HEAT+MASS TRANSFER(LL)-W/ACESS
5th Edition
ISBN: 9781260516906
Author: CENGEL
Publisher: MCG
expand_more
expand_more
format_list_bulleted
Videos
Question
Chapter 1, Problem 89P
To determine
The case for which energy required will be greater.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
7.Consider a person standing in a room maintained at 20°C at all times. The inner surfaces of the walls, floors, and ceiling of the house are observed to be at an average temperature of 12°C in winter and 23°C in summer. Determine the rates of radiation heat transfer between this person and the surrounding surfaces in both summer and winter if the exposed surface area, emissivity, and the average outer surface temperature of the person are 1.6 m2, 0.95, and 32°C, respectively.
2.
(a)
Consider a 25-cm-diameter spherical ball at 700 K suspended in air and assume the emissivity of the ball to be ε=0.95.
Calculate:
(i)
the total emissive power in kW/m2;
(ii)
the total amount of radiation emitted by the ball in 3 minutes.
(b)
The inner and outer surfaces of a 25-cm-thick wall are at 27 oC and 45 oC, respectively. The outer surface of the wall exchanges heat by radiation with surrounding surfaces at 40 oC, and convection with ambient air at 42 oC with convection heat transfer coefficient of 9.0 W/m2 K. Solar radiation incident on the surface is at a rate of 150 W/m2. If the emissivity and the solar absorptivity of the outer surface are 0.75 and 0.85, respectively:
(i)
write the expression of the energy balance at the outer surface;…
4: Consider a person standing in a room maintained at 20°C at all times. The inner surfaces of the walls, floors, and ceiling of the house are observed to be at an average temperature of 12°C in winter and 23°C in summer. Determine the rates of radiation heat transfer between this person and the surrounding surfaces in both summer and winter if the exposed surface area, emissivity, and the average outer surface temperature of the person are 1.6 m2, 0.95, and 32°C, respectively.
Chapter 1 Solutions
HEAT+MASS TRANSFER(LL)-W/ACESS
Ch. 1 - How does the science of heat transfer differ from...Ch. 1 - What is the driving force for (a) heat transfer,...Ch. 1 - Prob. 3CPCh. 1 - How do rating problems in heat transfer differ...Ch. 1 - What is the difference between the analytical and...Ch. 1 - Prob. 6CPCh. 1 - What is the importance of modeling in engineering?...Ch. 1 - When modeling an engineering process, how is the...Ch. 1 - On a hot summer day, a student turns his fan on...Ch. 1 - Consider two identical rooms, one with a...
Ch. 1 - An ideal gas is heated from 50C to 80C (a) at...Ch. 1 - Prob. 12CPCh. 1 - What is heat flux? How is it related to the heat...Ch. 1 - What are the mechanisms of energy transfer to a...Ch. 1 - A logic chip used in a computer dissipates 3 W of...Ch. 1 - Consider a 150-W incandescent lamp. The filament...Ch. 1 - A 15-cm-diameter aluminum ball is to be heated...Ch. 1 - Prob. 18PCh. 1 - Prob. 19PCh. 1 - A 60-gallon water heated is initially filled with...Ch. 1 - Prob. 21PCh. 1 - Prob. 22PCh. 1 - Prob. 23PCh. 1 - Prob. 24PCh. 1 - Prob. 25PCh. 1 - Prob. 26PCh. 1 - Prob. 27PCh. 1 - Prob. 28PCh. 1 - A 5-m6-m8-m room is to be heated by an electrical...Ch. 1 - Prob. 30PCh. 1 - Prob. 31PCh. 1 - Air enters the duct of an air-conditioning system...Ch. 1 - Define thermal conductivity, and explain its...Ch. 1 - Prob. 34CPCh. 1 - Which is a better heat conductor, diamond or...Ch. 1 - How do the thermal