Can a thermodynamic heat engine include all these processes?

In summary: You could use the ideal gas law, but I'm not sure how that would work in this context.So basically, you need to figure out how to use the four processes in order, and then you can use the ideal gas law to figure out the temperature.
  • #1
distalphalanx
3
0

Homework Statement


Hi, I'm a new user and got this problem. Sorry to bother, but I couldn't find any relevant information from my Physics books..
The problem states: Build a heat engine using these processes: adiabatic, isothermal, isochoric and isothermal. The work-cycle of the engine must include all these cycles.You are allowed to use each process only once.
a) Name the processes, and draw your cycle into a pV-diagram.
b) At which processes does your engine do work and when is work done on it? At which processes does your engine emit heat, and when is heat added to the cycle?
c) How does the 1st and 2nd law of thermodynamics restrict the operation of your engine?

I know there's a simple solution to this problem, but I just can't figure it out right now..
Thanks in advance for your assistance!

Homework Equations


So basically, I have to figure out which of all thermodynamic cycles works with this principle with all these four elements used just once?
EDIT: basically I just need to know in which order I need to put the processes into my pV-diagram. When I got that clear, I'll probably be able to calculate the rest.

Q=W (1st Law of TD)
pv=nRT
p1V1=p2V2 (isothermal)
Q=W (isothermal)
dE= Q-W (inner energy)
V1/T1 = V2/T2 (isobaric)
p1/T1=p2/T2 (isochoric)
further explanation needed from some kind of guru =)

The Attempt at a Solution

 
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  • #2
Try sketching the cycle on a PV diagram first.

The easy way to see this is starting from the Carnot cycle, where you replace one of the adiabatic steps with an isochoric (constant volume) step (two ways to do this). This wil have two isothermal steps, but you list isothermal twice, so I don't know if this is allowed. If you are to have only three steps, then you need to think about how you would arrange the three lines: isocharic (vertical), isotherm (gentle slope), adiabat (steeper slope than isotherm) between three points (I can see only one ways ot do this).
 
  • #3
I would assume 4 processes as the problem states: adiabatic, isothermal at T1, isochoric and isothermal at T2.

You also need an equation of state for an adiabatic process.
 

1. Can you explain the thermodynamic processes involved in a heat engine?

A thermodynamic heat engine includes four main processes: isothermal, adiabatic, isobaric, and isochoric. In the isothermal process, the temperature remains constant while the volume and pressure change. In the adiabatic process, there is no heat exchange and the temperature and volume change. In the isobaric process, the pressure remains constant while the temperature and volume change. In the isochoric process, the volume remains constant while the temperature and pressure change.

2. Is the Carnot cycle the only type of heat engine?

No, the Carnot cycle is just one type of heat engine. There are other types of heat engines, such as the Otto cycle, Diesel cycle, and Brayton cycle, which are commonly used in internal combustion engines.

3. Can a thermodynamic heat engine operate in a closed system?

Yes, a thermodynamic heat engine can operate in a closed system. In fact, most heat engines operate in a closed system, where the working fluid is continuously cycled through the engine, rather than being replenished.

4. What is the efficiency of a thermodynamic heat engine?

The efficiency of a thermodynamic heat engine is the ratio of the work output to the heat input. This is known as the Carnot efficiency and is given by the equation: efficiency = (T1-T2)/T1, where T1 is the temperature of the hot reservoir and T2 is the temperature of the cold reservoir.

5. Can a thermodynamic heat engine violate the laws of thermodynamics?

No, a thermodynamic heat engine cannot violate the laws of thermodynamics. The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted. The second law states that heat cannot spontaneously flow from a colder body to a hotter body. These laws limit the efficiency of a thermodynamic heat engine and prevent it from violating thermodynamic principles.

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