ThermoFluidCalc Engineering Report

Two-Phase Closed Thermosiphon (TPCT) Sizing Analysis — 2026-08-23 20:54:01
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⚡ Two-Phase Closed Thermosiphon & Heat Pipe Sizer

Size two-phase closed thermosiphons (TPCT) and heat pipes: flooding/entrainment limit, boiling burnout limit, effective thermal conductivity (W/m·K), and temperature drop.

⚡ Fortran 90 Engine Double Precision (IEEE 754) ✓ ISO / ASME Validated
📊 Solver Telemetry ● ACTIVE
👁️ Consultations 33
⚡ Calculs faits 27
💾 Téléchargements 400 📦 Code Fortran 4.1 KB
📅 Mise en service Jun 2026
⏱️ Latence < 1 ms
⚡ Outils & Rapports :
💾 Télécharger Fortran 90

⚡ Two-Phase Evaporation, Vapor Transport & Condensation Loop

Real-time visual simulation: Bottom pool boiling, rising vapor core, top condenser film return

📝 Configuration & Presets

☀️ Solar Evacuated Tube 🖥️ CPU Sintered Heat Pipe 🏭 Industrial Waste Heat TPCT 🛰️ Satellite Ammonia Loop
🧪 Working Fluid & Thermal Load
📐 Thermosiphon Tube Dimensions
Two-Phase Thermosiphon Formulation:
• Flooding Limit (Wallis/Faghri): Q̇flood = Ck² Av hfg [g·σ·(ρL−ρv)]1/4 [ρv-1/4 + ρL-1/4]-2
• Boiling Burnout Limit: Q̇boiling = 0.18 Ae hfg ρv1/2 [g·σ·(ρL−ρv)]1/4
• Effective Conductivity: keff = (Q̇ · Leff) / (Av · ΔT) >> 100,000 W/(m·K).

📊 Operating Limits & Results

📊 Output Summary
💾 Fortran Source

Maximum Heat Transport Capacity (Q̇max)
2340 W (2.34 kW)
Carried: 350 W | Critical limit: FLOODING / ENTRAINMENT LIMIT
OPTIMAL SAFE OPERATION
Effective Thermal Conductivity (keff) 91444 W/(m·K) 230x higher than copper
End-to-End Temp Drop (ΔT) 11.3 °C Nearly isothermal transport
Flooding / Entrainment Limit 2340 W Vapor-liquid shear threshold
Pool Boiling Burnout Limit 87984 W Evaporator CHF limit

📈 Max Capacity Qmax (W) vs Vapor Sat Temp Tv (°C)

📊 Effective Conductivity keff [W/(m·K)] vs Heat Load Q (W)

=================================================================
 THERMOFLUIDCALC — TWO-PHASE CLOSED THERMOSIPHON REPORT
=================================================================
Case Title                 : Solar Thermal Evacuated Tube Water Thermosiphon
Working Fluid Medium       : Water (High Latent Heat, 30°C to 200°C)
Operating State            : Q = 350.0 W, Tv = 85.0 deg C
Thermosiphon Geometry      : Do = 22.0 mm, Di = 20.0 mm, Le = 1500 mm, La = 100 mm, Lc = 150 mm
-----------------------------------------------------------------
MAX HEAT TRANSPORT CAPACITY: 2339.7 W (2.34 kW)
Critical Operating Limit   : FLOODING / ENTRAINMENT LIMIT
Flooding Limit (Wallis)    : 2339.7 W
Boiling Pool Burnout Limit : 87983.7 W
End-to-End Temp Drop (ΔT)  : 11.27 deg C
EFFECTIVE THERMAL CONDUCT. : 91444 W/(m.K) (Superconductor)
SAFETY OPERATING STATUS    : OPTIMAL SAFE OPERATION
=================================================================

📘 Calculation Methodology & Heat Pipe Standards

Latent Heat Phase-Change Loop

Heat is absorbed by liquid boiling in the evaporator, transported at high speed as vapor along the core, and released by condensation at the cold condenser end, achieving thermal conductivities $100\times$ to $500\times$ higher than solid copper.

Flooding / Entrainment Limit

Occurs when high-velocity upward vapor strips droplets from the downward-returning liquid film, causing evaporator dryout and sharp temperature runaway.

Key Engineering Assumptions

  • Gravity-assisted thermosiphon or wick-assisted heat pipe orientation.
  • Wallis/Faghri flooding correlation and Kutateladze boiling limit.
  • Widely used in solar evacuated tubes, electronics CPU coolers, permafrost ground stabilization, and industrial heat recovery.