Experimental investigation of a windthermal demonstrator with friction based direct wind-to-heat conversion

We investigate the feasibility of windthermal energy - direct conversion of a wind turbine’s rotational power into heat - using a first of its kind friction-based demonstrator that couples a small wind turbine to a thermal platform with a hydrodynamic retarder. We describe the experimental arrangement and provide an in-depth analysis of the thermal platform’s dynamics, heat-generation performance, and auxiliaries. A two-stage program combined motor-driven preliminary tests for set-up validation and optimization with wind-turbine-driven field trials. The demonstrator reliably generated heat, achieving a peak load of 8 kW and an overall system efficiency of 8.73 %. Challenges arose from off-design operation of the hydrodynamic retarder and temperature constraints, especially at oil temperatures below 50 ◦C. Efficiency can be improved by better matching the retarder to the load, refining the shaft system, and enhancing insulation. With these measures, windthermal energy could contribute to sustainable heat supply. • Experimental data on a pilot plant with 15 kW rated power to generate heat from wind energy in northern Germany. • Novel concept in windthermal energy systems. Integration of hydrodynamic retarder and thermal storage with a wind turbine. • Fully functional demonstrator in real operating condition.