module Pump
A variety of pump calculation methods that are the same regardless of pump type. These methods are available to PumpConstantSpeed, PumpVariableSpeed
Public Instance Methods
Set the pressure rise that corresponds to the target power per flow number, given the standard pump efficiency and the default EnergyPlus pump impeller efficiency of 0.78.
@param pump [OpenStudio::Model::StraightComponent] pump object, allowable types:
PumpConstantSpeed, PumpVariableSpeed
@param target_w_per_gpm [Double] the target power per flow, in W/gpm @return [Boolean] returns true if successful, false if not @author jmarrec
# File lib/openstudio-standards/standards/Standards.Pump.rb, line 14 def pump_apply_prm_pressure_rise_and_motor_efficiency(pump, target_w_per_gpm) # Eplus assumes an impeller efficiency of 0.78 to determine the total efficiency # http://bigladdersoftware.com/epx/docs/8-4/engineering-reference/component-sizing.html#pump-sizing # Rated_Power_Use = Rated_Volume_Flow_Rate * Rated_Pump_Head / Total_Efficiency # Rated_Power_Use / Rated_Volume_Flow_Rate = Rated_Pump_Head / Total_Efficiency # Total_Efficiency = Motor_Efficiency * Impeler_Efficiency impeller_efficiency = 0.78 # Get flow rate (whether autosized or hard-sized) flow_m3_per_s = 0 flow_m3_per_s = if pump.to_PumpVariableSpeed.is_initialized || pump.to_PumpConstantSpeed.is_initialized if pump.ratedFlowRate.is_initialized pump.ratedFlowRate.get elsif pump.autosizedRatedFlowRate.is_initialized pump.autosizedRatedFlowRate.get end elsif pump.to_HeaderedPumpsVariableSpeed.is_initialized || pump.to_HeaderedPumpsConstantSpeed.is_initialized if pump.totalRatedFlowRate.is_initialized pump.totalRatedFlowRate.get / pump.numberofPumpsinBank elsif pump.autosizedTotalRatedFlowRate.is_initialized pump.autosizedTotalRatedFlowRate.get / pump.numberofPumpsinBank end end flow_gpm = OpenStudio.convert(flow_m3_per_s, 'm^3/s', 'gal/min').get # Calculate the target total pump motor power consumption target_motor_power_cons_w = target_w_per_gpm * flow_gpm target_motor_power_cons_hp = target_motor_power_cons_w / 745.7 # 745.7 W/HP # Find the motor efficiency using total power consumption # Note that this hp is ~5-10% high because it is being looked # up based on the motor consumption, which is always actually higher # than the brake horsepower. This will bound the possible motor efficiency # values. If a motor is just above a nominal size, and the next size # down has a lower efficiency value, later motor efficiency setting # methods can mess up the W/gpm. All this nonsense avoids that. mot_eff_hi_end, nom_hp_hi_end = pump_standard_minimum_motor_efficiency_and_size(pump, target_motor_power_cons_hp) # Calculate the actual brake horsepower using this efficiency target_motor_bhp = target_motor_power_cons_hp * mot_eff_hi_end # Find the motor efficiency using actual bhp mot_eff_lo_end, nom_hp_lo_end = pump_standard_minimum_motor_efficiency_and_size(pump, target_motor_bhp) # If the efficiency drops you down into a lower band with # a lower efficiency value, use that for the motor efficiency. motor_efficiency = [mot_eff_lo_end, mot_eff_hi_end].min nominal_hp = [nom_hp_lo_end, nom_hp_hi_end].min # Calculate the brake horsepower that was assumed target_brake_power_hp = target_motor_power_cons_hp * motor_efficiency # Change the motor efficiency pump.setMotorEfficiency(motor_efficiency) total_efficiency = impeller_efficiency * motor_efficiency desired_power_per_m3_s = OpenStudio.convert(target_w_per_gpm, 'W*min/gal', 'W*s/m^3').get pressure_rise_pa = desired_power_per_m3_s * total_efficiency pressure_rise_ft_h2o = OpenStudio.convert(pressure_rise_pa, 'Pa', 'ftH_{2}O').get # Change pressure rise pump.setRatedPumpHead(pressure_rise_pa) # Report OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Pump', "For #{pump.name}: motor nameplate = #{nominal_hp}HP, motor eff = #{(motor_efficiency * 100).round(2)}%; #{target_w_per_gpm.round} W/gpm translates to a pressure rise of #{pressure_rise_ft_h2o.round(2)} ftH2O.") # Calculate the W/gpm for verification calculated_w = pump_pumppower(pump) calculated_w_per_gpm = calculated_w / flow_gpm OpenStudio.logFree(OpenStudio::Debug, 'openstudio.standards.Pump', "For #{pump.name}: calculated W/gpm = #{calculated_w_per_gpm.round(1)}.") return true end
Applies the minimum motor efficiency for this pump based on the motor’s brake horsepower.
