# ai4UCheE — Full Chemical Engineering Reference & Solver Guide (llms-full.txt)

Canonical URL: https://chemeng.ai4u.now/
Workbench URL: https://chemeng.ai4u.now/app
Markdown Twin: https://chemeng.ai4u.now/index.md
Last Updated: 2026-11-01

## 1. Mission & Engineering Rigor Invariants
`ai4UCheE` (ChemEng's Intelligent Workbench) is the Chemical Engineering AI vertical within the `ai4u` ecosystem (`ai4U23`), built for both students (`🎓 Learn Mode`) and EPC/plant engineers (`🏭 Plant Mode`). Every calculation enforces three non-negotiable physical guardrails:
1. **Gauge vs. Absolute Pressure (`psig` vs. `psia`):** All thermodynamic (`DIPPR Eq. 101`, `Peng-Robinson`), ideal-gas (`C_A0 = P_abs / RT`), and pump suction (`NPSH_A`) calculations explicitly convert gauge pressure `P_psig` to absolute pressure `P_psia = P_psig + 14.6959` (`101,325 Pa`).
2. **Fanning (`f_F`) vs. Darcy (`f_D = 4 * f_F`) Friction Factor:** *Perry's 9th Ed., Fig. 6-9 (p. 6-10)* plots the **Fanning** friction factor `f_F`, whereas the Darcy-Weisbach head-loss equation `h_f = f_D * (L/D) * (v^2 / 2g)` requires the **Darcy** friction factor `f_D = 4 * f_F` `[Perry's 9th Ed., Eqs. 6-37..6-39, p. 6-11]`.
3. **3-Stage White-Box Equation Proofs:** Every solver displays `Stage 1: Symbolic Equation` → `Stage 2: Live Numerical Substitution` → `Stage 3: Evaluated Result with Units & Textbook Citation`.

## 2. Complete Workbench & Solver Catalog

### WB1 — Calibrated Nomographs & Chart Verifier
- **10 Calibrated Multi-Book Nomographs:**
  1. `6-10`: Moody / Fanning Friction Factor `f_F(Re)` `[Perry's 9th Ed., Fig. 6-9, p. 6-10]`
  2. `14-37`: Fair's Souders-Brown Entrainment Flooding `C_sb(F_LV)` `[Perry's 9th Ed., Fig. 14-32, p. 14-37]`
  3. `14-57`: Eckert Generalized Pressure Drop Correlation (GPDC) `[Perry's 9th Ed., Fig. 14-55, p. 14-57]`
  4. `2-53`: DIPPR Eq. 101 Liquid Vapor Pressure `P_vp(T)` `[Perry's 9th Ed., Table 2-8, p. 2-53]`
  5. `19-6`: Levenspiel CSTR vs. PFR Volume Ratio `V_CSTR / V_PFR` `[Perry's 9th Ed., Sec. 19, p. 19-6; Fogler Ch. 2]`
  6. `6-52`: Terminal Settling Sphere Drag Coefficient `C_D(Re_p)` `[Perry's 9th Ed., Fig. 6-61, p. 6-52; BSL Ch. 6]`
  7. `4-18`: Lee-Kesler Compressibility Factor `Z^0(P_r, T_r)` `[Perry's 9th Ed., Sec. 4, p. 4-18; SVNA Ch. 3]`
  8. `15-10`: Spherical Catalyst Thiele Effectiveness `eta(phi_1)` `[Fogler 7th Ed., Ch. 15; BSL Ch. 18]`
  9. `14-15`: Kremser Absorption / Stripping Stages `N_OG(A)` `[Perry's 9th Ed., Sec. 14, p. 14-15; Seader Ch. 6]`
  10. `23-42`: Semenov Thermal Runaway Critical Locus `psi(T_c)` `[Perry's 9th Ed., Sec. 23; Crowl & Louvar Ch. 8]`

### WB2 — Thermodynamics, Phase Equilibria & DIPPR
- **DIPPR Eq. 101 Vapor Pressure:** `ln P_vp = A + B/T + C*ln(T) + D*T^E` (Pa, K) `[Perry's 9th Ed., Table 2-8, p. 2-53]`.
- **DIPPR Eq. 106 Heat of Vaporization:** `Delta H_vap = A * (1 - T_r)^(B + C*T_r + D*T_r^2 + E*T_r^3)` (J/kmol) `[Perry's 9th Ed., Table 2-69, p. 2-120]`.
- **Carlson Property-Package Decision Tree:** Nonpolar hydrocarbons (`Peng-Robinson` / `SRK`), Polar non-electrolytes (`Wilson` / `NRTL` / `UNIQUAC`), Liquid-liquid split LLE (`NRTL` or `UNIQUAC` — never `Wilson`), Vapor-phase carboxylic acid dimerization (`NRTL-HOC`).

