ikcape correlations

.github/workflows/tests.yml

@@ -0,0 +1,18 @@
+name: Run tests
+on: [push, pull_request]
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -e .[test]
+      - name: Test with pytest
+        run: |
+          pytest tests/ -v

README.md

@@ -3,8 +3,98 @@
   <img src="https://raw.githubusercontent.com/pathsim/pathsim-chem/main/docs/source/logos/chem_logo.png" width="300" alt="PathSim-Chem Logo" />
 </p>
 
-------------
+<p align="center">
+  <strong>Chemical engineering blocks for PathSim</strong>
+</p>
+
+<p align="center">
+  <a href="https://pypi.org/project/pathsim-chem/"><img src="https://img.shields.io/pypi/v/pathsim-chem" alt="PyPI"></a>
+  <img src="https://img.shields.io/github/license/pathsim/pathsim-chem" alt="License">
+</p>
+
+<p align="center">
+  <a href="https://docs.pathsim.org/chem">Documentation</a> &bull;
+  <a href="https://pathsim.org">PathSim Homepage</a> &bull;
+  <a href="https://github.com/pathsim/pathsim-chem">GitHub</a>
+</p>
+
+---
+
+PathSim-Chem extends the [PathSim](https://github.com/pathsim/pathsim) simulation framework with blocks for chemical engineering and thermodynamic property calculations. All blocks follow the standard PathSim block interface and can be connected into simulation diagrams.
+
+## Features
+
+- **IK-CAPE Thermodynamics** — 50+ blocks implementing the DECHEMA IK-CAPE standard for thermodynamic property calculations
+- **Pure Component Correlations** — Antoine, Wagner, Kirchhoff, Rackett, Aly-Lee, DIPPR, and 10 more temperature-dependent property correlations
+- **Mixing Rules** — Linear, quadratic, Lorentz-Berthelot, and other calculation-of-averages rules for mixture properties
+- **Activity Coefficients** — NRTL, Wilson, UNIQUAC, and Flory-Huggins models for liquid-phase non-ideality
+- **Equations of State** — Peng-Robinson and Soave-Redlich-Kwong cubic EoS with mixture support
+- **Fugacity Coefficients** — EoS-based and virial equation fugacity calculations
+- **Excess Enthalpy & Departure** — NRTL, UNIQUAC, Wilson, Redlich-Kister excess enthalpy and EoS departure functions
+- **Chemical Reactions** — Equilibrium constants, kinetic rate constants, and power-law rate expressions
+- **Tritium Processing** — GLC columns, TCAP cascades, bubblers, and splitters for tritium separation
+
+## Install
+
+```bash
+pip install pathsim-chem
+```
+
+## Quick Example
+
+Compute the vapor pressure of water at 100 °C using the Antoine equation:
+
+```python
+from pathsim_chem.thermodynamics import Antoine
+
+# Antoine coefficients for water (NIST)
+antoine = Antoine(a0=23.2256, a1=3835.18, a2=-45.343)
+
+# Evaluate at 373.15 K
+antoine.inputs[0] = 373.15
+antoine.update(None)
+P_sat = antoine.outputs[0]  # ≈ 101325 Pa
+```
+
+Use activity coefficients in a simulation:
+
+```python
+from pathsim_chem.thermodynamics import NRTL
+
+# Ethanol-water NRTL model
+nrtl = NRTL(
+    x=[0.4, 0.6],
+    a=[[0, -0.801], [3.458, 0]],
+    c=[[0, 0.3], [0.3, 0]],
+)
+
+# Evaluate at 350 K
+nrtl.inputs[0] = 350
+nrtl.update(None)
+gamma_ethanol = nrtl.outputs[0]
+gamma_water = nrtl.outputs[1]
+```
+
+## Modules
+
+| Module | Description |
+|---|---|
+| `pathsim_chem.thermodynamics.correlations` | 16 pure component property correlations (Antoine, Wagner, etc.) |
+| `pathsim_chem.thermodynamics.averages` | 10 mixing rules for calculation of averages |
+| `pathsim_chem.thermodynamics.activity_coefficients` | NRTL, Wilson, UNIQUAC, Flory-Huggins |
+| `pathsim_chem.thermodynamics.equations_of_state` | Peng-Robinson, Soave-Redlich-Kwong |
+| `pathsim_chem.thermodynamics.corrections` | Poynting correction, Henry's law |
+| `pathsim_chem.thermodynamics.fugacity_coefficients` | RKS, PR, and virial fugacity coefficients |
+| `pathsim_chem.thermodynamics.enthalpy` | Excess enthalpy and enthalpy departure functions |
+| `pathsim_chem.thermodynamics.reactions` | Equilibrium constants, rate constants, power-law rates |
+| `pathsim_chem.tritium` | GLC, TCAP, bubbler, splitter blocks for tritium processing |
+
+## Learn More
+
+- [Documentation](https://docs.pathsim.org/chem) — API reference and examples
+- [PathSim](https://github.com/pathsim/pathsim) — the core simulation framework
+- [Contributing](https://docs.pathsim.org/pathsim/latest/contributing) — how to contribute
 
