14-16 An 8-m^3 tank contains saturated air at 30^∘ C, 105 kPa Determine (a) the mass of dry air,

step 1 So as per the statement of this question, it says that the volume of a tank is equal to 8 meter

14-16 An 8-m^3 tank contains saturated air at 30^∘ C, 105...

14-16 An $8-\mathrm{m}^{3}$ tank contains saturated air at $30^{\circ} \mathrm{C}, 105 \mathrm{kPa}$ Determine $(a)$ the mass of dry air, $(b)$ the specific humidity, and $(c)$ the enthalpy of the air per unit mass of the dry air.

Key Concepts

Enthalpy of Moist Air

The enthalpy of moist air is the sum of the enthalpy of the dry air and the enthalpy of the water vapor it contains. It represents the total thermal energy per unit mass of dry air and includes contributions due to both sensible heat (from temperature) and latent heat (from the phase change of water), making it an essential parameter in energy analysis of air-conditioning and atmospheric processes.

Moist Air Composition

Moist air is a mixture of dry air and water vapor. In thermodynamics, air is typically analyzed by separating these two components because water vapor has significantly different properties from dry air. Recognizing the state as saturated implies that the water vapor present is at its maximum allowable pressure at that temperature, meaning it is in equilibrium with any condensed phase.

Ideal Gas Law

The ideal gas law (PV = nRT) is essential in calculating properties such as density and mass for the gaseous components. In problems involving air, the law is often applied separately to dry air and water vapor to compute their respective masses using the given pressure, volume, and temperature, ensuring accurate determination of mixture properties.

Specific Humidity

Specific humidity is defined as the mass of water vapor per unit mass of dry air. It is a key concept in psychrometrics that characterizes the moisture content of air without being affected by temperature or pressure changes, and it is used for various calculations in energy and mass balances in atmospheric and HVAC applications.

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