Flat tube heat exchangers - Direct and indirect noise levels in heat pump applications
Artikel i vetenskaplig tidskrift, 2014

In the outdoor unit of an air-source heat pump the fan is a major noise source. The noise level from the fan is dependent on its state of operation: high air-flow and high pressure drop often result in higher noise levels. In addition, an evaporator that obstructs an air flow is a noise source in itself, something that may contribute to the total noise level. To be able to reduce the noise level, heat exchanger designs other than the common finned round tubes were investigated in this study. Three types of heat exchanger were evaluated to detect differences in noise level and air-side heat transfer performance at varying air flow. The measured sound power level from all the heat exchangers was low in comparison to the fan sound power level (direct effect). However, the heat exchanger design was shown to have an important influence on the sound power level from the fan (indirect effect). One of the heat exchangers with flat tubes was found to have the lowest sound power level, both direct and indirect, and also the highest heat transfer rate. This type of flat tube heat exchanger has the potential to reduce the overall noise level of a heat pump while maintaining heat transfer efficiency.


Heat transfer

Sound power level

Pressure drop



Heat exchanger


Ola Gustafsson

SP Sveriges Tekniska Forskningsinstitut AB

Henrik Johansson

SP Sveriges Tekniska Forskningsinstitut AB

Monica Axell

SP Sveriges Tekniska Forskningsinstitut AB

Krister Larsson

SP Sveriges Tekniska Forskningsinstitut AB

Cedric Teuillieres

Applied Thermal Engineering

1359-4311 (ISSN)

Vol. 66 1-2 104-112


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Strömningsmekanik och akustik





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