
>
> Hope that helps.
>
>
>
> Fred
>
>
>
>
>
> *Fred Betz *PhD, LEED® AP BD+C
> *Building Performance*
> O: 608-238-2616 / D: 608-236-1175
>
> *Affiliated Engineers, Inc. <https://aeieng.com/>*
> 5802 Research Park Boulevard | Madison, WI 53719
> [image: Image removed by sender. twitter]
> <https://twitter.com/AEITweets?ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Eauthor>[image:
> Image removed by sender. instagram]
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> removed by sender. facebook]
> <https://www.facebook.com/affiliatedengineersinc/>
>
>
>
>
>
> *From:* chris.malcolm.yates at gmail.com <chris.malcolm.yates at gmail.com>
> *Sent:* Tuesday, January 19, 2021 4:16 AM
> *To:* 'David Eldridge' <DEldridge at grummanbutkus.com>; 'Jim Dirkes' <
> jvdirkes2 at protonmail.com>; bldg-sim at onebuilding.org
> *Subject:* Re: [Bldg-sim] exhaust air liquid heat recovery loop
>
>
>
> Hi David,
>
>
>
> Yes. Exactly. Dehum is also a good use-case as well, requiring
> simultaneous cooling and heating – which the heat pump gives.
>
>
>
> At the bottom of https://www.konvekta.ch/network-recovery-systems.html
> “Konvekta uses the DOE-2 building simulation software as a basis to design
> an energy recovery system.”.
>
>
>
> In terms of buildings, I was actually presenting this as a bit of a “blue
> sky” option for some older hospital estates that we’re doing some front end
> strategy work for. Many of the current systems use RAR coils. However, most
> have no heat recovery at all and we’re considering how to retrofit it
> without reworking duct routes to accommodate S&E air-handlers with plate
> heat recovery.
>
>
>
> I’ve seen this kind of system on laboratory jobs more recently, but not in
> hospitals or in a retrofit context.
>
>
>
> Kind regards
>
>
>
> Chris
>
>
>
> *From:* David Eldridge <DEldridge at grummanbutkus.com>
> *Sent:* 19 January 2021 03:06
> *To:* chris.malcolm.yates at gmail.com; 'Jim Dirkes' <
> jvdirkes2 at protonmail.com>; bldg-sim at onebuilding.org
> *Subject:* RE: [Bldg-sim] exhaust air liquid heat recovery loop
>
>
>
> Chris, I’m sorry I didn’t quite understand your scenario before. Something
> like this, except it would be a heat pump to make hot and cold
>
> Integrated Chiller - Konvekta AG
> <https://www.konvekta.ch/integrated-chiller.html>
>
>
>
> We’re primarily seeing the runaround type or plate-and-frame direct heat
> exchange instead of using a heat pump to boost the temperatures, although I
> can see some appeal.
>
>
>
> What type of buildings are you looking at this for?
>
>
>
> David
>
>
>
>
>
> *David S. Eldridge, Jr.**, P**.**E**.**, BEMP, BEAP, HBDP, GGA*
>
> Associate
>
>
>
> Direct: (847) 316-9224 | Mobile: (773) 490-5038
>
>
>
> *Grumman/Butkus Associates* | 820 Davis Street, Suite 300 | Evanston, IL
> 60201
>
> Energy Efficiency Consultants and Sustainable Design Engineers
>
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>
> grummanbutkus.com | Blog <http://grummanbutkus.com/blog> | Facebook
> <https://www.facebook.com/pages/GrummanButkus-Associates/1385285015032526>
> | Twitter <https://twitter.com/grummanbutkus>
>
>
>
> *From:* Bldg-sim <bldg-sim-bounces at lists.onebuilding.org> *On Behalf Of *Chris
> Yates via Bldg-sim
> *Sent:* Monday, January 18, 2021 6:29 AM
> *To:* 'Jim Dirkes' <jvdirkes2 at protonmail.com>
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] exhaust air liquid heat recovery loop
>
>
>
> Hi Jim,
>
>
>
> In a generic sense, this is one of a number of different systems that
> capture exhaust heat via a coil in the exhaust. In the list below I am
> trying to establish if anybody has
>
>
>
> *Similar systems*
>
>
>
>    1. We’ve already seen run-a-round coils described
>    2. Exhaust air heat pumps have been a very common system for
>    residential. They tend to use the refrigerant as the heat transfer medium.
>    Some manufacturers of these units are :
>
>
>    1. https://www.ivprodukt.com/products/home-concept-ecoheater
>       2.
>       https://www.nibe.eu/en-eu/products/heat-pumps/exhaust-air-heat-pumps/NIBE-F750-_-237
>
>
>    1. Supply and extract air handling with integrated heat pump
>    augmenting (straddling) a plate or wheel heat exchanger. They tend to use
>    the refrigerant as the heat transfer medium. Some manufacturers of these
>    units are :
>
>
>    1.
>       https://www.genvex.com/en/products/air-ventilation---air-heat-pump/premium-preheat-500
>       2.
>       https://www.youtube.com/watch?v=hzVOTjH_GIg&feature=emb_logo&ab_channel=Fl%C3%A4ktGroup
>
>
>
> *The system I’m describing*
>
> The heat transfer medium is water or brine (like the RAR coil), but this
> is piped to a compressor remote from the AHU. The attached is a crude
> mock-up of such a system using IDA’s ESBO interface (this has not been
> validated). Apart from a gas boiler for top-up heating, it would be an
> “all-electric” system. Britain and Scandinavia both have relatively low
> carbon electricity now. The fact that recovered heat can be re-used in a
> very general purpose way at a potentially high COP is quite an attractive
> idea. We may even pre-heat service hot water. Note also that the sum of UA
> for all the heaters in the zones will be much bigger than the heater coil’s
> UA in the AHU itself (meaning supplied heat can be a lower grade). It may
> also remove some of the perceived penalties of reheat (i.e. heat pumps
> simultaneously make both cold and heat).
>
>
>
> I’m searching for an appropriate quote…
>
>
>
> *There are two major products that came out of Berkeley: LSD and UNIX. We
> don't believe this to be a coincidence.*
>
>
>
> Cheers
>
>
>
> Chris
>
>
>
> *From:* Jim Dirkes <jvdirkes2 at protonmail.com>
> *Sent:* 15 January 2021 21:44
> *To:* chris.malcolm.yates at gmail.com
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] exhaust air liquid heat recovery loop
>
>
>
> 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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