Condensing units (or evaporators) for commercial applications are essentially composed of a compressor, an axial blower and a condenser (or evaporator). The pair heat exchanger, fan, together with a few accessories (filters, grilles and ducts), forms the air distribution system should be designed to maximize the heat transfer rate and minimize energy consumption and costs . Such a system is usually designed on the basis of characteristic curve of the fan and the heat exchanger provided by the manufacturers. The intersection of these curves determines the system operation point and therefore the air flow and the heat transfer rate. However, often the fan curve provided by the manufacturer does not reflect the same behavior when installed on the drive. The characteristic curve of the heat exchanger, in turn, is rarely supplied.

In order to fill these gaps, POLO built a wind tunnel able to meet the flow and pressure ranges typically found in commercial applications, following the standards imposed by ASHRAE 51. The apparatus consists of an open-loop tunnel where the air device to be tested is placed in one end, while on the other there is used an auxiliary fan for controlling the flow. This is accomplished indirectly by measuring the pressure drop through specific nozzles chosen to suit a range from 100 to 10,000 m3 / hr. The device under test can be either a complete unit as one of its components such as the blower or heat exchanger. The test section has 1100mm wide and 610mm high, being up to two fans can test up to 450 mm diameter simultaneously.