Class: OpenStudio::Model::AirTerminalSingleDuctParallelPIUReheat

Inherits:
Object
  • Object
show all
Defined in:
lib/openstudio-standards/standards/Standards.AirTerminalSingleDuctParallelPIUReheat.rb,
lib/openstudio-standards/hvac_sizing/Siz.AirTermSnglDuctParallelPIUReheat.rb

Overview

open the class to add methods to return sizing values

Instance Method Summary collapse

Instance Method Details

#apply_prm_baseline_fan_power(template) ⇒ Bool

Sets the fan power of a PIU fan based on the W/cfm specified in the standard.

Parameters:

  • template (String) —

    the template base requirements on

Returns:

  • (Bool) —

    returns true if successful, false if not



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# File 'lib/openstudio-standards/standards/Standards.AirTerminalSingleDuctParallelPIUReheat.rb', line 9

def apply_prm_baseline_fan_power(template)
  OpenStudio.logFree(OpenStudio::Debug, 'openstudio.model.AirTerminalSingleDuctParallelPIUReheat', "Setting PIU fan power for #{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

  # 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

  # 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

  # 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

  # 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

#applySizingValues ⇒ Object

Takes the values calculated by the EnergyPlus sizing routines and puts them into this object model in place of the autosized fields. Must have previously completed a run with sql output for this to work.



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# File 'lib/openstudio-standards/hvac_sizing/Siz.AirTermSnglDuctParallelPIUReheat.rb', line 13

def applySizingValues

  maximum_primary_air_flow_rate = self.autosizedMaximumPrimaryAirFlowRate
  if maximum_primary_air_flow_rate.is_initialized
    self.setMaximumPrimaryAirFlowRate(maximum_primary_air_flow_rate.get) 
  end
  
  maximum_secondary_air_flow_rate = self.autosizedMaximumSecondaryAirFlowRate
  if maximum_secondary_air_flow_rate.is_initialized
    self.setMaximumSecondaryAirFlowRate(maximum_secondary_air_flow_rate.get)
  end
  
  minimum_primary_air_flow_fraction = self.autosizedMinimumPrimaryAirFlowFraction
  if minimum_primary_air_flow_fraction.is_initialized
    self.setMinimumPrimaryAirFlowFraction(minimum_primary_air_flow_fraction.get) 
  end
  
  fan_on_flow_fraction = self.autosizedFanOnFlowFraction
  if fan_on_flow_fraction.is_initialized
    self.setFanOnFlowFraction(fan_on_flow_fraction.get)
  end

  
end

#autosize ⇒ Object

Sets all auto-sizeable fields to autosize



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# File 'lib/openstudio-standards/hvac_sizing/Siz.AirTermSnglDuctParallelPIUReheat.rb', line 6

def autosize
  OpenStudio::logFree(OpenStudio::Warn, "openstudio.sizing.AirTerminalSingleDuctParallelPIUReheat", ".autosize not yet implemented for #{self.iddObject.type.valueDescription}.")
end

#autosizedFanOnFlowFraction ⇒ Object

returns the autosized fan on flow fraction as an optional double



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# File 'lib/openstudio-standards/hvac_sizing/Siz.AirTermSnglDuctParallelPIUReheat.rb', line 60

def autosizedFanOnFlowFraction

  return self.model.getAutosizedValue(self, 'Design Size Fan On Flow Fraction', '')
     
end

#autosizedMaximumPrimaryAirFlowRate ⇒ Object

returns the autosized maximum primary air flow rate as an optional double



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# File 'lib/openstudio-standards/hvac_sizing/Siz.AirTermSnglDuctParallelPIUReheat.rb', line 39

def autosizedMaximumPrimaryAirFlowRate

  return self.model.getAutosizedValue(self, 'Design Size Maximum Primary Air Flow Rate', 'm3/s')
  
end

#autosizedMaximumSecondaryAirFlowRate ⇒ Object

returns the autosized maximum secondary air flow rate as an optional double



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# File 'lib/openstudio-standards/hvac_sizing/Siz.AirTermSnglDuctParallelPIUReheat.rb', line 46

def autosizedMaximumSecondaryAirFlowRate

  return self.model.getAutosizedValue(self, 'Design Size Maximum Secondary Air Flow Rate', 'm3/s')
  
end

#autosizedMinimumPrimaryAirFlowFraction ⇒ Object

returns the autosized minimum primary air flow fraction as an optional double



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# File 'lib/openstudio-standards/hvac_sizing/Siz.AirTermSnglDuctParallelPIUReheat.rb', line 53

def autosizedMinimumPrimaryAirFlowFraction

  return self.model.getAutosizedValue(self, 'Design Size Minimum Primary Air Flow Fraction', '')
    
end