OpenStudio - Create Central Plant Systems

In this video, we will show how to create steam and water loop systems using the district heating and cooling objects. We will also discuss fluid to fluid heat exchangers and how to connect equipment between loops. Transcript: The first task: We have to install some of the central plant loops. This building is served by a central steam system.   We have to create a central steam system plant loop. Go to the plus button at the top.   Let us scroll down to empty plant loop. Add to model.   I should note: OpenStudio does not support steam, although EnergyPlus does.  We are going to get around that by just increasing the system operating temperature. It will throw some errors when we run the simulation, but it should not cause a severe error. It will just be a warning saying that we are using too hot of a temperature for the loop. To start our loop we will install a pump. Go over to the library tab, let us input a variable speed pump.   Just drag and drop the variable speed pump over here. We can select this.   Once again, this is a steam system so we don't actually have a circulating pump.   In order to get around that we can just put the rated pump head at zero.   That way this pump will not use energy during the simulation. So, we will not have a pump energy penalty because of course the system is steam.  The rest of the stuff we can leave at auto-sized. This this should not matter. We will do "intermittent" for this pump. It does not matter since we are not going to have a penalty for this pump. Because this is a steam system. Next, we want to install a district system. You can use district heating or district cooling systems when you do not want to go through the trouble of sizing a boiler system and distribution piping and all that stuff. The district systems mean that they have unlimited capacity. Although, you can hard size the capacity.  With auto-size it basically means they will have unlimited capacity for heating or cooling. Now, we need to install an adiabatic pipe. Let us see. We need to go to pipe, adiabatic.   If you do have pipes that have interior or exterior heat losses, you can install those. But, for the most part, I do not worry about those unless there are significant pipe heat losses  on your system. We will install an adiabatic bypass pipe on here. Again, this is a steam system, so it it really should not matter. Anytime you create a loop, and specifically if you have a constant volume system, you must have a bypass pipe or duct. This is for when your boiler or chiller or VAV boxes are not operating. If you have a constant volume pump or fan, it can bypass around. If you have a variable speed pump or fan, generally, you do not need those bypasses. But, we will put that in here anyway.   Next, we want to create a setpoint manager. We will selecte a SetpointManager:Scheduled. Scheduled hot water temperature. We should probably rename these. District steam heating. Scheduled steam temperature. You can see that it dragged in a schedule for us called "hot water temperature". We need to go up to the schedules tab and rename that and adjust to steam temperature. I believe it is about 240 fahrenheit. I cannot remember what  the steam pressure for that is. We will go back to the HVAC systems tab. Go to plant loop one. Look at the set point manager. Now the schedule's name is steam temperature. We will call this steam loop. We will just leave this as water. We do not want to make things worse on the error outputs. This maximum loop temperature: 240 fahrenheit. We can leave the rest of this stuff as default. This building has a steam to hot water heat exchanger on it. We will put the heat exchanger on the demand side of this loop. Go down to heat exchanger. Were is that fluid-to-fluid...we can put that in here.   Same thing with the bypass pipe. Now we have our fluid to fluid heat exchanger. We can call this "steam to water heat exchanger".   Most of the stuff we can leave as auto sized unless you know specifically what size it is.   For the model type, again, you can choose what type of heat exchanger you have. We will just leave it as ideal for now. Like I said in previous videos, if you want to find out more about these components you can go into the EnergyPlus input output reference. You can look up HeatExchanger:FluidToFluid and read all about it. Type in HeatExchanger:FluidToFluid and then search for the item in the EnergyPlus input output reference. You can read about all of the inputs and outputs for this particular object.   We can leave these as auto sized for control type. We will choose "heating set point modulated" because we are going to be modulating the steam to control our heating water temperature. This is the temperature difference to activate the heat exchanger. It is the temperature difference across the heat exchanger that allows the heat exchanger to operate. … Full Transcript: https://www.helix-engineers.net/technical-articles