Leveraging the entropy generation minimization and designed porous media for the optimization of heat sinks employed in low-grade waste heat harvesting

2021 ◽  
Vol 181 ◽  
pp. 121850
Author(s):  
Kleber Marques Lisboa ◽  
José Luiz Zanon Zotin ◽  
Carolina P. Naveira-Cotta ◽  
Renato Machado Cotta
Keyword(s):  
Porous Media ◽  
Entropy Generation ◽  
Waste Heat ◽  
Heat Sinks ◽  
Low Grade ◽  
Entropy Generation Minimization ◽  
Waste Heat Harvesting

Design of a Multifunctional Aircraft Skin With Energy Harvesting via Entropy Generation Minimization

Aerospace ◽  
2006 ◽  
Author(s):  
K. Ahlers ◽  
K. P. Hallinan ◽  
B. Sanders ◽  
R. McCarty
Keyword(s):  
Energy Harvesting ◽  
Entropy Generation ◽  
Waste Heat ◽  
Skin Layer ◽  
Skin Thickness ◽  
Power Devices ◽  
Volume Fractions ◽  
Entropy Generation Minimization ◽  
The Matrix ◽  
Aircraft Skin

The Entropy Generation Minimization (EGM) approach is applied to the design of a new integrated radar aircraft skin, which both meets requisite aircraft structural needs and provides a pathway for the waste heat from structurally integrated power devices. Thermoelectric (TE) devices, sandwiched between a heterogeneous skin layer and the radar devices for the purpose of harvesting waste heat rejected to the ambient, are considered in the analysis. A heterogeneous skin layer is designed using the EGM approach, which is then applied to the overall mission of the aircraft to determine the optimal skin thickness and volume fractions of the matrix and inclusions in the composite skin.

Optimization of Pin-Fin Heat Sinks in Bypass Flow Using Entropy Generation Minimization Method

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
W. A. Khan ◽  
J. R. Culham ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Entropy Generation ◽  
Heat Sink ◽  
Heat Sinks ◽  
Entropy Generation Rate ◽  
Bypass Flow ◽  
Minimization Method ◽  
Pin Fin ◽  
Entropy Generation Minimization

An entropy generation minimization method is applied to study the thermodynamic losses caused by heat transfer and pressure drop for the fluid in a cylindrical pin-fin heat sink and bypass flow regions. A general expression for the entropy generation rate is obtained by considering control volumes around the heat sink and bypass regions. The conservation equations for mass and energy with the entropy balance are applied in both regions. Inside the heat sink, analytical/empirical correlations are used for heat transfer coefficients and friction factors, where the reference velocity used in the Reynolds number and the pressure drop is based on the minimum free area available for the fluid flow. In bypass regions theoretical models, based on laws of conservation of mass, momentum, and energy, are used to predict flow velocity and pressure drop. Both in-line and staggered arrangements are studied and their relative performance is compared to the same thermal and hydraulic conditions. A parametric study is also performed to show the effects of bypass on the overall performance of heat sinks.

Exergy Analysis and Entropy Generation Minimization of Thermoelectric Waste Heat Recovery for Electronics

2011 ◽  
Author(s):  
Kazuaki Yazawa ◽  
Ali Shakouri
Keyword(s):  
Entropy Generation ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Electronic Systems ◽  
Maximum Output ◽  
Entropy Generation Minimization ◽  
Energy Payback

Energy recovery from waste heat is attracting more and more attention. All electronic systems consume electricity but only a fraction of it is used for information processing and for human interfaces, such as displays. Lots of energy is dissipated as heat. There are some discussions on waste heat recovery from the electronic systems such as laptop computers. However the efficiency of energy conversion for such utilization is not very attractive due to the maximum allowable temperature of the heat source devices. This leads to very low limits of Carnot efficiency. In contrast to thermodynamic heat engines, Brayton cycle, free piston Stirling engines, etc., authors previously reported that thermoelectric (TE) can be a cost-effective device if the TE and the heat sink are co-optimized, and if some parasitic effects could be reduced. Since the heat already exists and it is free, the additional cost and energy payback time are the key measures to evaluate the value of the energy recovery system. In this report, we will start with the optimum model of the TE power generation system. Then, theoretical maximum output, cost impact and energy payback are evaluated in the examples of electronics system. Entropy Generation Minimization (EGM) is a method already familiar in thermal management of electronics. The optimum thermoelectric waste heat recovery design is compared with the EGM approach. Exergy analysis evaluates the useful energy flow in the optimum TE system. This comprehensive analysis is used to predict the potential future impact of the TE material development, as the dimensionless figure-of-merit (ZT) is improved.

