Quiz2s - = Then the ideal power is given by ( 29 kW 2784...

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Fall 2007 1 ME 416 Computer Assisted Design of Thermal Systems Quiz #2 Solution An actual axial compressor has inlet air at 270 K and 80 kPa applies a pressure ratio of 3.64. For a mass flow rate of 23 kg/s, determine the required actual power for the compressor and the actual exit temperature. The following properties of air may prove useful: density ( ρ ): 1.21 kg/m 3 specific heat (c P ): 1.004 kJ/(kg · K) specific heat ratio (k): 1.4 Solution: To get the actual power we will need to calculate the ideal power. The ideal power requires the ideal exit temperature, given by K 390.6 ) (270)(3.64 P P T T 1)/1.4 - (1.4 1)/k - (k in out in ideal out, = =
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Unformatted text preview: = Then the ideal power is given by ( 29 kW 2784 270)-)(390.6 (23)(1.004 T-T c m W in ideal , out P ideal = = = & & The actual power is calculated from W W ideal actual = & & which requires us to determine the efficiency. We will calculate the efficiency at P r of 3.5 and at 4 and then interpolate to obtain the efficiency at 3.64. At P r = 3.5, = 0.6475 At P r = 4, = 0.7456 Then interpolating, we find at P r = 3.64, = 0.675 Then kW 4124 675 . 2784 W actual = = & The actual exit temperature is calculated from the first law or K 448.6 70 2 ) (23)(1.004 4124 T c m W T in P out = + = + = & &...
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