conductivity of gases and...Ch. 1 - Why is the thermal conductivity of superinsulation...Ch. 1 - Why do we characterize the heat conduction ability...Ch. 1 - Prob. 39CPCh. 1 - What are the mechanisms of heat transfer? How are...Ch. 1 - Write down the expression for the physical laws...Ch. 1 - How does heat conduction differ from convection?Ch. 1 - Does any of the energy of the sun reach the earth...Ch. 1 - How does forced convection differ from natural...Ch. 1 - What is the physical mechanism of heat conduction...Ch. 1 - Consider heat transfer a windowless wall of house...Ch. 1 - Consider heat loss through two walls of house on a...Ch. 1 - Consider two houses that are identical except that...Ch. 1 - Consider two walls of a house that are identical...Ch. 1 - Define emissivity and absorptivity. What is...Ch. 1 - What is a blackbody? How do real bodies differ...Ch. 1 - A wood slab with a thickness 0.05 m is subjected...Ch. 1 - Prob. 53PCh. 1 - The inner and outer surfaces of a 0.5-cm thick...Ch. 1 - Prob. 55PCh. 1 - Prob. 56PCh. 1 - The north wall of an electrically heated home is...Ch. 1 - Prob. 58PCh. 1 - Prob. 59PCh. 1 - Prob. 60PCh. 1 - A concreate wall a surface area of 20 m2 and a...Ch. 1 - Prob. 62PCh. 1 - Prob. 63PCh. 1 - Prob. 64EPCh. 1 - Prob. 65EPCh. 1 - Air at 20C with a convection heat transfer...Ch. 1 - Prob. 67PCh. 1 - Prob. 68PCh. 1 - Prob. 69PCh. 1 - Prob. 70PCh. 1 - Prob. 71PCh. 1 - Prob. 72PCh. 1 - Prob. 73PCh. 1 - Prob. 74PCh. 1 - Prob. 75PCh. 1 - Prob. 76EPCh. 1 - Prob. 77EPCh. 1 - Prob. 78PCh. 1 - Prob. 79PCh. 1 - Prob. 80PCh. 1 - Prob. 81PCh. 1 - Prob. 82PCh. 1 - Using the conversion factors between W and Btu/h,...Ch. 1 - The outer surface of a spacecraft in space has an...Ch. 1 - Consider a person whose expose surface are is 1.7...Ch. 1 - Prob. 86PCh. 1 - Two surfaces, one highly polished and the other...Ch. 1 - A spherical interplanetary probe with a diameter...Ch. 1 - Prob. 89PCh. 1 - Can all three modes of heat transfer occur...Ch. 1 - Can a medium involve (a) conduction and...Ch. 1 - The deep human body temperature of a healthy...Ch. 1 - We often turn the fan on in summer to help us...Ch. 1 - Prob. 94PCh. 1 - Prob. 95PCh. 1 - Prob. 96PCh. 1 - An electronic package with a surface area of 1 m2...Ch. 1 - Consider steady heat transfer between two large...Ch. 1 - Prob. 99PCh. 1 - Prob. 100PCh. 1 - A 2-in-diameter spherical ball whose surface is...Ch. 1 - Prob. 102PCh. 1 - A 3-m-internal-diameter spherical tank made of...Ch. 1 - Prob. 104PCh. 1 - Solar radiation is incident on a 5-m2 solar...Ch. 1 - Prob. 106PCh. 1 - Prob. 107PCh. 1 - Prob. 108PCh. 1 - Prob. 109EPCh. 1 - An AISI 304 stainless steel sheet is going through...Ch. 1 - Prob. 111PCh. 1 - Prob. 112CPCh. 1 - Prob. 113PCh. 1 - Prob. 114PCh. 1 - Prob. 115PCh. 1 - Prob. 116PCh. 1 - Prob. 117PCh. 1 - Why is the metabolic rate of women, in general,...Ch. 1 - What is asymmetric thermal radiation How does it...Ch. 1 - How do (a) draft and (b) cold floor surfaces cause...Ch. 1 - Prob. 121CPCh. 1 - Why is it necessary to ventilate buildings? What...Ch. 1 - Consider a house in Atlanta, Georgia, that is...Ch. 1 - Prob. 124PCh. 1 - Prob. 125PCh. 1 - Prob. 126PCh. 1 - A 4m5m6m and room is to be heated by one ton (1000...Ch. 1 - Engine valves (cp=440J/kg.Kandp=7840kg/m3) are to...Ch. 1 - Prob. 129PCh. 1 - Prob. 130PCh. 1 - A 0.3 -cm-thick, 12-cm-high, and 18-cm-long...Ch. 1 - A 40-cm-long, 800-W electric resistance heating...Ch. 1 - It is well known that