Module: Pump
- Included in:
- OpenStudio::Model::HeaderedPumpsConstantSpeed, OpenStudio::Model::HeaderedPumpsVariableSpeed, OpenStudio::Model::PumpConstantSpeed, OpenStudio::Model::PumpVariableSpeed
- Defined in:
- lib/openstudio-standards/standards/Standards.Pump.rb
Overview
A variety of pump calculation methods that are the same regardless of pump type. These methods are available to PumpConstantSpeed, PumpVariableSpeed
Instance Method Summary collapse
-
#apply_prm_pressure_rise_and_motor_efficiency(target_w_per_gpm, template) ⇒ Bool
Set the pressure rise that cooresponds to the target power per flow number, given the standard pump efficiency and the default EnergyPlus pump impeller efficiency of 0.78.
- #apply_standard_minimum_motor_efficiency(template) ⇒ Object
-
#brake_horsepower ⇒ Double
Determines the brake horsepower of the pump based on flow rate, pressure rise, and impeller efficiency.
-
#motor_horsepower ⇒ Double
Determines the horsepower of the pump motor, including motor efficiency and pump impeller efficiency.
-
#pump_power ⇒ Double
Determines the pump power (W) based on flow rate, pressure rise, and total pump efficiency(impeller eff * motor eff).
-
#rated_w_per_gpm ⇒ Double
Determines the rated watts per GPM of the pump.
-
#standard_minimum_motor_efficiency_and_size(template, motor_bhp) ⇒ Array<Double>
Determines the minimum pump motor efficiency and nominal size for a given motor bhp.
Instance Method Details
#apply_prm_pressure_rise_and_motor_efficiency(target_w_per_gpm, template) ⇒ Bool
Set the pressure rise that cooresponds to the target power per flow number, given the standard pump efficiency and the default EnergyPlus pump impeller efficiency of 0.78.
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# File 'lib/openstudio-standards/standards/Standards.Pump.rb', line 13 def apply_prm_pressure_rise_and_motor_efficiency(target_w_per_gpm, template) # 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 autosizedRatedFlowRate.is_initialized autosizedRatedFlowRate.get else ratedFlowRate.get 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 = standard_minimum_motor_efficiency_and_size(template, 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 = standard_minimum_motor_efficiency_and_size(template, 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 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 setRatedPumpHead(pressure_rise_pa) # Report OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Pump', "For #{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_power calculated_w_per_gpm = calculated_w / flow_gpm OpenStudio.logFree(OpenStudio::Debug, 'openstudio.standards.Pump', "For #{name}: calculated W/gpm = #{calculated_w_per_gpm.round(1)}.") return true end |
#apply_standard_minimum_motor_efficiency(template) ⇒ Object
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# File 'lib/openstudio-standards/standards/Standards.Pump.rb', line 83 def apply_standard_minimum_motor_efficiency(template) # Get the horsepower bhp = brake_horsepower # Find the motor efficiency motor_eff, nominal_hp = standard_minimum_motor_efficiency_and_size(template, bhp) # Change the motor efficiency setMotorEfficiency(motor_eff) OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Pump', "For #{name}: brake hp = #{bhp.round(2)}HP, motor nameplate = #{nominal_hp.round(2)}HP, motor eff = #{(motor_eff * 100).round(2)}%.") return true end |
#brake_horsepower ⇒ Double
Determines the brake horsepower of the pump based on flow rate, pressure rise, and impeller efficiency.
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# File 'lib/openstudio-standards/standards/Standards.Pump.rb', line 194 def brake_horsepower # Get flow rate (whether autosized or hard-sized) flow_m3_per_s = 0 flow_m3_per_s = if autosizedRatedFlowRate.is_initialized autosizedRatedFlowRate.get else ratedFlowRate.get 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 = 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 |
#motor_horsepower ⇒ Double
Determines the horsepower of the pump motor, including motor efficiency and pump impeller efficiency.
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# File 'lib/openstudio-standards/standards/Standards.Pump.rb', line 224 def motor_horsepower # Get the pump power pump_power_w = pump_power # Convert to HP pump_hp = pump_power_w / 745.7 # 745.7 W/HP return pump_hp end |
#pump_power ⇒ Double
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.
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# File 'lib/openstudio-standards/standards/Standards.Pump.rb', line 159 def pump_power # Get flow rate (whether autosized or hard-sized) flow_m3_per_s = 0 flow_m3_per_s = if autosizedRatedFlowRate.is_initialized autosizedRatedFlowRate.get else ratedFlowRate.get 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 = 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 = ratedPumpHead # Calculate the pump power (W) pump_power_w = pressure_rise_pa * flow_m3_per_s / pump_total_eff return pump_power_w end |
#rated_w_per_gpm ⇒ Double
Determines the rated watts per GPM of the pump
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# File 'lib/openstudio-standards/standards/Standards.Pump.rb', line 238 def rated_w_per_gpm # Get design power (whether autosized or hard-sized) rated_power_w = 0 if autosizedRatedPowerConsumption.is_initialized rated_power_w = autosizedRatedPowerConsumption.get elsif ratedPowerConsumption.is_initialized rated_power_w = ratedPowerConsumption.get else OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Pump', "For #{name}, could not find rated pump power consumption, cannot determine w per gpm correctly.") return 0.0 end rated_m3_per_s = 0 if autosizedRatedFlowRate.is_initialized rated_m3_per_s = autosizedRatedFlowRate.get elsif ratedFlowRate.is_initialized rated_m3_per_s = ratedFlowRate.get else OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Pump', "For #{name}, could not find rated pump Flow Rate, cannot determine w per gpm correctly.") return 0.0 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 |
#standard_minimum_motor_efficiency_and_size(template, motor_bhp) ⇒ Array<Double>
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.
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# File 'lib/openstudio-standards/standards/Standards.Pump.rb', line 109 def standard_minimum_motor_efficiency_and_size(template, 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 = $os_standards['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 #{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 #{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 |