a steam power plant operates on a superheated rankine cycle where steam at 10kg/s entering the turbine at 5MPa and 375 degree celcius and leaving the turbine at saturated vapor at pressure 100 times less then initial. If the compressor efficiency is 85% ,
I) sketch the cycle of T-s diagram
ii) calculate the temperature and pressure for all points in the cycle
iii) calculate the compressor work
iv) calculate the turbine work and turbine efficiency
v.) calculate the thermal efficiency of the cycle
vi) if the efficiency of turbine and compressor is 100%;
a) is there any changes in temperature of the steam leaving the compressor and turbine? why?
b) Is there is any changes in the thermal efficiency of the cycle? prove the statement
In: Mechanical Engineering
3 kg of air in a closed movable container undergoes a few processes. Initially, the air with P1=330kPa and T1=70°C is cooled without producing any work until P2= 100kPa, and then it is expanded according to PVn=cont, where n=1.84 until the volume is double. The air again will be heated without changing the volume until the temperature of the air increase to the initial temperature. It is then cooled with constant pressure until the volume becomes 0.5m3. The air undergoes isothermal compression process with Wb=-130kJ. Finally, the air undergoes a polytropic expansion to the initial state.
1.1. Sketch the P-V diagram
1.2. Find all P’s, V’s and T’s
1.3. Calculate all Q’s
1.4. Determine the nett work of the cycle
In: Mechanical Engineering
In: Mechanical Engineering
4. 4MPa, 350°C of water vapor enters the insulating turbines,
and is discharged into 50kPa of saturated vapor after expansion.
Ignore kinetic energy and position energy.
1) Draw a schematic diagram and a T-s diagram of the turbine.
2) Obtain turbine efficiency.
3) Obtain entropy change from turbine.
In: Mechanical Engineering
Air at 50 ° C with 1.7 bar gauge pressure enters the
cylindrical bearing system, the diameter of which is below, and
standing in an upright position, with an average flow rate of 2.6 m
/ s for drying purposes. In the fluid state, the porosity value of
the bed is desired to be 0.61 m and its height 0.53 m. Inside the
bed are fresh kidney beans with a diameter of 8 mm.
a). When the air enters the bed, is the inlet speed of the air
sufficient for the bed to be in a fluid form as desired above, or
is it necessary to adjust the air speed in accordance with the
desired conditions?
b). Find the drag force that acts on a single kidney bean while the
bearing is fluid.
c) What is the absolute pressure value of the air when leaving the
fluidized bed?
You can get the density of kidney bean grains 1120 kg
/ m.
The diameter of the bed is 18 cm
In: Mechanical Engineering
a frozen ice cream is placed into a container before the freezing process is complete. The container has dimensions of infinite shapes 8, 10 and 12 cm and is then placed in a water blast freezer with a heat conductivity coefficient of 50W / (m2 K). product temperature of -14 degrees centigrade and air temperature of -25 degrees centigrade. product density is 700 Kg / m3, thermal conductivity (frozen) 1.2 W / (m K) and specific heat 1.9 kJ / (Kg K). if latent heat is lost during the 80kJ / kg freezing blast process, make an estimated freezing time ... (kJ / W)
In: Mechanical Engineering
Mastery Question:
1. Show an engineering problem and solve the kinematic parameters
by using normal-tangent coordinates systems used
to define the motion of an object.
Note: Provide a clear diagram of the suggested engineering problem with detailed calculation.
In: Mechanical Engineering
1. Show an engineering problem and solve the kinematic
parameters by using polar coordinates systems used
to define the motion of an object.
Note: Provide a clear diagram of the suggested engineering problem
with detailed calculation.
In: Mechanical Engineering
A centrifugal pump has an eye diameter and an impeller diameter of 300 mm and 600 mm respectively while running at 850 rpm. When rotating, the blade angle is measured at 35o at the outlet with considering the tangent. The flow velocity is limited at 5 m/s constantly. Determine the following;
(a) inlet blade angle
(b) outlet absolute velocity with its angle at outlet and
(c) the manometric head.
In: Mechanical Engineering
An engineer is conducted the centrifugal pump at aircraft hangar. The pump has an eye diameter and an impeller diameter of 200 mm and 500 mm respectively while running at 900 rpm. While it rotate, the blade angle is measured at 35o at outlet with considering the tangent. The flow velocity is limited at 3 m/s constantly. Evaluate the
(a) inlet blade angle
(b) outlet absolute velocity with its angle at outlet and
(c) the manometric head.
