Dew point and exhaust temperature

In summary, the dew point is the temperature at which water vapor in a sample of air condenses into liquid water at the same rate as it evaporates. This affects the enthalpy of moist air, causing it to have a higher heat content compared to dry air at the same temperature. As a result, air conditioners have to work harder in moist air, leading to a higher exhaust temperature. A psychrometric chart can provide more data on this relationship.
  • #1
princejan7
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Homework Statement


I'm trying to find some information on "How does the dew point control the exhaust temperature of a thermodynamic cycle?"

Homework Equations


"The dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates."

The Attempt at a Solution


I haven't really found anything on this yet.
 
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  • #2
All I can observe is that the enthalpy (heat content) of moist air (higher dew point) is higher than that of dry air (lower dew point) at the same temperature. This means that the same amount of heat removed from a given mass of air will drop the air temperature less if the dew point is higher. Which is why air conditioners have to work harder in moist air than in dry for the same indoor-outdoor temperature differential.

Get a psychrometric chart sometime which will give you that data.
 

FAQ: Dew point and exhaust temperature

1. What is the dew point?

The dew point is the temperature at which air becomes saturated with water vapor and condensation begins to form. It is a measure of the amount of moisture in the air.

2. How is the dew point different from relative humidity?

The dew point is the actual amount of water vapor present in the air, while relative humidity is a measure of how close the air is to its saturation point. The dew point is a more accurate measure of moisture in the air.

3. Why is the dew point important in exhaust temperature calculations?

The dew point is important because it affects the amount of water vapor that can be present in the exhaust gases. If the exhaust temperature is below the dew point, the water vapor will condense, potentially causing damage to the exhaust system.

4. How does the dew point affect engine performance?

The dew point can affect engine performance by impacting the amount of water vapor in the air that is taken in by the engine. If the dew point is high, the air is more saturated with water vapor, which can decrease the amount of oxygen available for combustion and decrease engine efficiency.

5. Is there a relationship between dew point and exhaust temperature?

Yes, there is a direct relationship between dew point and exhaust temperature. As the dew point increases, so does the exhaust temperature. This is because the higher dew point leads to more water vapor in the exhaust gases, which requires more energy to heat up and maintain the exhaust temperature.

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