Heat pumps are becoming quieter
All air-to-water heat pumps are now very popular and have become an important pillar of more sustainable heat generation. There is a demand for efficient, quiet systems, for indoor, outdoor or hybrid applications (Fig. 1), using natural refrigerants, with the ability to intelligently adjust performance to the actual conditions. That's why fans that are characterized by: cost-effective operation with optimal efficiency and low noise emissions, and are able to communicate and be used to create smart grids play such an important role. It is also necessary to have inverter electronics to reduce the noise generated during operation through optimal commutation, and to increase the energy savings of the heat pump.
Figure 1: The principle of a heat pump in a single-family home in a hybrid application.
© EBM-PAPST POLSKA
Motor and fan specialists from ebm-papst, which offers centrifugal and axial fans of various designs for indoor and outdoor air-to-water heat pumps, have developed two new fan series. Both types of fans are suitable for use with both natural and flammable refrigerants, and are very quiet, thanks to their special design. While the AxiEco Plug-In fan is suitable for heat pumps requiring large pressure reserves to the evaporator, the AxiTone fan is designed to provide increased airflow at low back pressure when the pump design requires it.
Axial fan with high pressure reserve
Tests have shown that the flow technology used in the AxiEco Plug-In fan (Figure 2) helps reduce icing, with the fan's airflow decreasing only slightly as the pressure increases. This also affects heat pumps that heat in the winter and cool in the summer, as the operating points change depending on the operating conditions.
Figure 2: AxiEco Plug-In: as the pressure increases, the airflow changes only slightly. FlowGrid air intake grille, reduces airflow disturbances that cause noise
© EBM-PAPST POLSKA
The fan is available in 450 and 500 sizes, typical for heat pumps for single-family or two-family homes, and has also been equipped with an air inlet grille. The FlowGrid air inlet grille, which is used to correct air flow, significantly reduces airflow disturbances that cause noise. This reduces sound pressure over the entire frequency range, particularly the annoying noise associated with blade motion, i.e. the unpleasant "hum" in the low frequency bands.
AxiEco Plug-In fans are supplied as units ready for installation, connection and use, including a nozzle plate and FlowGrid.
Quiet three-blade fan
For air-to-water heat pumps, the AxiTone three-blade fan - initially available in 450 mm size, and later also in 500 mm and 630 mm sizes (Fig. 3). It delivers large volumes of air and also operates very quietly. The large surface area of the blades and the steep slope provide high airflow, and the sickle-shaped design helps reduce vibrations and thus noise levels as well. The teeth on the front edge of the blade minimize the tonal components of the noise. AxiTone is available as a ready-to-install motor-impeller combination in both airflow directions, i.e., intake and exhaust airflow, as well as a safety grille and support ring option. It is also suitable for applications with flammable refrigerants.
Figure 3: The AxiTone fan delivers large volumes of air and operates extremely quietly in applications requiring low noise levels.
© EBM-PAPST POLSKA
Inverter electronics for efficient and quiet compressor drives
ebm-papst has developed inverter electronics suitable for, among other things, permanent magnet synchronous machines (PSMs) with speed control, typically used in compressors (Fig. 4). This new electronics, samples of which will be available from Q3. 2023, with outputs of up to 3.5 kW, 7.5 kW and 12 kW, offers several important advantages.
The ebm-papst commutation method, which the company has been optimizing for decades, significantly reduces the increase in noise while increasing efficiency. Depending on the variant, the control system also "detects" whether it is operating on one or three phases, and automatically switches depending on the type of voltage available to the heat pump. The electronics are also flexible in terms of cooling - it is possible to use either water or air cooling or cold plate cooling.
Figure 4: Inverter electronics with 3.5 kW and 12 kW output power for efficient and quiet compressor drives.
© EBM-PAPST POLSKA
The three-phase PFC active circuit integrated into the inverter electronics (power factor correction filter) provides good EMC characteristics. No additional measures are required to comply with harmonic current standards.
