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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Chapter 4, Problem 4.12P
In the heating seasons the heat loss from a building (and thus the heating cost) is strongly dependent on the difference between the indoor and outdoor temperature. If the average outdoor temperature in a particular city during the heating season is 45 F (7 C), what is the effect on heating cost percentage-wise if the thermostat setting is fixed at 74 F (23.3 F) instead of 68 F (20 C)?
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During a warm summer night, the air inside a house is maintained at a fixed temperaturevia an air conditioning system. Separating the inside air from the outside air is a plane wall.The inner surface of the wall exchanges energy with the air inside the house via convection;the outer surface of the wall exchanges energy with the surrounding air via convection andthe night sky via radiation. Known system parameters are listed below.Inner air temperature ?? = 26°CSurrounding air temperature ?∞ = 33°CNight sky temperature ?? = 4°CWall thermal conductivity ?Wall-air convection coefficient ℎ = 30 W/m2-KWall emissivity ? = 0.85Wall thickness ?a) Set up the equations that you allow you to calculate the heat flux through the wall.Keep everything symbolic and be careful with your heat transfer directions.Hint: If the AC is on, what does that tell you about the net direction of heat transfer?b) Write a computer script that calculates the heat flux through the wall for 20 values ofthe ratio of the…
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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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