Soil Water Content

Overview

Engineering reference data for Soil Water Content in combustion engineering.

Key Formulas

Heat Release

$Q = \dot{m} \cdot HV$

Fuel energy release rate.

Air-Fuel Ratio

$AF = \frac{m_{air}}{m_{fuel}}$

Mass of air per mass of fuel.

Excess Air

$EA = \frac{O_2}{21 - O_2} \times 100\%$

From flue gas oxygen measurement.

Variables

Symbol	Description	Unit
$Q$	Heat release rate	W
$\dot{m}$	Mass flow rate	kg/s
$HV$	Heating value	J/kg
$AF$	Air-fuel ratio	—

Testing and Measurement

The soil water content can be determined using the oven-drying method as per ASTM D 2216-92. This involves measuring the mass of a wet soil specimen, then drying it in an oven at a temperature of $110^\circ\text{C}$ for 12 to 16 hours. The water content is calculated using the formula:

$w = 100 \frac{M_w}{M_s}$

where:

• $w$ is the moisture content (%),
• $M_w$ is the mass of water in the soil (kg or lb),
• $M_s$ is the dry mass of the soil (kg or lb).

Typical Values

Soil water content varies widely depending on the soil type. Values can range from essentially 0% for near-surface rubble, gravel, or clean sand, up to 1200% for organic soils like fibrous peat.

References

• Original Source