AHU Water Cooled DX Coil Workaround

asked 2018-04-06 14:34:41 -0600

umop-3pisdn gravatar image

updated 2018-04-06 14:47:13 -0600

I'm modeling a residential high-rise building in E+ v8.9 with residential unit conditioning provided by cycling recirc water-source heat pumps and ventilation provided by a VFD DOAS equipped with a HW HC and water-cooled DX CC, plus hot gas reheat for dehumidification. The DOAS DX coil and the units' WSHPs are all tied to the same condenser loop served by a boiler and cooling tower. The boiler also serves the DOAS HW HC.

I am aware that coolingcoil:dx:singlespeed has only air-cooled and evap-cooled options. I am basically trying to figure what's a better approach to model this system... spoof the water-cooled DX coil as evap-cooled in tandem with coil:heating:desuperheater and break the resultant cooling energy down into compressor/condenser pump/evaporator fan to understand the cooling/pumping/heat rejection split? Or spoof it as a CHW CC served by a water-cooled chiller @ the DX coil's COP, with the HW HC behind it also serving dehumidification reheat in addition to main heating?

Neither solution is particularly satisfying, as in the first case the heat rejection and pumping energy increases aren't clearly associated, and in the second case the efficiency improvement due to hot gas reheat isn't captured (possibly accounted for by bumping up boiler efficiency?)

Ideas?

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