Results 1 - 6 of 6
Results 1 - 6 of 6. Search took: 0.015 seconds
|Sort by: date | relevance|
[en] We study a mixed spin-(3/2, 1) ladder system with antiferromagnetic rung coupling and next-nearest-neighbor interaction. The exactly solved Ising-chain model is employed to investigate the ground-state properties and thermodynamics of the low-dimensional ladder system. Our results show that the competition between different exchange couplings brings in a large variety of ground states characterized by various values of normalized magnetization equal to 0, 1/5, 2/5, 3/5, 1. Moreover, an interesting double-peak structure is also detected in the thermal dependence of magnetic susceptibility and specific heat when the frustration comes into play. It is shown that the double-peak phenomenon at zero-field for the case of AF2 ground-state arises from the very strong antiferromagnetic rung coupling, while other cases are attributed to the excitations induced by temperature and external field around the phase boundary. (paper)
[en] A facile self-doping and self-templating strategy to prepare three-dimensional nitrogen-doped hierarchical porous carbons via direct carbonization of mussel nacre (MN) is developed. Self-templating can be effective to retain the origin structure and the volatile organic components can serve as carbon precursors for porous carbon. The typical MN-derived carbon (MNC) carbonized at 800 °C is endowed with high surface area of unique hierarchical porosity (consisting of macropores, mesopores and micropores), and high content of heteroatom functionalities (1.30 at.% N). Consequently, the performance in the alkaline KOH electrolyte system was particularly promising with the MNC-6 electrodes showing a high capacitance of 243.7 F g−1 at a current density of 1.0 A g−1 and a promising cycling stability with 85.7% capacitance retention at 1.0 A g−1 after 10,000 cycles. The present work provides a new avenue for facile and high efficient construction of N-doped hierarchical porous carbons for potential supercapacitor.
[en] Metal-insulator-semiconductor back contact has been employed for a perovskite organic lead iodide heterojunction solar cell, in which an ultrathin Al_2O_3 film as an insulating layer was deposited onto the CH_3NH_3PbI_3 by atomic layer deposition technology. The light-to-electricity conversion efficiency of the devices is significantly enhanced from 3.30% to 5.07%. Further the impedance spectrum reveals that this insulating layer sustains part of the positive bias applied in the absorber region close to the back contact and decreases the carrier transport barrier, thus promoting transportation of carriers
[en] Highlights: • A new CAES system for trigeneration based on electrical peak load shifting is proposed. • The theoretical models and the thermodynamics process are established and analyzed. • The relevant parameters influencing its performance have been discussed and optimized. • A novel energy and economic evaluation methods is proposed to evaluate the performance of the system. - Abstract: The compressed air energy storage (CAES) has made great contribution to both electricity and renewable energy. In the pursuit of reduced energy consumption and relieving power utility pressure effectively, a novel trigeneration system based on CAES for cooling, heating and electricity generation by electrical energy peak load shifting is proposed in this paper. The cooling power is generated by the direct expansion of compressed air, and the heating power is recovered in the process of compression and storage. Based on the working principle of the typical CAES, the theoretical analysis of the thermodynamic system models are established and the characteristics of the system are analyzed. A novel method used to evaluate energy and economic performance is proposed. A case study is conducted, and the economic-social and technical feasibility of the proposed system are discussed. The results show that the trigeneration system works efficiently at relatively low pressure, and the efficiency is expected to reach about 76.3% when air is compressed and released by 15 bar. The annual monetary cost saving annually is about 53.9%. Moreover, general considerations about the proposed system are also presented.
[en] Highlights: • A solar thermoelectric with micro-channel heat pipe system was presented. • Mathematical model of the system was built. • Experiment and the simulation were compared to verify the model. • Performance of the system with different factors was analyzed. - Abstract: Micro-channel heat pipe can convert the low heat flux to the high heat flux by changing the ratio of the evaporator area to the condenser area and has a higher heat transfer performance than the common heat pipe. Combining the solar concentrating thermoelectric generation with micro-channel heat pipe can save the quantity of thermoelectric generation and reduce the cost significantly. In this paper, a solar concentrating thermoelectric generator using the micro-channel heat pipe array was designed, and the mathematical model was built. Furthermore, the comparison of the experiment and the simulation between the solar concentrating thermoelectric generator using the micro-channel heat pipe array and the thermoelectric generations in series was made. In addition, the performance on the different areas of selective absorbing coating, different concentration ratios, different ambient temperatures, different wind speed all were analyzed. The outcomes showed the overall performance of the solar concentrating thermoelectric generator using the micro-channel heat pipe array system.
[en] Highlights: • A novel solar thermoelectric cogenerations is studied, designed, realized, characterized, and tested. • The theoretical models and the thermodynamics process are established and analyzed. • The relevant parameters influencing its performance have been discussed and optimized. • The results demonstrated the system is one of the most efficient similar products among either open literature or products. - Abstract: In this paper, a high-performance solar thermoelectric system for combined heat and power is developed and investigated. This new system has achieved a higher performance by considering some of the features, including a simplified structure, lower contact thermal resistance, lower convection heat loss, and better heat transfer performance. The mathematical model was built and analyzed. And the models are verified via the experimental prototype test. In addition, the performance of the system under different environmental conditions and operating parameters are evaluated and predicted. The results show that the proposed system can be used for cogeneration of heat water and electric power. And when the solar irradiation is larger than 700 W/m"2, and water temperature of 13 °C, the maximum instantaneous electrical power output was found to be 0.659 W at the load resistance 4.2 Ω, and the power generation efficiency of the thermoelectric generator (TEG) is 1.956%, which is close to that of a low temperature organic Rankine cycle system. These results indicate the feasibility of the proposed high-performance solar thermoelectric system and give hints for future improvement of the solar thermoelectric system for combined heat and power.