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 3, Problem 3.45P
The design condition for a space is 77 F (25 C) db and 50 percent relative humidity with 55 F (13 C) db supply air at 90 percent relative humidity. A 50-ton, constant- volume space air-conditioning system uses face and bypass and water temperature control. Outdoor air is supplied at 95 F (35 C) db, 60 percent relative humidity with a ratio of 1 lbm (kg) to 5 lbm (kg) return air. A part-load condition exists where the total space load decreases by 50 percent and the SHF increases to 90 percent. The outdoor air condition changes to 85 F (29 C) db and 70 percent relative humidity. Assume sea-level pressure. (a) At what temperature must the air be supplied to the space under the part-load condition? (b) If the air leaving the coil has a dry bulb temperature of 60 F (15 C), what is the ratio of the air bypassed to that flowing through the coil? (c) What is the apparatus dew point temperature for both the design and part-load conditions? (d) Show all the processes on a psychrometric chart.
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The design condition for a space is 77oF db and 50% relative humidity with 55oF db supply air at 90% relative humidity. A 50-ton, constant-volume space air- conditioning system uses face and bypass and water temperature control. Outdoor air is supplied at 95oF db, 60% relative humidity with a ratio of 1 lbm to 5 lbm re-circulated air. A part-load condition exists where the total space load is decreased by 50% and the SHF is increased to 90%. The outdoor air condition changes to 85oF db and 70% relative humidity. Assume sea-level conditions.
a) At full – load conditions:a. Show all the processes on a psychrometric chart.b. Determine the temperature must the air be supplied to the space at fullload conditions.c. Determine the apparatus dew point temperature at full load conditions.
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Chapter 3 Solutions
Heating Ventilating and Air Conditioning: Analysis and Design
Ch. 3 - A space is at a temperature of 75 F (24 C), and...Ch. 3 - Determine the humidity ratio, enthalpy, and...Ch. 3 - Suppose the air of Problem 3-2 is at a pressure...Ch. 3 - What is the enthalpy of moist air at 70 F (20 C)...Ch. 3 - The inside surface temperature of a window in a...Ch. 3 - What is the mass flow rate of dry air flowing at a...Ch. 3 - Determine the dew point of moist air at 80 F (27...Ch. 3 - A room is to be maintained at 72 F (22 C) db. It...Ch. 3 - Air is cooled from 80 F db and 67 F wb until it is...Ch. 3 - Conditions in a room are measured to be 80 F db...
Ch. 3 - The environmental conditions in a room are to be...Ch. 3 - Air enters a cooling coil at the rate of 5000 cfm...Ch. 3 - Air flowing in a duct has dry and wet bulb...Ch. 3 - Air is humidified with the dry bulb temperature...Ch. 3 - Air at 38 C db and 20 C wb is humidified...Ch. 3 - Two thousand cfm (1.0 m3/s) of air at an initial...Ch. 3 - Air at 40 F (5 C) db and 35 F (2 C) wb is mixed...Ch. 3 - Rework Problem 3-25, using Chart 1a, with the...Ch. 3 - The design cooling load for a zone in a building...Ch. 3 - Assume that the air in Problem 3-22 is supplied to...Ch. 3 - The sensible heat loss from a space is 500,000...Ch. 3 - Air enters a refrigeration coil at 90 Fdb and 75...Ch. 3 - A building has a total heating load of 200,000...Ch. 3 - Reconsider Problem 3-36 for an elevation of 5000...Ch. 3 - The system of Problem 3-34 has a supply air fan...Ch. 3 - An evaporative cooling system is to be used to...Ch. 3 - A cooling system is being designed for use at high...Ch. 3 - Consider a space heating system designed as shown...Ch. 3 - A variable-air-volume VAV cooling system is a type...Ch. 3 - Rework Problem 3-43 for an elevation of 5000 feet...Ch. 3 - The design condition for a space is 77 F (25 C) db...Ch. 3 - Rework Problem 3-45 for an elevation of 5000 feet...Ch. 3 - It is necessary to cool and dehumidify air from 80...Ch. 3 - Conditions in one zone of a dual-duct conditioning...Ch. 3 - Rework Problem 3-48 for an elevation of 5000 ft...Ch. 3 - A water coil in Problem 3-48 cools return air to...Ch. 3 - A multizone air handler provides air to several...Ch. 3 - Under normal operating conditions a zone has a...Ch. 3 - An interior zone of a large building is designed...Ch. 3 - Outdoor air is mixed with room return air to...Ch. 3 - Consider an enclosed swimming pool. The pool area...Ch. 3 - One particular zone served by a multizone air...Ch. 3 - A research building requires 100 percent outdoor...Ch. 3 - A space requires cooling in the amount of 120,000...
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