Cone Reflector Research Articles

Highly efficient solar steam evaporation via elastic polymer covalent organic frameworks monolith

Three-dimensional solar steam evaporators with efficient water purification performance have received increasing attention recently. Herein, elastic polymer covalent organic frameworks (PP-PEG) containing PEG chains with intriguing adaptability to guests are prepared by forming porphyrin rings. PP-PEG foams demonstrate full spectrum absorbance and excellent photothermal conversion properties. Through well-designed thermal management and optimization of the hydrophilicity and PEG chain length, we obtain a highly efficient solar evaporator with an evaporation rate of 4.89 kg m−2 h−1 under 1 sun in self-contained mode. The optimized solar evaporation rate is increased to 18.88 kg m−2 h−1 under 1 sun with a facile truncated cone reflector, exceeding all known solar steam evaporators. This innovative design holds immense promise for desalination and water purification owing to its simple preparation, high efficiency and durability.

Detection Stability Improvement of Near-Infrared Laser Telemetry for Methane Emission from Oil/Gas Station Using a Catadioptric Optical Receiver

Open-path laser telemetry of methane leakage yields security guarantees of energy storage and transportation for oil/gas station production operation. In order to further improve the long-term detection stability under the condition of long-distance non-cooperative targets, a catadioptric optical receiver (COR) consisting of a Fresnel lens, cone reflector and parabolic reflector is proposed to focus the laser echo light that deviates gradually with the increase in atmospheric turbulence. The geometric configuration parameters of COR are optimized by the ray-tracing method, and the condensing performance of COR is further verified. The self-developed methane laser telemetry system coupled with COR is calibrated in the laboratory and then moved to the field for a signal receiving stability experiment under turbulence interference. The results show that the receiving angle of COR increases 3.8 times compared with the Fresnel lens optical receiver (FOR). The RMSE and IS of the COR system are 0.00173 V and 84.79%, respectively. For comparison, these two evaluating indicators of the FOR system are 0.00288 V and 76.23%. This self-developed methane laser telemetry system coupled with COR is feasible for improving the long-term detection stability of remote leakage monitoring in oil/gas stations.

The packing factor of the pebble bed in molten salt reactor

Many concepts of molten salt cooled pebble bed reactor have been developed in recent decades. The packing factor (PF) of the pebble bed in the molten salt reactor should be investigated because it is of great importance for reactor design. Model experiments based on the solid fuel thorium-based molten salt reactor (TMSR-SF) were performed. Experimental results show that the PF of the pebble bed in TMSR-SF (D = 21d, H = 18d, d is pebble diameter) is about 0.57 ± 0.02. The pebble bed in liquid environment is looser than that in dry condition. The PF increases with the diameter of the reactor core and the height of the pebble bed. The geometry of the lower cone reflector may induce large variety of packing factor if the angle of reflector is smaller than the angle of repose of the pebble bed. The loading rate and flow velocity in TMSR-SF are considered to be of little influence on PF. Results from the experiments will be of reference value for the design of reactors.

Effect of Reflector Structure on Solar Collecting Performance of Thermal Receive‐storage Cavity

Thermal receive‐storage cavity is made of superalloy. It work in harsh conditions, for example, high temperature, thermal shock and corrosion. What’s more, reflector structure has important influence on radiation utilization. Consequently, for cylindrical cavity receiver, the effects of conical reflector and (with different taper angles which marked with 2φ) hemispheric reflectors on radiation heat flux and temperature uniformity on the receiver cavity inside surface were studied. Solar radiation utilization of the cavity with hemisphere reflector is lower than that of cone reflector with any taper angles; when φ<40°, average temperature on cavity inside surface is relatively higher and decreases linearly with the increasing of φ. Synthesizes radiation utilization and temperature uniformity on the receiver cavity inside surface, conical reflector with φ=30° should be selected. The study can provide guidance on designing cylindrical thermal receive‐storage cavity.

Optical Spatial Filter to Suppress Beam Wander and Spatial Noise Induced by Atmospheric Turbulence in Free-Space Optical Communications

We propose an optical spatial filter (OSF) method to suppress beam wander and spatial noise effects. Signal from random displacements of the focus spot around the optical axis within the constricted area is collected. This method advantageously suppresses fluctuations in signal intensity. The OSF consists of a pinhole and cone reflector. The pinhole produces Fresnel diffraction on the focus spot. The cone reflector provides directed reflectance onto the pinhole for random focus spot displacements due to beam wander. The calculations of signal power are based on fluctuations of signal intensity that are minimized by the circular aperture function of the pinhole and the cosine of the reflectance angle from the cone reflector. The method is applied to free-space optical communications at a wavelength of 1.55 μm with an atmospheric chamber to provide optical propagation media. Based on calculations, the beam wander angles that can be received by the OSF are from 14.0° to 28.0°. Moreover, based on experiment, the OSF with a pinhole diameter of 20.0 μm and cone reflector diameter of 1.5 mm produces signal power of −15.3 dBm. Both calculations and experiment show that the OSF enhances the received signal power in the presence of turbulence.

