Mechanical Engineering

When a diesel engine, originally designed to be naturally aspirated, is turbocharged the fuel / air equivalence ratio at full load must be reduced to maintain the maximum cylinder pressure essentially constant. If the naturally aspirated engine was designed for = 0.75 at full load, estimate the maximum permissible value of for the turbocharged engine at full load if the air pressure at the engine inlet is 1.6 atm. Assume that the engine can be modeled with the limited-pressure cycle, with half the injected fuel burned at constant volume and half at constant pressure. The com pression ratio is 16. The fuel heating value is 42.5 MJ / Kg fuel. Assume γ =1.4, that the air temperature at the start of compression 330 K and (F / A) stoich = 0.0666, Cp 1,005 kJ / Kgk.

When a diesel engine, originally designed to be naturally aspirated, is turbocharged the fuel / air equivalence ratio at full load must be reduced to maintain the maximum cylinder pressure essentially constant. If the naturally aspirated engine was designed for = 0.75 at full load, estimate the maximum permissible value of for the turbocharged engine …

When a diesel engine, originally designed to be naturally aspirated, is turbocharged the fuel / air equivalence ratio at full load must be reduced to maintain the maximum cylinder pressure essentially constant. If the naturally aspirated engine was designed for = 0.75 at full load, estimate the maximum permissible value of for the turbocharged engine at full load if the air pressure at the engine inlet is 1.6 atm. Assume that the engine can be modeled with the limited-pressure cycle, with half the injected fuel burned at constant volume and half at constant pressure. The com pression ratio is 16. The fuel heating value is 42.5 MJ / Kg fuel. Assume γ =1.4, that the air temperature at the start of compression 330 K and (F / A) stoich = 0.0666, Cp 1,005 kJ / Kgk. Read More »

A burst of 1 x 10^9 neutrons from a pulsed accelerator is introduced into a subcritical assembly consisting of an array of natural uranium rods in water. The system has a multiplication factor of 0.968. Approximately 80% of the incident neutrons are absorbed in uranium

Problem 6 from Chapter 4 of Introduction to Nuclear Engineering (3rd Ed.) A burst of 1 x 10^9 neutrons from a pulsed accelerator is introduced into a subcritical assembly consisting of an array of natural uranium rods in water. The system has a multiplication factor of 0.968. Approximately 80% of the incident neutrons are absorbed …

A burst of 1 x 10^9 neutrons from a pulsed accelerator is introduced into a subcritical assembly consisting of an array of natural uranium rods in water. The system has a multiplication factor of 0.968. Approximately 80% of the incident neutrons are absorbed in uranium Read More »

From a pulsed accelerator, a burst of 1 x 1010 neutrons is introduced into a subcritical assembly consisting of an array of natural uranium rods in water. If the system has a multiplication factor of 0.97 and approximately 80% of the incident neutrons are absorbed in uranium, calculate: (a) The number of first-generation fissions that the neutrons produce in the assembly, and (b) The total fission energy in joules released in the assembly by the neutron burst?

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From a pulsed accelerator, a burst of 1 x 1010 neutrons is introduced into a subcritical assembly consisting of an array of natural uranium rods in water. If the system has a multiplication factor of 0.97 and approximately 80% of the incident neutrons are absorbed in uranium, calculate: (a) The number of first-generation fissions that the neutrons produce in the assembly, and (b) The total fission energy in joules released in the assembly by the neutron burst?

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From a pulsed accelerator, a burst of 1 x 1010 neutrons is introduced into a subcritical assembly consisting of an array of natural uranium rods in water. If the system has a multiplication factor of 0.97 and approximately 80% of the incident neutrons are absorbed in uranium, calculate: (a) The number of first-generation fissions that the neutrons produce in the assembly, and (b) The total fission energy in joules released in the assembly by the neutron burst?

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6.6 Lead melts at 620°F and tin melts at 450°F. They form a eutectic containing 62 percent tin at 360°F. The maximum solid solubility of tin in lead at this temperature is 19 percent; of lead in tin, 3 percent. Assume the solubility of each at room tempera- ture is 1 percent. 1 Draw the equilibrium diagram to scale on a piece of graph paper labeling all points, lines, and areas. 2 Describe the solidification of a 40 percent tin alloy. Sketch its microstructure at room temperature, giving the chemical composition and relative amounts of the phases present. 3 Draw the cooling curve for the above alloy. 4 Repeat 2 and 3 for an alloy containing 90 percent tin. 67 Calcium (melting point 1560°F) and magnesium (melting point 1200°F) form a compound Camg, which contains 45 percent calcium and melts at 1320°F. This compound forms a eutectic with pure magnesium at 960ºF and contains 16 percent calcium. The solubility of the compound in magnesium is about 2 percent at the eutectic temperature and decreases to almost zero at room temperature. Magnesium is not soluble in the compound. A second eutectic is formed between the compound and calcium at 830°F containing 78 percent calcium, and there is no solid solubility between the compound and pure calcium. 1 Draw the equilibrium diagram to scale on a piece of graph paper labeling all points, lines, and areas. 2 Describe the slow cooling of an alloy containing 30 percent calcium. Sketch the microstructures at room temperature and give the relative amounts of the phases present 3 Draw the cooling curve. 4 Write the specific equation of the reaction that takes place at each eutectic temperature.

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Newton’s Law of Cooling states that, when the temperature of an object is different from the temperature of its surroundings, then the rate at which the object will cool down (or heat up) is directly proportional to the difference in the temperatures. Symbolically, if Ts is the temperature of the surroundings and T(t) is the temperature of the object, then

Newton’s Law of Cooling states that, when the temperature of an object is different from the temperature of its surroundings, then the rate at which the object will cool down (or heat up) is directly proportional to the difference in the temperatures. Symbolically, if Ts is the temperature of the surroundings and T(t) is the …

Newton’s Law of Cooling states that, when the temperature of an object is different from the temperature of its surroundings, then the rate at which the object will cool down (or heat up) is directly proportional to the difference in the temperatures. Symbolically, if Ts is the temperature of the surroundings and T(t) is the temperature of the object, then Read More »

Water flows by gravity from the reservoir 1 to the reservoir 2 through a constant 5 cm diameter piping system as shown in the figure below. The flow rate is 5 L/s. The fluid at points 1 and 2 is open to the atmosphere (P P2-Patm). The density of the water is 1000 kg/m3, the dynamic viscosity is -1.307×10-3 kg/m, the roughness of the internal surface of the pipe is 0.00026 entrance, K-05 Standard elbow, langed, Ky-03 D 5 cm 4m Gate valve fully open volume boundary 80 m Esit, K-1.06 Question 3 Calculate: the average velocity, Reynolds number, Total pressure drop (sum of Minor and Major) Question 4 Assume that the fluid velocities at points 1 and 2 are nearly zero (V V2-0) apply the principle of energy conservation (Bernoulli with losses) (points 1 and 2) to determine the elevation zi

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