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HW17BC_probStatements

HW17BC_probStatements - M6307 Cooper Hw VIC 4.03 5.6?...

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Unformatted text preview: M6307; Cooper . Hw VIC. 4.03, 5.6,?» 6““ edition” 1: 2.33 Refrigerant 134a enters the flash chamber operating at steady state shown in Fig. P4.99 at 10 bar, 36°C, with a mass flow rate of 482 kg/h. Saturated liquid and saturated vapor exit as separate streams, each at pressure p. Heat transfer to the surroundings and kinetic and potential energy effects can be ignored. (a) Determine the mass flow rates of the exiting streams, each in kg/h, if p = 4 bar. - ' (b) Plot the mass flow rates of the exiting streams, each‘ in kg/h, versus p ranging from 1 to 9 bar. Saturated vapor, pressure p Saturated liquid, pressure p be 4.113 A two-phase liquid—vapor mixture of Refrigerant. 134a is contained in a 2-ft3, cylindrical storage tank at 1001bf/in.2 Initially, saturated liquid occupies 1.6 its. The valve at the top of the tank develops a leak, allowing saturated vapor to . escape slowly. Eventually, the volume or the liquid drops to 0.8 ft3. If the pressure in the tank remains constant, deter- mine the mass of refrigerant that has escaped, in lb, and the heat transfer, in Btu. $63 5.39 At steady state, a power cycle receives energy by heat , transfer at an average temperature of 865°F and discharges energy by heat transfer to a river. Upstream of the power plant the river has a volumetric flow rate of 2512 ft3/s and a temperature of 68°F. From environmental considerations, the temperature of the river downstream of the plant can be no more than 72°F. Determine the maximum theoretical power that can be developed, in MW, subject to this constraint. 7; 5.50 . 6: 5.50 An inventor has developed a refrigerator capable of maintaining its freezer compartment at 20°F while operat- ing in a kitchen at 70°F, and claims the device has a coeffi- cient of performance of (a) 10, (b) 9.6, (c) 4. Evaluate the claim in each of the three cases. HW we 4.‘3°lo.)4.l0l,6.3‘l,6.50 Soma KeVievv Pro Hams be 4.101 At steady state, water enters the waste heat recovery— steam generator shown in Fig. P4101 at 421bf/in.2,220°F, and exits at 401bf/in.2, 320°F. The steam is then fed into a turbine from which it exits at 1 Raf/in? and a quality'of 90%. Air from an oven exhaust enters the steam generator at 360°F, 1 atm, with a volumetric flow rate of 3000 ft3/min, and exits at 280°F, 1 atm. Ignore all stray heat transfer with the surroundings and all kinetic and potential energy effects If the power developed is valued at 8 cents per kW - h, do you recommend implementation of this waste-heat recovery sys- tem? Provide supporting calculations. Oven exhaust TA = 360°F , _ 3 ~ (A) (AWA — 3000 ft /mm. 172 = 40 lbf/in? r2 = 320°F W Power out ' _ ' 2 1;, =42 ibfrm? 53331:?“ 1 T. =220°F ' 3 - 0 Water in u 5.63 The refrigerator'shown in Fig. P563 operates at steady a state with a coefficient of performance of 4.5 and a power input of 0.8 kW. Energy is rejected from the refrigerator to the surroundings at 20°C by heat transfer from metal coils whose average surface temperature is 28°C. Determine Refrigerator [3 = 4,5 ' Surroundings, 20°C Coils, 28°C Q}: 3-— 0.8 kW (a) the rate energy is rejected, in kW. (b) the lowest theoretical temperature inside the refrigerator, in K. - (c) the maximum theoretical power, in kW, that could'be developed by a power cycle operating between the coils and the surroundings. Would you recommend making use of this opportunity for developing power? ...
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