On an uncomfortable summer day, the air is at 87 °F and 80 % relative humidity. A laboratory air conditioner is to deliver 1.0 x 103 ft3/min of air at 55 °F in order to maintain the interior air at an average temperature of 75°F and a relative humidity of 40%.If the vent switch on the air conditioner is turned to the "open" position, outside air enters the unit as shown below.Assume A = 87 οF, B = 80 %, C = 55 οF.In the air conditioner, the air is cooled to a temperature low enough to condense the necessary amount of water and reheated to 55°F, at which point it has the same absolute humidity as the room air.Use the psychometric chart to estimate the rate (lbm/min) at which water is condensed, the temperature to which the air must be cooled to condense water at this rate, and the net tons of cooling required (Q⋅), where 1 ton of cooling = -12,000 Btu/h.[Note: The humid volume of the delivered air (at 55°F), which is difficult to read from the psychrometric chart, is 13.07 ft3/lbm dry air, and the heat capacity of liquid water is 1.0 Btu/(lbm °F).] The image illustrates the air conditioning process for a laboratory, detailing the flow and regulation of air temperature and humidity within the system. The diagram includes the following components:1. **Air Conditioner System**: - **Reheater and Cooler**: The air conditioner has two main components— a reheater and a cooler. These components adjust the air's temperature before it is delivered to the lab. - **Heat Exchange**: The system regulates heat with a cooling capacity denoted as \( \dot{Q} \) measured in tons, impacting how the air temperature and humidity are controlled.2. **Air Flow**: - **Outside Air**: Enters the air conditioner with an initial temperature of \( A \, ^\circ \text{F} \) and relative humidity \( h_r = B \% \). - **Delivered Air**: After processing through the cooler and reheater, the delivered air exits at \( C \, ^\circ \text{F} \).3. **Condensed Water**: Indicates that water is removed from the air during cooling, which results in condensed water being expelled from the system.4. **Lab Environment**: - **Exhaust**: Air leaves the lab at 75°F with a relative humidity of 40%, maintaining consistent conditions as it enters and exits. - **Lab Conditions**: The internal environment of the lab is maintained at 75°F with a relative humidity of 40%.The diagram effectively demonstrates the cyclical nature of the air conditioning system, showing how air is drawn, conditioned, and expelled, ensuring a stable lab environment.

Consider outside air: Temperature, TA = 87°F Relative humidity, hr(A) = 80% From the psychrometric…

Answered: On an uncomfortable summer day, the air…

Introduction to Chemical Engineering Thermodynamics

8th Edition

ISBN:9781259696527

Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Chapter1: Introduction

Section: Chapter Questions

Problem 1.1P

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On an uncomfortable summer day, the air is at 87 °F and 80 % relative humidity. A laboratory air conditioner is to deliver 1.0 x 10³ft³/min of air at 55 °F in order to maintain the interior air at an average temperature of 75°F and a relative humidity of 40%.
If the vent switch on the air conditioner is turned to the "open" position, outside air enters the unit as shown below.

Assume A = 87 ^οF, B = 80 %, C = 55 ^οF.

In the air conditioner, the air is cooled to a temperature low enough to condense the necessary amount of water and reheated to 55°F, at which point it has the same absolute humidity as the room air.

Use the psychometric chart to estimate the rate (lb_m/min) at which water is condensed, the temperature to which the air must be cooled to condense water at this rate, and the net tons of cooling required (Q⋅), where 1 ton of cooling = -12,000 Btu/h.

[Note: The humid volume of the delivered air (at 55°F), which is difficult to read from the psychrometric chart, is 13.07 ft³/lb_m dry air, and the heat capacity of liquid water is 1.0 Btu/(lbm °F).]

The image illustrates the air conditioning process for a laboratory, detailing the flow and regulation of air temperature and humidity within the system. The diagram includes the following components:

1. **Air Conditioner System**:
- **Reheater and Cooler**: The air conditioner has two main components— a reheater and a cooler. These components adjust the air's temperature before it is delivered to the lab.
- **Heat Exchange**: The system regulates heat with a cooling capacity denoted as \( \dot{Q} \) measured in tons, impacting how the air temperature and humidity are controlled.

2. **Air Flow**:
- **Outside Air**: Enters the air conditioner with an initial temperature of \( A \, ^\circ \text{F} \) and relative humidity \( h_r = B \% \).
- **Delivered Air**: After processing through the cooler and reheater, the delivered air exits at \( C \, ^\circ \text{F} \).

3. **Condensed Water**: Indicates that water is removed from the air during cooling, which results in condensed water being expelled from the system.

4. **Lab Environment**:
- **Exhaust**: Air leaves the lab at 75°F with a relative humidity of 40%, maintaining consistent conditions as it enters and exits.
- **Lab Conditions**: The internal environment of the lab is maintained at 75°F with a relative humidity of 40%.

The diagram effectively demonstrates the cyclical nature of the air conditioning system, showing how air is drawn, conditioned, and expelled, ensuring a stable lab environment.

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