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 Energy and Exergy Analysis of Different Exhaust Waste Heat Recovery Systems for Natural Gas Engine Based on ORC

2019 ◽  
Author(s):  
Guillermo Valencia ◽  
Armando Fontalvo ◽  
Yulineth Cardenas ◽  
Jorge Duarte ◽  
Cesar Isaza
Keyword(s):  
Natural Gas ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Natural Gas Engine ◽  
Exhaust Waste Heat ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Net Power Output

One way to increase overall natural gas engine efficiency is to transform exhaust waste heat into useful energy by means of a bottoming cycle. Organic Rankine cycle (ORC) is a promising technology to convert medium and low grade waste heat into mechanical power and electricity. This paper presents an energy and exergy analysis of three ORC-Waste heat recovery configurations by using an intermediate thermal oil circuit: Simple ORC (SORC), ORC with Recuperator (RORC) and ORC with Double Pressure (DORC), and Cyclohexane, Toluene and Acetone have been proposed as working fluids. An energy and exergy thermodynamic model is proposed to evaluate each configuration performance, while available exhaust thermal energy variation under different engine loads was determined through an experimentally validated mathematical model. Additionally, the effect of evaportating pressure on net power output , absolute thermal efficiency increase, absolute specific fuel consumption decrease, overall energy conversion efficiency, and component exergy destruction is also investigated. Results evidence an improvement in operational performance for heat recovery through RORC with Toluene at an evaporation pressure of 3.4 MPa, achieving 146.25 kW of net power output, 11.58% of overall conversion efficiency, 28.4% of ORC thermal efficiency, and an specific fuel consumption reduction of 7.67% at a 1482 rpm engine speed, a 120.2 L/min natural gas Flow, 1.784 lambda, and 1758.77 kW mechanical engine power.

scholarly journals Exergy analysis of the Szewalski cycle with a waste heat recovery system

2015 ◽  
Vol 36 (3) ◽  
pp. 25-48 ◽  
Author(s):  
Tomasz Kowalczyk ◽  
Paweł Ziółkowski ◽  
Janusz Badur
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Reference Conditions ◽  
Heat Rate ◽  
Working Fluid ◽  
Regeneration System ◽  
Waste Heat Recovery System

Abstract The conversion of a waste heat energy to electricity is now becoming one of the key points to improve the energy efficiency in a process engineering. However, large losses of a low-temperature thermal energy are also present in power engineering. One of such sources of waste heat in power plants are exhaust gases at the outlet of boilers. Through usage of a waste heat regeneration system it is possible to attain a heat rate of approximately 200 MWth, under about 90 °C, for a supercritical power block of 900 MWel fuelled by a lignite. In the article, we propose to use the waste heat to improve thermal efficiency of the Szewalski binary vapour cycle. The Szewalski binary vapour cycle provides steam as the working fluid in a high temperature part of the cycle, while another fluid – organic working fluid – as the working substance substituting conventional steam over the temperature range represented by the low pressure steam expansion. In order to define in detail the efficiency of energy conversion at various stages of the proposed cycle the exergy analysis was performed. The steam cycle for reference conditions, the Szewalski binary vapour cycle as well as the Szewalski hierarchic vapour cycle cooperating with a system of waste heat recovery have been comprised.

RACER Conceptual Design

1983 ◽  
Vol 105 (3) ◽  
pp. 621-626 ◽  
Author(s):  
J. T. Halkola ◽  
A. H. Campbell ◽  
D. Jung
Keyword(s):  
Gas Turbines ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Fuel Saving ◽  
Fuel Savings ◽  
Waste Heat Recovery System ◽  
Recovery System

The Rankine Cycle Energy Recovery (or RACER) is an unfired waste heat recovery system designed for use aboard U.S. Navy gas turbine powered ships. The system converts waste heat from the exhaust of the main propulsion gas turbines into useful shaft horsepower and is currently planned for installation aboard the new DDG-51 class of ships. The design philosophy used in determining an overall system concept to minimize manning yet maximize availability, reliability and fuel savings is discussed. The paper also describes the trade-off analyses made to size the system in relation to overall fuel saving and gives a brief summary of the test programs to verify the system prior to ship installation.

scholarly journals Design and Simulation of a Waste Heat Recovery System for a Cement Manufacturing Process

2021 ◽  
Vol 23 (06) ◽  
pp. 1092-1101
Author(s):  
Tharun Sivakumar ◽  
Keyword(s):  
Energy Efficiency ◽  
Manufacturing Process ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Successful Implementation ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Heat Recovery System

As the ever-changing world continues to desperately look for alternative energy sources in the midst of an energy crisis, new technologies to recover power are revealing themselves and being implemented all across the globe. Most power plants are looking for more sustainable sources of energy over the long term. One such technology being adopted now by a lot of enterprises are Energy Recovery Systems. These systems work to retain and reuse energy that would otherwise be lost to the atmosphere after a certain process. They are sustainable and require comparatively lower capital. The objectives of this project revolve around the modelling of a Waste Heat Recovery System (WHRS) for a heat-intensive manufacturing process. The heat, which would otherwise be lost to the atmosphere, is trapped and converted by a heat recovery unit into reusable energy. The main principle on which such a system would operate is The Rankine Cycle, an idealized thermodynamic cycle. Successful implementation of such an energy recovery system would not just boost energy efficiency but also reduce operational costs. The modeling and simulation of the heat recovery system are done on an open-source chemical process flow software known as DWSIM. An analysis of this heat recovery model shows an increase of 19.66% in the energy efficiency of the manufacturing process. Heat recovery systems also have great benefits for the environment, as they reduce the emissions of greenhouse gases by such manufacturing plants and help reduce global warming.

Sign in / Sign up

Export Citation Format

Share Document