Add Boiler Subcategories

[f-innatech]

Description of the issue

In long term scenarios, boiler technologies are differentiated by their fuel. In OEO there is currently only one single bioler category.

Ideas of solution

add Subtechnologies:

• Natural Gas boiler
• Biomass Boiler
• Hydrogen Boiler
• Oil Boiler

"An x boiler is a boiler that increases the thermal energy of fluids via the combustion of the fuel x."

All of them should be a subclass of boiler and should have an axiom for the resepective fuel they use. Additionally, they need an equivalency axiom stating that it is equivalent to a combustion-based heater that has a participant some fluid

Workflow checklist

• [ ] 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