Heating, Ventilation, and Air Conditioning: Analysis and Design
6th Edition
ISBN: 9781119628798
Author: Faye C. McQuiston; Jerald D. Parker; Jeffrey D. Spitler
Publisher: Wiley Global Education US
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 5, Problem 5.32P
A small office building is constructed with a concrete slab floor. Estimate the heat loss per unit length of perimeter. Assume (a) R-5 (R-0.88) vertical edge insulation 2 ft (60 cm) wide; (b) edge insulation at slab edge only. Assume an outdoor design temperature of 5 F (—15 C) and indoor temperature of 70 F (21 C).
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
An electric wire having a diameter of 1.5 mm and covered with a plastic insulation (thickness = 2.5 mm) is exposed to air at 300 K and ho=20 W/m2.K. The insulation has a thermal conductivity (k) of 0.4 W/m.K.
Assuming the wire surface temperature is constant at 400 K and is not affected by the covering
a)Calculate the value of the critical radius.
b)Calculate the heat loss per meter of wire length with no insulation.
c)Calculate the heat loss per meter of wire length with insulation.
An electric wire having a diameter of 1.5 mm and covered with a plastic insulation (thickness = 2.5 mm) is exposed to air at 300 K and ho = 20 W/m2.K. The insulation has a thermal conductivity (k) of 0.4 W/m.K.Assuming the wire surface temperature is constant at 400 K and is not affected by the coveringa) Calculate the value of the critical radius.b) Calculate the heat loss per meter of wire length with no insulation.c) Calculate the heat loss per meter of wire length with insulation.
p.s Could you write the solution clearly? It is hard to understand when written in text. A paper photo with solution would be better. Thanks in advance
A dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheathing with a thermal
conductivity of k, = 0.1 W/m-K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by
applying an L; = 25-mm-thick layer of extruded insulation characterized by k; = 0.029 W/m-K to the exterior of the original
sheathing. The extruded insulation is, in turn, covered with an L, = 5-mm-thick architectural glass with kg = 1.4 W/m-K. Determine
the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are Ti = 22°C and T0
-15°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5 W/m?-K and h, = 25 W/m²-K, respectively.
The heat flux through the original walls is i
W/m?.
The heat flux through the retrofitted walls is i
W/m?.
Chapter 5 Solutions
Heating, Ventilation, 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...
Additional Engineering Textbook Solutions
Find more solutions based on key concepts
A 20-lb force is applied to the control rod AB as shown. Knowing that the length of the rod is 9 in. and that t...
Statics and Mechanics of Materials
Determine the length of the cantilevered beam so that the maximum bending stress in the beam is equivalent to t...
Mechanics of Materials (10th Edition)
List several uses of the arbor press.
Machine Tool Practices (10th Edition)
The spring of k and unstretched length 1.5R is attached to the disk at a radial distance of 0.75R from the cent...
Engineering Mechanics: Statics
A windowmounted air conditioner removes 3.5kJ from the inside of a home using 1.75 kJ work input. How much ener...
