How A Chiller works

Any word with fewer than 3 letters should not be capitalized, however, if any of those short words are verbs ("is," "are," "was," "be"), they need to be capitalized.

For example, "How a Chiller Works" is the best.

1. The refrigeration circuit ¶
The refrigerant flows through all the four components: compressor condenser, expansion valve, and evaporator.

I don't know anything about these things so I'm unsure if your technical words are correct. Although, they do seem correct :)

Please use capital letters when listing with bullet points.

2. cChilled water loop ¶
Water flows in the evaporator, AHU (air handling units), and athe pump.

The / A - These have slightly different meanings. If it is "the" then it is specific to that thing. So if there is one pump that it flows through, you should use "the".

I believe it is handling. I couldn't find anything on the internet for handing.

3. cCondenser circuit ¶
Water flows in the condenser, cooling tower, and a pump.

The chilled water loop and condenser circuit are totally separated, they transfer heat by the refrigeration circuit.