Mass Flux Density Converter

Kilogram per Hour per Square Meter (kg/h/m²)

The standard SI unit of mass flux density, representing the mass flow per unit area per unit time. 1 kg/h/m² = mass per unit area per hour. Essential for heat exchanger and mass transfer equipment design.

Common uses: Heat exchanger design, evaporator specifications, membrane filtration, gas absorption columns, and chemical equipment sizing.

Kilogram per Second per Square Meter (kg/s/m²)

Higher-rate mass flux density. 1 kg/s/m² = 3,600 kg/h/m². Used for high-intensity separation processes and rapid mass transfer applications.

Application: High-pressure operations, emergency venting systems, rapid separation processes, and high-throughput industrial equipment.

Gram per Second per Square Meter (g/s/m²)

Fine-scale mass flux density. 1 g/s/m² = 0.001 kg/s/m². Used for laboratory-scale and precision membrane processes.

Application: Laboratory membrane testing, micro-scale filtration, analytical separations, and research equipment.

Gram per Second per Square Centimeter (g/s/cm²)

Very fine mass flux density. 1 g/s/cm² = 10,000 g/s/m². Used for small-area laboratory devices and analytical instruments.

Application: Microfluidic devices, thin-film testing, analytical chromatography, and laboratory separation equipment.

Kilogram per Hour per Square Foot (kg/h/ft²)

Non-SI mass flux density unit. 1 kg/h/ft² ≈ 10.764 kg/h/m². Used in North American engineering practice and older technical literature.

Application: US equipment specifications, legacy chemical plant design, and North American industrial standards.

Pound per Hour per Square Foot (lb/h/ft²)

Common North American unit. 1 lb/h/ft² ≈ 4.88 kg/h/m². Standard in US chemical engineering design and industrial specifications.

Application: US chemical plants, HVAC design, American engineering standards, and legacy equipment documentation.

Pound per Second per Square Foot (lb/s/ft²)

High-rate North American unit. 1 lb/s/ft² ≈ 17,600 lb/h/ft². Used for high-intensity industrial processes in US facilities.

Application: High-pressure US industrial systems, rapid separation processes, and emergency venting in American plants.

Mass Flux Density in Equipment Design: Critical Concept

Mass flux density (also called mass flux or superficial mass velocity) is fundamental for designing separation equipment:

• Heat exchangers: Higher flux requires stronger materials and larger driving forces
• Membrane filtration: Flux is limited by membrane fouling and breakthrough pressure
• Distillation columns: Tray spacing and flooding limits depend on mass flux
• Gas absorption: Column diameter and height determined by allowable mass flux
• Evaporators: Heat transfer efficiency linked to mass flux through the surface

Design equation: Mass Flux = (Total Mass Flow) ÷ (Equipment Cross-Sectional Area)

Typical Mass Flux Density Values by Application

• Laminar flow membranes: 0.1-10 kg/h/m²
• Reverse osmosis: 10-50 kg/h/m²
• Ultrafiltration: 50-200 kg/h/m²
• Microfiltration: 200-1,000 kg/h/m²
• Shell-and-tube heat exchangers: 200-1,000 kg/h/m²
• Plate heat exchangers: 500-2,000 kg/h/m²
• Distillation columns (tray): 100-500 kg/h/m²
• Gas absorption: 50-300 kg/h/m²
• Evaporators: 200-1,500 kg/h/m²
• High-pressure filtration: 1,000-5,000 kg/h/m²

Key Conversion Factors & Relationships

• 1 kg/h/m² = 0.0002778 kg/s/m²
• 1 kg/s/m² = 3,600 kg/h/m²
• 1 kg/h/m² = 0.2048 lb/h/ft²
• 1 lb/h/ft² = 4.882 kg/h/m²
• 1 g/s/m² = 0.001 kg/s/m²
• 1 g/s/cm² = 10,000 g/s/m² = 10 kg/s/m²
• Mass Flux = (Volumetric Flow in m³/s) × (Fluid Density in kg/m³) / (Area in m²)
• For equipment comparison: Higher flux = smaller equipment but more operational challenges