scholarly journals Ionic thermoelectric materials for waste heat harvesting

2020 ◽  
Author(s):  
Boxuan Yang ◽  
Giuseppe Portale
Keyword(s):  
Ionic Liquid ◽  
Thermoelectric Materials ◽  
Waste Heat ◽  
Conductive Polymer ◽  
Performance Comparison ◽  
Low Grade ◽  
Working Mechanism ◽  
New Class ◽  
Potential Applications ◽  
Waste Heat Harvesting

AbstractIonic thermoelectric polymers are a new class of materials with great potential for use in low-grade waste heat harvesting and the field has seen much progress during the recent years. In this work, we briefly review the working mechanism of such materials, the main advances in the field and the main criteria for performance comparison. We examine two types of polymer-based ionic thermoelectric materials: ionic conductive polymer and ionogels. Moreover, as a comparison, we also examine the more conventional ionic liquid electrolytes. Their performance, possible directions of improvements and potential applications have been evaluated.

scholarly journals Entropy and Entransy Dissipation Analysis of a Basic Organic Rankine Cycles (ORCs) to Recover Low-Grade Waste Heat Using Mixture Working Fluids

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 818 ◽  
Author(s):  
Yong-qiang Feng ◽  
Qian-hao Luo ◽  
Qian Wang ◽  
Shuang Wang ◽  
Zhi-xia He ◽  
...  
Keyword(s):  
Entropy Generation ◽  
Mass Fraction ◽  
Waste Heat ◽  
Low Grade ◽  
Outlet Temperature ◽  
Entransy Dissipation ◽  
Minimum Entropy ◽  
Pinch Point ◽  
Working Fluids ◽  
Condenser Temperature

Mixture working fluids can reduce effectively energy loss at heat sources and heat sinks, and therefore enhance the organic Rankine cycle (ORC) performance. The entropy and entransy dissipation analyses of a basic ORC system to recover low-grade waste heat using three mixture working fluids (R245fa/R227ea, R245fa/R152a and R245fa/pentane) have been investigated in this study. The basic ORC includes four components: an expander, a condenser, a pump and an evaporator. The heat source temperature is 120 °C while the condenser temperature is 20 °C. The effects of four operating parameters (evaporator outlet temperature, condenser temperature, pinch point temperature difference, degree of superheat), as well as the mass fraction, on entransy dissipation and entropy generation were examined. Results demonstrated that the entransy dissipation is insensitive to the mass fraction of R245fa. The entropy generation distributions at the evaporator for R245/pentane, R245fa/R152a and R245fa/R227ea are in ranges of 66–74%, 68–80% and 66–75%, respectively, with the corresponding entropy generation at the condenser ranges of 13–21%, 4–17% and 11–21%, respectively, while those at the expander for R245/pentane, R245fa/R152a and R245fa/R227ea are approaching 13%, 15% and 14%, respectively. The optimal mass fraction of R245fa for the minimum entropy generation is 0.6 using R245fa/R152a.

Design Methodology for Branching Fluid Network Heat Sinks

2006 ◽  
Author(s):  
R. M. Moreno ◽  
Y.-X. Tao
Keyword(s):  
Entropy Generation ◽  
Design Methodology ◽  
Heat Sinks ◽  
Constructal Theory ◽  
Pumping Power ◽  
Thermal Systems ◽  
Entropy Generation Minimization ◽  
Fluid Network ◽  
Fluid Networks

In this paper recent works from the areas of entropy generation minimization and constructal theory are extended and combined with previous works from the area of physiological transport geometry prediction. From this a design methodology is developed which can be applied to branching fluid networks having the objective of maximizing the removal of heat from a given volume while minimizing the pumping power required. The methods are essentially a set of equations that serve as a resource for designers incorporating branching fluid networks as components within fluid-thermal systems that have the goal of transferring and remove heat while minimizing the entropy generation or destruction of available work.

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