Humidity Ratio Psychrometric Chart -

Understanding the Humidity Ratio: A Critical Analysis of Moisture Representation on the Psychrometric Chart

[ W = \fracm_vm_a ]

On the chart, the mix point lies on a straight line between the two state points, proportionally closer to the larger mass flow. In drying, air removes moisture from a product. The drying potential depends on the difference between the saturation humidity ratio at the product surface temperature and the air’s W. Lower W (drier air) increases the driving force. 4.4 Cooling Coil Dehumidification Air passing over a cold coil below dew point reduces W. The condensate removed per kg dry air = ( W_in - W_out ). This directly sizes condensate drains. 5. Humidity Ratio vs. Other Moisture Metrics | Property | Symbol | Temperature dependent? | Direct measure of moisture mass? | Use case | |----------|--------|------------------------|--------------------------------|-----------| | Humidity ratio | W | No (for fixed P) | Yes | Mass balances, drying, latent load | | Relative humidity | φ | Yes | No | Comfort, microbial growth | | Dew point temp. | T_dp | N/A (indirect) | Indirect (unique with W) | Avoiding condensation | | Wet-bulb temp. | T_wb | Yes | No | Evaporative cooling, enthalpy | humidity ratio psychrometric chart