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 5, Problem 5.18P
A wall exactly like the one described in Table construction 1, has dimensions of
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Two inches of urethane foam will reduce heat loss close to 1000% when applied to a 2-inch diameter uninsulated steel pipe. Assume the pipe wall thickness is 0.25-inches, the pipe interior convective heat loss (hi) is 500 BTU/hr-ft2-oF, and the pipe outside convective heat loss ho 20 BTU/hr-ft2-oF, k steel is 25 BTU/hr-ft-oF, and k insulaton is 0.023 BTU/hr-ft-oF. (hint - calculate heat loss with and without insulation.
c) A steel pipe of 100 mm bore, and 10 mm bore thickness, carrying dry saturated steam at 28
bars, is insulated with a 40 mm layer of moulded insulation. This insulation in turn is
insulated with a 60 mm layer of felt. The atmospheric temperature is 15 °C.
Calculate:
(i) the rate of heat loss by the steam per metre pipe length.
(ii) the temperature of the outside
Dimensions in mm
surface.zzzzzzz
h₂-15 W/m²K
Steel
k₁=50 W/mK
AVALEHT
Ø100
1₂
"
Steam 28 bar
h-550 W/m²K,
Inner heat transfer coefficient = 550 W/m² K
Outer heat transfer coefficient = 15 W/m² K
Thermal conductivity of steel = 50 W/m K
Thermal conductivity of felt = 0.07 W/m K
Moulded
insulation
Felt
Moulded insulation
K₂=0.09 W/mK
Thermal conductivity of moulded insulation = 0.09 W/m
40
10.
A
60
15°C
Felt
K₁=0.07 W/mK
zzzzzzzz
Project 3: It is vital to optimize the heat loss from a house through well designed composition and proper selection of the insulation layer of the wall layers. Your role as a thermal power engineer to investigate the heat transfer performance of a composite walls. Your head of department asked you to analyze the composite walls structure in Figure.3 and determine the steady rate of heat transfer and total heat loss, if the following design specifications must be met:
_Indoor room temperature must be maintained at 20??.
− Outdoor temperature mostly is -10?? in a hard winter.
− Wall is made of plywood with thermal conductivity constant of ?? = 0.115 ?/(?.?) .
− Fiberglass insulation is used with thermal conductivity constant of ?? = 0.045 ?/(?.?) .
− Plaster board is used as inner layer for decoration purpose with thermal conductivity constant of ?? = 0.27 ?/(?.?) .
− Convection heat transfer coefficients for indoor and outdoor are ℎ?? = 34 ?/(?2.?) and ℎ?? = 65 ?/(?2.?) , respectively.…
Chapter 5 Solutions
Heating Ventilating and Air Conditioning: Analysis and Design
Ch. 5 - Determine the thermal conductivity of 4 in. (100...Ch. 5 - Compute the unit conductance C for 512 in. (140...Ch. 5 - Compute the unit thermal resistance and the...Ch. 5 - What is the unit thermal resistance for an inside...Ch. 5 - Compute the thermal resistance per unit length for...Ch. 5 - Assuming that the blocks are not filled, compute...Ch. 5 - The partition of Problem 5-4 has still air on one...Ch. 5 - The pipe of Problem has water flowing inside with...Ch. 5 - Compute the overall thermal resistance of a wall...Ch. 5 - Compute the overall heat-transfer coefficient for...
Ch. 5 - Estimate what fraction of the heat transfer for a...Ch. 5 - Make a table similar to Table 5-4a showing...Ch. 5 - Estimate the unit thermal resistance for a...Ch. 5 - Refer to Problem 5-13, and estimate the unit...Ch. 5 - A ceiling space is formed by a large flat roof and...Ch. 5 - A wall is 20 ft (6.1 m) wide and 8 ft (2.4 m) high...Ch. 5 - Estimate the heat-transfer rate per square foot...Ch. 5 - A wall exactly like the one described in Table...Ch. 5 - Prob. 5.19PCh. 5 - Compute the overall heat-transfer coefficient for...Ch. 5 - Compute the overall heat transfer for a single...Ch. 5 - Determine the overall heattransfer coefficient for...Ch. 5 - A basement is 2020ft(66m) and 7 ft (2.13 m) below...Ch. 5 - Estimate the overall heat-transfer coefficient for...Ch. 5 - Rework Problem 5-23 assuming that the walls are...Ch. 5 - A heated building is built on a concrete slab with...Ch. 5 - A basement wall extends 6 ft (1.8 m) below grade...Ch. 5 - A 2440ft(7.312.2m) building has a full basement...Ch. 5 - The floor of the basement described in Problem...Ch. 5 - Assume that the ground temperature tg is 40 F (10...Ch. 5 - Use the temperatures given in Problem 5-30 and...Ch. 5 - A small office building is constructed with a...Ch. 5 - A 100 ft length of buried, uninsulated steel pipe...Ch. 5 - Estimate the heat loss from 100 m of buried...Ch. 5 - A large beverage cooler resembles a small building...Ch. 5 - Consider the wall section shown in Fig. 5-10. (a)...Ch. 5 - A building has floor plan dimensions of 3060ft....Ch. 5 - Compute the temperature of the metal roof deck of...Ch. 5 - Consider the wall section shown in Fig. -4a,...Ch. 5 - Consider the knee space shown in Fig. 5-11. The...Ch. 5 - Estimate the temperature in an unheated basement...
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