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A space is at a temperature of 75 F (24 C), and the relative humidity is 45 percent. Find (a) the partial pressures of the air and water vapor, (b) the vapor density, and (c) the humidity ratio of the mixture. Assume standard sea-level pressure.

**(a)**

The partial pressure of the air.

The partial pressure of water vapor.

## Answer to Problem 3.1P

The value of partial pressure of air is

The value of partial pressure of vapor is

### Explanation of Solution

**Given:**

The temperature of the space is

The relative humidity is

**Formula used:**

The expression for the partial pressure of air is given as,

Here,

The expression for the partial pressure of vapor is given as,

Here,

**Calculation:**

The partial pressure of vapor can be calculated as,

The partial pressure of air can be calculated as,

**Conclusion:**

Therefore, the value of partial pressure of air is

Therefore, the value of partial pressure of vapor is

**(b)**

The vapor density.

## Answer to Problem 3.1P

The value of vapor density is

### Explanation of Solution

**Given:**

The temperature of the space is

The relative humidity is

**Formula used:**

The expression for the vapor density is given as,

Here,

**Calculation:**

The vapor density can be calculated as,

**Conclusion:**

Therefore, the value of vapor density is

**(c)**

The humidity ratio of the mixture.

## Answer to Problem 3.1P

The value of humidity ratio is

### Explanation of Solution

**Given:**

The temperature of the space is

The relative humidity is

**Formula used:**

The expression for the humidity ratio is given as,

**Calculation:**

The humidity ratio can be calculated as,

**Conclusion:**

Therefore, the value of humidity ratio is

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# Chapter 3 Solutions

Heating Ventilating and Air Conditioning: Analysis and Design

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- "For an air-water system at a given moisture content, the temperature decreases as the humidity increases."Is this statement true or false? Shouldn't it be relative humidity?
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- Refrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning