Humidity control is emphasized in various fields. However, the effectiveness comparison between adiabatic dehumidifier (AD) and internally-cooled dehumidifier (ICD) was only conducted in limited ...cases, without comprehensive understanding of different cooling mediums and working conditions. In this study, the component effectiveness of these two dehumidifiers is parametrically compared. When chilled water serves as cooling medium, AD has sensible effectiveness of 0.65 and latent effectiveness of 0.84 under baseline case, while those of ICD are 0.52 and 0.85 respectively. AD performs better under higher sensible loads, and ICD is more capable of dealing with more moisture transfer. Low water temperature, low air-desiccant ratio and adequately low water-desiccant ratio also highlight the superiority of AD. When secondary air serves as cooling medium, AD always has higher effectiveness than ICD in the studied range, and the superiority is more significant at lower temperature and humidity of secondary air. Sensible effectiveness of 0.44 and latent effectiveness of 0.78 for AD are obtained under baseline case, while those of ICD are 0.07 and 0.74 respectively. ICD has better adaptivity than AD at a circumstance with great variation of operation parameters. The results contribute to enlightening insights for further design of moisture capture components.
•New comparison view for adiabatic and internally-cooled dehumidifiers is proposed.•Comparison results are obtained for different cooling mediums.•Adiabatic dehumidifier is favorable for cooling medium of secondary air.•Internally-cooled dehumidifier is capable of handling latent load.•Comprehensive comparison promotes development of moisture removal component design.
Based on the simulated non-uniformity solar radiation flux distribution of the absorber by the Soltrace software using the Monte Carlo Ray-Trace Method, an innovative parabolic trough solar receiver ...that employs two solar selective coatings with different properties on the outer surface of the absorber is proposed. The concentration ratio and absorber temperature that influence optimal cut-off wavelengths of the solar selective coatings are quantitatively analyzed to optimize the property of the coating. The optimal cut-off wavelength increases with the concentration ratio, but drops with the increasing absorber temperature. The heat transfer process of receivers is numerically simulated to predict the thermal performance of evacuated receivers based on spectrum parameters heat transfer model. Heat loss simulation results show that: the double-selective-coated receiver can reduce heat loss and boost the collecting efficiency significantly compared with PTR70 receiver. When the temperature of absorber is 500 °C, the double-selective-coated receiver can reduce heat loss by 157.8 W/m and increase the collecting efficiency from 64.7% to 68.1%. The System Advisor Model annual simulation results indicate that double-selective-coated receivers can decrease the levelized cost of electricity of concentrating solar plants by 2.78%–7.34%, and increase electricity production by 2.94%–8.21% compared with traditional PTR70 receivers.
•A novel parabolic trough receiver with double selective coating was proposed.•A heat transfer model was established and verified by NREL experimental data.•The cut-off wavelength and heat flux distribution of receivers were studied.•The heat loss and collecting efficiency of receivers were analyzed and compared.•The annual simulation was conducted to evaluate solar power plant performance.
The development of large-area diamond films with low dislocation density plays a key role in diamond-based devices. In this study, we present a straightforward and reasonably priced Ni-assisted ...etching and re-growth method to decrease the dislocation density of diamond. By adjusting the annealing temperature, a high-density inverted pyramid and/or trapezoidal pit can be effectively exposed because the interaction between carbon and Ni metal. The Ni tends to dissolve the diamond surrounding the dislocation at high temperature while maintaining the surface's flatness. The precipitated graphite layer is removed using wet etching, and the step flow mode is then restored via the re-growth procedure. It shows that the dislocations located beneath the etching pits are partially annihilated during the lateral coalescence, resulting in a decrease in dislocation density.
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•Ni etching and re-growth are adopted to decrease the dislocation density of diamond.•Ni dissolves the carbon atoms surrounding the dislocation at high temperature.•Step flow mode is restored during the re-growth procedure.•The dislocations beneath etching pits are partially annihilated during coalescence.
