Problem 1 - Heat Engine ( A heat engine that propels a ship produces 400,000 lbf-ft/lbm while rejecting 300 BTU/lbm of heat to a low temperature energy sink. Using what you know about heat engines, estimate its thermal efficiency. In your solution include a schematic of the heat engine with the transports of energy across its boundary and your expression for thermal efficiency in literal form before initiating your computation.

Problem 1 - Heat Engine ( A heat engine that propels a ship produces 400,000 lbf-ft/lbm while rejecting 300 BTU/lbm of heat to a low temperature energy sink. Using what you know about heat engines, estimate its thermal efficiency. In your solution include a schematic of the heat engine with the transports of energy across its boundary and your expression for thermal efficiency in literal form before initiating your computation.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.68P

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Hi, can you help me with the following problem? A thermally insulated tank of water 2 m x 2 m, depth 1 m is stirred with a paddle for threehours. If the paddle is driven by a motor whose shaft power is 8 kW determine the rate ofchange of temperature in degrees C per hr and the increase in temperature of the water.The specific heat of water is 4200 J/kgC. Identify a system and start your analysis from anappropriate form of the Fist Law of Thermodynamics
Task 02 Water flows through a cast steel pipe ( k = 50 W/m.K ) with an outer diameter of 104 mm and 2 mm wall thickness. (i). Calculate the heat loss by convection and conduction per metre length of un insulated pipe when the water temperature is 15 0C , the outside air temperature is -10 0C , the water side heat transfer coefficient is 30 kW/m2.K and the outside heat transfer coefficient is 20 W/m2.K . (ii). Calculate the corresponding heat loss when the pipe is lagged with insulation having an outer diameter of 365 mm, and thermal conductivity of k= 0.05 W/m.K
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The forced convective heater works in two ways: radiative heat in the form of light from the hot nichrome wire coils (like a toaster) and forced air heat (like a hair dryer). Derive an energy balance to determine the total rate of heat transfer from the device to the interior of the trailer. What percentage of the heat is leaving as light versus heating of the air stream?
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In the United States, energy for household heating is generally sold using English units, e.g., therm, gal, and cord. A house in Wisconsin uses 1200 therms of thermal energy during the heating season. Calculate the cost of fuel if the furnace uses (a) natural gas with an efficiency of 70%; (b) No. 2 fuel oil, efficiency 65%; (c) kerosene, efficiency 99.9% (unvented); and (d) wood with l5% moisture with an efficiency of 50%. Use the data in Tables 2.2, 2.7, and 2.13. The efficiencies are based on the HHV. Assume the cost of natural gas is $8/MBtu, the cost of No. 2 fuel oil is $3/gal, the cost of kerosene is $3.50/gal, and the cost of wood is $100/cord. Assume the bulk density of cord wood is 30 lbm/ft3 .
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A vertical cylinder 6 ft tall and 1 ft in diameter might be used to approximate a man for heat-transfer purposes. Suppose the surface temperature of the cylinder is 78°F, h=2 Btu/h · ft2 . °F, the surface emissivity is 0.9, and the cylinder is placed in a large room where the air temperature is 68°F and the wall temperature is 45°F. Calculate the heat lost from the cylinder. Repeat for a wall temperature of 80°F. What do you conclude from these calculations? Known, Find, Schematic Diagram, Assumption, Properties, Analysis and Comments
A vertical cylinder 6 ft tall and 1 ft in diameter might be used to approximate a man for heat-transfer purposes. Suppose the surface temperature of the cylinder is 78°F, h=2 Btu/h · ft2 . °F, the surface emissivity is 0.9, and the cylinder is placed in a large room where the air temperature is 68°F and the wall temperature is 45°F. Calculate the heat lost from the cylinder. Repeat for a wall temperature of 80°F. What do you conclude from these calculations?