wind makes the cold air feel...Ch. 1 - An engine block with a surface area measured to be...Ch. 1 - Prob. 135PCh. 1 - Prob. 136PCh. 1 - Prob. 137PCh. 1 - Consider a person standing in a room maintained at...Ch. 1 - Prob. 139PCh. 1 - Prob. 140PCh. 1 - Prob. 141PCh. 1 - Prob. 142PCh. 1 - Prob. 143PCh. 1 - Prob. 144PCh. 1 - Prob. 145PCh. 1 - Prob. 146PCh. 1 - A 2-kW electric resistance heater submerged in...Ch. 1 - Prob. 148PCh. 1 - A cold bottled drink (m=2.5kg,cp=4200J/kg.K) at...Ch. 1 - Prob. 150PCh. 1 - Air enters a 12-m-long, 7-cm-diameter pipe at 50oC...Ch. 1 - Prob. 152PCh. 1 - Steady heat conduction occurs through a...Ch. 1 - Heat is lost through a brick wall (k=0.72W/m.K),...Ch. 1 - Prob. 155PCh. 1 - A 40-cm-long, 0.4-cm-diameter electric resistance...Ch. 1 - Prob. 157PCh. 1 - Over 90 percent of the energy dissipated by an...Ch. 1 - On a still, cleat night, the sky appears to be a...Ch. 1 - Prob. 160PCh. 1 - Prob. 161PCh. 1 - A persons head can be approximated as a...Ch. 1 - A person standing in a room loses heat to the air...Ch. 1 - Prob. 164PCh. 1 - Write an essay on how microwave ovens work, and...Ch. 1 - Using information form the utility bill for the...Ch. 1 - It is well know that at the same outdoor air...
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
- Calculate the thermal resistance due to convection for the following situations:a. w arm water with h = 200 W⁄m2 .Kb. warm air with h = 10 W⁄m2 .Kc. warm moving air (windy situation) h = 30 W⁄m2 .Karrow_forwardCalculate the total heat gain of a restaurant at its peak occupancy load at about 1PM. When hundred dinners and 15 employees are present, Given: Heat gain through wall and roof: 2500Kj/hr; Heat gain through glass areas:500Kj; Number of florescent tube lights:60; Rating of each tube light:40W; Rating of toasters inside space:2650W; Sensible heat gain per dinner:250Kj/hr; Latent heat gain per dinner: 260Kj/hr Sensible heat per employee:305Kj/hr Latent heat per employee:545Kj/hr Inside design conditions:25 oC DB, 19 oC WB Outside design conditions: 40 oC DB, 27 oCWB Ventilation requirement: 0.4cmm/personarrow_forwardTwo parallel discs pf 1m diameter are situated 2m part in surroundings at a temparature 20 C. The inner side of one disc has an emissivity of 0.5 and is manintained at 500 C by electric resistance heating and the outer side of the disc is well insulated. The other disc is Two parallel discs of 1m diameter are situated 2m apart in surroundings at a temperature of 20 oC. The inner side of one disc has an emissivity of 0.5 and is maintained at 500 oC by electric resistance heating and the outer side of the disc is well insulated. The other disc is open to radiation on both sides and reaches an equilibrium temperature. Calculate this equilibrium temperature and the heat flow rate from the first disc, assuming heat transfer is entirely by radiation.arrow_forward
- A radiation shield that has the same emissivity 3 on both sides is placed between two large parallel plates, which are maintained at uniform temperatures of T1 = 650 K and T2 = 400 K and have emissivities of E1 = 0.6 and E2 = 0.9, respectively. Determine the emissivity of the radiation shield if the radiation heat transfer between the plates is to be reduced to 15 percent of that without the radiation shieldarrow_forwardQuestion 6 A 1000-W iron is left on the ironing board with its base exposed to the air at 23°C. The convection heat transfer coefficient between the base surface and the surrounding air is 35W/m2 ·°C. If the base has an emissivity of 0.9 and a surface area of 0.02 m2 , determine the temperature of the base of the iron (? = 0.6, σ = 5.67 × 10−8 W/?2 ? 4 )arrow_forwardDoes any of the energy of the sun reach the earth by conduction or convection?arrow_forward
