Abstract: Based on the designed mechanical vapor recompression(MVR) heat pump driven by a centrifuge fan, the way of theoretical analysis and experimental research is applied to study the fan type of MVR. Choosing water as the experimental medium, the operation characteristic of MVR applied to low evaporation is examined. The results shows as following：the pressure difference is likely to keep stable while the evaporation pressure goes up; the total evaporation water and total input energy increase as its evaporation pressure grows，but the increment is lower than that of theoretical calculation. The leakage loss of the fan inside goes up and its displacement efficiency reduces as the evaporation temperature and pressure rises, which brings forth the drop of the system’s adiabatic efficiency. As a result, its specific moisture extraction rate(SMER) and coefficient of performance(COP) decrease. The trend of average input power for compressed vapor is compared in three different terms and the result shows：The trend of average input power by calculation is the same as that in theory; that is to say, both of them descend when the evaporation pressure ascends. Because of the displacement efficiency, the trend of average input power by measure is different from that in theory-the average input power by measure grows slightly when the evaporation pressure goes up.

Key words: Adiabatic efficiency, Mechanical vapor recompression(MVR) driven by fan, System performance