[TRNSYS-users] TRNSYS-users Digest, Vol 157, Issue 3

Sat Jan 6 06:21:29 PST 2018

Ok, I need to do some study on the standards then. Thanks!

Javier

2018-01-05 21:15 GMT-03:00 <trnsys-users-request at lists.onebuilding.org>:

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> Today's Topics:
>
>    1. Radiant barrier (Ilyas Ismaili)
>    2. Doubt on the codes of some TESS Unglazed collector models
>       (Javier Vega)
>    3. Re: Doubt on the codes of some TESS Unglazed collector models
>       (Jeff Thornton)
>    4. trnsys-greenhouse (azeddine fantasse)
>
>
> ---------- Mensaje reenviado ----------
> From: Ilyas Ismaili <karaktus at gmail.com>
> To: "TRNSYS users mailing list at OneBuilding.org" <
> trnsys-users at lists.onebuilding.org>, d.bradley at tess-inc.com
> Cc:
> Bcc:
> Date: Fri, 5 Jan 2018 20:25:50 +0000
> Subject: [TRNSYS-users] Radiant barrier
> Dear TRNSYS users,
> I'm trying to model a radiant barrier in the roof of a building, so I put
> a 10cm airgap into the external roof layers, and I set the back absorptance
> of the roof to 0.05 (since radiant barrier can achieve up to 95% heat
> reduction, correct me if this value is wrong).
> Is this modelling correct, or there is another way to do it?
> Regards,
>
>
>
> ‌
>
>
> ---------- Mensaje reenviado ----------
> From: Javier Vega <jvega025 at gmail.com>
> To: trnsys-users at lists.onebuilding.org
> Cc:
> Bcc:
> Date: Fri, 5 Jan 2018 17:45:34 -0300
> Subject: [TRNSYS-users] Doubt on the codes of some TESS Unglazed collector
> models
> Hi TRNSYS users,
>
> I was just checking the codes of Type 553 and Type 1290 (Unglazed Solar
> Collector models) and something grabbed my attention. When both models do
> the Net Long Wave Radiation Balance, they do the following:
>
> !Account for the long wave losses from the collector surface
>  T_ambient_K = T_ambient+273.15
>  T_sky_K = T_sky+273.15
>  Sigma = 3.6*5.67d-08   !Stefan Boltmann constant
>  Net_Longwave = Sigma*(T_ambient_K**4.-T_sky_K**4.)*Emissivity/Absorptance
>
> That is a copy/paste of Type 553.
>
>
>
> Why the Net Long Wave is defined with the Ambient Temperature and not with
> the Collector  Average Temperature? It doesn't make sense to me. Is there
> something I'm uderstanding wrong?
>
> Bests of wishes,
>
> Javier Vega Benavente
> Universidad de Concepción, Chile.
>
>
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>
> ---------- Mensaje reenviado ----------
> From: Jeff Thornton <thornton at tess-inc.com>
> To: "TRNSYS users mailing list at OneBuilding.org" <
> trnsys-users at lists.onebuilding.org>
> Cc:
> Bcc:
> Date: Fri, 05 Jan 2018 15:08:17 -0600
> Subject: Re: [TRNSYS-users] Doubt on the codes of some TESS Unglazed
> collector models
>
> Javier,
>
> It's the net long wave radiation on the collector surface - not the long
> wave radiation from the collector surface to the sky.  It's taken directly
> from the standards for modeling un-glazed solar collectors.
>
>
>
> Jeff
>
>
>
> ---
> Jeff Thornton
> President - TESS LLC
> 22 N. Carroll Street, Madison WI USA 53703
> Office: (608) 274-2577  Fax: (608) 278-1475www.tess-inc.com
> E-Mail: thornton at tess-inc.com
>
> On 01/05/2018 2:45 pm, Javier Vega via TRNSYS-users wrote:
>
> Hi TRNSYS users,
>
> I was just checking the codes of Type 553 and Type 1290 (Unglazed Solar
> Collector models) and something grabbed my attention. When both models do
> the Net Long Wave Radiation Balance, they do the following:
>
> !Account for the long wave losses from the collector surface
>  T_ambient_K = T_ambient+273.15
>  T_sky_K = T_sky+273.15
>  Sigma = 3.6*5.67d-08   !Stefan Boltmann constant
>  Net_Longwave = Sigma*(T_ambient_K**4.-T_sky_K**4.)*Emissivity/Absorptance
>
> That is a copy/paste of Type 553.
>
>
>
> Why the Net Long Wave is defined with the Ambient Temperature and not with
> the Collector  Average Temperature? It doesn't make sense to me. Is there
> something I'm uderstanding wrong?
>
> Bests of wishes,
>
> Javier Vega Benavente
> Universidad de Concepción, Chile.
>
>
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Libre
> de virus. www.avast.com
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
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>
>
> ---------- Mensaje reenviado ----------
> From: azeddine fantasse <azeddinefantasse at gmail.com>
> To: trnsys-users at lists.onebuilding.org, d.bradley at tess-inc.com,
> thornton at tess-inc.com
> Cc:
> Bcc:
> Date: Fri, 5 Jan 2018 21:26:17 +0000
> Subject: [TRNSYS-users] trnsys-greenhouse
> hello Ms bradley i want to ask you if i can find a type of greenhouse in
> trnsys?
> if not i would like the mean for this.
> thanxs
> Cordialement
>
> Azeddine FANTASSE
> Doctorant en Sciences Physique et Ingenieurie
> Faculté des Sciences Samlalia
> Université Cadi Ayyad , Marrakech
> Mail : *azeddinefantasse at gmail.com <azeddinefantasse at gmail.com>*
> Tel : 06 35 74 41 33
>
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