Uniform and sufficient airflow through the evaporator of an air-to-water heat pump is important for the efficient utilization of its active surface. In two sets of measurements, we evaluated the effects of fan-to-evaporator spacing and the design and position of the heat pump’s protective panels on the volumetric airflow rate and its distribution across the height of the evaporator. Air velocity was measured at several locations in the evaporator inlet plane at different fan rotational speeds. The comparison was supplemented by measurements of the static pressure difference between the region downstream of the evaporator and the surroundings, as well as the fan electrical power. Increasing the spacing improved the airflow distribution without a detectable effect on the volumetric flow rate or electrical power. Installing the front protective panel improved the uniformity of the airflow distribution, but reduced the volumetric flow rate and increased the fan electrical power. The comparison of different designs provided a basis for selecting a more suitable protective panel design.
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