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[en] The manned deep-space exploration is a hot topic of the current space activities. The continuous supply of thermal and electrical energy for the scientific equipment and human beings is a crucial issue for the lunar outposts. Since the night lasts for periods of about 350 h at most locations on the lunar surface, massive energy storage is required for continuous energy supply during the lengthy lunar night and the in-situ resource utilization is demanded. A lunar based solar thermal power system with regolith thermal storage is presented in this paper. The performance analysis is carried out by the finite-time thermodynamics to take into account major irreversible losses. The influences of some key design parameters are analyzed for system optimization. The analytical results shows that the lunar based solar thermal power system with regolith thermal storage can meet the requirement of the continuous energy supply for lunar outposts. - Highlights: • A lunar based solar thermal power system with regolith thermal storage is presented. • The performance analysis is carried out by the finite-time thermodynamics. • The influences of some key design parameters are analyzed.
[en] The low grade heat utilization is not only an inevitable option to solve the energy and environment problems, but also a critical issue for many remote power applications and planetary explorations. In this study, a novel design called a heat engine aerobot which can convert planetary atmospheric energy to electricity is proposed and analysed. A dynamic theoretical model is established and some key issues, such as the thermodynamic performance and conversion efficiency are analysed. It shows that the heat engine aerobot is capable to convert the low grade atmospheric energy to electricity during its self-sustained vertical oscillation movement. Parametric analysis shows that some design parameters, such as the nozzle number, the nozzle outlet diameter, the initial liquid mass and the turbine start height may have significant influence on the energy generation performance. - Highlights: • A novel heat engine for low grade atmospheric energy utilization was proposed. • A theoretical model was established and the dynamic behaviour was simulated. • The parametric effects on its thermodynamic performance were analysed
[en] The gas temperature of a stratospheric airship plays an important role in its flight dynamics. A multi-nodes heat transient model is proposed and evaluated by the theoretical solutions of the adiabatic processes and the high altitude flight test data. A thermodynamic analysis code for stratospheric airships (TACSA) is developed to investigate the ascent subcooling induced by the thermodynamic expansion and the descent superheating induced by the thermodynamic compression. The simulation results show that the airship volume, vertical speed and the solar radiation have evident influence on the ascent subcooling descent superheating effects. - Highlights: • A multi-nodes heat transient model for stratospheric airships is proposed. • The thermal behaviors of the ascent and descent processes are predicted. • The volume, vertical speed and solar radiation have significant influence
[en] The thermal boundary characteristics at the contact interface between a porous media and an impermeable wall subject to a constant heat flux on its upper surface with and without consideration of the thermal contact resistance were investigated using a particle-level numerical simulation of single phase fluid flow and convection heat transfer in porous media. The numerical simulations assumed an ideal packed bed (simple cubic structure) formed by uniform diameter particles with small contact areas and a zero- or finite-thickness wall subject to a constant heat flux at the surface which mirrors the experimental setup. The numerical simulations showed that the temperature distribution at the contact interface is non-uniform for the porous media with a zero-thickness impermeable wall, and in the porous media with a finite-thickness impermeable wall with a thermal contact resistance between the particles and the plate (such as with a non-sintered porous media) with a constant heat flux on the outer surface, while the heat flux distribution at the contact interface is quite uniform for these cases. However, in the porous media with a finite-thickness impermeable wall without a thermal contact resistance between the particles and the plate (such as with a sintered porous media) with a constant heat flux on the outer surface, the heat flux distribution at the contact interface is very non-uniform, while the temperature distribution at the contact interface is quite uniform. Numerical simulations of the thermal boundary characteristics of the convection heat transfer in the porous media were used to investigate the applicability of various boundary conditions for the energy equations with and without a thermal contact resistance between the particles and the plate wall
[en] The work describes a simplified method for the preparation of liquid crystal (LC) bioassay using DNA-based capture molecules and having lower detection limits. The capture DNA probes of the stem-loop structure were immobilized on the surface of a glass slide. A homeotropic orientation of LC molecules can be obtained with the proper surface coverage of capture DNA probes. In the presence of analytes (specifically shown here for the progesterone as a model analyte), the molecular binding between capture DNA probes and progesterone opens the loop of the capture DNA probes. The opened sequence is then amenable to hybridization with a reporter DNA probe that is immobilized on gold nanoparticles. This changes the surface microstructure, disrupts the orientation of LC molecules, and results in an enhanced optical response, expressed as the average grey value of the images. This new kind of surface treatment for simultaneous recognition of target molecules and homeotropic anchoring of LCs reduces the number of preparation steps and makes the process of LC bioassay easier. This method has a detection limit as low as 0.1 pmol·L−1 of progesterone. .