### WB3 — Fluid Mechanics, Transport & Piping Hydraulics
- **Turbulent Colebrook / Haaland Friction & Darcy-Weisbach:** Explicit `f_D = 4 * f_F` guardrail across `Min 70%`, `Normal 100%`, and `Rated 120%` flow cases.
- **Pump Suction Cavitation (`NPSH_A`):** `NPSH_A = (P_suction,abs - P_vp) / (rho * g) + z_suction - h_f,suction` `[Perry's 9th Ed., Sec. 10, pp. 10-24..25]`.
- **ISA-75.01 Control Valve Choked Flow:** Liquid pressure recovery factor `F_L`, critical pressure ratio factor `F_F = 0.96 - 0.28 * sqrt(P_v / P_c)`, and choked pressure drop `Delta P_max = F_L^2 * (P_1 - F_F * P_v)` `[Perry's 9th Ed., Eqs. 8-77..8-81, p. 8-71]`.

### WB4 — Separation Processes, McCabe-Thiele & Column Hydraulics
- **Fenske-Underwood-Gilliland & McCabe-Thiele:** Minimum stages `N_min`, minimum reflux `R_min`, operating reflux `R = (R/R_min) * R_min`, and feed thermal quality `q`-line slope `q / (q - 1)`.
- **Fair's Entrainment Flooding & Column Sizing:** Flow parameter `F_LV = (L/V) * sqrt(rho_V / rho_L)`, Souders-Brown capacity parameter `C_sb`, flooding velocity `u_n,flood = C_sb * (sigma / 20)^0.2 * sqrt((rho_L - rho_V) / rho_V)`, and percent of flood `[Perry's 9th Ed., Fig. 14-32, p. 14-37]`.

### WB6 — Kinetics, Catalysis & Chemical Reactor Design
- **Levenspiel CSTR vs. PFR Sizing & PBR Ergun Pressure Drop:** `dX/dW = -r'_A / F_A0`, `dy/dW = -alpha * (1 + epsilon * X) / (2 * y)` where `y = P / P_0` `[Fogler 7th Ed., Ch. 2 & Ch. 5]`.
- **Internal Pore Diffusion (Thiele Modulus):** Spherical catalyst effectiveness `eta = (3 / phi^2) * (phi * coth(phi) - 1)` `[Fogler 7th Ed., Ch. 15; BSL Ch. 18]`.
- **Semenov Thermal Runaway:** Heat generation `G(T)` vs. removal `R(T)`, dimensionless Semenov number `psi`, critical runaway limit `psi_crit = 1/e ≈ 0.368` `[Fogler 7th Ed., Ch. 12; Crowl & Louvar 4th Ed., Ch. 8]`.

### WB5 — 6-Book Corpus & 25-Section Perry's Atlas
- Covers all 25 sections of *Perry's 9th Edition* (`Sec 1` Conversion Factors through `Sec 25` Materials of Construction) with interactive 2-parameter SVG curves and Back-of-Book Index lookup (`pp. 2244–2274`).

## 3. Curriculum Progression, Persistence, AI Data Flow & Engineering Boundary
- **Default Landing (`/app`):** Opens on **Subject 1: Year 2 Thermodynamics (`wb2-thermo-dippr`)** in `🎓 Learn Mode` (`?wb=` and `?mission=` / `?problem=` deep-links supported; bilingual `en`/`vi` via `/?lang=vi` and `/app?lang=vi`).
- **5-Step Causal Chain:** `1. Plant Symptom -> 2. ChE Subject (Year 2–4) -> 3. Governing Equation -> 4. Interactive SVG Lab -> 5. Preliminary Screening Window`.
- **Educational & Preliminary Engineering Boundary:** Calculations use deterministic textbook correlations for undergraduate instruction and preliminary screening — not a substitute for licensed PE sign-off, relief-device sizing (API 520/521), or HAZOP/SIL certification. All 24 plant cases are realistic educational composites grounded in published literature. Every individual result badge displays an inline steady-state textbook assumptions & preliminary-screening qualifier.
- **AI Co-Pilot Data Flow:** Interactive sliders and equation solvers run 100% locally in the browser without external calls. Submitting a chat prompt to `POST /api/copilot` sends only the prompt text, selected context chips, and numerical `<current-screen>` parameters to the AI4U.now LLM gateway (`gateway.ai4u.now`, model `gemini-4-argon-low`, with zero-network local deterministic fallback if offline); zero personal identifiers are attached and prompts are processed ephemerally without server-side conversation retention.
- **Persistence & Deletion Boundary:** Student practice points (`+35 pts DIY / +12 pts Assisted`; mastery % = average across 6 ChE concept domains) persist in browser `localStorage` only (`Local Browser Demo`, resettable via `↺ Reset Scorecard`). Exported preliminary calculation sheets persist anonymously in local SQLite (`saved_calculations`) and can be deleted anytime via `DELETE /api/saved-calculations` or the `🗑️ Delete Saved SQLite Sheets` button in the Calc Sheet modal.
- **Textbook Copyright & Support Boundary:** Independent bibliographic section/page index and equation solver; no copyrighted textbook PDFs/EPUBs are hosted or distributed. Maintained by AI4U.now Engineering Education Team (`support@ai4u.now`, `https://github.com/ai4U23/ai4UCheE/issues`).