EBK FUNDAMENTALS OF THERMODYNAMICS, ENH
19.8 Calculate the allowable tensile load for the connection shown. The plates are ASTM A36 steel and the weld ...
Applied Statics and Strength of Materials (6th Edition)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- 1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.arrow_forwardAs a designer working for a major electric appliance manufacturer, you are required to estimate the amount of fiberglass insulation packing (k = 0.035 W/m K) that is needed for a kitchen oven shown in the figure below. The fiberglass layer is to be sandwiched between a 2-mm-thick aluminum cladding plate on the outside and a 5-mm-thick stainless steel plate on the inside that forms the core of the oven. The insulation thickness is such that the outside cladding temperature does not exceed 40C when the temperature at the inside surface of the oven is 300C. Also, the air temperature in the kitchen varies from 15Cto33C, and the average heat transfer coefficient between the outer surface of the oven and air is estimated to be 12.0W/m2K. Determine the thickness of the fiberglass insulation that is required for these conditions. What would be the outer surface temperature when the inside surface of the oven is at 475C?arrow_forward2.30 An electrical heater capable of generating 10,000 W is to be designed. The heating element is to be a stainless steel wire having an electrical resistivity of ohm-centimeter. The operating temperature of the stainless steel is to be no more than 1260°C. The heat transfer coefficient at the outer surface is expected to be no less than in a medium whose maximum temperature is 93°C. A transformer capable of delivering current at 9 and 12 V is available. Determine a suitable size for the wire, the current required, and discuss what effect a reduction in the heat transfer coefficient would have. (Hint: Demonstrate first that the temperature drop between the center and the surface of the wire is independent of the wire diameter, and determine its value.)arrow_forward
- 1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.arrow_forward1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.4arrow_forwardWearing layers of clothing in cold weather is often recommended because dead-air spaces between the layers keep the body warm. The explanation for this is that the heat loss from the body is less. Compare the rate of heat loss for a single 2-cm-thick layer of wool [k=0.04W/(mK)] with three 0.67-cm layers separated by 1.5 mm air gaps. The thermal conductivity of air is 0.024 W(mK).arrow_forward
- Q2- Water flows inside a steel pipe with an ID of 2.5 cm. The wall thickness is 2 mm, and the convection coefficient on the inside is 100 Wm? C. The convection coefficient on the outside is 10 W/n C. The pipe is covered with a layer of asbestos. 1-determine the thickness of the asbestos layer at the critical insulation radius of the pipe. 2-calculate the change percent of heat transfer with and without the insulation. 3-commet on your results,arrow_forwardA dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheathing with a thermal conductivity of k, = 0.1 W/m-K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L; = 25-mm-thick layer of extruded insulation characterized by k; = 0.029 W/m-K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1.4 W/m-K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are Ti = 22°C and T.0 -17.5°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5W/m?-K and h, = 25 W/m²-K, respectively. The heat flux through the original walls is i W/m?. The heat flux through the retrofitted walls is i W/m?.arrow_forwardQ1. Double glazed window is made of 2 glass panes of 6 mm thick each with an air gap of 6 mm between them. Assuming that the air layer is stagnant and only conduction is involved, determine the thermal resistance and overall heat transfer coefficient. The inside is exposed to convection with h - 15 W/m?. K and the outside to 9 W/m'. K. Compare the values with that of a single glass of 12 mm thickness. The conductivity of the glass - 1.4 W/m. K and that for air is 0.025 W/m. K. h, = 15 Wim'k Glass Air gap Giass 14 Wmk =0.025 WimK h Wim'k 6 mm Q2. A 2m long, 0.3cm diameter electrical wire extends across a room at 15°C. Heat is generated in the wire as a result of resistance heating, and the surface temperature of the wire is measured to be 152°C in steady operation. Also, the voltage drop and electric current through the wire are measured to be 60 V and 1.5 A, respectively. Disregarding any heat transfer by radiation, determine the convection heat transfer coefficient for heat transfer…arrow_forward
- Required info: There is a 2.00 cm thick stagnant air pocket. a) What thickness of cork would have the same R-factor as the stagnant air pocket? The thermal conductivity of air is 0.0230 W/m-K and of cork is 0.0460 W/m-K. b) What thickness of tin would be required for the same R-factor as a 2.00-cm-thick stagnant air pocket? The thermal conductivity of air is 0.0230 W/m:K and of tin is 66.8 W/m-K. THANK Uarrow_forwardQ2/ An insulated steam pipe having an outside Steam pipe diameter of 30 mm is to be covered with two Better ination (4) Paer ination () layers of insulation, each haying thickness of 20 mm. The thermal conductivity of one material is 5 times that of the other. Sm L 1. Assuming that the inner and outer surface temperatures of composite insulation are fixed, how much will heat transfer be increased when better insulation material is next to the pipe than it is the outer layer?arrow_forwardSuppose a 3 in schedule 80 steel pipe is covered with 1 in of an insulation havingk = 60 mW/moC and the outside of the insulation is exposed to an environmenthaving h = 10 W/m2oC and Tf = 20oC. The temperature of the inside of the pipe is250oC. For unit length of the pipe calculate (a) the overall thermal resistance and(b) the heat loss (in Watts).arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
Principles of Heat Transfer (Activate Learning wi...
Mechanical Engineering
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Cengage Learning
Understanding Conduction and the Heat Equation; Author: The Efficient Engineer;https://www.youtube.com/watch?v=6jQsLAqrZGQ;License: Standard youtube license