💧 Falling Film Evaporator & Desalination Sizer

Size falling film evaporators and MED desalination plants: Chun & Seban falling film correlation, minimum wetting rate, vapor generation rate, and steam economy.

⚡ Fortran 90 Engine Double Precision (IEEE 754) ✓ ISO / ASME Validated

📊 Solver Telemetry ● ACTIVE

👁️ Consultations 35

⚡ Calculs faits 27

💾 Téléchargements 367 📦 Code Fortran 4.1 KB

📅 Mise en service Jun 2026

⏱️ Latence < 1 ms

💧 Falling Wavy Liquid Film & Steam Condensation Jacket

Real-time visual simulation: Gravity falling liquid film with vapor bubbles and outer condensing steam

📝 Configuration & Presets

🌊 Seawater MED Desalination 🥛 Skim Milk Concentration 🪵 Black Liquor Evaporator 🎋 Sugar Juice Evaporation

🧪 Liquid Feed Medium

Feed Solution Type:

Feed Mass Flow Rate [kg/h]:

Feed Temperature T_feed [°C]:

🌡️ Evaporator Operating Temperatures

Heating Steam Temp T_steam [°C]:

Evaporation Chamber T_evap [°C]:

📐 Vertical Tube Bundle Sizing

Number of Vertical Tubes N_t:

Tube Inner Diameter D_i [mm]:

Tube Length L [m]:

Chun & Seban Falling Film Model:
• Peripheral Wetting: Γ = ṁ_feed / (N_t · π · D_i) [kg/(m·s)]
• Film Reynolds: Re_f = 4 Γ / μ_L
• Minimum Wetting Criteria: Γ_min ≥ 0.04 kg/(m·s) (Prevents tube dryout & scaling)
• Evaporation Duty: Q̇ = U · A · (T_steam − T_evap) [kW].

📊 Evaporation Performance Results

📊 Output Summary
💾 Fortran Source

Evaporated Vapor Production Rate

6981 kg/h (1.94 kg/s)

Thermal Duty: 4547.1 kW (4.55 MW) | Area: 301.6 m²

SAFE (FULL WETTING FILM)

Wetting Rate (Γ) 0.088 kg/(m·s) Dryout limit = 0.04 kg/(m·s)

Falling Film Coeff (h_film) 872 W/(m²·K) Overall U = 754 W/(m²·K)

Film Reynolds Number (Re_f) 42 Laminar wavy film

Effective Temp Difference (ΔT) 20.0 °C Steam 110 °C → Evap 90 °C

📈 Evaporated Vapor Rate ṁevap (kg/h) vs Tube Count Nt

📊 Film Coeff hfilm [W/(m²·K)] vs Wetting Rate Γ [kg/(m·s)]

=================================================================
 THERMOFLUIDCALC — FALLING FILM EVAPORATOR SIZING REPORT
=================================================================
Case Title                 : Paper Mill Black Liquor Vertical Evaporator
Feed Liquid Medium         : Pulp & Paper Black Liquor (High Solids Evaporator)
Operating Temperatures     : Tfeed = 85.0 C, Tsteam = 110.0 C, Tevap = 90.0 C
Tube Bundle Geometry       : Nt = 240 tubes, Di = 50.0 mm, Length L = 8.00 m
-----------------------------------------------------------------
PERIPHERAL WETTING RATE (Γ): 0.0884 kg/(m.s) (SAFE (FULL WETTING FILM))
FILM REYNOLDS NUMBER (Ref) : 42
Falling Film Coeff (h_film): 872.4 W/(m2.K)
Overall Heat Transfer (U)  : 753.8 W/(m2.K)
Total Evaporator Area      : 301.59 m2
THERMAL HEAT DUTY (Q)      : 4547.10 kW (4.547 MW)
EVAPORATED VAPOR PRODUCTION: 6980.6 kg/h (1.94 kg/s)
=================================================================

📘 Calculation Methodology & Falling Film Standards

Thin Wavy Liquid Film Evaporation

Falling film evaporators operate with liquid descending as a thin film along the inner wall of vertical tubes under gravity, enabling very high heat transfer coefficients and low residence times.

Minimum Wetting Rate ($\Gamma_{min}$)

Maintaining adequate liquid flow per perimeter prevents dry spots, which cause severe fouling, scaling, and tube burnout.

Key Engineering Assumptions

Chun & Seban turbulent and laminar falling film correlation.
Saturated steam condensation on the outer shell side.
Widely used in multi-effect distillation (MED) seawater desalination, milk powder plants, and black liquor recovery.

ThermoFluidCalc Engineering Report