Hi Jean,
I think, the solar collector do not define itself as a primary/secondary system, unless you think that the instantaneous tank is the secondary system.
For a large HVAC system, it is usually divided into two or more systems in various sections of the installation.
I think the large and small chillers in EPlus is the one you are talking about. Use the priority to schedule the operation. The large one should have variable speed to reduce maximum demand charges.
In fact all large systems should be designed that way. A air to air heatpump for the transition period of a water to air system.
This is my own thinking not based on ASHRAE guidelines, because I do not have the ASHRAE document..
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Tue, 25 Oct 2011 11:40:24 +0000
Subject: Re:[EnergyPlus_Support] Re: How to model the primary/secondary pump system
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I think, the solar collector do not define itself as a primary/secondary system, unless you think that the instantaneous tank is the secondary system.
For a large HVAC system, it is usually divided into two or more systems in various sections of the installation.
I think the large and small chillers in EPlus is the one you are talking about. Use the priority to schedule the operation. The large one should have variable speed to reduce maximum demand charges.
In fact all large systems should be designed that way. A air to air heatpump for the transition period of a water to air system.
This is my own thinking not based on ASHRAE guidelines, because I do not have the ASHRAE document..
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Tue, 25 Oct 2011 11:40:24 +0000
Subject: Re:[EnergyPlus_Support] Re: How to model the primary/secondary pump system
From Dr Li:
"Look at an example file for the solar collector.
SolarCollectorFlatPlateWater.idf with .rvi
Then use the template to model the baseboard system.
HVACTemplate:Thermostat and HVACTemplate:Zone:Unitary with a hot water baseboard heater in the zone. This should be expended to a zone loop with a boiler tank. Use the code lines in the expIDF for the HW loop for pasting into the final IDF.
The solar collecter to the storage tank would heat the water in the storage tank. Use this tank as the interface between the two loops.
I.e. cut the solar collector loop at the storage tank and connet the use side of the tank as the supply to your zone baseboar branches.
No template model should be in the final IDF. All the unused branches and schedules for the domestic HW use should be removed.
Dr. Li "
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, é?©æ?? <foolishstar@...> wrote:
>
> Thanks Jean, I also saw your reply in the DB forum.
> However, I didn't find the water tank object. I cannot figure out the schematic flow of the primary/secondary pump system using a water tank either.
> Dr. Li, can you give us a hand?
>
>
>
> At 2011-10-25 12:34:34,"Jean marais" <jeannieboef@...> wrote:
>
>
>
> Excellent question. I would also love to know, especially if primary and secondary loops have different temperatures. E.g. it's common to feed 50degC water from a secondary loop into a radiant system, but 80 degC water to the AHU heating coil.
>
> Dr. Li proposed to use the water tank object. I've not looked at it. If it has 4 ports, and a temperature setpoint set lower than the primary loop, I would hope that the two connections to the primary loop will only circulate to maintain this setpoint. In theory I can see this working. In practice, I've not tried it or investigated, but it's on my to-do list.
>
> The last time I had this problem, I figured to send the AHU coil water at 40 degC, and blindly hoped that it would extract the required energy by simply increasing the coil surface area (tube length) indefinately large.
>
> --- InEnergyPlus_Support@xxxxxxxxxxxxxxx, º«�� <foolishstar@> wrote:
> >
> > According to the requirement of 90.1, chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed driveds on the secondary pumping loop.
> > I wonder how to model the primary/secondary system in E+. Is there any example file?
> > Thanks!
> >
>
> --- InEnergyPlus_Support@xxxxxxxxxxxxxxx, º«�� <foolishstar@> wrote:
> >
> > According to the requirement of 90.1, chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed driveds on the secondary pumping loop.
> > I wonder how to model the primary/secondary system in E+. Is there any example file?
> > Thanks!
> >
>
"Look at an example file for the solar collector.
SolarCollectorFlatPlateWater.idf with .rvi
Then use the template to model the baseboard system.
HVACTemplate:Thermostat and HVACTemplate:Zone:Unitary with a hot water baseboard heater in the zone. This should be expended to a zone loop with a boiler tank. Use the code lines in the expIDF for the HW loop for pasting into the final IDF.
The solar collecter to the storage tank would heat the water in the storage tank. Use this tank as the interface between the two loops.
I.e. cut the solar collector loop at the storage tank and connet the use side of the tank as the supply to your zone baseboar branches.
No template model should be in the final IDF. All the unused branches and schedules for the domestic HW use should be removed.
Dr. Li "
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, é?©æ?? <foolishstar@...> wrote:
>
> Thanks Jean, I also saw your reply in the DB forum.
> However, I didn't find the water tank object. I cannot figure out the schematic flow of the primary/secondary pump system using a water tank either.
> Dr. Li, can you give us a hand?
>
>
>
> At 2011-10-25 12:34:34,"Jean marais" <jeannieboef@...> wrote:
>
>
>
> Excellent question. I would also love to know, especially if primary and secondary loops have different temperatures. E.g. it's common to feed 50degC water from a secondary loop into a radiant system, but 80 degC water to the AHU heating coil.
>
> Dr. Li proposed to use the water tank object. I've not looked at it. If it has 4 ports, and a temperature setpoint set lower than the primary loop, I would hope that the two connections to the primary loop will only circulate to maintain this setpoint. In theory I can see this working. In practice, I've not tried it or investigated, but it's on my to-do list.
>
> The last time I had this problem, I figured to send the AHU coil water at 40 degC, and blindly hoped that it would extract the required energy by simply increasing the coil surface area (tube length) indefinately large.
>
> --- InEnergyPlus_Support@xxxxxxxxxxxxxxx, º«�� <foolishstar@> wrote:
> >
> > According to the requirement of 90.1, chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed driveds on the secondary pumping loop.
> > I wonder how to model the primary/secondary system in E+. Is there any example file?
> > Thanks!
> >
>
> --- InEnergyPlus_Support@xxxxxxxxxxxxxxx, º«�� <foolishstar@> wrote:
> >
> > According to the requirement of 90.1, chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed driveds on the secondary pumping loop.
> > I wonder how to model the primary/secondary system in E+. Is there any example file?
> > Thanks!
> >
>
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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