A modified Brayton cycle consists of a compressor, a heat exchanger which cools the fluid, a second compressor, a combustion chamber, and a turbine. Air is the working fluid, and flows with a constant mass flow rate of 5 kg/s, and enters both compressors at a temperature of 298 K. For each compressor, fp4. The first compressor is isentropic, while the second compressor has an isentropic efficiency of 60%. The pressure of air entering the first compressor is 1 bar. Air leaves the (non-isentropic) turbine at a pressure of 1 bar and a temperature of 325 K. Hydrogen (calorific value of fuel-140 MJ/kg) is burnt in the combustion chamber, providing a heat input at a rate of 270 KW. Answer the following questions by selecting the answers from the drop down menus. 1. What is the pressure of the air entering the turbine in bar? bar 2. What is the required mass flow rate of fuel in g/s? g/s 3. What is the temperature of the fluid leaving the first compressor in K? K

A modified Brayton cycle consists of a compressor, a heat exchanger which cools the fluid, a second compressor, a combustion chamber, and a turbine. Air is the working fluid, and flows with a constant mass flow rate of 5 kg/s, and enters both compressors at a temperature of 298 K. For each compressor, fp4. The first compressor is isentropic, while the second compressor has an isentropic efficiency of 60%. The pressure of air entering the first compressor is 1 bar. Air leaves the (non-isentropic) turbine at a pressure of 1 bar and a temperature of 325 K. Hydrogen (calorific value of fuel-140 MJ/kg) is burnt in the combustion chamber, providing a heat input at a rate of 270 KW. Answer the following questions by selecting the answers from the drop down menus. 1. What is the pressure of the air entering the turbine in bar? bar 2. What is the required mass flow rate of fuel in g/s? g/s 3. What is the temperature of the fluid leaving the first compressor in K? K

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter28: Special Refrigeration Applications

Section: Chapter Questions

Problem 15RQ: Why is two-stage compression popular for extra-low-temperature refrigeration systems?

