Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page

# Hard Sizing Coil Cooling Water

I am trying to hard size a water cooling coil in OpenStudio 2.8, there is no hard size option for the capacity of the cooling coil, the only available option is to hard size the flow rate. I tried to increase the flow rate to get the targeted capacity using the below formula from EnergyPlus guide. The output reports shows an increase in the coil flow rate but the cooling capacity is still the same. The reason I am doing this is to meet the requirement of App G of 90.1 of modeling the proposed system with actual capacities. Is there a work around to hard size the water cooling coil?

edit retag close merge delete

Sort by » oldest newest most voted

The routine starts at the Sizing:Zone object, where you can specify zone_cooling_design_supply_air_temperature. With this parameter E+ is then calculating the air flow rate needed (at the cooling design SAT) to satisfy the specified zone loads (to meet your design thermostat setpoint). This air flow rate is what goes to the coil design. Then you need to go to the Sizing:System table, where the important parameters for coil sizing are central_cooling_design_supply_air_temperature and central_cooling_design_supply_air_humidity_ratio. Now you're getting to the coil sizing routine where E+ says, "For the requested air flow rate (from Sizing:Zone), at temperature and humidity inlet conditions defined by the Site:Location object, to be cooled to the central cooling design parameters (from Sizing:System), the coil needs to provide X watts of cooling."

Fluid flow rate and deltaT are actually coming after this portion. After coils are sized, capacities are all added up for the plant, where E+ then looks at what you have for the parameters design_loop_exit_temperature and loop_design_temperature_difference in the Sizing:Plant object. You can tweak those parameters to get the desired flow rate, but energy-wise that is typically more important for your plant objects.

more

## Stats

Seen: 170 times

Last updated: Dec 04 '20