scholarly journals New Formulation of the Theory of Thermoelectric Generator for Operation under Constant Heat Flux

2021 ◽  
Author(s):  
Gao Min
Keyword(s):  
Heat Flux ◽  
Constant Temperature ◽  
Temperature Difference ◽  
Thermoelectric Generator ◽  
Current Theory ◽  
Constant Heat Flux ◽  
Constant Heat ◽  
Theoretical Formulation ◽  
New Formulation

The current theory of thermoelectric generator can only deal with the situations where a thermoelectric generator operates under a constant temperature difference. In this paper, a new theoretical formulation is...

Defining a Discretized Space Suit Surface Radiator With Variable Emissivity Properties

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Christopher J. Massina ◽  
David M. Klaus
Keyword(s):  
Heat Flux ◽  
Constant Temperature ◽  
Thermal Control ◽  
Constant Heat Flux ◽  
Order Estimate ◽  
Space Suit ◽  
Constant Heat ◽  
Load Range ◽  
Heat Rejection ◽  
Integration Architecture

Heat rejection for space suit thermal control is typically achieved by sublimating water ice to vacuum. Converting the majority of a space suit's surface area into a radiator may offer an alternative means of heat rejection, thus reducing the undesirable loss of water mass to space. In this work, variable infrared (IR) emissivity electrochromic materials are considered and analyzed as a mechanism to actively modulate radiative heat rejection in the proposed full suit radiator architecture. A simplified suit geometry and lunar pole thermal environment is used to provide a first-order estimate of electrochromic performance requirements, including number of individually controllable pixels and the emissivity variation that they must be able to achieve to enable this application. In addition to several implementation considerations, two fundamental integration architecture options are presented—constant temperature and constant heat flux. With constant temperature integration, up to 48 individual pixels with an achievable emissivity range of 0.169–0.495 could be used to reject a metabolic load range of 100 W–500 W. Alternatively, with constant heat flux integration, approximately 400 pixels with an achievable emissivity range of 0.122–0.967 are required to reject the same load range in an identical external environment. Overall, the use of variable emissivity electrochromics in this capacity is shown to offer a potentially feasible solution to approach zero consumable loss thermal control in space suits.

A comparison of turbulent thermal convection between conditions of constant temperature and constant heat flux

2008 ◽  
Vol 595 ◽  
pp. 203-219 ◽  
Author(s):  
R. VERZICCO ◽  
K. R. SREENIVASAN
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Heat Transport ◽  
Constant Temperature ◽  
Thermal Convection ◽  
Constant Heat Flux ◽  
Constant Heat ◽  
Experimental Conditions ◽  
Thermal Plumes ◽  
Dimensional Argument

We numerically investigate turbulent thermal convection driven by a horizontal surface of constant heat flux and compare the results with those of constant temperature. Below Ra ≈ 109, where Ra is the Rayleigh number, when the flow is smooth and regular, the heat transport in the two cases is essentially the same. For Ra > 109 the heat transport for imposed heat flux is smaller than that for constant temperature, and is close to experimental data. We provide a simple dimensional argument to indicate that the unsteady emission of thermal plumes renders typical experimental conditions closer to the constant heat flux case.

scholarly journals Transient response of a thermoelectric generator to load steps under constant heat flux

2018 ◽  
Vol 212 ◽  
pp. 293-303 ◽  
Author(s):  
Marcos Compadre Torrecilla ◽  
Andrea Montecucco ◽  
Jonathan Siviter ◽  
Andrew Strain ◽  
Andrew R. Knox
Keyword(s):  
Heat Flux ◽  
Transient Response ◽  
Thermoelectric Generator ◽  
Constant Heat Flux ◽  
Constant Heat

Rate of Sublimation of Ice by Radiative Heating in Freeze-Etching

1980 ◽  
Vol 38 ◽  
pp. 618-619
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Heat Flux ◽  
Freeze Fracture ◽  
Constant Heat Flux ◽  
Radiative Heating ◽  
Constant Heat ◽  
Entire Sample ◽  
Simplified Method ◽  
Freeze Etching ◽  
Sublimation Rates ◽  
Fractured Surface

To bring out details in the fractured surface of a frozen sample in the freeze fracture/freeze-etch technique,the sample or part of it is warmed to enhance water sublimation.One way to do this is to raise the temperature of the entire sample to about -100°C to -90°C. In this case sublimation rates can be calculated by using plots such as Fig.1 (Talmon and Thomas),or by simplified formulae such as that given by Menold and Liittge. To achieve higher rates of sublimation without heating the entire sample a radiative heater can be used (Echlin et al.). In the present paper a simplified method for the calculation of the rates of sublimation under a constant heat flux F [W/m2] at the surface of the sample from a heater placed directly above the sample is described.

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