Thermodynamics: adiabatic processes

In summary, a multicylinder engine in an airplane consuming 7.89 x 10^3 J of energy and exhausting 4.58 x 10^3 J for each revolution of the crankshaft operates at 2500 rev/min. The engine consumes fuel at a rate of 4.02 x 10^7 J/L. The mechanical power output of the engine is unknown as well as the torque exerted by the crankshaft on the load. The power that must be transferred out of the engine by the exhaust and cooling system is also unknown. Further information and steps to solve this problem can be found on various online sources.
  • #1
zandbera
18
0

Homework Statement


A multicylinder engine in an airplane operating at 2500 rev/min takes in energy 7.89 x 10^3 J and exhausts 4.58 x 10^3 J for each revolution of the crankshaft. (a) How many litres of fuel does it consume in 1.00 h of operation if the heat of combustion is 4.02 x 10^7 J/L ? (b) What is the mechanical power output of the engine? Ignore friction and express the answer in horsepower. (c) What is the torque exerted by the crankshaft on the load? (d) What power must the exhaust and cooling system transfer out of the engine?

Homework Equations


e = Weng / Qh = 1 - Qc/ Qh

The Attempt at a Solution


I just have no idea where to start this, so any tips would be greatly appreciated
 
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  • #2
bump for help
 
  • #3
Hi, Arin. It's Gareth. :) I was looking for help on the same question, and this was the first page on Google.

Anyway, if you still want help, I found this other page that has the step-by-step answers: http://www.csupomona.edu/~skboddeker/132/assign/ch22h.htm
 
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  • #4
haha hey, yeah i found another site that had a bit of an explanation to it, but it didn't have c) or d) to it. thanks
 
  • #5
hi zandbera, welcome to PF
so where are you at with the problem? helps to show some work so we know where you are getting stuck
 

FAQ: Thermodynamics: adiabatic processes

What is an adiabatic process?

An adiabatic process is a thermodynamic process in which there is no transfer of heat or matter between a system and its surroundings. This means that the system is insulated and isolated from external influences, and any changes in the system's energy are solely due to work being done on the system.

What is the first law of thermodynamics?

The first law of thermodynamics is the principle of energy conservation. It states that energy cannot be created or destroyed, but can only be transferred or converted from one form to another. This means that in an adiabatic process, the change in the internal energy of a system is equal to the work done on the system.

What is the difference between adiabatic and isothermal processes?

An adiabatic process is one in which there is no transfer of heat, while an isothermal process is one in which the temperature of the system remains constant. In an adiabatic process, the change in internal energy is due to work being done, while in an isothermal process, the change in internal energy is zero.

How does an adiabatic process affect the temperature of a system?

In an adiabatic process, the temperature of a system can change due to work being done on the system. If work is done on the system, the temperature will increase, and if work is done by the system, the temperature will decrease. This is because the internal energy of the system is directly proportional to its temperature.

What are some real-life examples of adiabatic processes?

Some real-life examples of adiabatic processes include the compression and expansion of air in a bicycle pump, the compression of gas in a diesel engine, and the expansion of air in a can of compressed air. These processes are adiabatic because there is no transfer of heat between the system and its surroundings.

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