Heating Ventilating and Air Conditioning: Analysis and Design
6th Edition
ISBN: 9780471470151
Author: Faye C. McQuiston, Jeffrey D. Spitler, Jerald D. Parker
Publisher: Wiley, John & Sons, Incorporated
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Textbook Question
Chapter 4, Problem 4.14P
To save energy in large, chilled water systems, the water temperature delivered to the cooling coils can be increased. A larger quantity of warmer supply air can remove the same energy from a space as a smaller quantity of cooler air. What could happen to the humidity of the space? Are there times during a daily cycle when the humidity load of certain spaces might be greatly reduced? Discuss.
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Is it possible that during sensible cooling process the condition of air reaches a relative humidity of more than 100%.
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An air-conditioning system operates at a total pressure of 1 atm and consists of a
heating section and a humidifier that supplies wet steam (saturated water vapor) at
100°C. Air enters the heating section at 10°C and 70 percent relative humidity at a rate
of 32 m /min, and it leaves the humidifying section at 20°C and 60 percent relative
humidity. Use data from the tables.
Sat. vapor
100°C
Heating
coils
Humidifier
10°C
Air
20°C
70%
60%
ymYmin
P=1 atm
Determine the temperature and relative humidity of air when leaves the heating section.
The temperature is
°C.
The relative humidity is
%.
Using a psychrometric diagram, describe the heating and humidification process from the following data. Initially the air is heated at dry bulb temperature (DBT) 40 ° C and RH 55%. The air is heated to DBT 90 ° C. The heated air is then flowed through a humidifier to increase the RH to 25%. For this process, calculate
a. change in absolute humidity of air from initial to final conditions = kg water / kg air
b. change in enthalpy of air from initial to final conditions = kj / kg air
Chapter 4 Solutions
Heating Ventilating and Air Conditioning: Analysis and Design
Ch. 4 - Using Fig. 4-1, draw a conclusion about the...Ch. 4 - Using Fig. 4-1, draw a conclusion about the...Ch. 4 - Select comfortable summer design conditions (dry...Ch. 4 - It is desired to use a space as a large classroom...Ch. 4 - An indoor tennis facility finds that it has...Ch. 4 - Work Problem 4-5 for an average air speed at court...Ch. 4 - In an occupied space the mean air velocity is...Ch. 4 - An occupied space is being held at 76 F (24 C) and...Ch. 4 - What do you think is the best thermostat setting...Ch. 4 - With the air conditioning running and the...
Ch. 4 - Discuss how an emergency government mandate to set...Ch. 4 - In the heating seasons the heat loss from a...Ch. 4 - Air motion can be good or bad, depending on the...Ch. 4 - To save energy in large, chilled water systems,...Ch. 4 - Overhead fans (Casablanca fans) are often reversed...Ch. 4 - A school classroom is designed for 30 people. (a)...Ch. 4 - Carbon dioxide is being generated in an occupied...Ch. 4 - Each person in a room is assumed to be producing...Ch. 4 - An air-handling system must handle 2000 cfm with a...Ch. 4 - Prob. 4.20PCh. 4 - How many filter modules will be required using the...Ch. 4 - Work Problem 4-21 assuming that the filter is a...Ch. 4 - The M-200, 0.60.60.2 filters of Table 4-3 are to...Ch. 4 - Investigate the feasibility of using 100 percent...Ch. 4 - Work Problem 4-24 but replace the 100 percent...Ch. 4 - Using M-15 filter media and the requirement of 60...Ch. 4 - A filter system is available that will filter out...Ch. 4 - A maximum of 10 smokers are anticipated in a smong...Ch. 4 - Solve Ex. 4-4 assuming that the filter is in...Ch. 4 - Solve Problem 4-28 assuming that the filter is in...Ch. 4 - Fora 3000-ft3 combination and exercise operation,...Ch. 4 - A classroom with a capacity of 225 people is...
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