NOZZLES and diffusers:Q = 0, as the nozzle is PERFECTLY insulated,W = 0, no WORK is done by the nozzle, V1 <<< V2 and potential energy change is neglected∴ \({h_1} + \frac{{v_1^2}}{2} = {h_2} + \frac{{v_2^2}}{2}\)