University:
Massachusetts Institute of Technology
Course:
16.01 | Unified Engineering I, II, III, & IV
Academic year:

2019
Views:

177

Pages:

2
Author:

Yasmin Shaffer

7 SOLUTIONS (WAHZ) (1 OF 2) MY DATA WERE OBTAINED 9/16/03 16:50 hrs. AMBIENT AIR TEMP = 75°F = 297K ATMOSPHERIC PRESSURE (ASSUMED) = 1 atm = 101.3 kPa COMPRESSOR DELIVERY PRESSURE = 200 PSIG = 214.77 PSIA (relative to absolute atmospheric) SO PRESSURE RATIO = 214.77 / 14.77 = 14.54 P | | | | | |_________________ V P₁ = 101.3 kPa, T₁ = 297K P₂ = 14.54 (101.3) = 1473 kPa, T₂ = 638K P₃ = 1473 kPa, T₃ = 1400K (Given) P₄ = 101.3 kPa, T₄ = 652K b) THERMAL EFFICIENCY η_th = 1 - (T₁/T₂) = 1 - 297/638 = 0.534 W = C_p (T₃ - T₂ + T₁ - T₄) = 1003.5 (1400 - 638 + 297 - 652) = 408.75 kJ/kg c) T2 Fixed: COLD DAY T1 = 273K HOT DAY T1 = 303K η_cold = 1 - 273/638 = 0.57 η_hot = 1 - 303/638 = 0.525 d) TOTAL GAS ENERGY FLOW = 66.610 MJ/s = 69.63 MW ACTIVE LOAD = 20 MW η = 20/69.63 = 0.287 e) For PRESSURE RATIO of 14.54, CALCULATED T2 = 638K (IDEAL) MEASURED T2 (COMP DISCHARGE TEMP) = 730°F = 661K HIGHER THAN IDEAL T2, ADIABATIC PROCESS BUT NOTE THERE IS ALSO SOME COOLING BETWEEN THE AMBIENT (T=75°F) AND THE COMPRESSOR INLET (COMP INLET TEMP = 62°F) WHICH WAS NOT ACCOUNTED FOR. IF YOU ACCOUNT FOR THIS OUR Q=3, ADIABATIC MODEL IS EVEN WORSE SHOWS A SMALLER ΔT THAN IN REAL DEVICE

T7 Solutions

of 2

Description

Free up your schedule!

Take 5 seconds to unlock