Standards.AirTerminalSingleDuctParallelPIUReheat.rb in openstudio-standards-0.1.5

- old
+ new
@@ -1,71 +1,62 @@
 
 # open the class to add methods to apply HVAC efficiency standards
 class OpenStudio::Model::AirTerminalSingleDuctParallelPIUReheat
-
   # Sets the fan power of a PIU fan based on the W/cfm
   # specified in the standard.
   #
-  # @param template [String] the standard
+  # @param template [String] the template base requirements on
   # @return [Bool] returns true if successful, false if not
-  def set_performance_rating_method_baseline_fan_power(template)
+  def apply_prm_baseline_fan_power(template)
+    OpenStudio.logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "Setting PIU fan power for #{name}.")
 
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "Setting PIU fan power for #{self.name}.")
-  
-      # Determine the fan sizing flow rate, min flow rate,
-      # and W/cfm
-      sec_flow_frac = 0.5
-      min_flow_frac = 0.3
-      fan_efficacy_w_per_cfm = 0.35
-      # case template
-      # when
-      # else
-      # end
-  
-      # Get the maximum flow rate through the terminal
-      max_primary_air_flow_rate = nil
-      if self.autosizedMaximumPrimaryAirFlowRate.is_initialized
-        max_primary_air_flow_rate = self.autosizedMaximumPrimaryAirFlowRate.get
-      elsif self.maximumPrimaryAirFlowRate.is_initialized
-        max_primary_air_flow_rate = self.maximumPrimaryAirFlowRate.get
-      end
-      
-      # Set the max secondary air flow rate
-      max_sec_flow_rate_m3_per_s = max_primary_air_flow_rate * sec_flow_frac
-      self.setMaximumSecondaryAirFlowRate(max_sec_flow_rate_m3_per_s)
-      
-      # Set the minimum flow fraction
-      #TODO Also compare to min OA requirement
-      self.setMinimumPrimaryAirFlowFraction(min_flow_frac)
-    
-      # Set the fan efficacy
-      fan = self.fan.to_FanConstantVolume.get
-      fan_rise_pa = fan.pressureRise
-      fan_rise_in_wc = OpenStudio.convert(fan_rise_pa, "Pa", "inH_{2}O")
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "=> Pressure Rise = #{fan_rise_pa} Pa")
+    # Determine the fan sizing flow rate, min flow rate,
+    # and W/cfm
+    sec_flow_frac = 0.5
+    min_flow_frac = 0.3
+    fan_efficacy_w_per_cfm = 0.35
 
-      max_sec_flow_rate_cfm = OpenStudio.convert(max_sec_flow_rate_m3_per_s, "m^3/s", "ft^3/min").get
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "=> Maximum Fan Flow Rate = #{max_sec_flow_rate_cfm} m3/s")
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "=> Maximum Secondary Air Flow Rate = #{self.maximumSecondaryAirFlowRate.get} m3/s")      
-      
-      fan_efficiency = fan.fanEfficiency
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "=> Fan Total Efficiency = #{fan_efficiency}")
+    # Convert efficacy to metric
+    # 1 cfm = 0.0004719 m^3/s
+    fan_efficacy_w_per_m3_per_s = fan_efficacy_w_per_cfm / 0.0004719
 
-      fan_power_w = fan_rise_pa * max_sec_flow_rate_m3_per_s / fan_efficiency
-      fan_efficacy_calc = fan_power_w / max_sec_flow_rate_m3_per_s
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "=> fan efficacy calculated = #{fan_efficacy_calc} W-s/m3")
+    # Get the maximum flow rate through the terminal
+    max_primary_air_flow_rate = nil
+    if autosizedMaximumPrimaryAirFlowRate.is_initialized
+      max_primary_air_flow_rate = autosizedMaximumPrimaryAirFlowRate.get
+    elsif maximumPrimaryAirFlowRate.is_initialized
+      max_primary_air_flow_rate = maximumPrimaryAirFlowRate.get
+    end
 
-      fan_efficacy_w_per_m3_per_s = fan_efficacy_w_per_cfm * OpenStudio.convert(1, 'm^3/s', 'cfm').get
+    # Set the max secondary air flow rate
+    max_sec_flow_rate_m3_per_s = max_primary_air_flow_rate * sec_flow_frac
+    setMaximumSecondaryAirFlowRate(max_sec_flow_rate_m3_per_s)
+    max_sec_flow_rate_cfm = OpenStudio.convert(max_sec_flow_rate_m3_per_s, 'm^3/s', 'ft^3/min').get
 
-      fan_rise_new_pa = fan_efficacy_w_per_m3_per_s * fan_efficiency
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "=> fan pressure rise new = #{fan_rise_new_pa} Pa")
-      fan.setPressureRise(fan_rise_new_pa)
-      fan_power_new_w = fan_rise_new_pa * max_sec_flow_rate_cfm / fan_efficiency
-      fan_efficacy_new_w_per_cfm = fan_power_new_w / max_sec_flow_rate_cfm
-      
-      OpenStudio::logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "For #{self.name}: fan efficacy set to #{fan_efficacy_new_w_per_cfm.round(2)} W/cfm, fan bhp = #{fan.brakeHorsepower} hp, motor efficiency = #{fan.motorEfficiency}.")
-      
-      return true
-    
-    end
+    # Set the minimum flow fraction
+    # TODO Also compare to min OA requirement
+    setMinimumPrimaryAirFlowFraction(min_flow_frac)
 
+    # Get the fan
+    fan = self.fan.to_FanConstantVolume.get
+
+    # Set the impeller efficiency
+    fan.change_impeller_efficiency(fan.baseline_impeller_efficiency(template))
+
+    # Set the motor efficiency, preserving the impeller efficency.
+    # For terminal fans, a bhp lookup of 0.5bhp is always used because
+    # they are assumed to represent a series of small fans in reality.
+    fan.apply_standard_minimum_motor_efficiency(template, fan.brake_horsepower)
+
+    # Calculate a new pressure rise to hit the target W/cfm
+    fan_tot_eff = fan.fanEfficiency
+    fan_rise_new_pa = fan_efficacy_w_per_m3_per_s * fan_tot_eff
+    fan.setPressureRise(fan_rise_new_pa)
+
+    # Calculate the newly set efficacy
+    fan_power_new_w = fan_rise_new_pa * max_sec_flow_rate_m3_per_s / fan_tot_eff
+    fan_efficacy_new_w_per_cfm = fan_power_new_w / max_sec_flow_rate_cfm
+    OpenStudio.logFree(OpenStudio::Info, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "For #{name}: fan efficacy set to #{fan_efficacy_new_w_per_cfm.round(2)} W/cfm.")
+
+    return true
+  end
 end