Reduce fan power for impact of the ductwork

NREL · Nov 15, 2024 · ed85efc · ed85efc
1 parent f501f6d
commit ed85efc
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/HPXMLtoOpenStudio/resources/hvac.rb b/HPXMLtoOpenStudio/resources/hvac.rb
@@ -2021,7 +2021,9 @@ def self.set_curves_gshp(heat_pump)
     hp_ap.heat_power_curve_spec = [[-8.4754723813072, 8.10952801956388, 1.38771494628738, -0.33766445915032, 0.0223085217874051]]
 
     # Fan/pump adjustments calculations
-    power_f = heat_pump.fan_watts_per_cfm * 400.0 / UnitConversions.convert(1.0, 'ton', 'Btu/hr') # 400 cfm/ton, result is in W per Btu/hr of capacity
+    # Fan power to overcome the static pressure adjustment
+    fan_duct_reduction_watts_per_cfm = 0.5*heat_pump.fan_watts_per_cfm # Assume the power to overcome the ductwork is 50 % of the fan power
+    power_f = fan_duct_reduction_watts_per_cfm * 400.0 / UnitConversions.convert(1.0, 'ton', 'Btu/hr') # 400 cfm/ton, result is in W per Btu/hr of capacity
     power_p = heat_pump.pump_watts_per_ton / UnitConversions.convert(1.0, 'ton', 'Btu/hr') # result is in W per Btu/hr of capacity
 
     cool_eir = UnitConversions.convert(((1 - UnitConversions.convert(power_f, 'Wh', 'Btu')) / heat_pump.cooling_efficiency_eer - power_f - power_p), 'Wh', 'Btu')