(a) A steam power plant shown schematically in Fig. Q1 operates on an ideal
Rankine cycle with boiler and condenser pressure of 80 and 0.5 bar,
respectively. Steam the rate of 18 kg/s leaves the oiler/superheater
unit, which has an efficiency 53% atemperature At the
condenser inlet the steam quality, x, is 0.82.
Show the cycle on T-s diagram with respect to saturation lines and
the turbine power output if its mechanical efficiency 88%:
the heat rejected in the condenser
the pumping power fthe mechanical efficiency pump is
the total heat added to the steam in the biler/superheater
the fuel consumption assuming fuel calorific value of
the overall thermal fficiency of the plant:
(viii) the rate of cooling water needed the condenser fthe increase
in the cooling water temperature is 20°C and its heat 4.2
the combustion air mass flow rate the air to fuel ratiois 12;
the temperature of the combus tion gases leaving
You may assume that both the air and fuel temperatures are 20°C before
entering the boiler/superheater unit. Assume, also, that the specific
capacity of the gases and air, 1.005 kJ/(kg.K)
(b) Explain the impact of low plant efficiency on the environment and fossil
(c) Explain the principle difference between the Kelvin- Plank and Clausius
statements of the second law of thermo namics
Fix. Q1 Schematic diagram of power generating plant
Consider refrigeration system that removes 4kw of heat from a
refrigerated space and operates on the vapour compression refrigeration
cycle that uses Isceon 49 the working fluid The refrigerant enters the
compressor superheated vapour pressure and temperature of 210
kPa and 10°C respectively. It is then compressed in non isentropic
manner to pressure of 1500 kPa and temperature of 50°C. The
refrigerant sub -cooled in the condenser toa temperature of 25'C.
Subsequently, the refrigerant is throttled in constant enthalpy process,
to the evaporator pressure.
Show the cycle T-s and p-h diagrams with respect to the saturation
line and determine:-
the mass flow rate of the refrigerant;
the quality of frigerant at the end of the throttling process
and the isentropic efficiency of the compressor;
the compressor power input its mechanical efficiency
the coefficient of performance of the refrigerator.
Use the Isceon pressure-enthalpy diagram provided to show the details of
the refrigeration cycle and attach with your answer.
Explain the operation principle of heat pumps and comment on their role
in energy saving when used in space heating. Explain why the energy
output of any heat pump always higher than its work input
A turbocharger operates on exhaust gases of an actual pressure and
temperature of 270kPa and 1000 C,respectively Exhaust gases at rate
of 0.070m³ enter the turbocharger velocity of 70m/s and leave at
an actual temperature of 750 K. Assuming turbine isentropic efficiency
of 83% sketch the expansion processes on diagram and determine:
the energy consumed bv the turbocharger;
(ii) the isentropic temperature of the exhaust gases the turbine
(iii) the diameter of the turbocharger inlet.
You may assumethat the exhaust gases flowing through the turbine
behave an ideal gas with constants identical to those of air room
Sub-cooled water at a steady rate of 13 kg/s enters gas fired
boiler/superheater combination Thetemperature and velocity of the
water the boiler inlet are 80 and m/s, respectively The pressure
and temperature of the generated steam at the superh eater outlet are 40
bar and 500 C. respectively. The oiler/superheater combination
consumes 2.5 kg/s of natural gas of calorific value of 43,000 kJ/kg.
the boiler/superhcater efficiency:
the diameter of the pipe feeding the boiler.
These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction
of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice.
Unethical use is strictly forbidden.