An open tank has a vertical rectangular gate as a partition, and on one side contains gasoline. The rectangular gate, that is 5 m high and 2 m wide, is hinged at the bottom end of the partition. A stopper is located at the top end of the gate, which only allows the gate to swing open towards the gasoline side of the tank. Water is slowly added to the empty side of the tank. If the depth of the gasoline is 4.5 m, determine the depth of the water when the gate is about to open.

Air flows through a nozzle which has inlet areas of (10 cm2
). If the air has a velocity of (120 m/s) a
temperature (300K) and a pressure of (700kpa) at the inlet section and a pressure of (250kpa) at the exit,
find the mass flow rate through the nozzle and the velocity at the exit of the nozzle, assuming one-
dimensional isentropic flow. (R=287 J/kg. K), (K=1.4). (25%)

An adiabatic gas turbine uses air to produce work. Air expands adiabatically from 600 kPa and 287 C to 90 kPa and 67 C. Take specific heats at room temperature (300 K). a) Find the isentropic efficiency of the turbine. b) Find the work produced by the turbine for a mass flow rate of 2.5 kg/s. c) If the mass flow rate of air is again 2.5 kg/s, find the entropy generation under steady conditions

Two long concentrie cylinders have diameters of 5 and 10

cm, respectively. The inside cylinder is at 900 C and the outer

cylinder is at 100-C. The inside and outside emisivities are 0.8

and 0.4, respectively. Calculate:

a) the percent reduction in heat transfer if a cylindrical radiation

shield having a diameter of 6 cm and emisivity af 0.3 is placed

between the two cylinders.

b)discuss the effect of decreasing the shield diameter on the

percent reduction in heat transfer

c)draw the network circuit

cxraw the network circuit

Dislocations can work as sinks and sources of vacancies. Explain.

A Dual cycle engine is analyzed using the cold air standard method. Given the conditions at state 1, compression ratio (r), and cutoff ratio (rc) determine the efficiency and other values listed below.

Note: The specific heat ratio and gas constant for air are given as k=1.4 and R=0.287 kJ/kg-K respectively.

Given Values

T1 (K) = 316

P1 (kPa) = 170

r = 18

rp = 1.44

rc = 1.22

a) Determine the specific internal energy (kJ/kg) at state 1.

b) Determine the temperature (K) at state 2.

c) Determine the pressure (kPa) at state 2.

d) Determine the specific internal energy (kJ/kg) at state 2.

e) Determine the temperature (K) at state 3.

f) Determine the pressure (kPa) at state 3.

g) Determine the specific internal energy (kJ/kg) at state 3.

h) Determine the specific enthalpy (kJ/kg) at state 3.

i) Determine the temperature (K) at state 4.

j) Determine the pressure (kPa) at state 4.

k) Determine the specific enthalpy (kJ/kg) at state 4.

l) Determine the temperature (K) at state 5.

m) Determine the pressure (kPa) at state 5.

n) Determine the specific internal energy (kJ/kg) at state 5.

o) Determine the net-work per cycle (kJ/kg) of the engine.

p) Determine the heat addition per cycle (kJ/kg) of the engine.

q) Determine the efficiency (%) of the engine.

USE EXCEL TO SOLVE

After heat treatment, the 2-cm thick metal plates (k = 180 W/m·K, ρ = 2800 kg/m3, and cp = 880 J/kg·K) are conveyed through a cooling chamber with a length of 10 m. The plates enter the cooling chamber at an initial temperature of 500°C. The cooling chamber maintains a temperature of 10°C, and the convection heat transfer coefficient is given as a function of the air velocity blowing over the plates h = 33V0.8, where h is in W/m2·K and V is in m/s. To prevent any incident of thermal burn, it is necessary for the plates to exit the cooling chamber at a temperature below 50°C. In designing the cooling process to meet this safety criteria, use EXCEL software to investigate the effect of the air velocity on the temperature of the plates at the exit of the cooling chamber. Let the air velocity vary from 0 to 40 m/s, and plot the temperatures of the plates exiting the cooling chamber as a function of air velocity at the moving plate speed of 2, 5, and 8 cm/s

1. The thermal efficiency of a Rankine power cycle may be improved by i. Superheating the steam ii. Reheating the steam between high and lower pressure sections of the turbine iii. Regenerative Feedwater Heating iv. Insulating the turbine and decreasing the entropy production during the expansion process v. Incorporating a Rankine cycle power system as part of a cogeneration system a. Items i), ii), and iv) only b. Items i), iii), and v) only c. Items ii), iv) and v) only d. All of these e. None of these

2. The back work ratio is … a. The ratio of the compressor outlet to inlet pressure in a vapor compression power system. b. The ratio of the pump work (power) input divided by the turbine work (power) output in a Rankine cycle power system. c. The ratio of the inlet pressure to the outlet pressure in a steam turbine. d. The ratio of the inlet pressure to the outlet pressure in the feedwater pump system of a Rankine cycle power system.

3. For the Rankine cycle process where steam expands through the turbine, in a realistic process, the entropy at the exit is … a. Greater than the entropy at the inlet. b. Equal to the entropy at the inlet. c. Less than the entropy at the inlet. d. Has no relationship to the entropy at the inlet.   e. None of these answers is correct.

4. Regenerative feedwater heaters may be … a. Devices where natural gas is used to heat feedwater to prevent freezing under cold conditions.   b. Open devices where the steam and the water being heated are at the same pressure, c. Closed devices where the steam and the water being heated may be at different pressures and do not mix, d. Open or closed devices, where both have their advantages and applications. e. Devices where steam is diverted, passed back into the steam generator, and then sent back into the turbine.   f. None of the above.

