What is the Enthalpy when the Dry Bulb Temperature is 90°F, Humidity Ratio is 106 grains, and Relative Humidity is 50%?

In thermodynamics, the enthalpy of a substance in the gas phase is an important property that can be calculated using various parameters, such as dry bulb temperature, humidity ratio, and relative humidity. In this scenario, with a dry bulb temperature of 90°F, a humidity ratio of 106 grains, and a relative humidity of 50%, you can utilize steam tables and psychrometric charts or equations to find the enthalpy.

The enthalpy is typically expressed in BTUs per pound of dry air and includes contributions from both the sensible heat and the latent heat of the moisture in the air. The sensible heat can be calculated based on the dry bulb temperature, while the latent heat is influenced by the humidity ratio.

Given the specific parameters for the dry bulb temperature and the humidity ratio, the calculated enthalpy corresponds to the logical outcome of using the appropriate formulas or charts that synthesize these variables.

Choosing the response that corresponds to 38 BTU's/lb illustrates the correct application of these psychrometric principles. This aligns with standard approximations and calculations found in air-conditioning and heating textbooks, supporting that for the given conditions, this is the accurate determination of enthalpy.