Time resolved and spectral analysis of solar absorber Cu-Al and Al-Al laser weld emission

Solar water heating systems involve several innovations and a number of mature renewable energy technologies that enable efficient energy conversion. The thermal efficiency of solar heat collectors strongly depends on the metallurgical characteristics of the weld between the collector panel and the heat transfer tube. Typically, the welding quality is evaluated by empirical criteria, based, for instance, on measuring the mechanical strength of the spot welds. Little or no use has been made of methods that monitor the welding process and correlate welding conditions with mechanical strength and thermal efficiency. The main objective of the present work is to monitor temporally and spectrally investigate the optical emission generated during laser welding in the fabrication of solar heat collectors and correlate its optical characteristics with mechanical and metallographic data.