Qibin Liu

Solar Hydrogen Production Integrating Low-Grade Solar Thermal Energy and Methanol Steam Reforming

In this paper, a novel approach of middle-temperature solar hydrogen production using methanol steam reforming is proposed. It can be carried out at around 200-300 degrees C, much lower than the temperatures of other solar thermochemical hydrogen production. For the realization of the proposed solar hydrogen production, solar experiments are investigated in a modified 5 kW solar receiver/reactor with one-tracking parabolic trough concentrators. The feature of significantly upgrading the energy level from lower-grade solar thermal energy to higher-grade chemical energy is experimentally identified. The interaction between the hydrogen yield and the energy-level upgrade of solar thermal energy is clarified. Also, this kind of solar hydrogen production is experimentally compared with methanol decomposition. The preliminarily economic evaluation of the hydrogen production is identified. As a result, in the solar-driven steam reforming, the thermochemical efficiency of solar thermal energy converted into chemical energy reached up to 40-50% under a mean solar flux of 550-700 W/m(2), and exceeding 90% of hydrogen production is achieved, with about 70% higher than that of methanol decomposition. The thermochemical performance of solar-driven methanol steam reforming experimentally examined at around 200-300 degrees C for hydrogen production may be competitive with conventional methane reforming. The promising results obtained here indicate that the proposed solar hydrogen production may provide the possibility of a synergetic process of both high production of hydrogen and effective utilization of solar thermal energy at around 200-300 degrees C.

Data-driven reconstruction method for electrical capacitance tomography

Abstract The appealing superiorities, including high-speed data acquisition, nonintrusive measurement, low cost, high safety and visual presentation, lead to the success of the electrical capacitance tomography (ECT) technique in the monitoring of industrial processes. High-accuracy tomographic images play a crucial role in the reliability of the ECT measurement results, which provide the powerful scientific evidences for investigating the complicated mechanisms behind the behaviors of the imaging objects (IOs). Beyond the existing numerical algorithms that are developed for the solution of the inverse problem in the ECT area, a data-driven two-stage reconstruction method is proposed to improve the reconstruction quality (RQ) in this paper. At the first stage, i.e., the learning stage, the regularized extreme learning machine (RELM) model solved by the split Bregman technique is developed to extract the mapping between the tomographic images reconstructed by the some algorithm and the true images according to a set of training samples. At the second stage, i.e., the prediction stage, a new IO is reconstructed by the same algorithm used in computing training samples, and then the imaging result is considered as an input of the trained RELM model to predict the final result. The performances of the proposed reconstruction method are compared and evaluated by the means of the numerical simulation approach using the clean and noisy capacitance data with different noise levels (NLs). Quantitative and qualitative comparison results validate the practicability and effectiveness of the proposed data-driven reconstruction method. Research findings provide a new insight for the improvement of the reconstruction accuracy and robustness in the ECT area.

Experimental Investigation of a Middle-and-Low Temperature Solar Receiver/Reactor Prototype

This paper designed and manufactured a 5-kW middle-and-low temperature solar receiver/reactor prototype at around 200°C–300°C, representing the development of a new kind of solar thermochemical technology. A representative experiment of solar-driven methanol decomposition was carried out. A specific equation of interrelationships among solar radiation, the kinetics of the middle-and-low temperature solar thermochemical reaction, and the diameter of the reactor tube is derived. The conversion of methanol decomposition yielded up to 50%–95% and the efficiency of solar thermal energy converted into chemical energy reached 30%–60%. The experimental results obtained here proves that the novel solar receiver/reactor prototype can provide a promising approach to effectively utilize the middle-and-low temperature solar thermal energy by means of solar thermochemical processes.