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 twophase liquid—vapor mixture of Refrigerant. 134a is contained in a 2ft3, 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 wasteheat 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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 Spring '06
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