EFFECTS OF SILICA DEPOSITION ON THE PERFORMANCE OF DOMESTIC EQUIPMENT IN THE NETHERLANDS

摘要

The effects of silica deposition on the performance of domestic appliances have been studied. Experiments on domestic boilers having different type of heat exchangers show that a large quantity of the silica particles formed in the flame deposit in the heat exchangers. The growth of the silica layer with time results in an increasing flow resistance over the heat exchangers and, as a consequence, a reduction of the boiler's thermal output. The degree of reduction in the thermal output strongly depends upon the configuration and material of the heat exchangers studied. Furthermore, the experiments reveal that the current measured in the ionization safety devices decreases in time due to silica deposition on the ionization probe, which ultimately results in boiler failure. Silica deposition in the studied hot water heater leads to an increased flow resistance across the heat exchanger. Consequently, the air intake from the surroundings reduces, and the CO emission increases over time. Analyses of the measurements show that the time to failure of the ionization device, the reduction in the thermal output of the boiler and the increased CO emissions of the hot water heater do not scale linearly with the concentration of siloxanes in the fuel. This effect is attributed to an increased density of the deposited silica at decreased siloxane concentrations.