Thermal Analysis of Organic Light Emitting Diodes Based on Basic Heat Transfer Theory

We investigate the thermal characteristics of standard organic light-emitting diodes （OLEDs） using a simple and clear 1D thermal model based on the basic heat transfer theory. The thermal model can accurately estimate the device temperature, which is linearly with electrical input power. The simulation results show that there is almost no temperature gradient within the OLED device working under steady state conditions. Furthermore, thermal analysis simulation results show that the surface properties （convective heat transfer coetficient and surface emissivity） of the substrate or cathode can significantly affect the temperature distribution of the OLED.

Operation strategy and energy-saving of the solar lighting/heating system through spectral splitting

The performance of a solar lighting and heating system(SLHS)based on the spectral splitting effect of nanofluids is presented in this paper.SLHS through nanofluids would split the sunlight spectrum into different wavelength,and then introduce the visible light into the offices for lighting and absorb infrared energy to generate hot water.The Energy Plus software was used to analyze the energy consumption of typical office building located in the city of Harbin in China coupled with SLHS.Based on the simulation results two lighting zones were identified in the offices and the optimal lighting control strategy was developed for a full year.The performance models of SLHS with different light-receiving areas of 10 m^(2)and 40 m^(2)were simulated and validated using the existing experimental data.The overall energy-saving of the offices over a full year were analyzed using the validated model.Results demonstrated that for SLHS with the area of 40 m^(2),the rate of the energy saving in the offices due to lighting and hot water systems were 58.9%,and 19.3%,respectively.The system also had the additional benefit of reducing the cooling load of the air conditioning system during summer period together with improving the quality of the indoor environment resulting in better health and productivity of the occupants.

Characteristics of Thermal Climate Resources Changes of Agricultural Production during Frost Period in Jianchang County

[Objective] The characteristics of thermal climate resources changes of agricultural production during frost period in Jianchang County were studied. [Method] By dint of Jianchang climate resources and routine numerical statistics method, the sunlight and temperature changes trend from 1960 to 2009 in Jianchang County were analyzed. [Result] The sunshine hours and sunshine percentages during frost period in Janchang County from 1960 to 2009 tended to decrease. The climate tendency rates were -55.556 h/10 a and -2.39%/10 a respectively, 287 h and 12% of deduction in recent 50 years. There were climate transition in 1981 and 1982. And there were a shortage of 161 h and 7% of sunshine hours and sunshine percentages before and after the transition. The temperature during the frost period generally was increasing. The average temperature, average maximum and lowest temperature tendency rate were 0.386, 0.392 and 0.567 ℃/10 a. There was a growth of 1.93, 1.96 and 2.84 ℃ in recent 50 years. There were temperature transition in 1987 and 1988. The average temperature, average maximum and lowest temperature increased 1.3, 1.2 and 1.7 ℃. In recent 50 years, the sunshine resources during frost period in Jianchang were decreasing, while the thermal resources were strengthening, forming complementary of light and heat. [Conclusion] The study provided climate accordance to the development of local facility agriculture during frost period.

Manufacturing of Long Products Made of Innovative Lightweight Materials

The processing of innovative lightweight materials to sheet metal components and assemblies with globally or locally defined properties is the object of this work. It takes a load-dependent design of components and assemblies, for example, based on the composition of different construction materials or a targeted setting of component areas with specified characteristics to fully exploit the lightweight potential when substituting conventionally used materials. Different process chains for the manufacturing of roll-formed long products made of magnesium alloys and high-strength steels with locally defined properties will be presented in this paper. Depending on the kind of material to be formed and the desired product characteristics, different temperature managements are needed for capable processes. Due to limited formability at room temperature, magnesium alloys require a heating of the forming zones above 200–225 °C throughout the bending process in order to activate additional gliding planes and to avoid any failures in the radii. The realization of local hardening effects requires at least one process-integrated heat treatment when roll forming manganese–boron steels. For both processes, it is imperative to realize a heating and cooling down or quenching appropriate for the manufacturing of long products with the required quality. Additionally, proper line speeds that allow a continuously operated economical production have to be considered. Research results including design, FEA, realization and experimentation of the mentioned process chains and strategies will be described in detail.

Nano-enabled solar driven-interfacial evaporation:Advanced design and opportunities

Solar-driven interfacial evaporation(SDIE)is emerging as a promising pathway to solving the worldwide water shortage and water pollution.Nanomaterials(e.g.,plasmonic metals,inorganic/organic semiconductors,and carbon nanomaterials)and related nanochemistry have attracted increasing attention for the solar-to-vapor process in terms of broadband absorption,electronic structure adjustment,and surface/interface chemistry manipulation.Furthermore,the assembly of nanomaterials can contribute to the mass transfer,heat management,and enthalpy regulation of water during solar evaporation.To date,numerous nano-enabled materials and structures have been developed to improve the solar absorption,heat management(i.e.,heat confinement and heat transfer),and water management(i.e.,activation,evaporation,and replenishment).In this review,we focus on a systematical summary about the composition and structure engineering of nanomaterials in SDIE,including size and morphology effects,nanostructure optimizations,and structure-property relationship decoupling.This review also surveys recent advances in nanochemistry(e.g.,preparation chemistry and structural chemistry)deployed to conceptual design of nanomaterials.Finally,the key challenges and future perspectives of nanomaterials for solar evaporation are overviewed.This review aims at providing guidance for the design and construction of nanomaterials for high-efficiency SDIE on the basis of the aspects of materials science and chemical engineering.