| Energy is closely related with human's life,and also is the basis of the rapid economic and social development.Human being is faced with the crisis of energy shortage and environmental pollution caused by a large number of fossil energy consumption.It is imperative to develop clean renewable energy and explore its efficient utilization,the fundamental way to address energy and environmental problems lies in the structural transformation from fossil energy to renewable energy.Currently,the study of efficient solar energy utilization technologies has become significant research direction in the field of energy,the methods of solar energy utilization mainly includes solar photovoltaic and photothermal power generation,however,it still faces the practical problems of high cost,low efficiency,difficulty in energy storage,and unsteady energy supply,which seriously restricts the development of solar energy utilization.This paper proposes a method of efficient solar power generation system based on methane steam reforming,and studies the key thermochemical part of system:solar methane reforming reactor and catalyst,which is vital to solar energy utilization efficiency.The main contents of this paper are outlined as follows:(1)A hybrid solar power generation system integrating concentrating photovoltaics and methane steam reforming with spectral splitting has been proposed.The short-wavelength part is distributed to the photovoltaics,converted into electric energy and low-temperature heat energy,and the long-wavelength part is absorbed by the methane steam reforming reactor and converted to chemical energy,which is stored or fed to gas steam combined cycle for power generation.Optimizing distribution of the solar spectrum and photovoltaics-thermochemistry coupling,which makes that the maximum net solar-electric efficiency of the hybrid system reaches up to 37.1%,additionally,part of solar energy of the hybrid system can be stored as chemical energy in syngas in order to address the difficulty in energy storage of PV modules,which enhances the stability of power output of the hybrid system,and the introduction of PV modules significantly decreases dependence on fossil fuels.(2)The solar absorption efficiency and methane conversion of solar methane reforming reactor decide whether solar energy is used efficiently.Study mainly on the structure design and performance of reactor:cutoff wavelength coating over quartz window for incident solar energy in order to efficiently reduce heat radiation;a compound parabolic concentrator(CPC)device for further increasing concentration ratio and reduce the diameter of quartz window,simultaneously,enhancing uniformity of the energy distribution of the spot;and reticulated porous ceramics(RPC)structure used as the catalyst support,the PRC has dual-scale pores with mm-size ones for enhancing heat and mass transport properties and ?m-sized ones for increasing surface area of catalyst for fast reaction rates.Results show that when the reforming temperature is 925? and the concentration ratio is 300,the solar absorption efficiency of reactor with coating is increased by 31 percentage points,and at the operating temperature of 850?,the net solar-to-chemical efficiency reaches up to 59.4%with 90.0%heat recovery.(3)The catalyst in the reactor affects methane steam reforming rate.The perovskite oxide was prepared by sol-gel method to accelerate the methane steam reforming rate.The effects of substitution and substitution ratio of B-site elements on the catalyst of La1.6Sr0.4B'B"O6(B=Ni?Co?Fe?Cu)were investigated.It was found that the doping effect of Fe and Ni was the best,and especially the proportion of Ni was 1.4,the methane conversion can reach 100.0%at the temperature of 750?,and the stability lasted for 4 h,which is nearly 100%,and then decreases gradually,while the methane conversion above 50.0%could maintain over 32 h.Additionally,the carbon deposition was weak. |
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