![Fundamentals of Heat and Mass Transfer](https://www.bartleby.com/isbn_cover_images/9780470501979/9780470501979_largeCoverImage.gif)
A natural convection air healer consists of an array of parallel, equally spaced vertical plates, which may be maintained at a fixed temperature
For
![Check Mark](/static/check-mark.png)
Want to see the full answer?
Check out a sample textbook solution![Blurred answer](/static/blurred-answer.jpg)
Chapter 9 Solutions
Fundamentals of Heat and Mass Transfer
Additional Engineering Textbook Solutions
Engineering Mechanics: Statics
Thermodynamics: An Engineering Approach
Thermodynamics: An Engineering Approach
EBK FUNDAMENTALS OF THERMODYNAMICS, ENH
Heat and Mass Transfer: Fundamentals and Applications
Vector Mechanics for Engineers: Statics, 11th Edition
- An electrical transmission line of 1.2-cm diameter carries a current of 200 amps and has a resistance of 310-4 ohm per meter of length. If the air around this line is at v, determine the surface temperature on a windy day, assuming a wind blows across the line at 33 km/h.arrow_forwardChips of width L _ 15 mm on a side are mounted to a substrate that is installed in an enclosure whose walls and air are maintained at a temperature of Tsur=T∞=25oC. The chips have an emissivity of ε=0.60 and a maximum allowable temperature of Ts=85oC. (a) If heat is rejected from the chips by radiation and natural convection, what is the maximum operating power of each chip? The convection coefficient may be approximated as h=11.7 W/m2K. (b) If a fan is used to maintain airflow through the enclosure and heat transfer is by only forced convection, with h=250 W/m2K, what is the maximum operating power?arrow_forward)د.ضمیاء( H.w 1-ch.5 Q1/ A large vertical plate 6.1 m high and 1.22 m wide is maintained at a constant temperature of 57•C and exposed to atmospheric air at 4 C. calculate the heat lost by the plate. 57+4 Tf =- = 30.5°C = 303.5 K 2 v = 16.1×106 %3D k = 0.0265 Pr = 0.7 W Nu =1118 h = 4.86 m2 .°C Nu = 1012arrow_forward
- Chips of width L _ 15 mm on a side are mounted to a substrate that is installed in an enclosurewhose walls and air are maintained at a temperature of Tsur=T∞=25oC. The chips have an emissivity ofε=0.60 and a maximum allowable temperature of Ts=85oC.(a) If heat is rejected from the chips by radiation and natural convection, what is the maximum operatingpower of each chip? The convection coefficient may be approximated as h=11.7 W/m2K.(b) If a fan is used to maintain airflow through the enclosure and heat transfer is by only forcedconvection, with h=250 W/m2K, what is the maximum operating power?arrow_forwardA circular plate of diameter (2.20 m) is placed some how 1.5 meter above the room floor, if the Raleigh number can be approximated by Ra=7.653E7*D and temperature difference between surface and room air temperature is 73 C, air properties: k= 0.0372 W/m.K, Pr = 0.686.What is the initial rate of cooling by convection from the Upper surface ONLY (Watts)?arrow_forward3. An electric immersion heater, 10 mm in diameter and 300 mm long, is rated at 550 W. The emissivity of the heater is ε = 0.85. a) If the heater is horizontally positioned in a large tank of water at 20°C, estimate its surface temperature. b) If the heater is accidentally operated in air at 20°C, estimate the surface temperature. Hint: Radiation heat transfer can be neglected in liquids, but not in gases like air.arrow_forward
- Q2/A vertical cylinder having a length of 30 cm is maintained at 100°C and exposed to room air at 15°C. Calculate the minimum diameter the cylinder can have in order to behave as a vertical flat plate. Ans. 9.01 cmarrow_forwardWrite the appropriate Nusselt value for the each set of conditions provided below.1. Forced convection over a flat plate at constant qs. Calculated Re at mean temperature is 3500 and Pr= 0.7154. 2. Natural convection in a small holding tank with a heating element at the bottom. The calculated Ra number is 2.37 x10^93. Forced convection through an elliptical duct at constant Ts, where a/b=8. The temperature of the fluid at the inlet is higher than at the exit. Flow is fully developed with Re = 33370 and Pr= 0.693. 4. Natural convection over a sphere with Ra = 5 x 10^9 and Pr = 0.7362 PS. Do not round off intermediate valuesarrow_forwardProblem 3 A wet towel (a=75 cm wide, b=1.5 m long) hangs on a cloths line under conditions for which one towel surface receives solar radiation of Qs=900 W/m². Both towel surfaces are exposed to the atmospheric (sky) and ground radiation of Qshy=200 W/m² and Qg=250 W/m², respectively. Under the moderately windy conditions (airflow at a temperature T, = 27 °C, air relative humidity =60%) the convective heat transfer coefficient is o= 20 W/m²-K at both towel surfaces. The wet towel has an emissivity of = 0.96 and the solar absorption coefficient a,=0.65. Determine the towel temperature and the corresponding evaporation rate of moisture from the towel. Assume the air properties at temperature T, = 27 °C.arrow_forward
- R3arrow_forwardA black 20-by-20-cm plate has air forced over it at a velocity of 2 m/s and a temperature of 0◦C. The plate is placed in a large room whose walls are at 30◦C. The back side of the plate is perfectly insulated. Calculate the temperature of the plate resulting from the convection-radiation balance. H = 12 W/m2.C.arrow_forwardA device is used to measure the solar flux incident on it. The environment temperature ?∞=20℃ and H=20 cm, W=10 cm. Solar flux is dissipated as convection and back side of the plate is well insulated. Determine the wrong step Writing energy balance for the system Fluid properties are determined at the film temperature Nusselt number is important for this problem None of all It is a combination of free and forced convection therefore we have to determine combined coefficient External convection correlation must be foundarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
![Text book image](https://www.bartleby.com/isbn_cover_images/9781305387102/9781305387102_smallCoverImage.gif)