I have a problem with sizing Coil:Cooling:Water. My model is a data center with single conditoned zone. A Coil:Cooling:Water object is located in an airloop with Fan:Variable:Volume and AirTerminal:SingleDuct:VAV:NoReheat. The thermostat setpoint is 40ºC, and the suppy air temperature setpoint is 23ºC throughout the year.
There is no latent load in the conditioned zone because there are no fresh air supply, no infiltration, and no people. However, the sizing result in the sumary report shows that the cooling coil has latent capacity. Sensible Heat Ratio is not 1 but 0.74. I'm concerned that the Nominal Coil UA Value may not be sized corectly due to the unreasonable latent capacity.
My input for the cooling coil is shown below. I tried changing various parameters. Design Inlet Air Humidity Ratio and Design Outlet Air Humidity Ratio affect the coil sizing, but I couldn't get the latent capacity of 0W.
Coil:Cooling:Water,
Air Loop AHU Cooling Coil, !- Name
On 24/7, !- Availability Schedule Name
0.0447, !- Design Water Flow Rate {m3/s}
70, !- Design Air Flow Rate {m3/s}
11, !- Design Inlet Water Temperature {C}
40, !- Design Inlet Air Temperature {C}
23, !- Design Outlet Air Temperature {C}
0.0178, !- Design Inlet Air Humidity Ratio {kgWater/kgDryAir}
0.0178, !- Design Outlet Air Humidity Ratio {kgWater/kgDryAir}
Air Loop AHU Cooling Coil Water Inlet Node, !- Water Inlet Node Name
Air Loop AHU Cooling Coil Water Outlet Node, !- Water Outlet Node Name
Air Loop AHU Mixed Air Outlet, !- Air Inlet Node Name
Air Loop AHU Cooling Coil Air Outlet Node, !- Air Outlet Node Name
DetailedAnalysis, !- Type of Analysis
CounterFlow, !- Heat Exchanger Configuration
, !- Condensate Collection Water Storage Tank Name
10; !- Design Water Temperature Difference {deltaC}
What could be the cause of the unreasonable coil latent capacity?
I also tried changing the design air conditions in SizingPeriod:DesignDay, Sizing:Zone and Sizing:System, but they do not seem to be the cause.
