Experimental investigation of a wind to thermal energy hydraulic system

In EU households, heating and hot water alone account for 79% of total final energy use (192.5 Mtoe) [1]. The development of smart technologies to cover the heating requirements of the building sector constitutes a major challenge of the EU scientific community. Wind to thermal energy technologies, although they have been investigated thoroughly since the 50’s, did not gain much interest in the recent years. This study aims to analyse a novel wind to thermal energy conversion system, which could potentially be used in the EU building sector, in regions with high wind potential and increased requirements for space heating. The rationale of the proposed solution is based on a hydraulic system and the heat produced mainly due to friction losses of this system. The main idea behind the system is that the energy required to drive the hydraulic pump will be directly provided by a wind turbine. For the investigation of the proposed system, a scale-down test facility, which simulates the performance of the proposed system, was developed and operated at the Kaunas University of Technology. The wind turbine was simulated with the use of an electric motor with variable rotational frequency. Flow control valves were used both as the main energy converter of mechanical energy of the hydraulic fluid to heat as well as to regulate the load of the hydraulic pump. The optimal working conditions of the experimental set-up were defined in terms of the maximum thermal power delivered. The results of the research were summarized by empirical equations, which can be used for further development of the proposed hydraulic system. The study concluded that under optimal conditions, the system may reach an overall efficiency of 58.8%, which is comparable to efficiencies delivered by solar thermal systems for space heating in regions with increased solar potential (EU Mediterranean countries).