A gas turbine plant consists of a compressor with a pressure ratio of 10, a combustion chamber, and a turbine mounted on the same shaft as the compressor; the net electrical power of the unit is 20 MW. The inlet air conditions are 1.013 bar and 15 ?C and the maximum cycle temperature is 1100 K. The exhaust gases from the turbine are passed through a heat exchanger to heat water for space heating before passing to the chimney; by this means water at 60 ?C flowing at a rate of 2×106 kg/h is heated to 80 ?C. Using the further data below and neglecting the mass flow rate of fuel, calculate; (i) the temperature of the gases leaving the turbine;

(ii) the mass flow rate of air entering the unit;

(iii) the temperature of the gases entering the chimney;

(iv) the overall efficiency of the system defined as the useful energy output divided by the energy input from the fuel. Combined mechanical and electrical efficiency of gas turbine unit, 90 %; combustion efficiency, 99 %; isentropic efficiency of air compressor, 80 %; isentropic efficiency of gas turbine, 83 %; pressure drop in combustion chamber, 0.20 bar; pressure drop of gases in heat exchanger, 0.15 bar; pressure drop in chimney, 0.05 bar; specific heat capacity and ? of combustion gases, 1.15 kJ/kg K and 4/3; mean specific heat capacity of water, 4.191 kJ/kg K.

ANSWER (453.8 ?C; 240 kg/s; 285 ?C; 50 %)

What is a unit step function?

Is the value U(0) = 1?

Ex. when t=20 and equate to U(t-20)=U(0)=1???

. In a gas turbine plant, air enters a compressor at atmospheric conditions of 15 ?C, 1.0133 bar and is compressed through a pressure ratio of 10. The air leaving the compressor passes through a heat exchanger before entering the combustion chamber. The hot gases leave the combustion chamber at 800 ?C and expand through an HP turbine which drives the compressor. On leaving the HP turbine the gases pass through a reheat combustion chamber which raises the temperature of the gases to 800 ?C before they expand through the power turbine, and hence to the heat exchanger where they flow in counter-flow to the air leaving the compressor. Using the data below, neglecting the mass flow rate of fuel and changes of velocity throughout,

calculate: (i) The airflow rate required for a net power output of 10 MW;

(ii) The work ratio of the cycle;

(iii) The temperature of the air entering the first combustion chamber;

(iv) The overall cycle efficiency.

Data: Isentropic efficiency of compressor, 80 %; isentropic efficiencies of HP and power turbine, 87 and 85 %; mechanical efficiency of HP turbine-compressor drive, 92 %; mechanical efficiency of power turbine drive, 94 %; thermal ratio of heat exchanger, 0.75; pressure drop on air side of heat exchanger, 0.125 bar; pressure drop in first combustion chamber, 0.100 bar; pressure drop in reheat combustion chamber, 0.080 bar; pressure drop on gas side of heat exchanger, 0.100 bar.

ANSWERS(91.0 kg/s; 0.25; 611 ?C; 18.9 %)

why is the linear coefficient of thermal expansion in polymers greater than that of ceramic?

Describe with a neat sketch the working of a single plate friction clutch

Elaborate briefly on the various types of friction experience by a body.

Water flows in a horizontal pipeline at a steady flow rate of 0.03 m3 s-1. The pipeline terminates with a reducing bend that deflects the water upwards at an angle of 45 degrees, as shown in Figure QB2. The water issues into the atmosphere. The area of the pipe is 150 x 10-4 m2 and the area at the exit to the bend is 25 x 10-4 m2. The gauge pressure at the inlet to the bend is 73.9 kN m-2. The mass of water in the bend is 50 kg.

Determine the resultant force on the bend due to the water flow

Is the thrust generated typical of a small jet aircraft engine? I got -99 N explain and give me a source

USE SI UNITS

Problem Statement Normalizing is a heat treatment process used to relieve internal stresses, refine the grain size and improve mechanical properties. Normalizing is done to give steel a uniform and fine-grained structure. Normalizing is often used for ferrous alloys that have been austenitized and then cooled in open air. Normalizing not only produces pearlite, but also bainite and sometimes martensite, which gives harder and stronger steel, but with less ductility than full annealing. The normalizing experiment in Materials Science lab is conducted by preparing a small sample of metal. The metal will be heated inside a small furnace up to a certain temperature and it is expected that upon heating the metal will have a uniform temperature thoughout the body. The hot metal is then cooled until its temperature is back to room temperature again. You will help to establish the normalizing experiment in by designing all necessary requirement, such as the following: - Decide the material type and size. - Decide the heating temperature and the heating time. - Determine the cooling time, i.e. up to room temperature. - Generate the heating and cooling charts, i.e (time vs temperature for each heating and cooling process). For the report, you have to show the assumptions taken, the properties of material, details of calculation, and other necessary engineering aspects.

4. (a) Draw a P-V diagram of a real refrigerator that uses 1 kg of HFC-134a as the working fluid.
Identify the compressor. condenser. throttle and the evaporator stages of the cycle and indicate
where heat Qc, is extracted from the cold refrigerator and where. Qa is released to the
environment. Also indicate where the refrigerant is in liquid. gas. or a mixed phase.

(b) Show that the COP = Qc(Qh -Qc) can be expressed in terms of the enthalpies at three points of the
cycle, explaining all steps of the derivation.

4. A Rankine cylce operates between pressures of 2 psia and 1500 psia. If the steam entering the turbine is superheated to 800^oF, calculate the efficiency of the cycle. Neglect pump work. Note: The peak of the superheat phase of this cycle is outside the range of the text steam tables and is difficult to locate on the text Mollier chart since it does not have a 1500 psia constant pressure line. Please use the following information taken from the Combustion Engineering steam tables. At 1500 psia and 800 ^oF, the steam would have an h = 1364 Btu/lbm and an s = 1.5073 Btu/lbm ^oR. You should be able to find the value of h at 2 psia and an s = 1.5073 Btu/lbm ^oR from the text steam tables or the Mollier chart. Then you can calculate the parameters requested by questions 4 and 5.

State your answer as a percent to one decimal place. Example: 35.2

5. A Rankine cycle operates between pressures of 2 psia and 1500 psia. If the steam entering the turbine is superheated to 800^oF, calculate the work produced per pound mass of steam. Neglect pump work.

State your answer to two decimal places. Example:125.25

I WILL RATE YOU

8. In a Rankine cycle steam enters the turbine at 900 psia and 1000^oF and exhausts at 1 psia. What is the thermal efficiency? Neglect pump work.

State your answer as a percent to one decimal place. Example: 25.2

9. Steam is expanded to 12% moisture at 1 psia in a Rankine cycle. If the initial pressure is 400 psia, what is the efficiency? Neglect pump work.

Express your answer as a percent to one decimal place. Example: 32.5

I WILL RATE YOU

An ideal diesel engine uses air as the working fluid and operates with a thermal efficiency ?th =0.5 with a rate of heat addition Qin=120 kW. The temperature at the beginning and the end of the addition heat (combustion) are respectively: T2=900 K and T3=2100 K. Assume constant specific heats (Cp and Cv). The air properties at a room temperature T1=293.0 K are: Cp=1.005 kJ/kg.K, Cv=0.718KJ/kg.K, the gas constant of air is R=0.287 kJ/kg.K and the ratio of specific heats k=1.4. Calculate:
a/ The network Wnet and the rate of the heat rejected Qout in kW.
b/ The mass flow rate of the air mair.
c/ The cutoff ratio rc.and the compression ratio r.
d/ T4