@param pump [OpenStudio::Model::StraightComponent] pump object, allowable types:
PumpConstantSpeed, PumpVariableSpeed
@return [Boolean] returns true if successful, false if not
# File lib/openstudio-standards/standards/Standards.Pump.rb, line 98 def pump_apply_standard_minimum_motor_efficiency(pump) # Get the horsepower bhp = pump_brake_horsepower(pump) # Find the motor efficiency motor_eff, nominal_hp = pump_standard_minimum_motor_efficiency_and_size(pump, bhp) # Change the motor efficiency pump.setMotorEfficiency(motor_eff) OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Pump', "For #{pump.name}: brake hp = #{bhp.round(2)}HP, motor nameplate = #{nominal_hp.round(2)}HP, motor eff = #{(motor_eff * 100).round(2)}%.") return true end
Determines the brake horsepower of the pump based on flow rate, pressure rise, and impeller efficiency.
@param pump [OpenStudio::Model::StraightComponent] pump object, allowable types:
PumpConstantSpeed, PumpVariableSpeed
@return [Double] brake horsepower
# File lib/openstudio-standards/standards/Standards.Pump.rb, line 223 def pump_brake_horsepower(pump) # Get flow rate (whether autosized or hard-sized) # Get flow rate (whether autosized or hard-sized) flow_m3_per_s = 0 flow_m3_per_s = if pump.to_PumpVariableSpeed.is_initialized || pump.to_PumpConstantSpeed.is_initialized if pump.ratedFlowRate.is_initialized pump.ratedFlowRate.get elsif pump.autosizedRatedFlowRate.is_initialized pump.autosizedRatedFlowRate.get end elsif pump.to_HeaderedPumpsVariableSpeed.is_initialized || pump.to_HeaderedPumpsConstantSpeed.is_initialized if pump.totalRatedFlowRate.is_initialized pump.totalRatedFlowRate.get elsif pump.autosizedTotalRatedFlowRate.is_initialized pump.autosizedTotalRatedFlowRate.get end end # E+ default impeller efficiency # http://bigladdersoftware.com/epx/docs/8-4/engineering-reference/component-sizing.html#pump-sizing impeller_eff = 0.78 # Get the pressure rise (Pa) pressure_rise_pa = pump.ratedPumpHead # Calculate the pump power (W) pump_power_w = pressure_rise_pa * flow_m3_per_s / impeller_eff # Convert to HP pump_power_hp = pump_power_w / 745.7 # 745.7 W/HP return pump_power_hp end
Determines the horsepower of the pump motor, including motor efficiency and pump impeller efficiency.
@param pump [OpenStudio::Model::StraightComponent] pump object, allowable types:
PumpConstantSpeed, PumpVariableSpeed
@return [Double] motor horsepower
# File lib/openstudio-standards/standards/Standards.Pump.rb, line 262 def pump_motor_horsepower(pump) # Get the pump power pump_power_w = pump_pumppower(pump) # Convert to HP pump_hp = pump_power_w / 745.7 # 745.7 W/HP return pump_hp end
Determines the pump power (W) based on flow rate, pressure rise, and total pump efficiency(impeller eff * motor eff). Uses the E+ default assumption of 0.78 impeller efficiency.