The parabolic trough collector is widely recognized as the leading and mature technology for concentrated solar thermal applications, allowing for the generation of high-temperature thermal energy. ...However, the parabolic trough collector still faces challenges in achieving high solar-thermal efficiency due to significant radiation heat loss incurred, particularly under high operating temperatures. To address this issue and maximize the capture of solar irradiation, a novel parabolic trough collector system integrated with photovoltaic cells and a high-reflective coating was proposed. The proposed novel systems in different configurations were manufactured and tested in the indoor solar simulator laboratory to assess their feasibility and performance. Additionally, a comprehensive mathematical model regarding the novel system was developed and validated by the experiments. This study then involved assessing the potential application of the novel parabolic trough collector system in a concentrated solar power plant. And the overall techno-economic performance of the novel power plant was analyzed and evaluated for three typical areas across the globe. The results showed that the novel configurations of photovoltaic cells and high-reflective coating in the proposed system exert excellent roles in significantly improving the efficiency of the solar irradiance utilization and reducing the radiation heat loss. Compared to the prototype power plant, the proposed power plant with the novel system possessed superior techno-economic performance, including a significant improvement of 10.1% in annual power output, a noteworthy reduction of 87.0% in electricity consumption for annual freeze protection, and an effective reduction of 6.9% in levelized cost of electricity.
•A hybrid parabolic trough collector with photovoltaic and functional coating is proposed.•Techno-economic models of proposed collector and CSP plant are built and validated.•The novel systems with different configurations are manufactured, tested and evaluated.•The hybrid CSP plant achieves a remarkable improvement of 10.1% in annual power output.•An effective reduction of 6.9% in levelized cost of electricity is obtained.
•A hybrid system combining solar photovoltaic, solar thermal and radiative cooling.•A verified model was developed to investigate the performance of the system.•Sensitivity analysis was performed to ...examine the effect of various parameters.•Annual performance assessment of the system was conducted as a reference.
Radiative cooling (RC) with the outer space as a natural heat sink has stimulated widespread attention in the research community and has achieved rapid developments in recent years. However, most available radiative coolers exhibit low power density and long payback periods. To overcome such shortcomings, a cost-effective solution that integrates RC into a solar photovoltaic/thermal (PV/T) collector as a secondary function was proposed. In this study, a trifunctional photovoltaic–photothermic–radiative cooling (PV-PT-RC) system was developed. The proposed system could convert solar energy into electricity and/or heat during daytime and offer cooling energy at night through RC. A mathematical model was built to assess the performance of the PV-PT-RC system quantitatively and investigate the key performance indicators of the system numerically. Moreover, a practical-scale PV-PT-RC testing system was built, and experiments were performed to verify the effectiveness of the numerical model. Results revealed that the mean relative errors are less than 5% for the electrical power, aluminum plate temperature, and water temperature in the tank and 6.83% for the cooling power, thereby proving that the mathematical model can accurately assess the performance of the hybrid system. On the basis of the verified model, the overall performance of the system was examined under different insulation thicknesses, initial water temperatures in the tank, packing factors, panel emissivity values, and tank volumes. Furthermore, the results of the annual performance analysis suggested that the annual electrical, heat and cooling gains of the system in Eastern China are 479.67, 2369.07, and 1432.49 MJ, respectively.
Conventional parabolic trough solar receivers are widely used to harvest heat energy at temperatures ranging from 400 °C to 550 °C. However, high temperatures cause excessive heat loss in solar ...receivers. Two types of novel solar receivers with an inner metal radiation shield (RS), one with solar selective absorbing coating on the outer surface and one without, were proposed and constructed to improve the thermal performance of solar receivers. Experiments were conducted in an enthalpy difference lab, and mathematical models with spectral radiant distributions were established to predict the thermal performance of the solar receivers. A comparison between the simulated and experimental results showed satisfactory consistencies. Predictions were obtained using the models with the root mean square deviation of less than 6%. The novel solar receiver without solar selective absorbing coating on the outer surface of the RS showed superior performance at absorber temperatures exceeding 550 °C. At the absorber temperature of 600 °C, the percentage of heat loss reduction of the receiver with solar selective absorbing coating and of that without reached 23.4% and 24.2%, respectively.