In: Mechanical Engineering
A Rankine cycle power plant is being developed to operate an irrigation system. In this power plant solar energy will be used to boil a low boiling point fluid within glazed flat plate solar collectors. The working fluid that has been selected is the commonly used refrigerant R 134a (1, 1, 1, 2 tetrafluoroethane), tabulated properties of which may be found in Tables A11, A12 and A13 at the rear of the prescribed text.
The plates being used for the solar collector are made of 2 layers of aluminium bonded together for much of their area and incorporating tubular passages of oval cross-section in the unbonded areas, within which the refrigerant boils. The working pressure of this construction is 1400 kPa. It is intended that the refrigerant will boil at this pressure and be slightly superheated, thereby bringing the temperature up to 55 C. The quality of the glazing and insulation on the solar collectors is such that at these fluid conditions, and with a solar intensity of 1 kW per square metre onto the glazing, the efficiency of solar energy collection into the fluid is 70%.
The superheated vapour is fed from the boiler to a small turbine, the isentropic efficiency of which is 85 % x (1.07). The turbine will drive an electric generator whose output will be used in part to provide power for the boiler feed pump whose isentropic efficiency is 96 % / (1.02). The remainder of the electricity will be used to drive an irrigation pump and charge up batteries for use in less sunny periods.
The irrigation pump is responsible for taking cold water from a stream, through the condenser of the power plant and on from that to drip irrigation trickle hoses in the fields nearby. The condenser and a water pump are positioned in a concrete lined pit below the stream level to ensure the pump is always primed and the condenser water tubes are free of air locks. The trickle hoses are laid out in the fields above the stream level. When the power plant is operating at the design condition of 1 kW per square metre solar intensity, the water flow rate through the condenser is to be such that it rises in temperature from 12 to 23 C. At this condition the saturation temperature of the refrigerant in the condenser will be 32 C. The refrigerant is to enter the boiler feed pump at the saturation temperature as a fully condensed liquid.
The various components of the power plant are to be sized such that the net electric output available for the water pump and battery charging is 1.8 kW when the rate of solar energy incidence on the collector glazing is 1 kW per square metre. The efficiency of the electric generator is 82% / (1.07) and the efficiency of the electric motor driving the boiler feed pump it is 75% x (1.02).
2. Considering the real case, where the turbine and feed pump are not isentropic, and the feed pump electric motor and the electric generator are not 100% efficient (assume no pressure drop in boiler and condenser):
a. Determine the specific enthalpy of the refrigerant at the
entry and exit of the feed pump, and the entry and exit of the
turbine;
b. Sketch and label the process paths of the cycle on a T-s
diagram, an h-s diagram and a p-v diagram, also showing the
saturated liquid and vapour lines on each diagram.
c. Determine, per kg/sec of refrigerant circulated
d. For the design requirement of 1.8 kW net electrical power
output, determine, for the real case
i. the necessary mass flow rate of refrigerant;
ii. the electrical power input to the boiler feed pump motor
iii. the electric output power rating of the turbo generator
iv. the necessary solar collector area
v. the necessary water flow rate through the condenser
In: Mechanical Engineering
Use the passion curve handout to make an n = 200, c = 1 OC curve and answer the following questions.
(4 pts)
Use the OC curve to determine the percentage of lots that will be accepted when the true lot
proportion defective is 1%, 2%, and 4%.
What is the AQL?
What is the RQL?
What is the IQL?
In: Mechanical Engineering
An ideal Otto engine has a compression ratio of 10 and uses air as the working fluid. The state of air at the beginning of the compression process is 100 kPa and 27 0C. The maximum temperature in the cycle is 2100K. (R=0.287 for air) (using variable specific heat)
In: Mechanical Engineering
An air conditioning system is to take outdoor air at 30 oC and 70% relative humidity at a steady rate of 10 m3/s and to condition it to 25 oC and 50% relative humidity. The outdoor air is first cooled down to 13.9 oC using cooling coil and then heated to the desired condition in the heating section. Assuming the air is at 1 atm pressure,
In: Mechanical Engineering