Design of optical systems for handling very high power densities

2005 ◽  
Author(s):  
Leo H. J. F. Beckmann
Keyword(s):  
High Power ◽  
Optical Systems ◽  
Power Densities ◽  
Very High

scholarly journals On the understanding and feasibility of “Breakthrough” Osmosis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jun Jie Wu ◽  
Robert W. Field
Keyword(s):  
High Power ◽  
Forward Osmosis ◽  
Solute Concentration ◽  
Pressure Retarded Osmosis ◽  
Permselective Membrane ◽  
Order Of Magnitude ◽  
Theoretical Paper ◽  
Salt Diffusion ◽  
Power Densities ◽  
Very High

Abstract Osmosis is the movement of solvent across a permselective membrane induced by a solute-concentration gradient. Now in ‘Forward Osmosis’ it is empirically observed that the diffusion of the solute is counter to that of the solvent i.e. there is so-called “reverse salt diffusion”. However it has been recently suggested, in a theoretical paper, that if allowance is made for minor deviations from ideal semi-permeability then operation in an overlooked mode of “breakthrough” osmosis would be possible and importantly it would yield relatively large rates of osmosis. A consequential prediction was that in “breakthrough mode”, Pressure-Retarded Osmosis (PRO) would generate very high power densities exceeding those in the conventional mode by one order of magnitude. The practicality of this suggestion was explored and necessarily questions were then raised regarding the foundation of the Spiegler-Kedem-Katchalsky model. Arising from: Yaroshchuk, A., Sci. Rep. 7, 45168 (2017); 10.1038/srep45168

Recent Progress in SiC Microwave MESFETs

1999 ◽  
Vol 572 ◽  
Author(s):  
S. T. Allen ◽  
S. T. Sheppard ◽  
W. L. Pribble ◽  
R. A. Sadler ◽  
T. S. Alcorn ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
Recent Progress ◽  
Rf Power ◽  
Power Added Efficiency ◽  
Power Densities ◽  
Hybrid Circuit ◽  
Very High

ABSTRACTSiC MESFET's have shown an RF power density of 4.6 W/mm at 3.5 GHz and a power added efficiency of 60% with 3 W/mm at 800 MHz, demonstrating that SiC devices are capable of very high power densities and high efficiencies. Single devices with 48 mm of gate periphery were mounted in a hybrid circuit and achieved a maximum RF power of 80 watts CW at 3.1 GHz with 38% PAE.

scholarly journals Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rohith Mittapally ◽  
Byungjun Lee ◽  
Linxiao Zhu ◽  
Amin Reihani ◽  
Ju Won Lim ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Efficiency ◽  
Near Field ◽  
Electrical Power ◽  
Photovoltaic Cells ◽  
High Power Density ◽  
Pv Cell ◽  
Electrical Power Output ◽  
Power Densities

AbstractThermophotovoltaic approaches that take advantage of near-field evanescent modes are being actively explored due to their potential for high-power density and high-efficiency energy conversion. However, progress towards functional near-field thermophotovoltaic devices has been limited by challenges in creating thermally robust planar emitters and photovoltaic cells designed for near-field thermal radiation. Here, we demonstrate record power densities of ~5 kW/m2 at an efficiency of 6.8%, where the efficiency of the system is defined as the ratio of the electrical power output of the PV cell to the radiative heat transfer from the emitter to the PV cell. This was accomplished by developing novel emitter devices that can sustain temperatures as high as 1270 K and positioning them into the near-field (<100 nm) of custom-fabricated InGaAs-based thin film photovoltaic cells. In addition to demonstrating efficient heat-to-electricity conversion at high power density, we report the performance of thermophotovoltaic devices across a range of emitter temperatures (~800 K–1270 K) and gap sizes (70 nm–7 µm). The methods and insights achieved in this work represent a critical step towards understanding the fundamental principles of harvesting thermal energy in the near-field.

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