Gas Power Systems

What are the two principal types of reciprocating internal combustion engines described in the text?

In an air-standard analysis of an internal combustion engine, what is the combustion process replaced by?

For an air-standard Otto cycle, the net work of the cycle is expressed as W_cycle/m = (u3 - u4) - (u2 - u1). Given the following specific internal energies in kJ/kg: u1 = 214.07, u2 = 491.2, u3 = 1678.7, and u4 = 795.8, what is the thermal efficiency?

What phenomenon places an upper limit on the compression ratio of spark-ignition engines?

How does the heat addition process in the air-standard Diesel cycle differ from that in the air-standard Otto cycle?

For an air-standard Diesel cycle with a compression ratio of 18 and a cutoff ratio of 2, what is the thermal efficiency? Use the following specific energy values in kJ/kg: u1 = 214.07, u4 = 664.3, h2 = 930.98, and h3 = 1999.1.

How is heat added in the air-standard dual cycle?

An air-standard dual cycle has the following specific energy values in kJ/kg: u1 = 214.07, u2 = 673.2, u3 = 1065.8, h3 = 1452.6, h4 = 1778.3, and u5 = 475.96. What is the thermal efficiency?

The cycle that results from the idealization of a simple gas turbine, where exhaust air is considered restored to the inlet state via a heat exchanger, is called the:

What is the typical range for the back work ratio of gas turbines?

For an ideal air-standard Brayton cycle, calculate the thermal efficiency given the following specific enthalpies in kJ/kg: h1=300.19, h2=579.9, h3=1515.4, h4=808.5.

According to the cold air-standard analysis, what is the sole factor determining the thermal efficiency of an ideal Brayton cycle, as shown in Equation 9.25?

In a Brayton cycle analysis with an isentropic compressor efficiency of 80 percent, the isentropic work per unit mass is determined to be 279.7 kJ/kg. What is the actual work per unit mass required by the compressor?

A gas turbine has an isentropic work output of 706.9 kJ/kg per unit mass. If the isentropic turbine efficiency is 80 percent, what is the actual work developed per unit mass?

What is the primary function of a regenerator in a regenerative gas turbine cycle?

In an ideal Brayton cycle with regeneration, the regenerator effectiveness is defined as the ratio of the actual enthalpy increase of the air to the maximum theoretical enthalpy increase. Given h_x as the enthalpy of air leaving the regenerator, h_2 as enthalpy entering, and h_4 as enthalpy of exhaust gas entering, what is the correct formula for regenerator effectiveness (η_reg)?

An ideal regenerative Brayton cycle has the following specific enthalpies (in kJ/kg): h1=300.19, h2=579.9, h3=1515.4, h4=808.5. The enthalpy of the air at the regenerator outlet, hx, is 762.8 kJ/kg. What is the thermal efficiency?

What is the primary advantage of using reheat in a gas turbine with a multistage turbine?

What is the purpose of using multistage compression with intercooling in a gas turbine power plant?

For a two-stage compressor with intercooling, what condition leads to the minimum total work input for a specified overall pressure ratio, according to a cold air-standard analysis?

In a combined gas turbine-vapor power cycle, what is the primary function of the interconnecting heat exchanger?

In a combined gas turbine-vapor power plant, the gas turbine has a net work output of 29.03 MW and the vapor cycle has a net work output of 15.97 MW. The total rate of heat transfer into the gas turbine combustor is 59.48 MW. What is the overall thermal efficiency of the combined cycle?

In a turbojet engine, what component is responsible for decelerating the incoming air and creating a pressure rise known as the ram effect?

In an ideal turbojet analysis, the work developed by the turbine is just sufficient to do what?

An ideal turbojet engine has an inlet air velocity of 278 m/s and a specific enthalpy of 240.02 kJ/kg. After the diffuser, the velocity is negligible. What is the specific enthalpy h1 after the diffuser?

The Ericsson and Stirling cycles are of theoretical interest primarily because they can exhibit the same thermal efficiency as which other cycle?

What is the key difference in the combustion process of a Stirling engine compared to a typical internal combustion engine?

