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 5.26P
A heated building is built on a concrete slab with dimensions of
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Q2/ A composite wall is formed of a 2.5 cm copper plate, a 3.2 mm layer of
asbestos, and a 5 cm layer of fiberglass. The wall is subjected to an overall
temperature difference of 560 C. Calculate the heat flow per unit area
through the composite structure.
R Value:
Wall: 0.961m2k/w
Floor: 0.676m2k/w
Roof: 0.7465m2k/w
In a table format show with calculations and research how much money you can save by installing a 115mm layer of insulation (R2.9) in your walls, floor and ceiling over a 5 and 10 year period. Consider the capital costs. Hint: State the current R value of each component. Convert to U value. Calculate new R value of each component (walls, floor and ceiling). Convert to U value. Use Q(W)=A*(change in U)*temperature change. Determine price for installation of new insulation. Determine price saved based on less heat loss through each component separately, then add all values together, and calculate per 5 years and per 10 years. Present all of this information in a table. You do not need to draw any diagrams, simply add the R value in series with your current components R values.
Assume the energy cost is 25 cents kWh
[2] A reservoir of hot water kept at 380K is well insulated except for a copper rod with a
cross sectional area of 0.25 m? and a length of 0.50 meters. The rod is also well insulated
except for its ends and the other end is in a second well insulated reservoir of water held
at 280K.
a) Determine the rate of heat flow through the copper rod.
b) Calculate the temperature at the center of the rod (0.25 meters from either end).
Then extend the process to find the temperature at each point 0.1m along the rod.
c) Calculate the rate of entropy change at each end of the rod.
d) Using your answer for (c), show that the statements "Heat flows spontaneously from
high temperature to low temperature." and "Any spontaneous process causes the entropy
of the universe to increase." are logically equivalent for situations with heat flow.
e) Each reservoir of water holds 1 m of water. With a steady flow established, the power
fails so that the heating and cooling of the water ceases. What are the…
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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- 1.3 A furnace wall is to be constructed of brick having standard dimensions of Two kinds of material are available. One has a maximum usable temperature of 1040°C and a thermal conductivity of 1.7 W/(m K), and the other has a maximum temperature limit of 870°C and a thermal conductivity of 0.85 W/(m K). The bricks have the same cost and are laid in any manner, but we wish to design the most economical wall for a furnace with a temperature of 1040°C on the hot side and 200°C on the cold side. If the maximum amount of heat transfer permissible is 950 , determine the most economical arrangement using the available bricks.arrow_forward2. Calculate the heat loss for the structure described below. Use the indoor design setpoint of 70°F. ● . . . ● ● Hint: Utilize the Q=U*A*(ti-to) & Q = U'*P*(ti-to). Make sure to reference the following tables and examples to help assist you solve this problem; Table 5-5a, Table 5-8, Table 5-4a, Example 5-3, Eq. 5-23, and Fig 5-8. Given: i. Location: Des Moines, IA @ 99% winter OAT ii. Walls: Table 5.7, Construction 2 iii. Floor: Concrete slab with 2-ft, R-5.4, vertical edge insulation iv. Windows: Double-Insulating Glass; 1/4-in. air space; e = 0.6 on surface 2, 3x4-ft, double hung, reinforced vinyl frame; three on each side v. vi. Roof-Ceiling: Same as Example 5.3, height of 8-ft vii. House Plan: Single story, 36-ft x 64-ft Doors: Wood, 1-3/4-in. panel doors with metal storm doors, three each, 3x6.75-ft Qwindows = Qdoors= Qwalls = Qroof/ceiling= Qfloor = QTOTAL = Btu/(hroft²0F) Btu/h Heat Loss Btu/h Heat Loss Btu/h Heat Loss Btu/h Heat Loss Btu/h Heat Lossarrow_forwardyou are assigned by your food engineering professor to assist a food manufacturing company as part of your task. On your first day of report, the owner wants to know if their furnace is still in condition, in which the heat loss per square meter should be at least 1,000 W/m2. The details of the furnace are as follows. The furnace wall is 1m by 1m. It is made up of 3 layers, in which the inner wall is made up of fire brick, followed an insulating brick and finally, red brick for the outer layer. You checked the inside surface temperature and got a temperature of 870oC which is 830oC hotter than the outer surface. Other data are provided from the furnace manual and specs. Co-efficient of thermal conduciveness and thickness of the layers are as follows: 1.0 W/m-K, thickness: 22 cm 0.12 W/m-K, thickness: 7.5 cm 0.75 W/m-K, thickness: 11 cmarrow_forward
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