- In liquid and gases, heat transmission is primarily caused by A. conduction as well as convection B. conduction C. convection D. Radiationarrow_forwardUnlike conduction and convection, heat transfer by radiation can occur between two bodies even when they are separated by a medium colder than both of them.arrow_forwardDetermine the following at 3 P.M. solar time at 30°N latitude. i) Altitude and solar azimuth angle on June 21. (ii) Angle of incidence on June 8 on a vertical wall facing south. (iii) Direct solar radiation on June 21. (iv) Diffuse radiation on a roof facing SE with ø = 60° on July 21. (v) Instantaneous heat gain through 3 m wide x 2.5 m high glass window facing SE recessed 0.4 m inside. Outside and inside temperatures are 40 C and 25°C.arrow_forward
- Consider a room whose door and windows are tightly closed, and whose walls are well-insulated so that heat loss or gain through the walls is negligible.arrow_forwardHavard University campus has 200 classrooms and 400 faculty offices. The classrooms are equipped with 12 fluorescent tubes, each consuming 110 W, including the electricity used by the ballasts. The faculty offices, on average, have half as many tubes. The campus is open 240 days a year. The classrooms and faculty offices are not occupied an average of 4 h a day, but the lights are kept on. If the unit cost of electricity is $ 0.082/kWh, determine how much the campus will save a year if the lights in the classrooms and faculty offices are turned off during unoccupied periods.arrow_forwardConsider a black spherical ball, with a diameter of 25 cm, is being suspended in air. Determine the surface temperature of the ball that should be maintained in order to heat 11.7 kg of air from 20°C to 30°C in the duration of 5 minutes.Given: cv = 718 J/kg∙K Stefan-Boltzmann constant (σ) = 5.67 × 10–8 W/m2∙K The surface temperature of the ball is Ts = _____ °C.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University Press
Mechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSON
Thermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEY
Mechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage Learning
Engineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY
Elements Of Electromagnetics
Mechanical Engineering
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Oxford University Press
Mechanics of Materials (10th Edition)
Mechanical Engineering
ISBN:9780134319650
Author:Russell C. Hibbeler
Publisher:PEARSON
Thermodynamics: An Engineering Approach
Mechanical Engineering
ISBN:9781259822674
Author:Yunus A. Cengel Dr., Michael A. Boles
Publisher:McGraw-Hill Education
Control Systems Engineering
Mechanical Engineering
ISBN:9781118170519
Author:Norman S. Nise
Publisher:WILEY
Mechanics of Materials (MindTap Course List)
Mechanical Engineering
ISBN:9781337093347
Author:Barry J. Goodno, James M. Gere
Publisher:Cengage Learning
Engineering Mechanics: Statics
Mechanical Engineering
ISBN:9781118807330
Author:James L. Meriam, L. G. Kraige, J. N. Bolton
Publisher:WILEY
Heat Transfer – Conduction, Convection and Radiation; Author: NG Science;https://www.youtube.com/watch?v=Me60Ti0E_rY;License: Standard youtube license