Acoustic optimisation of heat pumps

The range of services includes acoustic characterization of heat pumps, development support and optimization, and scientific consulting.

Our services

• Location- and frequency-dependent measurement of sound pressure levels with the acoustic measurement dome
• Transient frequency-resolved measurement of sound power level and directionality
• Performance of measurements under different climatic conditions
• Sound source localization with the acoustic camera
• Vibration measurements and correlation with acoustic measurements
• Visualization of icing processes with image capturing and thermal camera
• Transient weight determination of icing heat pump components
• Supporting fluidic investigations with particle image velocimetry (PIV) and hot wire anemometry (CTA) as well as numerical flow simulation (CFD)

Our work

Sound pressure and power level determination

The acoustic measurement dome allows the positioning of up to 64 microphones around the heat pump in a climate chamber. The data can be recorded over several cycles of the heat pump so that a time-, frequency-, and direction-dependent analysis of the sound field is possible. A comparison of different insulation materials, components or control strategies can be realized directly and easily with this system.

Sound source localization

For the frequency-resolved localization of sound sources, an acoustic camera is available, which can be combined with a thermal camera. This system allows the quantification of acoustic sources on the surface and inside the heat pump depending on their position in the frequency band.

Vibration measurements

Measurements can be made simultaneously with multiple microphone signals (to measure sound pressure levels) and a hot-wire probe (to measure flow velocity and flow turbulence). This allows correlation of vibration, sound pressure and flow turbulence levels.

Investigation of transient processes

Icing of heat pump components as well as flow reversal of the refrigerant during defrosting can lead to time-dependent acoustic characteristics. These show up in an increase of the total sound level but also in the generation of tonal components. The available measurement methods allow data acquisition and analysis of short-time and multi-hour transient processes. For the visualization of icing processes conventional image capturing as well as a thermal camera is available. Time-dependent weight determination can also be performed for heat pump components. Refrigerant distribution is accessible by combining it with the analysis of the incident flow of the heat exchanger.

Measurements in acoustically optimized climatic chambers

For the measurements, climatic chambers are available which allow optimum climatic conditions in a temperature range from -25°C to 50°C by introducing air over the entire side. The humidity can be set according to the temperature. For acoustic measurements, the good insulation of the system allows the air conditioning to be deactivated for a short time in order to achieve optimal conditions.

Fluidic investigation

Supporting the acoustic characterization we offer fluidic analysis with experimental and numerical methods (CFD), which is available for the calculation of flows as well as for the characterization of icing scenarios at the heat exchanger.

Reference projects