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MEASUR-Tools-Suite v1.2.4
The MEASUR Tools Suite is a collection of industrial efficiency calculations written in C++ and with bindings for compilation to WebAssembly.
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MEASUR-Tools-Suite v1.2.4
The MEASUR Tools Suite is a collection of industrial efficiency calculations written in C++ and with bindings for compilation to WebAssembly.
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The final result is average package power and delivered airflow over a repeating storage cycle. For an airflow input, the model computes the power of one operating cycle directly. For a power input, it samples the cycle across 76 airflow points, fits a sixth-order curve, and evaluates the inverse relationship.
The cycle can include modulation, blowdown, off-load time, reload, and reload pump-up. Modulation-with-unload and variable-displacement-with-unload use the same cycle shell, but delegate high-flow points to the modulation-without-unload curve.
Average package power over one load/unload cycle.
Runtime-weighted cycle power is calculated from the energy in each active stage. If the requested airflow is at or above the unload airflow, the model uses the modulation stage power directly.
\begin{equation}\label{eq:load-unload-average-power} P_{cycle} = \frac{E_{bd} + E_{off} + E_{reload} + E_{pump} + E_{mod}} {t_{bd} + t_{off} + t_{reload} + t_{pump} + t_{mod}} \end{equation}
| \(P_{cycle}\) | Average package power for the operating cycle \([\unit{ \kilo\watt}]\) |
| \(E_{bd}\) | Blowdown energy \([\unit{ \kilo\watt\second}]\) |
| \(E_{off}\) | Off-load energy \([\unit{ \kilo\watt\second}]\) |
| \(E_{reload}\) | Reload energy \([\unit{ \kilo\watt\second}]\) |
| \(E_{pump}\) | Reload pump-up energy \([\unit{ \kilo\watt\second}]\) |
| \(E_{mod}\) | Modulation energy \([\unit{ \kilo\watt\second}]\) |
| \(t_{bd}\) | Blowdown runtime \([\unit{ \second}]\) |
| \(t_{off}\) | Off-load runtime \([\unit{ \second}]\) |
| \(t_{reload}\) | Reload runtime \([\unit{ \second}]\) |
| \(t_{pump}\) | Reload pump-up runtime \([\unit{ \second}]\) |
| \(t_{mod}\) | Modulation runtime \([\unit{ \second}]\) |
Core storage and blowdown runtime calculations.
Runtime depends on storage volume, atmospheric pressure, airflow demand, and the pressure band between full-load and unload pressure. Blowdown runtime is limited by the configured blowdown time.
\begin{equation}\label{eq:load-unload-unload-runtime} t_{unload} = \frac{V_s \cdot 60(P_{UL} - P_{FL})}{Q \cdot P_{atm}} \end{equation}
\begin{equation}\label{eq:load-unload-blowdown-runtime} t_{bd} = \min(t_{bd,set}, t_{unload}) \end{equation}
\begin{equation}\label{eq:load-unload-decay-time} \tau_{bd} = \frac{t_{bd,set}}{\ln(1/\epsilon)} \end{equation}
| \(t_{unload}\) | Time available during unloaded decay \([\unit{ \second}]\) |
| \(V_s\) | Receiver storage volume \([\unit{ \cubicFoot}]\) |
| \(P_{UL}\) | Unload pressure \([\unit{ \psig}]\) |
| \(P_{FL}\) | Full-load pressure \([\unit{ \psig}]\) |
| \(Q\) | Airflow demand represented by the curve point \([\unit{ \acfm}]\) |
| \(P_{atm}\) | Atmospheric pressure \([\unit{ \psia}]\) |
| \(t_{bd,set}\) | Configured blowdown time \([\unit{ \second}]\) |
| \(\tau_{bd}\) | Blowdown exponential decay time constant \([\unit{ \second}]\) |
| \(\epsilon\) | Legacy decay tolerance (0.02) \([\unit{ \unitless}]\) |
Modulating power while the compressor remains loaded.
Modulating power is anchored by maximum power and the maximum modulating power. Variable-displacement unloading uses exponent 2; modulation unloading uses exponent 1.
\begin{equation}\label{eq:load-unload-max-mod-power} P_{max,mod} = f_{P,FL}P_{max} \end{equation}
\begin{equation}\label{eq:load-unload-mod-power} P_{mod} = (P_{max} - P_{max,mod})\left(\frac{Q}{Q_{FL}}\right)^m + P_{max,mod} \end{equation}
| \(P_{max,mod}\) | Maximum modulating power floor \([\unit{ \kilo\watt}]\) |
| \(f_{P,FL}\) | Full-load power fraction used for modulation \([\unit{ \unitless}]\) |
| \(P_{max}\) | Maximum package power \([\unit{ \kilo\watt}]\) |
| \(P_{mod}\) | Modulation-stage package power \([\unit{ \kilo\watt}]\) |
| \(Q\) | Airflow demand represented by the curve point \([\unit{ \acfm}]\) |
| \(Q_{FL}\) | Full-load airflow \([\unit{ \acfm}]\) |
| \(m\) | Modulation exponent, 1 for modulation and 2 for variable displacement \([\unit{ \unitless}]\) |
Modules | |
| Load/Unload Average Power Formula | |
| Average package power over one load/unload cycle. | |
| Load/Unload Runtime Formula | |
| Core storage and blowdown runtime calculations. | |
| Load/Unload Modulation Formula | |
| Modulating power while the compressor remains loaded. | |
Files | |
| file | load_unload_compressor.h |
| Load/unload compressor assessment model declarations. | |
1.9.8