Coupling solar thermal energy accumulation methods with existing energy conversion technologies is fundamental to enlarge the field of applicability and lower the costs of renewable energy sources. Traditional combustion technologies have been coupled with solar energy mainly by heating up the fuel/oxidizer stream and recently high flux radiation technology has been tested to heat up directly a flame. This latter setup has the advantage of relative compactness, minimizing the heat losses, and to use the high absorption coefficient of combustion by-products present in flame such as soot particles. In fact, soot particles formed in flame are responsible for more than 90% of the total radiation flux and thus it is also responsible for the majority of the solar radiation adsorbed. The solar thermal radiation has been already tested in these conditions and an increase of the flame temperature and soot volume fraction inside the flame have been found, but with an even reduced soot emission from the flame. In this work, we use a detailed model of soot formation and oxidation to simulate the behaviors of a coflowing diffusion ethylene flame with and without the exposure to a concentrated solar radiation. Modelling data are compared with experimental data reported in the literature. Our model is able to reproduce the effect of radiation both matching the temperature and soot volume fraction increase. Then, a modified version of the solar-combustion hybrid system has been setup to test the effect of solar light orientation on the combustion process. The concentrated solar light has been sent from the top. The flame was placed in the focus of solar concentrator. However, the burner was heated up by the solar lamp, resulting in a reduced operational time before the flame start emitting considerable amount of particles. Thermocouple-based temperature measurements were performed, showing that the flame effectively adsorbed solar radiation increasing the local temperature. Finally, the model tested in literature conditions helped to discern the effect of the heating from the solar radiation onto the burner and directly on the flame.
EXPERIMENTAL AND NUMERICAL STUDY OF A HYBRID SOLAR-COMBUSTOR SYSTEM FOR ENERGY EFFICIENCY INCREASING
Claudio Tregambi;
2019-01-01
Abstract
Coupling solar thermal energy accumulation methods with existing energy conversion technologies is fundamental to enlarge the field of applicability and lower the costs of renewable energy sources. Traditional combustion technologies have been coupled with solar energy mainly by heating up the fuel/oxidizer stream and recently high flux radiation technology has been tested to heat up directly a flame. This latter setup has the advantage of relative compactness, minimizing the heat losses, and to use the high absorption coefficient of combustion by-products present in flame such as soot particles. In fact, soot particles formed in flame are responsible for more than 90% of the total radiation flux and thus it is also responsible for the majority of the solar radiation adsorbed. The solar thermal radiation has been already tested in these conditions and an increase of the flame temperature and soot volume fraction inside the flame have been found, but with an even reduced soot emission from the flame. In this work, we use a detailed model of soot formation and oxidation to simulate the behaviors of a coflowing diffusion ethylene flame with and without the exposure to a concentrated solar radiation. Modelling data are compared with experimental data reported in the literature. Our model is able to reproduce the effect of radiation both matching the temperature and soot volume fraction increase. Then, a modified version of the solar-combustion hybrid system has been setup to test the effect of solar light orientation on the combustion process. The concentrated solar light has been sent from the top. The flame was placed in the focus of solar concentrator. However, the burner was heated up by the solar lamp, resulting in a reduced operational time before the flame start emitting considerable amount of particles. Thermocouple-based temperature measurements were performed, showing that the flame effectively adsorbed solar radiation increasing the local temperature. Finally, the model tested in literature conditions helped to discern the effect of the heating from the solar radiation onto the burner and directly on the flame.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
