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EMS - Controlling condenser supply outlet node

asked 2016-07-02 02:31:14 -0500

nielex's avatar

updated 2016-07-02 02:36:27 -0500

I tried to use a EMS program to control the condenser supply outlet node. There should be two essential operation conditions: HX ON (1 = active) and HX off (0 = not active). The concept is, that for the request if the HX is active or not active the "Fluid Heat Exchanger Operation Status" should be used. The operation status shows also interim values between 0 and 1. Based on the operation condition I would set the setpoint. I tested the following program and found out that when the operation status reached "HXStatus" = 0 it is not possible to get back (when a change could be happens to HX=ON, a change of the OutdoorTemp from high to low). It seems to be that the command "SET CondLoopTempSched = 20" will be always executed. With the command "SET CondLoopTempSched = OutdoorTemp" in the first programm line I wanted to stop this case. But I think the problem is, that the "Fluid Heat Exchanger Operation Status" couldn't have some changes within the EMS program. So currently I have no concept to save this problem.

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answered 2016-07-05 14:51:55 -0500

Archmage's avatar

Those interim values between 0.0 and 1.0 are because of hourly reporting. You want to use Detailed Reporting Frequency to see the raw values without any time averaging.

I would try the calling point InsideHVACSystemIterationLoop. What you have here is going to be lagged. It will set the setpoint schedule according to conditions at the end of the previous zone timestep, but the HX status could be different during the current timestep. That might be why it seems to get stuck.

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I'am using "DesignBuilder Results Viewer" to read eso files. It is not possible to use detailed reporting frequency (using timestep is possible). With xEsoView I have also some troubles to work properly (stability). So what's your preferred method to read and analyse eso files?

However using InsideHVACSystemIterationLoop didn' t change the behavior, it get stuck.

nielex's avatar nielex  ( 2016-07-13 09:51:52 -0500 )edit

@Chandan Sharma: Maybe you have an idea or an approach to solve the problem?

nielex's avatar nielex  ( 2016-07-26 05:08:53 -0500 )edit

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Asked: 2016-07-02 02:31:14 -0500

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Last updated: Jul 05 '16