@param pump [OpenStudio::Model::StraightComponent] pump object, allowable types:
PumpConstantSpeed, PumpVariableSpeed
@return [Double] pump power in watts
# File lib/openstudio-standards/standards/Standards.Pump.rb, line 177 def pump_pumppower(pump) # Get flow rate (whether autosized or hard-sized) flow_m3_per_s = 0 flow_m3_per_s = if pump.to_PumpVariableSpeed.is_initialized || pump.to_PumpConstantSpeed.is_initialized if pump.ratedFlowRate.is_initialized pump.ratedFlowRate.get elsif pump.autosizedRatedFlowRate.is_initialized pump.autosizedRatedFlowRate.get else pump.ratedFlowRate.get end elsif pump.to_HeaderedPumpsVariableSpeed.is_initialized || pump.to_HeaderedPumpsConstantSpeed.is_initialized if pump.totalRatedFlowRate.is_initialized pump.totalRatedFlowRate.get elsif pump.autosizedTotalRatedFlowRate.is_initialized pump.autosizedTotalRatedFlowRate.get end end # E+ default impeller efficiency # http://bigladdersoftware.com/epx/docs/8-4/engineering-reference/component-sizing.html#pump-sizing impeller_eff = 0.78 # Get the motor efficiency motor_eff = pump.motorEfficiency # Calculate the total efficiency # which includes both motor and # impeller efficiency. pump_total_eff = impeller_eff * motor_eff # Get the pressure rise (Pa) pressure_rise_pa = pump.ratedPumpHead # Calculate the pump power (W) pump_power_w = pressure_rise_pa * flow_m3_per_s / pump_total_eff return pump_power_w end
Determines the rated watts per GPM of the pump
@param pump [OpenStudio::Model::StraightComponent] pump object, allowable types:
PumpConstantSpeed, PumpVariableSpeed
@return [Double] rated power consumption per flow in watts per gpm, W*min/gal
# File lib/openstudio-standards/standards/Standards.Pump.rb, line 277 def pump_rated_w_per_gpm(pump) # Get design power (whether autosized or hard-sized) rated_power_w = 0 if pump.ratedPowerConsumption.is_initialized rated_power_w = pump.ratedPowerConsumption.get elsif pump.autosizedRatedPowerConsumption.is_initialized rated_power_w = pump.autosizedRatedPowerConsumption.get else OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Pump', "For #{pump.name}, could not find rated pump power consumption, cannot determine w per gpm correctly.") return 0.0 end rated_m3_per_s = 0 if pump.to_PumpVariableSpeed.is_initialized || pump.to_PumpConstantSpeed.is_initialized if pump.ratedFlowRate.is_initialized rated_m3_per_s = pump.ratedFlowRate.get elsif pump.autosizedRatedFlowRate.is_initialized rated_m3_per_s = pump.autosizedRatedFlowRate.get else OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Pump', "For #{pump.name}, could not find rated pump Flow Rate, cannot determine w per gpm correctly.") return 0.0 end elsif pump.to_HeaderedPumpsVariableSpeed.is_initialized || pump.to_HeaderedPumpsConstantSpeed.is_initialized if pump.totalRatedFlowRate.is_initialized rated_m3_per_s = pump.totalRatedFlowRate.get elsif pump.autosizedTotalRatedFlowRate.is_initialized rated_m3_per_s = pump.autosizedTotalRatedFlowRate.get else OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Pump', "For #{pump.name}, could not find rated pump Flow Rate, cannot determine w per gpm correctly.") return 0.0 end end rated_w_per_m3s = rated_power_w / rated_m3_per_s rated_w_per_gpm = OpenStudio.convert(rated_w_per_m3s, 'W*s/m^3', 'W*min/gal').get return rated_w_per_gpm end
Determines the minimum pump motor efficiency and nominal size for a given motor bhp. This should be the total brake horsepower with any desired safety factor already included. This method picks the next nominal motor catgory larger than the required brake horsepower, and the efficiency is based on that size. For example, if the bhp = 6.3, the nominal size will be 7.5HP and the efficiency for 90.1-2010 will be 91.7% from Table 10.8B. This method assumes 4-pole, 1800rpm totally-enclosed fan-cooled motors.
@param pump [OpenStudio::Model::StraightComponent] pump object, allowable types:
PumpConstantSpeed, PumpVariableSpeed
@param motor_bhp [Double] motor brake horsepower (hp) @return [Array<Double>] minimum motor efficiency (0.0 to 1.0), nominal horsepower
# File lib/openstudio-standards/standards/Standards.Pump.rb, line 126 def pump_standard_minimum_motor_efficiency_and_size(pump, motor_bhp) motor_eff = 0.85 nominal_hp = motor_bhp # Don't attempt to look up motor efficiency # for zero-hp pumps (required for circulation-pump-free # service water heating systems). return [1.0, 0] if motor_bhp == 0.0 # Lookup the minimum motor efficiency motors = standards_data['motors'] # Assuming all pump motors are 4-pole ODP search_criteria = { 'template' => template, 'number_of_poles' => 4.0, 'type' => 'Enclosed' } motor_properties = model_find_object(motors, search_criteria, motor_bhp) if motor_properties.nil? OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Pump', "For #{pump.name}, could not find motor properties using search criteria: #{search_criteria}, motor_bhp = #{motor_bhp} hp.") return [motor_eff, nominal_hp] end motor_eff = motor_properties['nominal_full_load_efficiency'] nominal_hp = motor_properties['maximum_capacity'].to_f.round(1) # Round to nearest whole HP for niceness if nominal_hp >= 2 nominal_hp = nominal_hp.round end # Get the efficiency based on the nominal horsepower # Add 0.01 hp to avoid search errors. motor_properties = model_find_object(motors, search_criteria, nominal_hp + 0.01) if motor_properties.nil? OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Fan', "For #{pump.name}, could not find nominal motor properties using search criteria: #{search_criteria}, motor_hp = #{nominal_hp} hp.") return [motor_eff, nominal_hp] end motor_eff = motor_properties['nominal_full_load_efficiency'] return [motor_eff, nominal_hp] end