Describe the difference between spectral and total blackbody emissive power.
In: Mechanical Engineering
The clausius statement of the second law denies the possiblity of transferring energy by heat from a cooler to a hotter body. I think it true because the statement says that " no process is possible in which the sole result of it would be the transfer of heat from a cooler to a hotter body" However, the textboox solution says otherwise. can somebody explain
In: Mechanical Engineering
Thermodynamics
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1. Correct Answer: 8.0087 ± 0.1% Steam at 1 MPa, 593.2oC, expands in a turbine to 0.01 MPa. If the process is isentropic, find the specific entropy (kJ/kg-K) at the exit of the turbine. Note: Give your answer to four decimal places. |
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2. Correct Answer: 301.43 ± 0.08% |
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Initially, an insulated rigid tank contains 19.37 kg of water at 27.04oC and 101 kPa. The tank also contains a 4.42 kg copper block at 87.13oC. Assume constant specific heats where Cwater = 4.179 kJ/kg-K and CCu = 0.385 kJ/kg-K. Determine the final equilibrium temperature (K). Note: Give your answer to two decimal places. |
In: Mechanical Engineering
Air at 40 degrees C is humidified by flowing over a 1-m-long container filled with water. The surface area of container is 0.5m^2.The interfacial temperature is 20 degrees C. If the initial humidity of the air is 0% and its velocity is 0.5 m/s, calculate the mass flow rate of vapor evaporated.
In: Mechanical Engineering
Compute the maximum thrust density, power density and specific impulse for a 3-grided ion engine, having an acceleration voltage of 2000 V, and a voltage difference of 2500 V and a gap of 1.5 mm between the plasma and the first acceleration screens. Compute the propulsive parameters for the following propellants: xenon, argon, and molecular hydrogen.
In: Mechanical Engineering
Discuss the bene?ts and drawbacks of bond-then-form versus form-then-bond approaches. In your discussion, include discussion of processes which can use secondary support material and those which do not.
In: Mechanical Engineering
Thermodynamics
Air at 3.5 MPa and 500°C is expanded in an adiabatic gas turbine to 0.2 MPa. Assume that the process is reversible. Changes in KE and PE may be neglected and the average temperature of the gases is 550 K.
(a) Create a schematic representation of the equipment. (b) Represent the process on a T-s diagram. (c) Determine the polytropic exponent. (d) Determine the change in entropy for this expansion process
In: Mechanical Engineering
A rocket motor burns LH2 and LOX. The combustion chamber pressure and temperature are 25 atmospheres and 3517 K, respectively. The area of the nozzle throat is 0.1 m^2. The nozzle exit area is designed so that the exit pressure equals the ambient pressure at 30 km altitude. For the combustion gases, assume gamma is 1.22 and the molecular weight is 16. At an altitude of 30 km, where the local atmospheric pressure is 1186 Pa, calculate (a) the specific impulse, (b) the thrust, (c) the area of the exit, and (d) the exit Mach number
In: Mechanical Engineering
The measurement of heat loss through egg shell and the thermal energy contained in a boiled egg.
Deriving the convection heat transfer coefficient between the egg shell and ambient air might be the key in solving this question.
How can I determine this through experimentation?
In: Mechanical Engineering
3.) Product with Cp = 0.75 Btu/lb°F is flowing at a rate of 3300 lb/h and has to be cooled from 221°F to 160°F. ? Cooling water at 60°F at a mass flow rate of 10,000 lb/h is used. ? The overall U of the heat exchanger is 115 Btu/h ft2 °F. Calculate the outlet water temperature (will be the same for both) ____________________ and the heat exchanger area for: A co-current flow shell-and-tube heat exchanger. ____________________ A counter-current flow shell-and-tube heat exchanger. __________________
In: Mechanical Engineering
Q: Does chainfolding occur in polystyrene? Please explain.
In: Mechanical Engineering
Q: If a plastic can be recycled, what is its functionality?
In: Mechanical Engineering
Consider two-dimensional incompressible plane viscous flow between parallel plates a distance 2h apart, with the origin along the centerline. The plates are very wide and very long, so that the flow is essentially axial. The present case is where the upper plate moves at velocity V but there is no pressure gradient. Neglect gravity effects. Determine the velocity profile for this flow.
In: Mechanical Engineering
A four-cylinder four-stroke engine is operating at a bmep of 2 bar. The pressure at inlet valve closure is 0.37 bar, and the fmep is 0.8 bar. Assuming that the engine gross indicated efficiency is unchanged, verify that disablement of the valves on two cylinders would reduce the fuel consumption by about 13 per cent compared with about an 8 per cent fuel saving if the fuel was not supplied to two cylinders. Assume that the gross imep is proportional to the pressure at inlet valve closure, and that the gross indicated efficiency is constant. State any additional assumptions that you make. By means of p–V diagram sketches, explain why disabling only the inlet or exhaust valves would have a fuel economy benefit comparable to fuel disablement to two cylinders.
In: Mechanical Engineering
Describe the differences in valve timing on a naturally aspirated diesel engine, a turbocharged diesel engine, and a high-performance petrol engine.
In: Mechanical Engineering