TiO2 nanotube（TiNT） arrays were deposited on boron-doped diamond films by a liquid-phase deposition method with ZnO nanorod arrays as the template.The different morphologies of TiNTs have been ...obtained by controlling the morphology of ZnO template.The X-ray diffraction and energy-dispersive X-ray analysis show that the ZnO nanorod array template has been removed in the TiNTs formation process.The crystalline quality of the TiNTs is improved by increasing the annealing temperature.The band gap of the TiNTs is about 3.25 eV estimated by the UV-Vis absorption spectroscopy,which is close to the value of bulk TiO2.In the photoluminescence spectrum,a broad visible emission in a range of ca.550-750 nm appears due to the surface oxygen vacancies and defects.
In this paper, we systematically investigated the influence of structure parameters on the performance of diamond trench MIS barrier-controlled Schottky (TMBS) diode by using Silvaco simulation. It ...demonstrates that the charge-coupling effect introduced by a proper dielectric thickness helps to uniform the electric field in dielectric and diamond simultaneously. In addition, a relatively large (small) mesa width (etching depth) is beneficial to balance the breakdown voltage and on-resistance, resulting in a high BFOM value. Furthermore, the effect of dielectric constant on the electrical properties is also evaluated. Those results may provide a guide for engineering of diamond TMBS diode.
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•A vertical TMBS diamond diode is designed and optimized through TCAD.•The charge-coupling effect of MIS suppress the electric field crowding effectively.•A medium oxide thickness is beneficial to realize high performances.
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•A modified trough receiver with two solar mirrors and a hot mirror is proposed.•An optical-thermal coupled model is developed to analyze the collector performance.•The receiver can ...reduce the heat loss and improve the efficiency effectively.•Heat loss of the absorber can be reduced by 13.5% at the fluid temperature of 823 K.•The best improvement in the collector efficiency of 4.70% is achieved.
Parabolic trough collector is an up-and-coming technology for urban energy supply. To further enhance the optical-thermal efficiency of the collector, a modified receiver enhanced by solar and hot mirrors was proposed. In this receiver, two symmetrical solar mirrors were designed to collect more solar irradiance, and a transparent hot-mirror shield was employed to lessen the thermal loss. After the design, the collector performance was studied by developing an optical-thermal coupled model. Based on the model, firstly, the proposed receiver was compared with the conventional receiver and two existing modified receivers. Results indicate the proposed receiver can achieve an optical efficiency of 78.02%, which is higher than those of the existing modified receivers and is just 0.22% lower than that of the conventional one. Moreover, compared with the conventional receiver, the two existing modified receivers cannot improve the optical-thermal efficiency at sufficiently high direct normal irradiance or relatively low fluid temperature, which can be overcome by the proposed receiver. Furthermore, compared with the conventional receiver, the proposed receiver can lessen the thermal loss by 11.2–89.6 W·m−1, thus improving the receiver efficiency and the optical-thermal efficiency by 0.03–5.26% and 0.03–4.70%, respectively, under the typical ranges of the inlet temperature (573–823 K) and the direct normal irradiance (0.3–1 kW·m−2). Then, parameter analysis indicates the hot mirror with low emissivity is necessary for efficiently improving the optical-thermal efficiency. Finally, the proposed receiver can improve the optical-thermal efficiency more effectively at higher fluid temperature or larger coating emissivity. The above results signify that the proposed receiver can be helpful for enhancing the efficiency of the trough collector.
Abstract
The wall thickness of the sewage pipeline on a shale gas platform is seriously reduced. In order to explore the specific reasons for the pipeline failure, this paper carried out analysis by ...means of macroscopic inspection, mechanical property test, chemical composition analysis of base metal and corrosion product analysis. The analysis results show that the site of this pipeline corroded most seriously is at 5 o ′clock and 12 o ′clock near the outlet, and the corrosion of liquid accumulation containing CO
2
is the main reason for the serious failure of the inner wall of this pipeline. This paper explores the specific reasons for the failure of the sewage pipeline on a shale gas platform, and provides a reference for the corrosion prevention of the sewage pipeline.