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3. In a gas turbine power plant, the air is preheated by the exhaust gases in a heat exchanger called a regenerator. Air enters at 1 MPa, 550 K, and the mass flow rate of 900 kg / min. Heat is transferred to the air with a rate of 3500 kJ / s. While the exhaust gas enters the regenerator at 150 kPa, 800 K and leaves at 130 kPa and 600 K. Assuming the air and the exhaust gases are ignoring kinetic and potential energy effects, determine the a) the air temperature at the outlet b) the exhaust gas flow rate [Assuming that air and exhaust gas has the same Cp = 1.005 kJ/kg.K]
(3). A gas turbine unit consists of a compressor, combustion chamber, turbine and heat exchanger. The unit has a pressure ratio of 6:1 and a maximum cycle temperature of 600°C. The isentropic efficiencies of the compressor and turbine are 0.8 and 0.85 respectively. The air enters the compressor at 15°C at a rate of 17kg/s. the heat exchanger effectiveness is 80%. If the compressor and turbine are connected by a rigid shaft, calculate: (a). the net power (b). the thermal efficiency (c). the thermal efficiency with the heat exchanger bypassed.
In a closed cycle gas turbine there is a two stage compressors and a single stage turbine. All the components are mounted on the same shaft. The pressure and temperature at the inlet of the first stage compressor are 1 bar and 20°C. The intercooling is perfect and the compressor efficiencies are 0.9. The maximum cycle temperature and pressure are limited to 750°C and 6 bar. After the expansion in turbine, a regenerator with effectiveness 0.70 is using to extract the waste heat. Calculate: (i) The net work out put (ii) The cycle efficiency. The working fluid used in the cycle is air.
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In a gas turbine cycle. the pressure ratio is 6 and maximum cycle temperature is 650°C. The efficiencies of turbine and compressor are 0.85 and 0.82. Air enters the compressor at 15°C and flow rate of air is 12 kg/sec. For compression process. C = 1.005 kJ/kg-K. y 1.32. For combustion process, C= 1.11 kJ/kg-K. Determine, (a) Power developed (b) Thermal efficiency (c) Work ratio.
HMW-2 In a closed cycle gas turbine, there is two stage compressor and two-stage turbine. All the components are mounted on the same shaft. The pressure and temperature of air at inlet to the first stage compressor are 1.5 bar and 20°C respectively. The maximum cycle pressure and temperature are limited to 750°C and 6 bar. A perfect intercooling and reheating are used between the compressors and the turbines. A regenerator whose effectiveness is 0.7 was employed. Assuming the compressors and turbines efficiencies as 0.82, calculate: a. Thermal efficiency of the cycle. b. Mass of working fluid for a power output of 350 kW. Assume the working fluid is air has Cp 1.005 kJ/kg K, y = 1.4.
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In a Rankine Cycle , saturated liquid water at 1 bar is compressed isentropically to 150 bar. First by heating in a boiler and then by superheating at constant pressure of 150 Bar, the water substance is brought to 750 K. After Adiabatic reversible expansion in a turbine at 1 Bar, it is then cooled in a condenser to a saturated liquid. What is the thermal efficiency of the cycle (%)?
As shown in figure 4, a combined gas turbine power plant operates with state 5 being an air compressor inlet at a temperature of 300 K and state 3 being a steam turbine inlet with a temperature of 1500 K. The pressure ratio of the gas- turbine cycle is 16. The isentropic efficiency of the compressor and turbine are 80% and 85% respectively. Air flow in the system with mass flow rate of 10 kg/s and the with turbine outlet temperature of 400 °C. The heat exchanger operates at 12 MPa and the combustion gas exit at 420 K. Steam leaves the condenser at 19.947 kPa. If the pump efficiency is 90%, Complete the table below: All to one decimal place except the Pr, 's and x to 4 decimal places. If there are no numbers to write on decimal, replace the value with zero. For example, 6.56 to 4 decimal places may be written as 6.5600 and 898.8878 may be entered as 899.0 ein Combustion chamber 6 Gas turbine Gas cycle Compressor 3 Heat exchanger 8 Steam turbine Steam cycle Air in O 9 gases - Exhaust, 2…
As shown in figure 4, a combined gas turbine power plant operates with state 5 being an air compressor inlet at a temperature of 300 K and state 3 being a steam turbine inlet with a temperature of 1500 K. The pressure ratio of the gas-turbine cycle is 16. The isentropic efficiency of the compressor and turbine are 80% and 85% respectively. Air flow in the system with mass flow rate of 10 kg/s and the with turbine outlet temperature of 400 °C. The heat exchanger operates at 12 MPa and the combustion gas exit at 420 K. Steam leaves the condenser at 19.947 kPa. If the pump efficiency is 90%, Complete the table below: All to one decimal place except the Pr, s and x to 4 decimal places. If there are no numbers to write on decimal, replace the value with zero. For example, 6.56 to 4 decimal places may be written as 6.5600 and 898.8878 may be entered as 899.0 h (kJ/kg) pr state P (kPa) 5 T(K) 300.0000 air Combustion chamber air 6s Gas air 6 turbine Gas cycle air 7 1500.0000 Compressor air 8s…
A generator uses a gas turbine cycle. Air enters the compressor at a pressure of 1 bar and a temperature of 30°C with a compressor efficiency of 0.85. Hot gas exits the combustion chamber at a pressure of 9 bar and a temperature of 900°C. The power generated by the turbine is 2400 kW with a turbine efficiency of 0.82. a. Draw installation diagrams and T-s cycle process diagramd b. Determine the work of the compressor and turbine and the mass rate of the air requirement c. Cycle thermal efficiency (air: Cp=1,005 kJ/kg. K dan γ=1.4; Gas hot: cp=1,005 kJ/kg K and γ=1.4)
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