Re: [TRNSYS-users] Type 941(Air to water heat pump)

Dear David,

Thanks for your rapid reply. As you said, I turned off the automatic heating and cooling. I can see the temperature of the zone is floating. I also used a second stage thermostat (type 1503) and adjust the high and low stage temperatures.

However, it does not change although the temperature floats between 19 °C and 30 C°.

Regards.

HG Ozcan

From: David BRADLEY <d.bradley@tess-inc.com>
Sent: Friday, March 27, 2020 3:12 PM
To: Hüseyin Günhan Özcan <huseyin.ozcan@yasar.edu.tr>; TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>
Cc: Muhammad Zeeshan <zeeshanmuhammad922@gmail.com>
Subject: Re: [TRNSYS-users] Type 941(Air to water heat pump)

Hüseyin

This may seem very basic but make sure that you have turned off the automatic heating and cooling in TRNBuild so that the temperature of your zone is floating. You can verify this by running your simulation; the zone temperature should more or less follow the ambient temperature. You will then implement a thermostat to watch the zone temperature and turn on/off the heat pump accordingly.

If that is what you are doing already and the power and capacity of the heat pump is not changing at all then it must mean that neither the return air temperature nor the water inlet temperature is changing at all. It could also mean that the return air temperature and inlet water temperature are outside the range of data values given in the data file. The routine that reads the data file and interpolate within the range but cannot extrapolate beyond the range given.

kind regards,

David

On 03/27/2020 09:29, Hüseyin Günhan Özcan wrote:

Dear all,

I have a similar question about modeling air source heat pump.

In my case I am working the model inverter heat pump so I selected the multi stage heat pump (Type 922c).

Meanwhile, I connected its return temperature value to the Type 56 indoor temperature (I am following a single room) and I also use Type 15-6 for outdoor conditions. Although I make some changes in the building file (internal heat gain, regimes, etc.) and weather data the model shows always the same values.

Therefore, I realized that it only works based on external catalogue values. But, it does not make sense. Do you have an idea about this case ? How can type 922c operates based on temperature variations belongs to the building.

Another question is how can I change the catalogue values ? (I have no problem in proforma including parameter, input and output parts).

Thanks in advance.

Huseyin Gunhan Ozcan

Visiting Researcher

Porto Uni., Dept. of Mech. Eng.

From: TRNSYS-users <trnsys-users-bounces@lists.onebuilding.org> On Behalf Of David BRADLEY via TRNSYS-users
Sent: Friday, March 27, 2020 1:45 PM
To: TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>
Cc: David BRADLEY <d.bradley@tess-inc.com>; Muhammad Zeeshan <zeeshanmuhammad922@gmail.com>
Subject: Re: [TRNSYS-users] Type 941(Air to water heat pump)

Muhammad,

Please refer to the Type941 documentation. It explains how the external files and the parameters relate to each other to compute the overall capacity and power consumption of the heat pump.

The evaporator does not really need to be designed more than to choose a machine with an appropriate rated capacity. Traditionally that might mean adding a safety factor to the peak cooling load (10% is often used) and then selecting a machine that will meet that capacity. Also bear in mind that Type941 models a single speed (ie single capacity) heat pump that is either on or off. Depending on how variable the load in your building it, you might want to meet that load with multiple smaller heat pumps rather than one big one.

kind regards,

David

On 03/27/2020 08:02, Muhammad Zeeshan via TRNSYS-users wrote:
Hello Everyone,

I am working on cooling a building with type 41(air to water source heat pump). The cooling load of the building is 25 tons. I want to know

1)- how the compressor power will be calculated? as the external files of type 941 contains fractions of compressor power which shows no link to the equations provided in manual. How to link the external file with the provided equations?

2)-As the cooling load of the building is 25 tons, how to design the evaporator for this building load?

Your help in this regard will be highly appreciated.

Regards,

Muhammad Zeeshan
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David BRADLEY
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Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
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David BRADLEY

Principal

Thermal Energy Systems Specialists, LLC

3 North Pinckney Street - suite 202

Madison, WI  53703 USA

P:+1.608.274.2577

F:+1.608.278.1475

d.bradley@tess-inc.com

http://www.tess-inc.com

http://www.trnsys.com