In a simple gas turbine power plant operating on an open basis, what fluid is continuously drawn into the compressor?

What is the mean effective pressure (mep) of an air-standard Otto cycle that produces a net work of 0.394 kJ and has a displacement volume (V1 - V2) of 560 cm3 * (1 - 1/8)?

For the same compression ratio, how does the thermal efficiency of a cold air-standard Diesel cycle compare to that of a cold air-standard Otto cycle?

In a regenerative gas turbine cycle with an 80 percent effective regenerator, the specific enthalpies at the compressor inlet and outlet are h1=300.19 and h2=579.9 kJ/kg, and at the turbine inlet and outlet are h3=1515.4 and h4=808.5 kJ/kg. What is the specific enthalpy (hx) of the air leaving the regenerator (entering the combustor)?

In a two-stage air compressor with intercooling, air is compressed from 100 kPa to 300 kPa in the first stage, cooled, and then compressed to 1000 kPa in the second stage. The inlet temperature to both stages is 300 K. For an isentropic process, what is the work input for the first stage, given h1=300.19 kJ/kg and the enthalpy after the first stage, hc, is 411.3 kJ/kg?

A regenerative gas turbine with intercooling and reheat operates with a total turbine work per unit mass of 645.8 kJ/kg and a total compressor work input of 293.4 kJ/kg. The heat added is 795.9 kJ/kg. What is the thermal efficiency?

What is the function of an afterburner in a turbojet engine?

In a gas turbine cycle, how does the specific volume of the gas flowing through the compressor compare to the specific volume of the liquid flowing through the pump of a vapor power plant for the same pressure rise?

Why is it desirable for gas turbines intended for transportation to operate near the compressor pressure ratio that yields the most work per unit of mass, rather than the one for the greatest thermal efficiency?

In the analysis of a two-stage compressor with intercooling, what is the work input for a single stage of isentropic compression from 100 kPa and 300 K to 1000 kPa, given h1 = 300.19 kJ/kg and h3 = 579.9 kJ/kg?

In a combined cycle, the gas turbine exhaust gas enters a heat exchanger at an enthalpy of 858.02 kJ/kg and leaves at 400.98 kJ/kg. The water for the vapor cycle enters at 183.96 kJ/kg and leaves at 3138.3 kJ/kg. What is the ratio of the mass flow rate of the vapor to the mass flow rate of the gas (m_v / m_g)?

What is the defining characteristic of the working fluid in a gas refrigeration system, such as a Brayton refrigeration cycle?

In an ideal Brayton refrigeration cycle, the net power input is 33.97 kW and the refrigeration capacity is 92.36 kW. What is the coefficient of performance?

How does the net work of an ideal Brayton cycle change if a regenerator is added?

An ideal gas, modeled as air with k=1.4, is used in a cold air-standard Otto cycle. How does the thermal efficiency change as the compression ratio (r) increases?

In a Brayton cycle with reheat and regeneration, an ideal two-stage turbine expands air from 1000 kPa to an intermediate pressure of 300 kPa, reheats, and then expands to 100 kPa. What is the pressure ratio of the second turbine stage?

What is the primary reason for the high back work ratio in gas turbines compared to vapor power cycles?

In a regenerative gas turbine with intercooling and reheat, as analyzed in Example 9.11, the total compressor work is 293.4 kJ/kg and the total turbine work is 645.8 kJ/kg. What is the back work ratio?

The four internally reversible processes of the air-standard Stirling cycle are:

What is the primary role of the gas generator section in a turbojet engine?

In a combined cycle analysis, an energy balance on the interconnecting heat exchanger shows that the rate of energy decrease of the gas turbine exhaust is 46.1 MW. If the mass flow rate of the gas is 100.87 kg/s, what is the change in specific enthalpy (h4-h5) of the gas?

What is a 'cold air-standard analysis' in the context of gas power cycles?

A simple ideal Brayton cycle has a compressor pressure ratio of 10. The back work ratio is calculated to be 0.414. If the turbine work per unit mass is 782.3 kJ/kg, what is the compressor work per unit mass?