Question

Consider an ideal Brayton cycle that takes in air at 5°C and 80 kPa. The combustion adds 900 kJ/kg of energy to the air. Due to material properties of the engine, the maximum temperature in the cycle is 1200°C. Using cold-air-standard assumptions, determine

a) The maximum permissible pressure ratio (i.e. the pressure ratio that corresponds to the maximum temperature being 1200°C).

b) The maximum power output of the engine (i.e. the power output at the pressure ratio found in question 3) if the flow rate of air is 12 kg/s.

Answer #1

Consider a cold air-standard Diesel cycle. At the beginning of
compression, 102 kPa, and 300 K. The mass of air is 0.120 kg, the
compression ratio is 16, and the cut-off ratio is 2.0
For a cold air-standard analysis use the following values: cp =
1.005 kJ/kgK, cv = 0.718 kJ/kgK, k=1.40, M=28.97 kg/kmol.
Determine the following :
(a) pressure at end of compression stroke, in kPa
(b) temperature at end of compression stroke, in K
(c) maximum temperature in...

n ideal air-standard Brayton cycle operates at steady state with
compressor inlet conditions of 290 K and 95 kPa and a fixed turbine
inlet temperature of 1650 K. For a compressor pressure ratio of 10,
determine:
(a) the exhaust temperature of the cycle, in K.
(b) the back work ratio.
(c) the net work developed per unit mass flowing, in kJ/kg.
(d) the heat addition per unit mass flowing, in kJ/kg.
(e) the thermal efficiency for the cycle.

Air enters the compressor of an ideal brayton refrigeration
cycle at 100 kPa, 300K. The compressor presure ratio is 3.75, and
the temperature at the turbine inlet is 350 K. The Brayton cycle is
then modified by the introduction of a regenerative heat exchanger.
In the modified cycle, compressed air enters the regenerative heat
exchanger at 350 K and is cooled to 320 K before enetering the
turbine. Determine, for the modified cycle, (A) the lowest
temperature, in K. (B)...

1) An air-standard Otto cycle has a compression ratio of 9. At
the beginning of the compression process, the temperature is 20°C,
and the pressure is 100 kPa. The heat added is 500 kJ/kg. Determine
the cycle efficiency, work output, and the heat rejected
2) An air-standard Otto cycle operates with a minimum
temperature of 300 K and a maximum temperature of 1700 K. The
compression ratio of the cycle is 7. At the beginning of the
compression process, the...

10) An air-standard Otto cycle has a compression ratio of 9. At
the beginning of the compression process, the temperature is 20°C,
and the pressure is 100 kPa. The heat added is 500 kJ/kg. Determine
the cycle efficiency, work output, and the heat rejected.
11)An air-standard Otto cycle operates with a minimum
temperature of 300 K and a maximum temperature of 1700 K. The
compression ratio of the cycle is 7. At the beginning of the
compression process, the pressure...

7.2 A Brayton cycle gas engine is analyzed using the air
standard method. Given the conditions at state 1, pressure ratio
(rp), and cutoff ratio (rc) determine the efficiency and other
values listed below. The specific heat ratio and gas constant for
air is given as k=1.4 and R=0.287 kJ/kg-K
respectively.
T1 (K) = 333
P1 (kPa) = 170
rp = 10.7
rc = 2.54
AV (m3/s) = 1.7
a) Determine the specific enthalpy (kJ/kg) at state 1.
b) Determine...

A simple Brayton cycle using air as the working fluid has a
pressure ratio of 10. The minimum and maximum temperatures in the
cycle are 295 and 1240 K. Assuming air standard analysis, determine
(a) the air temperature at the turbine exit, (b)
the net-work output (in kJ/kg), and (c) the thermal
efficiency.

Use cold-air-standard analysis with the fluid modeled as an
ideal gas with R=0.287 kJ/kg-K and constant k=1.4. Neglect changes
in kinetic and potential energy. Consider a SSSF of air at 300 K
and 100 kPa entering the compressor of a Simple Brayton Cycle Gas
Turbine powerplant. The cycle pressure ratio is 40 and maximum
cycle temperature is 1800 K. For compressor isentropic efficiency
of 82% the compressor work input per unit mass = __ kJ/kg (enter
the nearest positive integer...

Consider an ideal Ericsson cycle with air as the working fluid
executed in a steady-flow system. Air is at 27°C and 110 kPa at the
beginning of the isothermal compression process, during which 150
kJ/kg of heat is rejected. Heat transfer to air occurs at 950 K.
The gas constant of air is R = 0.287 kJ/kg·K.
a.)The maximum pressure in the cycle is? kPa
b.)The net work output per unit mass of air is? kJ/kg
c.)The thermal efficiency of...

An ideal Diesel cycle has a cut off ratio of 2. The
temperature of the air at the beginning and
at the end of the compression process are 300 K and 900 K
respectively. By utilizing constant
specific heats, taking the specific heat ratio, k = 1.4, Cp = 1.005
kJ/kg K and Cv = 0.718 kJ/kg
K. Determine the followings:
(i) The compression ratio. [5 marks]
(ii) The maximum cycle temperature. [5 marks]
(iii) The amount of heat transferred...

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