Heat exchanger design aspects related to noise in heat pump applications

Abstract

An increased use of heat pumps is one of the measures that can be taken to reduce energy consumption on a large scale. For a wider acceptance, and major heat pump market expansion, it is crucial to develop heat pumps that cause minimal disturbance.Results from field measurements made by SP Technical Research Institute of Sweden indicate that the use of indirect heat pumps has potential to significantly reduce the outdoor noise level of ambient air heat pumps. The noise level caused by such heat pumps has been shown to be highly influenced by the design of the air-to-fluid heat exchanger.The overall purpose of this study is to propose a design of an air-to-fluid heat exchanger that allows for a well performing system as well as a low level of noise and cost. Two different types of heat exchangers, with flat tubes and round tubes, are compared theoretically.According to the modelling results, a heat exchanger with flat tubes and plain fins is the most suitable out of the studied designs due to its low heat transfer resistance on the tube side. The round tube heat exchangers showed to be significantly less suitable, displacing more than twice the volume.