Q1: Moist air is cooled along the line of constant __________ , when it is passed over a cold & dry cooling coil, such that no condensation occurs.

ANS:D - dew point temperature

The dew point temperature is the temperature at which air becomes saturated with moisture and water vapor begins to condense into liquid water, forming dew or fog. In other words, it is the temperature at which the air's relative humidity reaches 100% under constant pressure and constant volume conditions. When the temperature drops to the dew point, the air has reached its maximum capacity to hold water vapor. If the air continues to cool beyond the dew point, the excess moisture in the air must condense out as liquid water. This process can occur on surfaces such as grass, leaves, windows, or any other object that cools below the dew point temperature of the surrounding air. The dew point temperature is an important parameter in weather forecasting and comfort analysis. Higher dew point temperatures indicate more moisture in the air, while lower dew point temperatures indicate drier air. When the dew point temperature is close to the actual air temperature, the air is considered humid, and discomfort due to mugginess may be experienced. Conversely, when the dew point temperature is significantly lower than the air temperature, the air is considered dry, and evaporative cooling can be more effective in providing comfort. In summary, the dew point temperature is a critical measure of atmospheric moisture content and plays a significant role in determining weather conditions and human comfort levels.