HVAC & Psychrometrics Simulators

How to Use

1. Select air condition state (dry-bulb temperature, wet-bulb temperature, or relative humidity) and enter numeric values in SI units (°C, %).
2. Choose the psychrometric process type: sensible heating/cooling, humidification, dehumidification, or adiabatic saturation.
3. Input mass flow rate (kg/s) and system parameters (pressure, duct area); simulator computes enthalpy, humidity ratio, density, and outlet conditions.
4. Review plotted state points on the psychrometric chart; export results for ductwork sizing and load calculations.

Worked Example

Office supply air at 21°C dry-bulb, 50% RH, 2.5 kg/s flow rate enters a VAV cooling coil. Target outlet: 13°C dry-bulb, saturated. Initial state: h₁ = 45.2 kJ/kg, ω₁ = 7.8 g/kg. After 8 K sensible cooling and condensation: h₂ = 28.5 kJ/kg, ω₂ = 5.2 g/kg. Cooling duty Q = 2.5 × (45.2 − 28.5) = 41.75 kW; latent load from dehumidification = 2.5 × (7.8 − 5.2) × 2501 = 13.0 kW. Total coil load = 54.75 kW; condensate drainage rate = 6.5 mL/s.

Practical Notes

1. Verify barometric pressure (101.325 kPa at sea level; adjust for elevation above 500 m to recalculate saturation properties).
2. Adiabatic saturation processes (swamp coolers, wet-bulb temperature measurement) follow constant wet-bulb locus; use for evaporative cooling feasibility in dry climates (RH < 30%).
3. Cross-check coil performance: bypass factor typically 0.1–0.2 for residential units; actual outlet approaches wet-bulb by factor × (inlet − saturation) plus saturation temperature.
4. Duct leakage and thermal losses reduce effective sensible cooling; multiply theoretical capacity by 0.85–0.95 for field conditions.