A Leeds-based manufacturer of solar assisted heat pump systems improved quality and examined the potential to cut costs by using innovative welding technology, following feasibility trials by TWI under a regionally funded business support programme. Endoenergy Systems Ltd are co-ordinating the Endohousing project - an initiative funded by the European Commission under the Energie Programme to investigate using renewable energy sources to supply heating and hot water in houses.
Endohouses are designed to demonstrate the potential for making major savings in space heating and cooling costs in houses using the endothermic technology. A key feature of the energy saving system is the array of liquid filled aluminium panels that act as solar energy collectors and heat exchangers. These panels can form the roof of the house, wall cladding, or could be a standalone structure. Further information about these thermal systems can be found on the Endohousing website: www.endohouses.com.
The panels are constructed from aluminium extrusions with end-caps welded on to seal the units, and manifold connections to allow circulation of the liquid around the system. The standard method of fabrication of the panels is TIG welding. However, the end product was not totally satisfactory, in terms of cosmetic appearance and weld integrity. Through the FriSC programme, TWI was able to offer Endoenergy the opportunity to fabricate the panels using friction stir welding.
The scope of the work included:
- Designing the end-cap joint
- Determining the tool design and welding parameters suitable for the fabrication
- Designing the fixture for holding the assembly during welding
- Completing welding trials
- Testing the welded panels
- Continued support after the completion of the programme, including provision of the process parameters required to produce satisfactory welds.
Success at each stage of the work demonstrated to Endoenergy that friction stir welding is a viable alternative for the fabrication of their panels, with several advantages over TIG welding, including ease of automation, speed of fabrication, minimal cosmetic post weld finishing operations and appearance of the finished weld.
The FriSC programme, supported by the European Regional Development Fund, South Yorkshire Objective 1 and Yorkshire Forward allows TWI to provide free and subsidised technical support to small and medium sized companies in the Yorkshire and Humber region, which, in the case of Endoenergy, equated to a £15,000 product development programme.
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