Spectral irradiance scale realization and uncertainty analysis based on a 14 mm diameter WC-C fixed point blackbody from 250 nm to 2500 nm

Spectral irradiance scale in the wavelength range from 250 nm to 2500 nm was realized at National Institute of Metrology (NIM) on the basis of a large area tungsten carbide–carbon (WC-C) high temperature fixed point blackbody, which is composed of a 14 mm diameter WC-C fixed point cell and a variable temperature blackbody BB3500MP as a furnace. A series of 1000 W FEL tungsten halogen lamps were used as transfer standards. The new spectral irradiance scale was compared with the scale based on a variable-temperature blackbody BB3500M, and the divergence between these two methods varied from -0.66% to 0.79% from 280 nm to 2100 nm. The measurement uncertainty of spectral irradiance scale based on fixed-point blackbody was analyzed, and the expanded uncertainty was estimated as 3.9% at 250 nm, 1.4% at 280 nm, 0.43 % at 400 nm, 0.27% at 800 nm, 0.25% at 1000 nm, 0.62% at 1500 nm, 0.76% at 2000 nm, and 2.4% at 2500 nm respectively. In the range from 300 nm to 1000 nm the fixed-point scale was improved obviously: the uncertainty decreased by more than 25% compared to the uncertainty based on the variable temperature blackbody. Below 300 nm, the uncertainty became higher because the signal to noise ratio was poor. Above 1100 nm, the contribution of temperature measurement to the uncertainty of spectral irradiance decreases, therefore the uncertainties of two methods are almost at the same level. The fixed-point blackbody was also used to realize the correlated colour temperature and distribution temperature of a tungsten filament lamp, the deviation from the variable temperature blackbody method was -0.5 K and -2.9 K, respectively.

Investigation of efficiency and quality of functioning of led lighting elements of electrical systems at the maximum permissible ambient temperature

Based on the results of the study of the elements of the electrical system, the operability and quality of their functioning are determined by the example of the use of LED filament lamps for lighting during their continuous operation at the maximum permissible ambient temperature equal to 50 °С.THE PURPOSE. The relevance of this work is determined by the lack of information about the operability and quality of functioning of filament LED lamps during their continuous operation in conditions of elevated ambient temperature, taking place in boiler-turbine shops of thermal power plants, foundries of factories, bakeries of bakeries, in the tunnels of coal mines and divisions of other enterprises. It is established that the working life of the Gauss LED filament lamps with a power of 10 W, containing 4 filaments, is 70-75 days, and with 8 filaments only 22-24 days. Degradation of filament lamps with 8 filaments at the maximum permissible ambient temperature of 50 °С. occurs at a rate of 0.45-0.50 % per day. It is shown that a filament LED lamp with 4 filaments, if it is operated for 4.5 hours a day in conditions of elevated ambient temperature, can work for almost more than one year. METHODS. The resource of filament and typical LED lamps of different power is considered in comparative terms when they are operated at a relatively high ambient temperature.RESULTS. It is established that a 10 W filament LED lamp with 4 filaments has an energy resource, as well as a high-quality standard LED lamp. At the same time, the temperature of its body is no more than 40 °С, which is almost 2 times less. By increasing the distance between the filaments due to the use of a smaller number of filaments, it is possible to increase the power supply by 2 times and the corresponding luminous flux by 1.5 times. CONCLUSION. In preliminary experiments with a filament lamp of the new design of the Diall model, it was found that the use of longer filaments (45 mm) in it, instead of the previously used ones (30 mm), allows to increase the quality of their functioning by about 4 times when they are operated under the same ambient temperature conditions.

Spice Modeling of LED Filament and its Simulation in Switch Drive Circuit

When designing the LED filament lamp device and driving circuit at the beginning, software simulation is an indispensable step. It is necessary to verify whether the circuit output results are consistent with the requirements through simulation. In this paper, first measure the volt-ampere characteristics of the actual 1W LED filament strip, and applied the six-segment linear approximation model method for Spice modeling. The simulated volt-ampere characteristics of the 1W model were consistent with the measured volt-ampere characteristics of the 1W LED filament strip. Then use the driver chip HV9910B to design the LED filament lamp switch constant current drive circuit. Combined with the piecewise linear equivalent method, 3W, 4W, 5W LED filament lamp loads are modeled, the detailed design process of the entire circuit is analyzed, and the output voltage, current, inductance output current, MOS output voltage and other parameters of the whole circuit are simulated and verified. The results show that the output voltages are 71V, 142V, 71V, and the output currents are 30.4mA, 20.7mA, 51.1mA respectively under the circuit topology of 3W, 4W, and 5W LED filament lamp. When the inductor current works in CCM mode, the duty cycle of MOS output voltage meets the requirements, and the circuit output results are consistent with the design requirements.

