A System is the transfer of energy between two mediums?

[wrenchtime]

Can a system be defined as the transfer of energy between two mediums?

An example of this approach is the Rankine cycle for a power plant (water and steam cycle)
This cycle would be defined by four systems.

System 1 (boiler feed pump)
Energy released by boiler feed pump…...Energy added to water

System 2 (boiler)
Energy released by boiler…...Energy added to water to make steam

System 3 turbine)
Energy added to the turbine …...Energy released by the steam

System 4 (condenser)
Energy added to the condenser…. Energy released by the steam

A system is required for each energy gain or loss in the water/steam.
This includes devices (turbine) and the surroundings (uninsulated pipe)

This cycle is a network of systems with a common medium
Each system need to meet the laws of thermodynamics.

Take care of yourself and your family

 

[BvU]

Can a system be defined as the transfer of energy between two mediums?

Yes. Anything can be defined as anything.
But in a given context definitions have to make sense to be meaningful for others working in that context.
In thermodynamics it is not customary to define a system as the transfer of energy between two media

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[wrenchtime]

Thanks for the response

One benefit to my approach is to account for all the energy losses to the surroundings or the energy usage by a source typically required in the real world applications. The goal was to tie a thermodynamic system to the laws of thermodynamics (rules of energy).

Also, it simplifiies the definition of a thermodynamic system.
Below is wikipedia's definition

A thermodynamic system is a body of matter and/or radiation, confined in space by walls, with defined permeabilities, which separate it from its surroundings. The surroundings may include other thermodynamic systems, or physical systems that are not thermodynamic systems. A wall of a thermodynamic system may be purely notional, when it is described as being 'permeable' to all matter, all radiation, and all forces. A state of a thermodynamic system can be fully described in several different ways, by several different sets of thermodynamic state variables.

I think wikipedia's definition may be difficult for someone to understand.

 

[Philip Koeck]

Thanks for the response

One benefit to my approach is to account for all the energy losses to the surroundings or the energy usage by a source typically required in the real world applications. The goal was to tie a thermodynamic system to the laws of thermodynamics (rules of energy).

Also, it simplifiies the definition of a thermodynamic system.
Below is wikipedia's definition

A thermodynamic system is a body of matter and/or radiation, confined in space by walls, with defined permeabilities, which separate it from its surroundings. The surroundings may include other thermodynamic systems, or physical systems that are not thermodynamic systems. A wall of a thermodynamic system may be purely notional, when it is described as being 'permeable' to all matter, all radiation, and all forces. A state of a thermodynamic system can be fully described in several different ways, by several different sets of thermodynamic state variables.

I think wikipedia's definition may be difficult for someone to understand.

I would say there are some minimum requirements for a system:
It has to be possible to transfer heat to or from the system or the system has to be able to do work on the surroundings or vice versa or the system has to have some defined energy, which can change or stay the same.
Thermodynamics is about working out how these various energies and energy flows are related to each other.
The important message: The energies themselves are not systems.
A system is something that receives, gives off and/or contains energy.

 

[wrenchtime]

Thank you for your feedback

Let me rephrase it in a different way with an example.
I have system that contains two mediums "A" and "B".
Assume medium "A" has a higher energy level than medium "B
The system is the transfer of energy from medium "A" to medium "B"
From medium "B" viewpoint it received energy either by work, heat or rotational energy.

This system must follow the laws of thermodynamics.
The change in energy loss from medium "A" must equal the energy gained medium "B"
1st law...energy can not be created or destroyed
The energy gained from medium "B" can"t be used to replace the energy loss from medium "A"
2nd law ...no perpetual motion.

The benefits with this approach may be seen using the boiler from original Rankine cycle example.
Image the boiler has two systems.
System 1 Boiler to water
System 2 Boiler to surrounding (air around the boiler)

Below are three different energy results from the two systems
A. system 1 @ 100 Btu/min system 2 @ 0 Btu/min (Boiler well insulated)
B. system 1 @ 85 Btu/min system 2 @ 15 Btu/min (Boiler NOT insulated)
C. system 1 @ 85 Btu/min system 2 @ 0 Btu/min (Boiler well insulated)

Result "A" shows both systems performing per design
Result "B" shows 15 Btu/min energy loss to the surroundings from poor insulation
Result "C" shows a poor performing boiler at 85 Btu/min instead of 100 Btu/min

It is important to distinguish between poor performing equipment or poor insulation.

 

[hutchphd]

A system is something that receives, gives off and/or contains energy.

Agreed. Or perhaps information (although I suppose one cannot have one without the other...and I am too ignorant to really understand).

 

[BvU]

The system is the transfer of energy

We are not making much progress here. Abundant use of the word 'system' without much clarity about the meaning.

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[Philip Koeck]

Let me rephrase it in a different way with an example.
I have system that contains two mediums "A" and "B".
Assume medium "A" has a higher energy level than medium "B
The system is the transfer of energy from medium "A" to medium "B"
....

Two things:
It doesn't make sense to redefine words, as several other colleagues have also pointed out.
The definition of system in your quote from Wikipedia is perfectly fine, I would say.
An energy transfer is not a system.
An energy transfer is an energy transfer and it makes no sense to give it a new name.
The only thing you will achieve is that nobody understands.

Second point:
If medium A has more energy than B (more inner energy, let's say), that doesn't mean that energy flows from A to B.
There's no direct connection between the relative amount of energy in two systems and the direction of transfer.
Not even the energy density of A and B will tell you which way the transfer will go.

 

[wrenchtime]

Thank you for the feedback

I must be missing the point using my definition of a system which is
"A System is the transfer of energy between two mediums."

Could you explain what the system is in my boiler example using the wikipedia's definition.
Also how to define performance issues using your approach.

 

[hutchphd]

A thermodynamic system is a body of matter and/or radiation, confined in space by walls, with defined permeabilities, which separate it from its surroundings.

What part of this is difficult to understand? You definition is different and therefore inappropriate and incorrect. Do not use it.

 

[wrenchtime]

I will not use it if you...

Could you explain what the system is in my boiler example using the wikipedia's definition.
Also how to define performance issues using your approach.

 

[hutchphd]

It is wrong for the reason I stated. If you wish to make up definitions that is your prerogative.
If you have a specific substantive question, I will be happy to help. My "approach" is known as classical thermodynamics and I cannot claim it.

 

[Philip Koeck]

I will not use it if you...

Could you explain what the system is in my boiler example using the wikipedia's definition.

In the Rankine cycle, which is an idealization of a steam engine, the most obvious system is the water that's evaporated and recondensed as it cycles round and round.
I'm far from an expert, though. I just googled it. Here's an example: https://en.wikipedia.org/wiki/Rankine_cycle

The surrounding is hot (the fire) for the evaporation part of the cycle and cold (air cooling) for the condensation part.

Can't tell you about performance issues. I guess that's quite technical and must depend on the exact heat engine you are considering.

 

[wrenchtime]

So, the water cycle of the Rankine cycle is the system.
Therefore the
Energy used by the boiler feed pump
Energy used to heat the water in the boiler
Energy released to the turbine
Energy released in the condenser to cool the water

Are the surrounding?

 

[Philip Koeck]

So, the water cycle of the Rankine cycle is the system.
Therefore the
Energy used by the boiler feed pump
Energy used to heat the water in the boiler
Energy released to the turbine
Energy released in the condenser to cool the water

Are the surrounding?

Edit: Maybe a typo in your text. Yes, the water (alternatingly liquid and vapor) is the system (not the water cycle).

Everything that heats the water and cools the steam and also the pump is part of the surroundings.