Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Development of redox-type thermochemical energy storage module: A support-free porous foam made of CuMn2O4/CuMnO2 redox couple
No full textIn this study, we developed a CuMn2O4/CuMnO2-based porous foam thermochemical energy storage (TCES) module, which is free from any supporting materials. The raw material of CuMn2O4/CuMnO2 was synthesized using co -precipitation method which is different with the Pechini method we have used in the previous study, aiming to a large-scale synthesis. The porous foam modules were prepared using polyurethane (PU) foam replica method. We investigated the sintering temperature and holding time as critical parameters affecting the module's mechanical strength, chemical reactivity, and durability. The optimal condition for CuMn2O4/CuMnO2- based porous foam TCES module were identified as 1100 degrees C and 6 h. Our findings suggests that these modules are promising for the fixed -bed reactors in redox-type TCES systems
Mitigation of Silicon Contamination in Fuel Cell Gasket Materials through Silica Surface Treatment
No full textGaskets and seals are essential components in the operation of proton exchange membrane (PEM) fuel cells and are required for keeping hydrogen and air/oxygen within their individual compartments. The durability of these gaskets and seals is necessary, as it influences not only the lifespan but also the electrochemical efficiency of the PEM fuel cell. In this study, the cause of silicon leaching from silicone gaskets under simulated fuel cell conditions was investigated. Additionally, to reduce silicon leaching, the silica surface was treated with methyltrimethoxysilane, vinyltriethoxysilane, and (3,3,3-trifluoropropyl)trimethoxysilane. Changes in the silica surface chemistry were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis, elemental analysis, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Inductively coupled plasma-optical emission spectroscopy analysis revealed that surface-treated silica was highly effective in reducing silicon leaching
Numerical investigation of electricity generation potential by water circulating through three horizontal wells at Fengshun geothermal field in China
No full textFengshun geothermal field is the first medium and low temperature geothermal area in China, which is used for electricity generation. At present only vertical wells are employed to extract heat energy. After about 40 years of exploitation, the production temperature and rate are all declined. In this work, based on the hydrogeological data of the study area, the deep reservoir temperature and corresponding circulation depth of underground hot water are predicted with a silica thermometer. To fully develop the deep heat reservoir, we proposed a new heat exploitation scheme through three horizontal wells, computed the electricity generation potential and efficiency, and analyzed the main factors affecting heat production. The results indicate that under the reference conditions, the three horizontal well system attaches an electric power of 2.70-1.5 MW, a reservoir impedance of 0.13-0.27 MPa/(kg/s), a pump power of 0.29-1.16 MW, and energy efficiency of 7.34-1.30 during the reservoir lifetime of 43.6 years. Thus, this three-horizontal-well system has significant development potential in Fengshun deep geothermal reservoir. Sensitivity analysis indicates that water production rate, injection temperature and initial reservoir temperature have a significant impact on heat production performance. Reducing the water production rate and injection temperature within a certain range can improve energy efficiency. For the precise design of power generation systems and the accurate evaluation of production performance, field logging data is necessary
Numerical investigation of electricity generation potential by water circulating through three horizontal wells at Fengshun geothermal field in China
No full textFengshun geothermal field is the first medium and low temperature geothermal area in China, which is used for electricity generation. At present only vertical wells are employed to extract heat energy. After about 40 years of exploitation, the production temperature and rate are all declined. In this work, based on the hydrogeological data of the study area, the deep reservoir temperature and corresponding circulation depth of underground hot water are predicted with a silica thermometer. To fully develop the deep heat reservoir, we proposed a new heat exploitation scheme through three horizontal wells, computed the electricity generation potential and efficiency, and analyzed the main factors affecting heat production. The results indicate that under the reference conditions, the three horizontal well system attaches an electric power of 2.70-1.5 MW, a reservoir impedance of 0.13-0.27 MPa/(kg/s), a pump power of 0.29-1.16 MW, and energy efficiency of 7.34-1.30 during the reservoir lifetime of 43.6 years. Thus, this three-horizontal-well system has significant development potential in Fengshun deep geothermal reservoir. Sensitivity analysis indicates that water production rate, injection temperature and initial reservoir temperature have a significant impact on heat production performance. Reducing the water production rate and injection temperature within a certain range can improve energy efficiency. For the precise design of power generation systems and the accurate evaluation of production performance, field logging data is necessary
Analysis of the factors affecting heat transfer performance and prediction of heat transfer coefficient for MVR evaporator: A case study
No full textThe heat transfer coefficient of evaporation is one of the key factors affecting the design and management of evaporators. This paper presented an industrial case to investigate the influencing factors on the evaporator's heat transfer coefficient, as well as the interaction between the influencing factors. Besides, a comparison of accuracies was made between the heat transfer coefficients predicted by physical models and the support vector regression (SVR) model. The study results showed that due to the interaction between the influencing factors, changes in the heat transfer coefficient varied greatly from the laboratory results. The impact of other variables must be controlled for in industrial research. There were big errors between the results predicted by the early experimental or numerical models and the observed results. The root mean square error (RMSE) values and mean absolute percentage error (MAPE) values of the physical models were all greater than 150 and 5%, respectively, and their R2 values were all lower than 0.50. The data mining-based SVR predictions were more accurate than the predictions by physical models, with a maximum relative error of 5.38% and a minimum relative error of -5.60%
Heat extraction performance of the super-long gravity heat pipe applied to geothermal reservoirs of multi-aquifers
No full textThe super -long gravity heat pipe (SLGHP) is a novel down -hole heat exchanger (DHE), which is in fastdeveloping and extremely suitable for deep -earth geothermal energy exploitation. The SLGHP itself has very high heat transfer coefficient, making the poor heat transfer capability of the surrounding geothermal formulations become the bottleneck constraining the overall performance of the SLGHP geothermal system. Inspired by the enhancing effect of the flowing groundwater in the aquifers on the thermal performance of the traditional DHE system, the present work proposes a heat transfer enhancement strategy based on arousing inter -layer crossflow in wellbore-connected multi -aquifers for the SLGHP geothermal system. A detailed numerical study is conducted to examine the effects of key parameters like the permeability and thickness of aquifers, the distance and pressure difference between aquifers. It is found that: i) a larger aquifer permeability leads to larger heat extraction rate of the SLGHP, but the heat extraction rate increment decreases due to the marginal effect when the aquifer permeability is larger than 10-12 m2; ii) a larger pressure difference improves the heat extraction of the SLGHP, the groundwater flow pattern from the deep to the shallow aquifers rather than the reversed pattern is found to be more beneficial due to the geothermal gradient; iii) the distance between aquifers shows a composite impact on the heat extraction performance of the SLGHP. A larger distance not only enlarges the heat transfer area between the SLGHP and the groundwater, but also creates an impeding effect on the heat uptake of SLGHP from the geothermal formation owing to the presentence of temperature -lowered groundwater in the flow path ending -part in the wellbore. In addition, the aquifer's thickness is found to have great impacts on the SLGHP heat extraction rate, and the "cask" effect may be encountered when the thickness difference between the connected aquifers is considerably large
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