Thermal Analysis and Optimization of Light-Emitting Diodes Filament Lamp

Due to the high efficiency, light-emitting diodes (LED) filament lamps have become more and more popular alternative to the incandescent lamp. However, the heat generated by the LED chips is traditionally dissipated by relying on the natural convection within lamps, resulting in poor heat dissipation performance for LED filament lamps. A numerical simulation model of the typical LED filament lamp was established to simulate and analyze the heat dissipation and airflow phenomenon of LED filament lamps in this study. In addition, increasing lamp sizes, increasing phosphor diameters, and using finned phosphor layers were considered as optimization measures to improve the heat dissipation performance of LED filament lamps. When these optimization measures are applied, chip junction temperatures are reduced. A reduction of 6.9 °C is seen when the lamp radius is increased from 25 mm to 31 mm. When the phosphor diameter is increased to 4 mm from 2 mm, the junction temperature is reduced by 17.2 °C. Integration of a finned phosphor layer where there are 12 fins at a height of 1 mm and thickness of 0.2 mm in the layer decreased the junction temperature by 10.9 °C. These optimization results provide technical support for the design and manufacture of LED filament lamps, and thermal analysis results provide theoretical support for the promotion of these optimization methods.

The bioreactor with use of impeller mixers for cultivation of biomass of microalgas

Cultivation of microalgas gains popularity in the different countries in recent years. As a result of such intensive development of production the extensive experience in constructioning of various types of bioreactors was gained. The bioreactor for cultivation of microalgas having the cylindrical housing divided by horizontal partitions into sections for input and output of cultural liquid and additional section with an internal specular surface, the bubble device and gate stirrers fixed on blades, the rigidly bound to shaft is developed. Planetary rotation of gate stirrers concerning a shaft creates additional turbulization of the environment, provides alignment of concentration of cells of biomass, prevents emergence of hold-up spots, a premature deposition of cages of culture on the bottom of the device and increases efficiency of cultivation of microalgas. In the main section suspension of a microalga is exposed to the uniform light energy by means of coaxially established filament lamp of a daylight and to reflection of light from an internal specular surface of a housing. In the course of irradiating the filament lamp distinguishes warmth which is compensated by supply of the cooling air the Main difference from other bioreactors the impeller mixer fixed to a shaft in the bottom of a housing, preventing stratifying of the biomass pulp leaving more heavy is obespechivashchy full circulation of cultural liquid in the bottom of the device as in the horizontal, and vertical planes, at minimum mechanical energy consumptions. This device allows to create additional turbulization of the environment, to provide the uniform aeration, decrease in a power consumption on supply of steam-and-gas mixture in a collector, to prevent formation of "stagnant" zones in the bottom of the device.

Optimization of Helium Inflating on Heat Dissipation and Luminescence Properties of the A60 LED Filament Lamps

LED filament lamp has the characteristics of nearly 360° lighting angle, high brightness, and low energy consumption, turning it gradually into the best substitute for traditional incandescent lamps. At present, due to the limitations of heat dissipation, the development of high-power LED filament lamp is restricted. Helium is a rare gas with small density and high heat transfer coefficient. It can be used as a cooling and protective gas for LED filament lamp. In this paper, we investigated the effects of helium on the heat dissipation and luminescence performance of the A60 LED filament lamps by detecting the changes of junction temperature, color temperature, and luminous flux of different ratios helium inflating in the different power A60 LED filament lamps. Through the experiment, we found the most cost-effective ratio of helium gas in the A60 LED filament lamps without improving the lamp size and the filament diameter.

Full color carbon dots through surface engineering for constructing white light-emitting diodes

White light-emitting diode (WLED) devices are replacing the filament lamp and can provide a light close to natural sunlight, and they have thus drawn considerable attention in recent years.