Answer :
To determine the enthalpy of air with a given dry-bulb and wet-bulb temperature, you would typically use a psychrometric chart. Here’s how you can interpret these values:
1. Understand the Terms:
- Dry-bulb Temperature (DBT): This is the temperature of air measured by a regular thermometer when the air is dry. For this scenario, the dry-bulb temperature is 95°F.
- Wet-bulb Temperature (WBT): This is the temperature indicated by a thermometer covered in a water-soaked cloth over which air is passed. The wet-bulb temperature is 75°F.
2. Using a Psychrometric Chart:
- Locate the given dry-bulb temperature (95°F) on the horizontal axis of the psychrometric chart.
- Find the wet-bulb temperature (75°F) line on the chart. Wet-bulb lines usually slope upwards to the right.
- Follow both these lines until they intersect. This point represents the state of the air in terms of dry-bulb and wet-bulb temperatures.
3. Finding Enthalpy:
- Once you have located the intersection point on the psychrometric chart, look at the enthalpy lines, which are usually slanted lines on the chart.
- The enthalpy of air at the intersection point can then be read from the corresponding enthalpy line.
By analyzing these values, the enthalpy of the air with a 95°F dry-bulb and 75°F wet-bulb temperature is found to be approximately 38.0 Btu/lb.
Hence, the correct answer is b. 38.0 Btu/lb.
1. Understand the Terms:
- Dry-bulb Temperature (DBT): This is the temperature of air measured by a regular thermometer when the air is dry. For this scenario, the dry-bulb temperature is 95°F.
- Wet-bulb Temperature (WBT): This is the temperature indicated by a thermometer covered in a water-soaked cloth over which air is passed. The wet-bulb temperature is 75°F.
2. Using a Psychrometric Chart:
- Locate the given dry-bulb temperature (95°F) on the horizontal axis of the psychrometric chart.
- Find the wet-bulb temperature (75°F) line on the chart. Wet-bulb lines usually slope upwards to the right.
- Follow both these lines until they intersect. This point represents the state of the air in terms of dry-bulb and wet-bulb temperatures.
3. Finding Enthalpy:
- Once you have located the intersection point on the psychrometric chart, look at the enthalpy lines, which are usually slanted lines on the chart.
- The enthalpy of air at the intersection point can then be read from the corresponding enthalpy line.
By analyzing these values, the enthalpy of the air with a 95°F dry-bulb and 75°F wet-bulb temperature is found to be approximately 38.0 Btu/lb.
Hence, the correct answer is b. 38.0 Btu/lb.
