air in the smoke house has WBT of 20 degree centigrade and DBT of 25 deg.centigrade,determine RH,DPT and % moisture content.What will be the change if the air is heated to DBT of 40 degree centigrade ?

To determine the relative humidity (RH), dew point temperature (DPT), and percent moisture content, we can use psychrometric calculations. We will also calculate the changes after heating the air to a DBT of 40 degrees Celsius.

1. Relative Humidity (RH):
The relative humidity can be determined using the formula:
RH = (Pw / Pws) * 100
where Pw is the partial pressure of water vapor in the air, and Pws is the saturation vapor pressure at the given temperature.

Given:
WBT = 20 degrees Celsius
DBT = 25 degrees Celsius

Find the saturation vapor pressure (Pws) at 25 degrees Celsius using a psychrometric chart or an online calculator. Let's assume Pws = 3.17 kPa.

Next, we need to find the partial pressure of water vapor (Pw) in the air. To do this, we can use the formula:
Pw = Pws * (RH / 100)

Assuming RH is 100% for a smokehouse, we have:
Pw = 3.17 kPa

Therefore, the RH is 100%.

2. Dew Point Temperature (DPT):
The dew point temperature represents the temperature at which the air reaches 100% relative humidity. We can find it using a psychrometric chart or an online calculator.

Using the given information, the dew point temperature can be determined as follows:
DPT = 20 degrees Celsius (since the WBT is equal to the dew point temperature at 100% relative humidity).

Therefore, the Dew Point Temperature (DPT) is 20 degrees Celsius.

3. Percent Moisture Content:
The percent moisture content can be found using the formula:
Percent Moisture Content = (Mass of Water Vapor / Mass of Dry Air) * 100

Since the relative humidity is 100%, the air is saturated, which means the mass of water vapor is equal to the mass of dry air. Therefore, the percent moisture content is 100%.

Now, let's calculate the changes when the air is heated to a DBT of 40 degrees Celsius.

Given:
DBT = 40 degrees Celsius

To determine the new RH and DPT, we follow the same steps as above, but using the new DBT values.

Calculate the new Pws at 40 degrees Celsius, assuming Pws = 7.38 kPa.

Next, calculate the new Pw using the new RH value (which will remain 100%):

Pw = Pws * (RH / 100)
= 7.38 kPa

Therefore, the RH remains 100%.

Calculating the new DPT using the new WB temperature (=DPT) at 100% RH:

DPT = 40 degrees Celsius

The Dew Point Temperature (DPT) also remains 40 degrees Celsius.

Finally, since the RH remains 100%, and the mass of water vapor is equal to the mass of dry air, the percent moisture content also remains 100%.

In summary, when the air is heated to a DBT of 40 degrees Celsius, the relative humidity, dew point temperature, and percent moisture content all remain the same at 100%.