Research Progress of Photo-/Electro-Driven Thermochromic Smart Windows

Thermochromic smart windows can automatically control solar radiation according to the ambient temperature. Compared with photochromic and electrochromic smart windows, they have a stronger applicability and lower energy consumption, and have a wide range of application prospects in the field of building energy efficiency. At present, aiming at the challenge of the high transition temperature of thermochromic smart windows, a large amount of innovative research has been carried out via the principle that thermochromic materials can be driven to change their optical performance by photothermal or electrothermal effects at room temperature. Based on this, the research progress of photo- and electro-driven thermochromic smart windows is summarized from VO2-based composites, hydrogels and liquid crystals, and it is pointed out that there are two main development trends of photo-/electro-driven thermochromic smart windows. One is exploring the diversified combination methods of photothermal materials and thermochromic materials, and the other is developing low-cost large-area heating electrodes.

Analysis of Electrothermal Effects in Devices and Arrays in InGaP/GaAs HBT Technology

In this paper, the dc electrothermal behavior of InGaP/GaAs HBT test devices and arrays for power amplifier output stages is extensively analyzed through an efficient simulation approach. The approach relies on a full circuit representation of the domains, which accounts for electrothermal effects through the thermal equivalent of the Ohm’s law and can be solved in any commercial circuit simulator. In particular, the power-temperature feedback is described through an equivalent thermal network automatically obtained by (i) generating a realistic 3-D geometry/mesh of the domain in the environment of a numerical tool with the aid of an in-house routine; (ii) feeding the geometry/mesh to FANTASTIC, which extracts the network without performing simulations. Nonlinear thermal effects adversely affecting the behavior of devices/arrays at high temperatures are included through a calibrated Kirchhoff’s transformation. For the test devices, the thermally-induced distortion in I–V curves is explained, and the limits of the safe operating regions are identified for a wide range of bias conditions. A deep insight into the electrothermal behavior of the arrays is then provided, with particular emphasis on the detrimental nonuniform operation. Useful guidelines are offered to designers in terms of layout and choice of the ballasting strategy.

Highly Salt-Resistant and All-Weather Solar-Driven Interfacial Evaporators with Photothermal and Electrothermal Effects Based on Janus Graphene@Silicone Sponges

Solar-driven interfacial evaporators are very promising for obtaining clean water, but suffer from serious performance degradation by salt-fouling, low evaporation rate under weak illumination and low clean water collection rate. Here, we report highly salt-resistant and all-weather evaporators with photothermal and electrothermal effects based on the Janus graphene@silicone sponges with opposing wettability. The evaporators achieve a remarkable high evaporation rate of 6.53 kg m-2 h-1 for 3.5 wt% NaCl solution under 1 sun illumination with a 5 V solar cell as compensation owing to their high solar absorption, low thermal conductivity, unique Janus structure and synergetic photothermal and electrothermal effects. Even in gloomy and dark environments, the evaporators could still generate vapor (1.51 kg m-2 h-1). Moreover, the evaporators feature long-term excellent salt-resistance, e.g., >10 d continuous evaporation in 10 wt% NaCl solution without performance degradation and salt precipitation, because of ultrafast water supply and salt diffusion in the macroporous superhydrophilic shell. Furthermore, the evaporators show high clean water collection rates of 21.92 kg m-2 d-1 (1 sun-9 h/0 sun-15 h + 5 V, indoor) and 9.65 kg m-2 d-1 (natural sun light + 5 V, outdoor). This study offers a new approach for efficiently obtaining clean water via solar desalination.

An Installation for Electrothermal Effects on a Workpiece

This paper presents a modernized installation for impacting a workpiece with electric current pulses whereby ensuring high quality of parts manufactured from titanium alloys. Electrical processes that occur when using a new method of switching an active-inductive load using a three-phase contactless thyristor starter are examined. The use of such a device can eliminate long transient processes during switching, improve control of the heating parameters of the workpiece and provide plasticization of the metal in short periods of time. Other positive effects of the three-phase contactless thyristor starter include the elimination of defects in the structure of the material, increase in the thermodynamic stability of the metals as well as in the structural strength and endurance, reduction of the anisotropy of the metals and the level of residual stress.