Concentrated Solar Power Plant using air blended with nanoparticles as working fluid

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Abstract Adopting efficient power plants based on renewable energy sources is extremely important to face the challenges of global warming. Concentrated Solar Power Plant (CSP) is a technology option that can achieve the decarbonization target of the electricity sector in large power plants and simultaneously meet the growing demand for electricity. In this study, a CSP plant using air as heat transfer fluid, whose transformations realize a Discrete Ericsson Cycle (DEC), was referenced. Solar fields are based on parabolic trough collectors. The DEC consists of a series of inter-cooled compressions and inter-heated expansions (four and two, respectively, in this paper), whose net result is a useful work. In this paper, a mixture of air and Cr2O3 nanoparticles at different particle concentration has been considered as working fluid to enhance the performances of the compression and expansion transformations in a DEC-based plant. The presence of particles cools the air during compression and heat the air during expansion, approaching isothermal processes. A sensitivity analysis referred to the particle concentration has been discussed and the power and the efficiency of the plant have been discussed outlining benefits and drawbacks. Nanoparticle concentration less that 0,05% in volume (10 % in mass) produce a power and efficiency output increase close to 3 % without any sensible constraint. At higher concentrations, more significant variations are achieved with a 15 % power output increase for a mass concentration of nanoparticles of 50%. Such mass concentration corresponds to just 0.05 % in volume, allowing a potential operativity of the turbomachines. In this condition, the overall CSP efficiency improve by 1.5 percentage points.