5. With regenerative feedwater heating, a powerplant will not have more than one stage of feedwater pump (i.e., each feedwater pump will take in water at condenser pressure and deliver water at steam generator/turbine inlet pressure). a. True b. False

6. In a power plant, the heat rejected from the condenser … a. Is not a significant amount of heat, is rejected into the surroundings, and is not a concern.   b. Is a significant amount of heat and is captured to turn the main turbine.   c. Is a significant amount of heat, is rejected into the surroundings, and can change the local environment. d. Heat is not rejected in the condenser.

7. Deaeration is needed in systems using water as a working fluid to remove air from the water and to minimize corrosion.   a. True b. False

8. A closed feedwater heater may be used for deaeration. a. True b. False
9. In a reciprocating power system,   i. Material flows at a constant rate through the device and passes through a turbine to produce shaft power output, ii. Material does not flow at a constant rate through every section of the device.   iii. Power is produced at all times. iv. Power is produced only during part of the cycle in each section of the device and is not produced uniformly at every instant.   v. The power unit consists of one or more piston and cylinder sections with intake and exhaust valves and where fresh fuel and air are taken in during one part of the process, exhaust gases are ejected during another part of the process, and at other times the cylinder is closed off from the intake and exhaust sections (manifolds).   vi. The power unit consists of a compressor, a burner section, and a turbine.   a. Items i), iii), and vi) are correct. b. Items ii) and iii) are correct. c. Items ii), iv) and v) are correct. d. Items ii), iv), and vi) are correct. e. None of these combinations are correct.

10. The Otto cycle model is used with … a. Reciprocating internal combustion engines where the fuel-air mixture is ignited by a spark. b. Reciprocating internal combustion engines where the fuel-air mixture is ignited by high pressures in the cylinders. c. Internal combustion engines with continuous flow of fuel and air (i.e., gas turbine engines). d. External combustion “hot air” engines. e. Vapor compression refrigeration.

11. In an air standard analysis, we pretend that the substance in an engine is pure air, and we analyze this as if energy is put into the air from the outside and, later, waste heat is removed from the air. a. True b. False




12. The Brayton cycle is used to model the operation of … a. Steam Power Plants b. Spark Ignition Internal Combustion Engines c. Compression Ignition Internal Combustion Engines d. Gas Turbine Engines e. Vapor Compression Refrigeration Machines f. None of these

13. For high thermal efficiency, the compression ratio in a spark ignition reciprocating engine is likely to be in the range of … a. 8:1 to 10:1. b. 15:1 to 20:1. c. 20:1 to 40:1. d. None of these are reasonable.

14. For high thermal efficiency, the compression ratio in a compression ignition reciprocating engine is likely to be in the range of … a. 8:1 to 10:1. b. 15:1 to 20:1. c. 20:1 to 40:1. d. None of these are reasonable.

15. The environmental aspects of refrigerants are important considerations in selection. a. True b. False

16. Ammonia may be used as a refrigerant. a. True b. False

17. Carbon Dioxide may be used as a refrigerant. a. True b. False

A company owns a refrigeration system whose refrigeration capacity is 200 tons (1 ton of refrigeration = 211 kJ/min), and you are to design a forced-air cooling system for fruits whose diameters do not exceed 7 cm under the following conditions: The fruits are to be cooled from 28°C to an average temperature of 8°C. The air temperature is to remain above -2°C and below 10°C at all times, and the velocity of air approaching the fruits must remain under 2 m/s. The cooling section can be as wide as 3.5 m and as high as 2 m. Assuming reasonable values for the average fruit density, specific heat, and porosity (the fraction of air volume in a box), recommend reasonable values for

(a) the air velocity approaching the cooling section,

(b) the product-cooling capacity of the system, in kg·fruit/h, and

(c) the volume flow rate of air.

Compare the martensite and tempered martensite in terms of the phases they contain, ductility, strength and microstructure, explain the reasons for the differences.

A rotating shaft has four masses A, B, C, and D attached to it. The planes that these masses rotating at are spaced equally. The magnitude of the masses are 6.5, 11.8, 4.2, and 5.1 kg, respectively. Calculate the radii that the masses should be placed at from the center of the shaft such that the system be in a complete dynamic balance. The shaft angular speed varies between 1760 and 1875 r.p.m. Assume whatever dimension or quantity that you decide it is necessary.

A thin-walled tube with a diameter of 6 mm and length of 20 m is used to carry exhaust gas from a smoke stack to the laboratory in a nearby building for analysis. The gas enters the tube at 200°C and with a mass flow rate of 0.005 kg/s. Autumn winds at a temperature of 15°C blow directly across the tube at a velocity of 5 m/s. Assume the thermophysical properties of the exhaust gas are those of air. (a) Estimate the average heat transfer coefficient for the exhaust gas flowing inside the tube. (b) Estimate the heat transfer coefficient for the airflowing across the outside of the tube. (c) Estimate the overall heat transfer coefficient U and the temperature of the exhaust gas when it reaches the laboratory. (Note: 90°C is a reasonable guess for the tube temperature.)

1.What is the value for the Nusselt number on the inside of the tube?

2.What is the average inside heat transfer coefficient, in W/m²·K?

3.What is the value of the Nusselt number on the outside of the tube?

4.What is the average outside heat transfer coefficient, in W/m²·K?

5.What is the overall heat transfer coefficient, U, in W/m²·K?

6.What is the temperature of the gas at the outlet of the tube, in °C?

1. Consider example of any four bar mechanism. first perform the kinematic analysis(Position,Velocity,Acceleration).And then find the following
   1. Complete Free body diagram.
   2. Complete Matrix equation for the mechanism force analysis.
   3. Values of all Variables involved ( mass, mass moment of Inertia, Force, Torque ).
   4. Equations used for mass, mass moment of Inertia of each link.
2. Find center of Percussion of a sports stick, racket or bat