Índice de Temperatura Efetiva

Summary

This video lesson focuses on how to determine the effective temperature index in a workplace environment, ensuring thermal comfort as per NR17 regulations. Key factors include measuring dry and wet bulb temperatures, air velocity, and relative humidity, all of which influence the comfort level. The video also introduces the psychrometric chart, which helps in calculating humidity and effective temperature. The lesson includes practical examples, demonstrating how to read the effective temperature index and assess whether the environment meets the comfort standards, such as air speed limits and temperature ranges. Understanding these parameters is essential for maintaining a comfortable work environment.

Takeaways

• 😀 Effective temperature index in work environments must be between 20°C and 23°C to meet the comfort standards established by NR17.
• 😀 Air velocity should not exceed 0.75 meters per second in a comfortable work environment.
• 😀 The relative humidity of the air in the work environment should not fall below 40%.
• 😀 To calculate the effective temperature index, the dry bulb temperature, wet bulb temperature, and air velocity are key parameters.
• 😀 A psychrometric chart can be used to relate dry bulb temperature, wet bulb temperature, and relative humidity to each other.
• 😀 The effective temperature index can be determined using a psychrometric chart if two of the three key parameters are known.
• 😀 Air velocity plays an important role in determining the effective temperature in a work environment.
• 😀 In practice, the effective temperature can be obtained from an effective temperature chart or psychrometric chart after identifying the correct temperature and air velocity parameters.
• 😀 For example, in one exercise, the effective temperature was determined to be 23°C based on the provided parameters (dry bulb 25°C, wet bulb 20°C, air velocity 0 m/s).
• 😀 If the temperature of the wet bulb is 19°C, the dry bulb is 22°C, and the air velocity is 1 m/s, the effective temperature is found to be 19°C, which does not meet the comfort standards of NR17.

Q & A

What is the effective temperature index (Índice de Temperatura Efetiva)?

The effective temperature index is a measure used to assess the comfort of an environment based on its temperature, air velocity, and humidity. According to NR17, it should range between 20°C and 23°C for a comfortable working environment.

What parameters must be measured to determine the effective temperature index?

To calculate the effective temperature index, you need to measure the dry bulb temperature, wet bulb temperature, air velocity, and relative humidity.

What are the required conditions for air velocity and relative humidity in a comfortable work environment?

The air velocity should not exceed 0.75 meters per second, and the relative humidity should be no lower than 40%, according to NR17 guidelines.

How can the effective temperature index be obtained using the psychrometric chart?

The psychrometric chart shows the relationship between dry bulb temperature, wet bulb temperature, and relative humidity. If two of these values are known, the third can be determined using the chart.

What is the role of the wet bulb and dry bulb temperatures in determining comfort?

The wet bulb and dry bulb temperatures are key measurements for determining comfort in a workspace. They represent the amount of moisture in the air and the actual air temperature, respectively.

In the first exercise example, what were the results for the effective temperature index?

In the first example, the wet bulb temperature was 20°C, the dry bulb temperature was 25°C, and the air velocity was 0 m/s. Using these values, the effective temperature index was calculated to be 23°C.

Why was the effective temperature index in the second example not within the required range?

In the second example, the wet bulb temperature was 19°C, the dry bulb temperature was 22°C, and the air velocity was 1 m/s. The effective temperature index calculated was 19°C, which is outside the acceptable range of 20–23°C according to NR17.

What does the psychrometric chart display and how is it used in these exercises?

The psychrometric chart displays various thermodynamic properties of air, including the relationship between temperature and humidity. It is used in these exercises to calculate relative humidity and determine the effective temperature index when given dry and wet bulb temperatures.

What does the chart indicate when you have the values for wet bulb temperature and dry bulb temperature?

When you have the values for both the wet bulb and dry bulb temperatures, the chart allows you to trace a line to find the relative humidity. It can also help you determine the effective temperature index by relating air velocity to these temperatures.

What was the relative humidity in the second exercise, and how was it calculated?

In the second exercise, the relative humidity was calculated to be 75%. This was done by using the psychrometric chart, where the wet bulb temperature was 19°C and the dry bulb temperature was 22°C, then finding the corresponding humidity curve.