Detailed Description

The calculator supports Heatless, Externally Heated, Blower Purge with and without Sweep, Heat of Compression HC and SP, and Refrigerated dryers. Input validation, type defaults, and user-facing unit conversion belong to the caller. The Suite receives U.S. customary engineering inputs and returns water removal in lb/hr and annual cost in dollars/year.

Public API

The C++ implementation follows the stateless compressed-air calculator pattern: callers populate dryer_operating_cost::Input, including the dryer type, and pass it to dryer_operating_cost::calculate. The WebAssembly binding exposes the equivalent calculateDryerOperatingCost(input) function. Both the JavaScript input and result are plain value objects and require no delete() cleanup.

Water load

Saturation pressure is calculated by SaturatedPressure at the inlet temperature. Refrigerated dryers subtract saturation pressure at 40 degrees F.

\begin{equation}\label{eq:dryer-water-load} W = \frac{Q \cdot 60 \cdot 18.016 \cdot (P_{sat,in} - P_{sat,out})} {(P_g + 14.7) \cdot 379} \end{equation}

\(W\)	Water removed \([\unit{ lb/hr}]\)
\(Q\)	Inlet airflow \([\unit{ SCFM}]\)
\(P_{sat,in}\)	Saturation pressure at inlet temperature \([\unit{ psia}]\)
\(P_{sat,out}\)	Zero for desiccant dryers or saturation pressure at 40 degrees F for refrigerated dryers \([\unit{ psia}]\)
\(P_g\)	Inlet gauge pressure \([\unit{ psig}]\)

Desiccant and dryer sizing

Heatless dryers preserve the source calculator's distinct sizing relation:

\begin{equation}\label{eq:dryer-heatless-size} V = Q \cdot \frac{114.7}{P_g + 14.7} \end{equation}

Other desiccant dryers use:

\begin{equation}\label{eq:dryer-desiccant-size} m_d = \frac{W \cdot t_c}{f_{DDC}}, \qquad V = \frac{m_d}{0.5784} \end{equation}

where \(t_c\) is regeneration half-cycle length in hours and \(f_{DDC}\) is the design desiccant capacity percentage divided by 100. SP dryers use the caller-supplied v2 values of two hours and four percent.

Purge, heater, and motor

Purge airflow is either \(V \cdot f_p\) or a direct SCFM input. Direct flow is converted to an effective capacity percentage for the output. Automatic heater and motor formulas follow the Dryer Calculator V2 formula reference; positive heater kW or motor HP inputs override automatic sizing where the selected dryer type permits manual sizing. HC heater power is always calculated from inlet flow.

Annual cost

\begin{equation}\label{eq:dryer-total-cost} C_{total} = C_{heater} + C_{motor} + C_{purge} + C_{controls} + C_{cooling} \end{equation}

Heater energy is scaled by heating hours per day and annual operating hours divided by 24. Motors run for all annual operating hours. Purge cost uses the greater of the entered compressed-air rate and its electricity-equivalent rate, multiplied by the dryer-type duty factor. Desiccant dryers include a 100 W controls load; only refrigerated dryers include cooling-water cost.

Migration from v1

Replace construction of DryerOperatingCost and its instance calculate call with one calculateDryerOperatingCost call. Move dryerType into the input object and remove cleanup calls for the calculator and returned result. The v2 input also replaces the three schedule fields with annual operating hours and adds regeneration-cycle, purge-mode, direct-purge-flow, and motor-power fields.

Files
file	dryer_operating_cost.h
	Declarations for compressed-air dryer annual operating-cost calculations.

Namespaces
namespace	dryer_operating_cost
	Compressed-air dryer annual operating-cost calculations.