(a) The sun radiates 650 W/m? on the surface of a particular lake. At what rate (in mm/hr) would the lake evaporate if all of this energy went to evaporating water? Discuss as many other ways you can think of that this energy can be distributed (hfg for water is 2,257,000 J/kg). Do you suppose much of the 650 W/m² goes to evaporation?

(a) The sun radiates 650 W/m? on the surface of a particular lake. At what rate (in mm/hr) would the lake evaporate if all of this energy went to evaporating water? Discuss as many other ways you can think of that this energy can be distributed (hfg for water is 2,257,000 J/kg). Do you suppose much of the 650 W/m² goes to evaporation?

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.39P: The tip of a soldering iron consists of a 0.6-cm- diameter copper rod, 7.6 cm long. If the tip must...

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The tip of a soldering iron consists of a 0.6-cm- diameter copper rod, 7.6 cm long. If the tip must be 204C, what are the required minimum temperature of the base and the heat flow, in watts, into the base? Assume that h=22.7W/m2KandTair=21C.
Exhaust gases leave an internal combustion engine at 800deg C and 1 atmosphere, after having done 1050 kJ work per kg of gas in the engine (Cp of gas 1.1 kJ/kg K). The temperature of surrounding is 30 degrees C (i) How much available energy per kg of gas is lost by throwing away the exhaust Gases? (ii) What is the ratio of the lost available energy to the engine work ?
A steam power station uses coals of calorific value of 6045-kcal/kg. The overall efficiency ofthe power station is 21.5% and a coal power station uses 4.05-tonnes of coal every 15 minutesto generate the maximum demand. The purchasing price of coals is R600 per tonne. (NB:1 kWh = 861 kcal)(a) Determine the coal consumption in kg per kWh.(b) Determine the cost of purchasing the coals per week if the load factor is 65%.
Methane enters a compressor at 14 psia with a very low velocity and is compressed to 55 psia. The entering methane has a density of 0.04 lbm/ft. The methane leaves the compressor with a velocity of 250 fps. The flow rate is 0.38 lbm/s. Assuming a quasiequilibrium process in which pu calculate the work done on the methane in hp. 1.33-constant, [ans: -57.4 hp]
Assume the price of coal is 0.04 $/kp and that this coal has a heat of combustion of 28 MJ /kg. What is the cost of energy for this coal in $/GJ.
Unreasonable Results - A slightly deranged Arctic inventor surrounded by ice thinks it would be much less mechanically complex to cool a car engine by melting ice on it than by having a water-cooled system with a radiator, water pump, antifreeze, and so on. (a) If 80% of the energy in 1.00 gal of gasoline is converted into “waste heat” in a car engine, how many kilograms of 0C ice could it melt? (b) Is this a reasonable amount of ice to carry around to cool the engine for 1.00 gal of gasoline consumption? (c) What premises or assumptions are unreasonable?
Air must be compressed in a well-insulated piston cylinder from a volume of 6.4 litres to a volume of 1 litres. If the air is initially at 398 K, what is the minimum work per unit mass of air required to carry out this compression? Give your answer in k) to the nearest whole number. For air: Co = 1.005 kj/kg K and cy= 0.718 kj/kg K.
0.5 kg of an ideal gas undergoes an isentropic process from 657 kPa gage and a volume of 0.017 cubic meter to a final volume of 0.1 cubic meter. If Cv = 0.384 kJ/kg-K and Cp = 0.52 kJ/kg-K, calculate: (ANSWER MUST BE EXACT TO CHOICES ONLY) a) the final temperature in deg. C CHOICE -171 102 171 b) the final pressure in kPa CHOICES 68.94 73.84 63.84 c) the change in enthalpy in kJ CHOICES -25 -23 23 d) the work nonflow in kJ CHOCIES 13.87 18.97 16.97
8. Air is compressed in a frictionless steady-flow process from 70 kN/m2, -29°C and a specific volume of 1 m³/kg to 100 kN/m² in such a manner that p(u+0.5)=constant, where v is in m³/kg. Inlet velocity is negligibly small and discharge velocity is 100 m/s. The flow rate is %3D 0.2 kg/s. Calculate the work required in kW. [ans: -5.49 kW]
What is dynamics and how does dynamics affect our daily life?
1.06 lbm of water fills a container whose volume is 2.06 ft3. The pressure in the container is 100 psia. Calculate the total internal energy and enthalpy in the container. Use data from the steam tables. The total internal energy in the container is 1284.7 Btu. The enthalpy in the container is 1284.7 Btu.
1 kg of Oxygen has initial volume of 2 x 10° cm³ is heated at Isobaric process from 298 K to 200°C. Calculate (i) ratio of specific heats (i) heat transfer in 'kl' (ii) work transfer in 'kJ'(V) change in internal energy in 'kl' (V) volume after heating (vi) pressure before heating in "bar'. Gas (kJlkg K) (kJ/kg K) Air 1.005 0.718 Oxygen Nitrogen Hydrogen 0.920 0.660 1.046 0.754 14.40 10.40 Carbon monoxide 1.046 0.754