$1)$Describe the direct expansion $($DX$)$ system with its different types in general, its role and importance and its efficiency. Perform a comparative study between all types of HVAC systems chiiler, AHU, DX$,$ and VRF$/$VRV$.$ I want curves relating their efficiencies and the Coefficient of performance with their respective analysis. Lastly, provide me references on these topics from articles or books. $2)$ Discuss the behavior of the listed Hvac systems when working in a hospital context with curves and analysis, and why is the presence of HVAC systems vital in such conditions