Experimental investigation into the thermal performance of a solar steam generator based on spray cooling heat transfer and porous silicon carbide ceramic

Abstract

A solid oxide electrolysis cell require high-temperature steam. However, using electricity to generate steam is highly energy intensive, and concentrated solar power is a good substitute for it. The authors of this study propose a solar steam generator with an enhanced capacity for heat transfer by installing a porous ceramic material inside it and using spray cooling technology. Currently used steam generators produce steam at a temperature that rarely reaches 700–1000 °C. The steam generator developed here can produce steam at a temperature of up to 800 °C by using concentrated solar power. Moreover, we tested two porous silicon carbide ceramic materials for use in the generator under various experimental conditions and investigated the effects of the irradiation power, rate of flow at the inlet, and porosity of the ceramic material (ranging from 70% to 85%) on its thermal performance. The results showed that the temperature at the outlets of steam generators equipped with the two kinds of ceramic materials increased as the irradiation power was increased from 2.3 to 4.6 kW, and their thermal efficiency increased from 17% to 65.5% as the rate of flow of water at the inlet was raised from 0.92 to 4.68 L/h. The thermal efficiency of the generator equipped with the ceramic with a low porosity (70%) was approximately 26% greater than that of the generator equipped with the ceramic with a high porosity (85%) at an irradiation power of 4.2 kW. When the solar simulator was suddenly turned off, the generator with the lower porosity was more resistant to interference. The results here provide an important reference for optimizing the steam generator.