Re: [TRNSYS-users] issue with active layer

To: TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>

Subject: Re: [TRNSYS-users] issue with active layer

From: Toni Calabrese <toni.calabrese@ost.ch>

Date: Mon, 5 Dec 2022 14:49:33 +0000

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Thread-topic: [TRNSYS-users] issue with active layer

Hi,

if I understood correctly your problem, maybe I can help you. With the modelling of an active layer, you can have a mass flow rate of zero during the simulation because this is not a problem. The only limit is that the mass flow rate through the active layer during the simulation can not be lower than this minimum allowed mass flow rate. If you get an error about the mass flow rate through this active layer, the only reason could be that the temperature of the room is controlled through a thermostat that allows the reduction of the mass flow rate to a value lower than the minimum allowed. This is not possible and that's why you get an error.

So what I can suggest you is to use a simple On/Off controller that allows you to have or not to have a mass flow rate through the active layer. You can control the temperature of the room through this controller. Be careful that the specified nominal mass flow rate through the active layer need to be higher than the minimum allowed.

As I told you, the problem is not if the mass flow is zero, but if 0 < mass flow < min. allowed. I hope everything is clear now.

Toni Calabrese, MSc.

Wissenschaftlicher Projektleiter

toni.calabrese@spf.ch | toni.calabrese@ost.ch

T +41 58 257 4827

SPF Institut für Solartechnik

OST – Ostschweizer Fachhochschule

Oberseestr. 10 | CH-8640 Rapperswil | Switzerland | www.spf.ch | www.ost.ch

From: TRNSYS-users <trnsys-users-bounces@lists.onebuilding.org> On Behalf Of Amirreza Heidari via TRNSYS-users
Sent: Saturday, December 3, 2022 3:43 PM
To: TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>
Cc: Amirreza Heidari <amirrezaheidarysbu@gmail.com>
Subject: [TRNSYS-users] issue with active layer

Hello,

I am trying to model a multi-floor building with Ceiling heating. The temperature of each floor is controlled by a thermostat, that closes inlet valve when indoor temperature reaches a specific level. But I have a problem to model this control, because as you see in the picture below there is a "min. allowed inlet mass flowrate" . So if the valve closes the inlet water I receive an error that flowrate is below the level.

How can I design it in a way that the inlet flowrate can be zero sometimes?
Also my other question is about the surfaces section also shown in the picture below. I do not know why two CEILINGs appeared there, and I cannot delete them.

Thank you

References:

[TRNSYS-users] issue with active layer
- From: Amirreza Heidari <amirrezaheidarysbu@gmail.com>