Heat exchangers can be utilised in thermo-acoustic engines to facilitate through acoustic oscillations electrical power generation via linear alternators and/or cooling effects. Provision of a heat exchanger arrangement (31) which can be associated with a traditional open flame stove utilised in third world countries would be advantageous. However, such heat exchanger arrangements must be lightweight and robust to withstand operational use. By creating a heat exchanger arrangement formed from plates having apertures which develop a folded conduit to act as a resonance tube of appropriate length it is possible to more easily accommodate thermo-acoustic electrical power generation and cooling effects in a traditional stove configuration.