Auxiliary Power Used Calculator

Detailed Description

This calculator estimates the energy use of motors and auxiliary systems associated with process heating equipment. It uses electrical parameters and operating time to compute total power consumption, converting electrical power from kW to BTU/hr using a physical constant. The algorithm is suitable for modeling auxiliary energy losses in industrial furnaces, ovens, and similar systems.

The calculation follows a top-down approach:

1. Total Auxiliary Power - Calculate electrical power consumption and convert to BTU/hr

Total Auxiliary Power Used

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Total auxiliary power consumption.

The formula calculates the electrical power in kilowatts based on voltage, current, power factor, and phase, adjusts for operating time, then converts to BTU/hr using the conversion constant.

\begin{equation}\label{eq:aux-power-used} Q_\text{aux} = \sqrt{P} \cdot V \cdot I \cdot PF \cdot OT \cdot \frac{1}{1000} \cdot k_{\text{kW}\to\text{BTU/hr}}\end{equation}

Symbols

\(Q_\text{aux}\)	Auxiliary power used \([\unit{ \btu\per\hour}]\)
\(P\)	Number of motor phases \([\unit{ \unitless}]\)
\(V\)	Supply voltage \([\unit{ \volt}]\)
\(I\)	Average current \([\unit{ \ampere}]\)
\(PF\)	Power factor \([\unit{ \unitless}]\)
\(OT\)	Operating time (fraction, 0-1) \([\unit{ \unitless}]\)
\(1000\)	Conversion from watts to kilowatts \([\unit{ \watt\per\kilowatt}]\)
\(k_{\text{kW}\to\text{BTU/hr}}\)	Conversion factor - see physics::conversions::kKilowattToBtuPerHour \([\unit{ \btu\per\hour\per\kilowatt}]\)

See also

Perry's Chemical Engineers' Handbook; NIST Engineering Statistics; ASHRAE Handbook

physics::conversions::kKilowattToBtuPerHour for the conversion constant

Modules
	Auxiliary Power Used Formula
	Total auxiliary power consumption.

Files
file	auxiliary_power_used.h

Namespaces
namespace	auxiliary_power_used
	Calculates auxiliary power usage for electrical systems in process heating equipment.

Functions
double	auxiliary_power_used::calculatePowerUsed (double number_of_motor_phases, double supply_voltage, double avg_current, double power_factor, double operating_time)
	Calculates the auxiliary power used by electrical systems associated with process heating equipment.

Function Documentation

calculatePowerUsed()

double auxiliary_power_used::calculatePowerUsed	(	double	number_of_motor_phases,
		double	supply_voltage,
		double	avg_current,
		double	power_factor,
		double	operating_time
	)

This function computes the energy use of motors and other auxiliary systems using electricity, based on electrical parameters and operating time.

Parameters

[in]	number_of_motor_phases	Number of motor phases \([\unit{\unitless}]\)
[in]	supply_voltage	Supply voltage \([\unit{\volt}]\)
[in]	avg_current	Average current \([\unit{\ampere}]\)
[in]	power_factor	Power factor \([\unit{\unitless}]\)
[in]	operating_time	Operating time (percent, 0-100) \([\unit{\percent}]\)

Returns

Auxiliary power used \([\unit{\btu\per\hour}]\)

See also

Auxiliary Power Used Formula