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.

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.

Theoretical and experimental investigation of an organic Rankine cycle for a waste heat recovery system

2009 ◽  
Vol 223 (5) ◽  
pp. 523-533 ◽  
Author(s):  
W Gu ◽  
Y Weng ◽  
Y Wang ◽  
B Zheng
Keyword(s):  
Heat Source ◽  
Entropy Generation ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Entropy Generation Rate ◽  
Working Fluid ◽  
Total Entropy ◽  
Waste Heat Recovery System ◽  
Cycle Efficiency

This article describes and evaluates an organic Rankine cycle (ORC) for a waste heat recovery system by both theoretical and experimental studies. Theoretical analysis of several working fluids shows that cycle efficiency is very sensitive to evaporating pressure, but insensitive to expander inlet temperature. Second law analysis was carried out using R600a as a working fluid and a flow of hot air as a heat source, which is not isothermal, along the evaporator. The result discloses that the evaporator's internal and external entropy generation is the main source of total entropy generation. The effect of the heat source temperature, evaporating pressure, and evaporator size on the entropy generation rate is also presented. The obtained useful power is directly linked to the total entropy generation rate according to the Gouy—Stodola theorem. The ORC testing system was established and operated using R600a as a working fluid and hot water as a heat source. The maximum cycle efficiency of the testing system is 5.2 per cent, and the testing result also proves that cycle efficiency is insensitive to heat source temperature, but sensitive to evaporating pressure. The entropy result also shows that internal and external entropy of the evaporator is the main source of total entropy generation.

Entropy Generation Minimization in a Tubular Solid Oxide Fuel Cell

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Entropy Generation ◽  
Energy Equation ◽  
Solid Oxide ◽  
Geometrical Parameters ◽  
Oxide Fuel ◽  
Cell Geometry ◽  
Cell Efficiency ◽  
Entropy Generation Minimization

The aim of the paper is to investigate possible design modifications in tubular solid oxide fuel cell geometry to increase its performance. The analysis of the cell performances is conducted on the basis of the entropy generation. The use of this technique makes it possible to identify the phenomena provoking the main irreversibilities, understand their causes and propose changes in the system design and operation. The different contributions to the entropy generation are analyzed in order to develop new geometries that increase the fuel cell efficiency. To achieve this purpose, a CFD model of the cell is used. The model includes energy equation, fluid dynamics in the channels and in porous media, current transfer, chemical reactions, and electrochemistry. The geometrical parameters of the fuel cell are modified to minimize the overall entropy generation.

Experimental Research of Energy Harvesting and Storage Based on Ferroelectric Materials

2012 ◽  
Vol 476-478 ◽  
pp. 1336-1340
Author(s):  
Kai Feng Li ◽  
Rong Liu ◽  
Lin Xiang Wang
Keyword(s):  
Energy Harvesting ◽  
Electromagnetic Waves ◽  
Vibrational Energy ◽  
Waste Heat ◽  
Mechanical Strain ◽  
Electrical Potential ◽  
Electrical Energy ◽  
Ferroelectric Materials ◽  
Energy Scavenging ◽  
And Storage

The concept of energy harvesting works towards developing self-powered devices that do not require replaceable power supplies. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. A number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy. While each of these sources of energy can be effectively used to power remote sensors, the structural and biological communities have placed an emphasis on scavenging vibrational energy with ferroelectric materials. Ferroelectric materials have a crystalline structure that provide a unique ability to convert an applied electrical potential into a mechanical strain or vice versa. Based on the properties of the material, this paper investigates the technique of power harvesting and storage.

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