Enhancing Thermoelectric Energy Recovery via Modulations of Source Temperature for Cyclical Heat Loadings

2006 ◽  
Vol 129 (6) ◽  
pp. 749-755 ◽  
Author(s):  
R. McCarty ◽  
K. P. Hallinan ◽  
B. Sanders ◽  
T. Somphone
Keyword(s):  
Heat Flow ◽  
Energy Recovery ◽  
Waste Heat ◽  
Temperature Drop ◽  
Source Temperature ◽  
Physical Conditions ◽  
Thermal Switch ◽  
Thermoelectric Energy ◽  
In Series ◽  
Flow Through

Recent improvements in thermoelectric (TE) materials have expanded the potential to use this technology to generate electricity from waste heat in a variety of applications. The performance of a TE generator improves when the temperature difference across the generator is as large as possible given the constraints associated with its application. This paper considers the use of a “thermal switch,” located physically between the heat source and the TE device, to modulate the heat flow through the TE device. A control schema is envisioned which permits heat to flow from the source to the TE device only when the source temperature is near maximum, yielding a higher time-averaged temperature drop across the TE and therefore a higher efficiency. A numerical model is used to evaluate the benefits of an active thermal switch in series with a TE generator relative to a baseline case defined by the absence of a thermal switch for both time-varying and constant heat inputs. The results demonstrate that modulating the heat flow through the TE device and maintaining the source temperature at a near constant maximal value is capable of improving the time-averaged TE device energy recovery efficiency. For some conditions, improved efficiencies of more than five times are realized. The requisite physical conditions necessary for achieving these improvements are also identified.

Enhancing Thermoelectric Energy Recovery Via Modulations of Source Temperature for Cyclical Heat Loadings

2005 ◽  
Author(s):  
R. McCarty ◽  
K. P. Hallinan ◽  
B. Sanders ◽  
T. Somphone
Keyword(s):  
Energy Recovery ◽  
Waste Heat ◽  
Equivalent Model ◽  
Thermoelectric Device ◽  
Thermoelectric Efficiency ◽  
Source Temperature ◽  
Thermal Switch ◽  
Thermoelectric Energy ◽  
Recovery System ◽  
Heat Loading

Very recent thermoelectric (TE) device materials improvements have pushed this technology to the cusp of usefulness in converting waste heat to electricity in a variety of applications — from automotive to aerospace. For applications where the heat loading is cyclical or non-constant, the effect of active control to maintain the source temperature at or near the peak allowable temperature while maximizing the temperature difference across a TE temporally on the overall thermoelectric efficiency is investigated. Efficiencies for constant heat loading applications that are not at near peak allowable temperatures are also investigated. The modulation of the source temperature would be achieved through the use of a ‘thermal switch’ or ‘active thermal potentiometer’ between the heat source and the thermoelectric device. Two methods are used to model the thermoelectric energy recovery system. First, an RC equivalent model is used to define the controlling factors for efficiency on a first order basis. Second, a numerical model is created to investigate the system in more detail. Both models demonstrate that maximizing the exergy of the source by maximizing its temperature during off-peak heat loadings is capable of improving the time-averaged efficiency of a thermoelectric device. For some conditions, improved time averaged efficiencies of more than 4 times are realized. Criteria defining the operation space where efficiency improvements are realized are also developed.

Thermoelectric Energy Recovery From Power Amplifier Transistors

2010 ◽  
Author(s):  
Kyoung Joon Kim
Keyword(s):  
Power Generation ◽  
Power Amplifier ◽  
Energy Recovery ◽  
Waste Heat ◽  
Electrical Energy ◽  
Load Resistance ◽  
Heat Flows ◽  
Thermoelectric Energy ◽  
Term Performance ◽  
Fully Coupled

A thermoelectric energy recovery module (TERM) is proposed. The TERM seeks to generate electrical energy from waste heat of power amplifier transistors. The TERM consists of a thermoelectric generator (TEG), a heat spreader, and a heat sink. A fully-coupled thermoelectric (TE) model of the TERM is developed to predict the power generation and the thermal performance of the TERM. A first order prototype of the TERM and a measurement setup are constructed to demonstrate the TERM performance. Power generation values and junction temperatures of a heat source are measured at various source heat flows. The measured results are used to verify the predicted results and to demonstrate the TERM performance. Load resistance effects to the TERM performance are also investigated utilizing the TE model and the measurement setup.

Study on Energy Recovery from Waste Heat in Solar Array Panel Using Thermoelectric Generating Modules

2020 ◽  
Vol 68 (2) ◽  
pp. 65-71
Author(s):  
Kazushi Sekine ◽  
Kazunori Takagaki ◽  
Masahiro Miyashita ◽  
Takayuki Morioka
Keyword(s):  
Energy Recovery ◽  
Waste Heat ◽  
Solar Array

Comparison of Aerobic and Anoxic-Aerobic Digestion of Waste Activated Sludge

1985 ◽  
Vol 17 (8) ◽  
pp. 1475-1478 ◽  
Author(s):  
A P. C. Warner ◽  
G. A. Ekama ◽  
G v. R. Marais
Keyword(s):  
Experimental Data ◽  
Activated Sludge ◽  
Waste Activated Sludge ◽  
Activated Sludge Process ◽  
Cycle Times ◽  
Waste Sludge ◽  
Volatile Solids ◽  
In Series ◽  
Flow Through ◽  
Theoretical Simulations

The laboratory scale experimental investigation comprised a 6 day sludge age activated sludge process, the waste sludge of which was fed to a number of digesters operated as follows: single reactor flow through digesters at 4 or 6 days sludge age, under aerobic and anoxic-aerobic conditions (with 1,5 and 4 h cycle times) and 3-in-series flow through aerobic digesters each at 4 days sludge age; all digesters were fed draw-and-fill wise once per day. The general kinetic model for the aerobic activated sludge process set out by Dold et al., (1980) and extended to the anoxic-aerobic process by van Haandel et al., (1981) simulated accurately all the experimental data (Figs 1 to 4) without the need for adjusting the kinetic constants. Both theoretical simulations and experimental data indicate that (i) the rate of volatile solids destruction is not affected by the incorporation of anoxic cycles and (ii) the specific denitrification rate is independent of sludge age and is K4T = 0,046(l,029)(T-20) mgNO3-N/(mg active VSS. d) i.e. about 2/3 of that in the secondary anoxic of the single sludge activated sludge stystem. An important consequence of (i) and (ii) above is that denitrification can be integrated easily in the steady state digester model of Marais and Ekama (1976) and used for design (Warner et al., 1983).

scholarly journals Determining the heat flow through the cabinet walls of household refrigerating appliances

2021 ◽  
Vol 121 ◽  
pp. 235-242
Author(s):  
Andreas Paul ◽  
Elmar Baumhögger ◽  
Andreas Elsner ◽  
Lukas Moczarski ◽  
Michael Reineke ◽  
...  
Keyword(s):  
Heat Flow ◽  
Flow Through
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