-# PathSim Chemical Engineering Toolbox
+## License
 
-This toolbox extends the core pathsim package with domain specific component models for chemical engineering.
+MIT

docs/source/examples/equation_of_state.ipynb

@@ -0,0 +1,211 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Cubic Equations of State\n",
+    "\n",
+    "Simulating the compressibility factor of methane across a pressure sweep using the Peng-Robinson and Soave-Redlich-Kwong equations of state wired into a PathSim simulation."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Cubic equations of state compute the compressibility factor $Z = Pv/(RT)$ by solving a cubic polynomial at each $(T, P)$ condition. The EoS blocks take two inputs (temperature and pressure) and produce two outputs (molar volume and compressibility factor).\n",
+    "\n",
+    "At low pressure $Z \\to 1$ (ideal gas). At moderate pressure attractive forces cause $Z < 1$, and at high pressure excluded-volume effects push $Z > 1$."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import matplotlib.pyplot as plt\n",
+    "\n",
+    "from pathsim import Simulation, Connection\n",
+    "from pathsim.blocks import Source, Constant, Scope\n",
+    "\n",
+    "from pathsim_chem.thermodynamics import PengRobinson, RedlichKwongSoave"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## System Definition\n",
+    "\n",
+    "Create Peng-Robinson and SRK blocks for pure methane. A `Constant` block supplies a fixed temperature while a `Source` sweeps pressure from 0.1 MPa to 30 MPa."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Critical properties of methane\n",
+    "Tc, Pc, omega = 190.6, 4.6e6, 0.011\n",
+    "\n",
+    "# EoS blocks\n",
+    "pr = PengRobinson(Tc=Tc, Pc=Pc, omega=omega)\n",
+    "rks = RedlichKwongSoave(Tc=Tc, Pc=Pc, omega=omega)\n",
+    "\n",
+    "# Fixed temperature, logarithmic pressure sweep\n",
+    "import numpy as np\n",
+    "T_const = Constant(250)  # 250 K (above Tc, supercritical)\n",
+    "P_src = Source(func=lambda t: 10**(4 + t * 0.035))  # 10 kPa to ~30 MPa over 100s\n",
+    "\n",
+    "# Scopes: record Z from both EoS (output port 1)\n",
+    "scp_pr = Scope(labels=[\"Z_PR\"])\n",
+    "scp_rks = Scope(labels=[\"Z_RKS\"])"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Wiring\n",
+    "\n",
+    "Both EoS blocks receive the same $(T, P)$ inputs. We record the compressibility factor (output port 1) from each."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "sim = Simulation(\n",
+    "    blocks=[T_const, P_src, pr, rks, scp_pr, scp_rks],\n",
+    "    connections=[\n",
+    "        # Temperature -> both EoS (input port 0)\n",
+    "        Connection(T_const, pr, rks),\n",
+    "        # Pressure -> both EoS (input port 1)\n",
+    "        Connection(P_src, pr[1], rks[1]),\n",
+    "        # Z output (port 1) -> scopes\n",
+    "        Connection(pr[1], scp_pr),\n",
+    "        Connection(rks[1], scp_rks),\n",
+    "    ],\n",
+    "    dt=1.0,\n",
+    ")\n",
+    "\n",
