Answer:
Based on the search results, the specific question is:
During wintertime, the inside surface temperature of a glass door is 5°C where the air has a temperature of 22°C Dry Bulb, 20 percent relative humidity, and a pressure of 101.325 kPa pressure. Perform hand calculation using steam table to evaluate the enthalpy of air in this stage. Will moisture condense on the glass door?
To calculate the enthalpy of air in this stage, we can use a psychrometric chart or steam tables. Assuming we use steam tables, we can follow these steps:
Step 1: Find the saturation pressure of water vapor at 5°C using steam tables. From [2] and [7], we know that the partial pressure of water vapor in the air is equal to the saturation pressure at the current temperature times the relative humidity. Thus, we need to determine if the partial pressure of water vapor = the saturation pressure. If the partial pressure of water vapor is greater than the saturation pressure, then moisture will condense on the glass door.
From the steam tables, we find that the saturation pressure of water vapor at 5°C is 0.871 kPa.
Step 2: Calculate the partial pressure of water vapor in the air. From the given relative humidity of 20%, we can calculate the partial pressure of water vapor using:
Partial pressure of water vapor = Relative humidity x Saturation pressure
Partial pressure of water vapor = 0.20 x 0.871 kPa = 0.174 kPa
Step 3: Calculate the partial pressure of dry air. From the given pressure of 101.325 kPa and the partial pressure of water vapor calculated in step 2, we can determine the partial pressure of dry air using:
Partial pressure of dry air = Total pressure – Partial pressure of water vapor
Partial pressure of dry air = 101.325 kPa – 0.174 kPa = 101.151 kPa
Step 4: Find the enthalpy of dry air and water vapor at 22°C and 101.151 kPa using steam tables. Then, calculate the enthalpy of the air mixture using:
Enthalpy of air mixture = (Enthalpy of dry air x Mass of dry air) + (Enthalpy of water vapor x Mass of water vapor)
Mass of water vapor = partial pressure of water vapor / (Gas constant x Temperature)
Mass of dry air = Total mass of air – Mass
Step-by-step explanation: