Ontology: Include "energy conversion efficiency" class

[k-knosala]

Description of the issue

We need a class for energy conversion efficiency:

Energy conversion efficiency is the ratio between the useful output of an energy
conversion component and the input, in energy terms.

The definition of energy conversion efficiency refers to all useful outputs. Energy conversion efficiency for a certain output can be distiguished by e.g. electrical efficiency, mechanical efficiency and thermal efficiency.

Energy storage efficiency is different from energy conversion efficency and should be covered in a seperate issue.

Ideas of solution

Definition: Energy conversion efficiency is the ratio between the
useful output of an energy converting device and the input, in energy terms.

Existent classes that can be used to integrate energy conversion efficieny:

• energy conversion efficiency is a ratio
• energy converting device does Energy Transformation with
  energy conversion effiency

Workflow checklist

• [x] I discussed the issue with someone else than me before working on a solution
• [x] I already read the latest version of the workflow for this repository
• [x] The goal of this ontology is clear to me

I am aware that

• [x] every entry in the ontology should have a definition
• [x] classes should arise from concepts rather than from words

[stap-m]

We have ratio in the OEO imported from the UO. It's there twice:

• As subclass of dimensionless unit: A dimensionless unit which denotes an amount or magnitude of one quantity relative to another.
• As subclass of the other ratio: A dimensionless ratio unit which, given a pair of quantities a and b, for which b is a multiple of a, denotes b by giving the multiplier (coefficient) c for a to result in b.

I don't find it easy to classify energy conversion efficiency. From my point of view, an efficieny is specifically dependent to an object.
On the other hand, a ratio is something generically dependent and mathematically calculated: it could be a subclass of quantity with a property has unit and a unit dimentionless unit or ratio (is this how the UO is used? @jannahastings ).

[jannahastings]

I think the way UO is used is something along these lines:

There are always four separate things: (1) the entity in reality (some sort of specifically dependent continuant, perhaps, or a process) (2) a number (3) a unit. The entity then has_value some (4) quantity value entity, that has_unit the unit. (And may have a specified value with a data property). The relationship between the quantity value entity (4) and the entity in the world (1) is is_about.

[k-knosala]

Thank you @jannahastings for the clarification.

We have process attribute as a suclass of process. It already contains power as "the process attribute that is the amount of energy transformed or transferred per time unit". Would that be the right place to implement a generic energy efficiency ?

The chain would go: process attribute entity energy efficiency (has_unit ratio) is_about process entity energy transformation (has_value energy efficiency, has_input some energy, has_output some energy) is a property of some sort of independent continuant (e.g. energy converting device).

Then it would be possible to assign the specifically dependent continuants like chemical energy, electrical energy etc. to the energy converting device.

Instead of energy transformation, the entity energy efficiency could be used for the (afaik not yet existing) processes energy storage or energy transport.

Is that the right way to think?

[stap-m]

I like your approach @k-knosala.
Still, the definition of energy transformation is currently focussing on the "whole" process, i.e. losses are also seen as output: for example rotational energy is transformed into electirc energy and heat (losses)
From your proposed point of view the process would transform rotational energy into electric energy with a certain efficiency which reflects the losses.
We could of course change the def of energy transformation or creating a new process, to solve this. Any good ideas @jannahastings @l-emele?

[l-emele]

The current definition of the energy transformation is: _Energy transformation is a process in which one ore more certain types of energy as input result in certain types of energy as output._ It is rather generic and does not say that the amount of energy in equals the energy out. So I do not see the need for a redefinition here.

[k-knosala]

@l-emele I totally aggree that the definition of energy transformation does not need to be changed. I am thinking of a quality value entety that is_about energy transformation.

@stap-m Maybe the definition of "useful" should not be made in the ontology. A way to circumvent the definiton of "useful" would be to have a conversion factor for every output.

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

Energy conversion efficiency is the ratio between the useful output of an energy
conversion component and the input, in energy terms.

This is correct for efficiencies propper (η). Coefficient of performance (COP) ignores (the free) part of energy inputs. Although they measure the same thing, engineers tend to be testy when it comes to conflating the two, so I think they should both be represented in the ontology. Specifically, limiting efficiencies to values less then one (constraining attributes was discussed on OEO Dev Meeting 7) would not work for COPs.

[stap-m]

There are always four separate things: (1) the entity in reality (some sort of specifically dependent continuant, perhaps, or a process) (2) a number (3) a unit. The entity then has_value some (4) quantity value entity, that has_unit the unit. (And may have a specified value with a data property). The relationship between the quantity value entity (4) and the entity in the world (1) is is_about.

So, we could define energy convertion efficiency as process attribute (1) and a corresponding quantity value efficienty quantity value (2) with unit ratio (3). And equally for coefficient of performance as separate process attribute.

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

So, we could define energy convertion efficiency as process attribute (1) and a corresponding quantity value efficienty quantity value (2) with unit ratio (3). And equally for coefficient of performance as separate process attribute.

I'm not sure I got how attributes fit in the ontology, but sounds right.

[sfluegel05]

So far we have:

• energy conversion efficiency, a subclass of process attribute, which has the relations process attribute of some energy transformation and has value some efficiency value
• efficiency value, a subclass of quantity value, which has the relation has unit some ratio

We still need definitions for these terms. My suggestions (based on the discussion above):

• energy conversion efficiency: _Energy conversion efficiency is a process attribute describing the ratio between the input of an energy transformation and its output._
• efficiency value: _An efficiency value is a quantity value stating the ratio between a processes inputs and outputs of a certain type._

Also, I'd propose opening a new issue for coefficient of performance

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

• efficiency value: _An efficiency value is a quantity value stating the ratio between a processes inputs and outputs of a certain type._

Can't we be more specific about the outputs? They are either used or lost/dissipated/cooled away, so how about

• efficiency value: _An efficiency value is a quantity value stating the ratio between a process's inputs and the outputs that are used._
  ("processes" is plural, the genitive is "process's")

• energy conversion efficiency: _Energy conversion efficiency is a process attribute describing the ratio between the input of an energy transformation and its output._

The output needs specification, else the ratio is 1 by definition. So

• energy conversion efficiency: _Energy conversion efficiency is a process attribute describing the ratio between the input of an energy transformation and the outputs that are used._

Also, I'd propose opening a new issue for coefficient of performance

Actually it's quite analogous to efficiency. Efficiency disregards heat _outputs_ (unless they are used, e.g. co-production of heat and power), whereas COP disregards heat _inputs_. So I would suggest:

• coefficient of performance value: _An coefficient of performance value is a quantity value stating the ratio between the work input and the total output of an energy conversion process._
• energy conversion performance: _Energy conversion performance is a process attribute describing the ratio between the work input of an energy transformation and the outputs that are used._

[l-emele]

What do you mean by "work input"? Physical work or something else? I am asking because we have not yet defined work.

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

I thought about mechanical work, as in "_the energy transferred to or from an object via the application of force along a displacement_" (your source). But actually, it could also be electrical work. So to be really precise (obnoxiously so), it should be "non-heat input of an energy transformation".

[sfluegel05]

Now we have these four concepts with definitions and relations:

• energy conversion efficiency: _Energy conversion efficiency is a process attribute describing the ratio between the input of an energy transformation and the outputs that are used._
  
  
  
  • process attribute of some energy transformation
  
  
  • has value some efficiency value
  
  
• efficiency value: _An efficiency value is a quantity value stating the ratio between a process's inputs and the outputs that are used._
  
  
  
  • has unit some ratio
  
  
• coefficient of performance value: _A coefficient of performance value is a quantity value stating the ratio between the work input and the total output of an energy conversion process._
  
  
  
  • has unit some ratio
  
  
• energy conversion performance: _Energy conversion performance is a process attribute describing the ratio between the non-heat input of an energy transformation and the outputs that are used._
  
  
  
  • process attribute of some energy transformation
  
  
  • has value some coefficient of performance value
  
  

Does everybody agree with this?

[sfluegel05]

Since everyone seems to agree, I'll implement this.