+    "sim.run(100)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "time, Z_pr = scp_pr.read()\n",
+    "_, Z_rks = scp_rks.read()\n",
+    "P_vals = 10**(4 + time * 0.035) / 1e6  # MPa\n",
+    "\n",
+    "fig, ax = plt.subplots(figsize=(7, 5))\n",
+    "ax.semilogx(P_vals, Z_pr[0], label=\"Peng-Robinson\")\n",
+    "ax.semilogx(P_vals, Z_rks[0], \"--\", label=\"Soave-Redlich-Kwong\")\n",
+    "ax.axhline(1.0, color=\"gray\", linestyle=\"-.\", alpha=0.5, label=\"Ideal gas\")\n",
+    "ax.set_xlabel(\"Pressure [MPa]\")\n",
+    "ax.set_ylabel(\"Compressibility Factor Z\")\n",
+    "ax.set_title(\"Methane at T = 250 K\")\n",
+    "ax.legend()\n",
+    "ax.grid(True, alpha=0.3)\n",
+    "plt.tight_layout()\n",
+    "plt.show()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Both EoS give very similar results. The characteristic dip below $Z = 1$ at moderate pressures reflects attractive intermolecular forces, while the rise above $Z = 1$ at high pressures is due to repulsive (excluded volume) effects."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Mixture\n",
+    "\n",
+    "The EoS blocks also support mixtures through van der Waals one-fluid mixing rules. Here we set up a methane-ethane mixture and sweep pressure."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "pr_mix = PengRobinson(\n",
+    "    Tc=[190.6, 305.3],\n",
+    "    Pc=[4.6e6, 4.872e6],\n",
+    "    omega=[0.011, 0.099],\n",
+    "    x=[0.7, 0.3],\n",
+    ")\n",
+    "\n",
+    "T_const2 = Constant(300)\n",
+    "P_src2 = Source(func=lambda t: 10**(4 + t * 0.035))\n",
+    "scp_mix = Scope(labels=[\"Z_mixture\"])\n",
+    "\n",
+    "sim_mix = Simulation(\n",
+    "    blocks=[T_const2, P_src2, pr_mix, scp_mix],\n",
+    "    connections=[\n",
+    "        Connection(T_const2, pr_mix),\n",
+    "        Connection(P_src2, pr_mix[1]),\n",
+    "        Connection(pr_mix[1], scp_mix),\n",
+    "    ],\n",
+    "    dt=1.0,\n",
+    ")\n",
+    "\n",
+    "sim_mix.run(100)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "time_m, Z_mix = scp_mix.read()\n",
+    "P_mix = 10**(4 + time_m * 0.035) / 1e6\n",
+    "\n",
+    "fig, ax = plt.subplots(figsize=(7, 5))\n",
+    "ax.semilogx(P_vals, Z_pr[0], label=\"Pure CH₄ (250 K)\")\n",
+    "ax.semilogx(P_mix, Z_mix[0], \"--\", label=\"70/30 CH₄-C₂H₆ (300 K)\")\n",
+    "ax.axhline(1.0, color=\"gray\", linestyle=\"-.\", alpha=0.5)\n",
+    "ax.set_xlabel(\"Pressure [MPa]\")\n",
+    "ax.set_ylabel(\"Compressibility Factor Z\")\n",
+    "ax.set_title(\"Peng-Robinson: Pure vs Mixture\")\n",
+    "ax.legend()\n",
+    "ax.grid(True, alpha=0.3)\n",
+    "plt.tight_layout()\n",
+    "plt.show()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The mixture shows a deeper dip because ethane ($T_c = 305.3$ K) is near its critical temperature at 300 K, leading to stronger non-ideal behavior."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "name": "python",
+   "version": "3.11.0"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}