Pressure drop is a change in energy. Fluid flow in the pipe due to energy loss caused by the pressure reduction. This energy loss is caused by the fluid flow to overcome internal friction and overcome turbulence when the fluid mass collision between each other and the exchange of momentum, manifested in the front and back of the fluid flow to produce a pressure difference, that is, the pressure drop.

The size of the pressure drop directly affects the energy efficiency and operating costs of the LiBr absorption units. A higher pressure drop requires more energy from the pump or fan to maintain the fluid flow, which consumes more electrical energy. The pressure drop can be effectively reduced and the overall efficiency of the system improved by optimizing the piping layout of the lithium bromide unit, selecting piping of appropriate diameter, and reducing the number of elbows and valves in the piping at the time of design.