Consider the design of an engine for a high-efficiency automobile engine design that is to work in conjunction with an electric motor in a hybrid drive. Management wants to know what would be the displacement and efficiency of an engine producing 50 hp (net). Since engines are always rated at ISO (sea level) conditions where their performance is best, take the inlet air to be at 14.7 psia and 59°F. Consider two different directions the company could take:

a) Otto Cycle (four-stroke): In order to convince customers that fuel costs will be low, the sales department recommends that a gasoline engine should use regular-octane fuel, which will limit the maximum CR to 9. The manufacturing engineers have suggested an aluminum alloy that they would like to use in building the engine block and heads, and the strength of this alloy will limit maximum cylinder pressures to 1000 psia. A peak engine speed of 8000 RPM is feasible for this small gasoline engine.

b) Diesel Cycle: Assume a compression ratio of 20 is feasible. Lower cutoff ratios are preferable, and you should design for a value of 1.3 based on the company’s experience with other Diesel engine designs. Maximum engine speeds are typically lower for Diesel engines – assume that 3500 RPM is the upper limit here. For simplicity, assume specific heats can be assumed constant, and take cp=0.24 Btu/lbm-R, cv=0.17 Btu/lbm-R, and k=1.4 throughout both calculations.

After modeling the two cycles, generate a table that compares the two cycles – the table should include (in the following order please) the maximum cycle pressure (in psia), maximum cycle temperature (in °F), volumetric flow rate into the engine (in CFM = cubic feet/min), engine displacement (in liters), and thermal efficiency. Finally, summarize in one or two sentences the primary trade-offs (from your tabular summary) that will dictate the final design choice.

A vehicle burns 150 mole/h of gasoline (C8H18) with 12% excess air in a combustion chamber with 90% fuel conversion.

a) What is the molar flow of incoming air to the combustion chamber? (mol/h)

b) What are the mass flows of the combustion products at the chamber’s exit? (g/h)

Problem 6.082 SI

Steam undergoes an isentropic compression in an insulated piston–cylinder assembly from an initial state where T₁ = 120°C, p₁ = 1 bar to a final state where the pressure p₂ = 50 bar.


Determine the final temperature, in °C, and the work, in kJ per kg of steam.

can anyone exolain to me what is the uses and applictions of (Optical Metamaterials)

please write clear

A thin plate is initially at a uniform temperature of 200°C. At a certain timet = 0 the temperature of the east side of the plate is suddenly reduced to 0°C. The other surface is insulated. Use the explicit finite volume method in con- junction with a suitable time step size to calculate the transient temperature distribution of the slab and compare it with the analytical solution at time (i) t = 40 s, (ii) t = 80 s and (iii) t = 120 s. Recalculate the numerical solution using a time step size equal to the limit given by (8.13) for t = 40 s and com- pare the results with the analytical solution. The data are: plate thicknessL = 2 cm, thermal conductivity k = 10 W/m.K and ?c = 10 × 106 J/m3.K.

1)10 m³ /h of water flows through a pipe with 100 mm inside diameter. Calculate the flow velocity inside this pipe. ?

2) A river discharges 100 m³ of water to the sea every 2 seconds. What is the flow-rate of this river expressed in m3/s?

Using MATLAB:

The velocity, v, and the distance, d, as a function of time, of a car that accelerates from rest at constant acceleration, a, are given by

= a n d = 12

Determine v and d at every second for the first 10 seconds for a car with acceleration of = 15 ft/s2. Your output must have exactly the same format as the template table below. Note that dots have been added to the table below; you can count the dots to determine the exact spacings. Also note the units.

··········Time (s) ······· ···Distance (ft) ·········Velocity (mph) ··········x.x·················x.xxe+yy···············x.xxx

A power plant operates on a regenerative vapor power cycle with one open feedwater heater. Steam enters the first turbine stagge at 12 MPa, 560*C and expands to 1 MPa, where some of the steam is extracted and diverted to the open feedwater heater operating at 1 MPa. The remaining steam expands through the second turbine stage to the condenser pressure of 6 kPa. Saturated liquid exits the open feedwater heater at 1 MPa. The net power output for the cycle is 330 MW. For isentropic processes in the turbines and pumps, determine

(a) The cycle thermal efficiency.

(b) The mass flow rate into the first turbine stage, in kg/s.

(c) The rate of entropy production in the open feedwater heater, in kW/K.

This is a heat transfer problme.

Prove that Nu=4.36 for fully-developed laminar flow in a tube subject to a constant surface heat flux boundary condition.

This was posted before but it was a bit unclear, thanks!

what are  superchargers.

2 and half page.(summary)

The information presented should be technical, current, appropriately detailed, and include elements of design .

Design elements of historical significance are valuable and should be included; however the research and presentation should focus on the current state of the art and future expectations of superchargers, discuss evolution (history) ,current widespread designs, trends -conclusion

include references (web AND papers, books).

Textbook Internal Combustion Engines Applied Thermosciences Third Edition Colin R. Ferguson Allan T. Kirkpatrick Mechanical Engineering Department Colorado State University, USA Internal Combustion Engines

What derivatives associated with static stability for airplanes? How these derivatives may affect dynamic rigid body modes?

A vapor-compression heat pump with a heating capacity of 500 kJ/min is driven by a power cycle with a thermal efficiency of 20%. For the heat pump, Refrigerant 134a is compressed from saturated vapor at -10°C to the condenser pressure of 10 bar. The isentropic compressor efficiency is 80%. Liquid enters the expansion valve at 9.6 bar, 34°C. For the power cycle, 80% of the heat rejected is transferred to the heated space. (a) Determine the power input to the heat pump compressor, in kW (b) Evaluate the ratio of the total rate that heat is delivered to the heated space to the rate of heat input to the power cycle. Round answers to 3 significant digits.

The capacity of a propane vapor-compression refrigeration system is 8 tons. Saturated vapor at 0°F enters the compressor, and superheated vapor leaves at 120°F, 180 lbf/in.² Heat transfer from the compressor to its surroundings occurs at a rate of 3.5 Btu per lb of refrigerant passing through the compressor. Liquid refrigerant enters the expansion valve at 85°F, 180 lbf/in.² The condenser is water-cooled, with water entering at 65°F and leaving at 80°F with a negligible change in pressure. Determine

Round answers to 3 significant digits.

A fixed-mass system contains water (H20) in a rigid (fixed-volume) container. The mass of the water is mass, m= 1.805719781 kgs. A process occurs having the following initial and final thermodynamic properties.

Initial Pressure: P1 = 1000kPa   Initial Temperature: T1 = 600 ^oC   Final Temperature: T2 = 140 ^oC

Determine the following: (Neglect changes in kinetic and potential energy)  

1. 1W2 (work done on.by the system, in kJoules)  

2. 1Q2  (heat transfer to/from the system, in kJoules)

3. (S₂ - S₁)sys (Entropy change of the system, in kJ/K)  

4. What is the maximum temperature of the surroundings (I.e., T₀ in degrees K) for which there is no 2nd Law violation? (Hint: consider the net entropy change, system plus surroundings.)

) One of the major functions of cooling tower is to cool hot but dry gas flow via spray vaporization under a counter-flow mode.  

a);List governing mechanisms (e.g., mass, momentum and heat transfer) and major assumptions for problem simplification;

b);Establish a heat transfer model of gas cooling, as well as a hydrodynamics model of droplet transport that is coupled with gas heating and vaporization