Performance assessment of an electrode boiler for power-to-heat conversion in sustainable energy districts

Renewable energy production is rapidly increasing, but it is not demand-oriented, and this makes challenging its integration into national distribution grids. Sector coupling strategies (i.e., power-to-heat) represent a solution to this issue since they enable demand-side management strategies by increasing energy flexibility. Among the others, electric boilers are commonly used to convert electricity into heat, but they are characterized by high radiative heat losses (i.e., the high surface temperature of components) with the consequent risk of unwanted combustion events. Electrode boilers that are based on ion acceleration principles can reduce this risk since they usually operate at a lower temperature. This study focuses on the performance assessment of an electrode boiler. The power-to-heat conversion efficiency is experimentally determined for three configurations of the apparatus, which are determined by varying the velocity of the pumped fluid. The II and III velocity levels are respectively assessed in test one and test two, while the ‘‘underfloor heating system” setting (i.e., constant hydraulic head) is evaluated in test three. The electrode boiler is activated within a closed environment equipped with sensors to monitor the air temperature, the surface temperature of the walls, and the consumed electricity. The heat losses and gains are estimated to quantify the heat produced by the electrode boiler. The configuration of the electrode boiler from test one is the most effective, with an efficiency of 97 %. The boiler converted 1444 Wh of electricity into 1404 Wh of thermal energy, heating the pumped fluid by up to 55 °C. Such a temperature regime makes the electrode boiler ideal for being coupled to high-temperature radiators in the renovation of obsolete buildings while reducing fire-related risk compared to traditional electric boilers.