Thank you for your information, Dr.Li.
I think I need some basic understanding of the rules of EP HVAC system input.
Now I have got that the pump should be the first branch in supply side.
Let me explain my problem one by one so that you could help me cracking them.
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The hvac system in this case is not a good one, but it's a real system already in operation that I have to simulate.
If you are simulating a real system, you should mention the duct, diffusers, etc. I am sure you are using two big fans for the whole floors, blowing in from one corner.
The original envelop is downloaded from somebody else's case without any hvac input. That is an DesignBuilder output exactly. I added hvac component to the original file and developed my idf file. I haven't used any templates.
If this is your first EPlus simulatioon, you should try the template, You are doing quite well without it.
I do not intend to have 3 air loops in one zone. Just OAU sys and AHU sys. The exh fan is designed for the OAU. The input of OutdooeAirUnit asks for an exhaust fan. Is the OutdoorAirUnit and Exhaust fan input correct? I am not clear how to set the exhaust air node. The OutdoorAirUnit input do not asks for exh. air node, but the ZoneHvac:EquipmentConnection needs an exhaust air node. And the fan object also should have inlet and outlet air node. I think the ZoneHvac:EquipConnection object is not related to the OutdoorAirUnit. So how to relate the fans to the oau and the zone?
The OA mixer box may be connected to either the OAU or the AHU. If you are not using separate ducts to feed the fresh air, OAU is not required.
Move the OA mixer box to the main branch of the air loop. Because you do not have duct to feed other zones, the thermostat for the zone can be used to control the AHU.
Therefore all those setpoint manager/controllers for the OAU are not required.
The fresh air inlet is the inlet of the OA mixer, and this is the actuator node of the OA box. If you wanted to have variable OA intake, a controller need to be used to calculate the air flow in accordance to a schedule.
Because the AHU is defined as a system, an ATU is needed to feed the Zone. The zone return air or exhaust air node would be connected to the return air node of the OA mixer box. It is not necessry to provide an exhaust fan, because the relief node of the OA box will send air out to balance the intake volume.
The OA intake can be zero. 100% of the zone return air is circulated.
The OA intake equals to the fan volume, 100% OA is fed to the zone. All zone return air would leave the OA relief node.
By the way the Fig93 ( OutdoorAirUnit) of Input Output Reference is something wrong in the four nodes caption. The node numbering are wrong.
And should the outdoor air unit branches stated in the NodeBranchManagement object? I think it's not necessary. You need to insert the OA mixer as a component in the main branch. A conponent in the system equipment list. In the connection, the mixed air node should be connect to the coil or fan, in the correct sequence. The zone return ai would be connected to the air loop inlet and the return air node of the OA box. The air loop supply and air loop demand nodes are duplicated, I think, in a primary loop object.
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For the thermostat and controller, I have two coils in each AHU, one heating and one cooling. They both respond to the zone return air temperature. If I set two setpoint manager for the two coils the reference the same setpoint node: RA Node, there are errors then. But if I delete one setpoint (ie heating coil), errors asking for an setpoint appears. You have not declared that the AHU is the zone equipmet (four pipe fan coil unit) It is still a system equipment. But because you onlyhave one zone, this is not clear. There is field in the AHU for you to declare the theremostat location.
If this field is not present, then you may be using a different object which is set point controlled.
What confused me much is that the ZoneEquipment is an Uncontrolled object (AirTerminal:SingleDuct:Uncontrolled), and how the thermostat could respond and control. So I think the thermostat is not necessary in this case. Just controllers are enough.? This ATU does not require thermostat control. The first listed zone with this ATU gives up the thermostat to the system AHU. This is know as the master zone and will have the zone temperature controlled to the thermostat value. All the other zone, if available, will have HVAC proportional to the damper setting.
In your case, only one damper, the damper setting would be one. All the fan volume flow to this zone.
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I agree with you in the performance and simulation of The absorption chiller heater. Dividing into one chiller and one boiler should have the same performance.
What I do not understand is that point in your email " In fact, if the chiller is entered in two places, all the branches will be in correct order." What do you mean by "entered in two places"
In your schematic, the absorption chiller has three sections. CW loop, HW loop and Condenser loop. In fact there are only two loops, hot and cold.