Improvement of beam quality in unstable resonators by a conical output coupler

A novel conical output coupler for positive-branch unstable resonators has been proposed to improve the output beam quality. With the application of an inner cone annular scraper and an outer cone reflector, a realization of the output beam from unstable resonator with solid core is introduced. The feasibility of this conical output coupler with solid beam is examined numerically and experimentally with the help of a commercial fast transverse flow (FTF) CO2 laser. The characteristics of the output coupling beam in near field and far field are discussed. Under the definition of 86.5 % power content, the M pc 2 factors of original annular beam and improved solid beam are 5.22 and 1.16 in simulation. In experiment, the M pc 2 factor of the original annular beam from the commercial FTF CO2 laser is more than 10, while the M pc 2 factor of the improved solid beam is 3.82. Both simulation and experimental results show that the beam quality can be improved a lot by introducing this output coupling configuration.

Shock Reflection Detonation Initiation Studies for Pulse Detonation Engines

A new technique to initiate a detonation wave via the interaction of a high-speed flame/shock complex and an obstacle is investigated. Experiments were performed in which a flame was ignited at the closed end of a tube partially filled with orifice plates leading up to the obstacle. Two different types of obstacles were tested. The obstacles include assemblies consisting of a circular plate followed by an orifice plate and a cone followed by an orifice plate. The flame accelerates in the orifice plate laden section of the tube to a high velocity producing a shock wave ahead of it. This shock wave interacts with the obstacle by first colliding with the leading central blockage, that is, the circular plate or the cone, and then reflecting off the orifice plate. Shock reflection produces a region of high temperature and pressure that ignites the reactants, which under certain circumstances, can initiate a detonation wave. The experiments were performed with stoichiometric ethylene-oxygen mixtures at atmospheric conditions with nitrogen dilution. The nitrogen dilution was varied, and the maximum nitrogen dilution that resulted in detonation initiation, that is, the critical mixture, was found. For experiments performed with the circular plate reflector obstacle, detonation initiation was observed for mixtures with a nitrogen-oxygen concentration ratio up to 3.98. In experiments with the cone reflector obstacle, detonation initiation occurred for less reactive mixtures, that is, mixtures with a nitrogen-to-oxygen concentration ratio of up to 4.33. Additional experiments were performed where the cone obstacle was moved closer to the Ignition point to find the minimum flame acceleration distance required for detonation initiation. For stoichiometric ethylene-air mixtures, detonation initiation was observed with the cone obstacle located at least 1.36 m from the ignition point. It was found that detonation initiation occurred for the cone reflector when the incident shock wave velocity was above roughly 750 m/s.

Cone reflector/coupler speaker system and method

A speaker system (10) including a cone reflector (14) connected to a speaker driver (12). The cone reflector (14) has at least one included angle used to reflect sound in a desired pattern in the horizontal and vertical planes. Where the sound is dispersed in the vertical plane as a function of the included angles. These angles may be varied or more included angles may be added to achieve certain sound energy distributions. The speaker driver (12) is located above the cone reflector (14) with the narrower end of the cone (14) facing the output of the speaker driver (12). Sound generated by the speaker driver (12) is reflected off the cone reflector (14) and dispersed as a function of the included angles of the cone reflector.

Non-axisymmetric reflectors concentrating radiation from an asymmetric heliostat field onto a circular absorber

In solar tower plants, where a rotationally symmetric field of heliostats surrounds the tower, an axisymmetric secondary concentrator such as a compound parabolic concentrator (CPC) or a tailored concentrator or a cone is the obvious choice. For locations at higher latitudes, however, the reflecting area of the heliostats may be used more efficiently if the field of heliostats is located opposite to the sun as seen from the tower. Then the field is asymmetric with regard to the tower. In the case of an asymmetric field, an axisymmetric concentrator necessarily has a concentration significantly lower than the upper limit. Furthermore, the area on the ground from which a tilted axisymmetric concentrator accepts radiation is an ellipse, including also heliostats very distant to the tower producing a large image of the sun. For these reasons we investigate asymmetric secondaries. From the shape of the edge ray reflectors constructed for rays in the central south–north plane we conclude that a skew cone reflector might be appropriate for the field, and optimize its free parameters by means of ray tracing. Asymmetric concentrators may increase the concentration by up to 25% at the same efficiency compared to optimized axisymmetric CPC or cone reflectors.