Found This Helpful. Comstock/Comstock/Getty Images. Temperature can affect both the structure of a molecule and how it interacts with surrounding molecules. Heating some molecules, particularly large, biological molecules such as proteins or nucleic acids, will cause them to change shape or even to break up.
The air comes through the diffusers in much larger velocities and different temperatures than the ones tolerated in the space. Due to diffusion, the velocity and the temperature differences are gradually decreased until they reach the tolerable limits.
In the case of the motor it is the rotor and the stator and for the pump it is the impeller and the volute (or diffuser). Of course the friction produced by bearings and other mechanical components (seals, stuffing box, etc) also affect pump efficiency, but the impeller and volute have the greatest influence.