An experimental and numerical investigation has been undertaken to study the heat transfer process in horizontal mantle heat exchangers used in solar water heaters. A rectangular cavity has been as a simplified geometry. With the aid of particle image velocimetry (PIV) the flow field in the centre-plane of the rectangular cavity has been visualized. Three-dimensional flow simulations were performed using a commercial CFD package. The impinging jet formed by the inlet flow directed towards the opposite wall was found to produce localised turbulence in the cavity, with an inlet Reynolds number as low as 360. This turbulence was found to effect the flow field and heat transfer in the cavity when the inlet Reynolds number was above 1200. It is shown that, with the boundary conditions used in this study, most of the heat transferred was in the bottom half of the cavity. This is not the ideal situation for optimization of solar water heating systems.
|Number of pages||10|
|Journal||International Journal of Energy Research|
|Publication status||Published - Sep 1999|
- Mantle heat exchanger
- Solar water heater