scholarly journals Optimization of Thermoelectric Performance of Offset-strip Fin Type Exhaust Heat Exchanger

2021 ◽  
Vol 57 (6) ◽  
pp. 184
Keyword(s):  
Heat Exchanger ◽  
Thermoelectric Performance ◽  
Exhaust Heat ◽  
Offset Strip Fin

A Variable-Curvature Spiral-Coil Heat Exchanger for Automobile Exhaust Heat Recovery

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Yu Zhu ◽  
Fengye Yang ◽  
Yueguang Guo
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Recovery ◽  
Heat Transfer Performance ◽  
Cone Angle ◽  
Spiral Coil ◽  
Variable Curvature ◽  
Exhaust Heat ◽  
Coil Heat Exchanger ◽  
Coil Heat

Abstract To improve the fuel efficiency of automobile engines and reduce pollution owing to automobile exhaust, this study discusses a fixed-curvature spiral-coil heat exchanger that recovers exhaust heat. Herein, the heat transfer performance of the spiral coil is studied via experimental testing and numerical simulation. In this study, a new type of variable-curvature spiral coil is designed to improve the efficiency of the heat exchanger. The effect of different conical angles on the resistance and heat transfer performance of the spiral coil within a range of Reynolds numbers of 4000–14,000 was analyzed. The heat exchange efficiency is a combination of the convective heat transfer and the overall heat recovery. The results of this study indicate that for a spiral-coil tube of length L, increasing the cone angle improves the convective heat transfer outside the tube. However, as the flow resistance increases, the exhaust heat recovery of a variable-curvature spiral-coil heat exchanger (VSE) is up to 18.8% higher than that of a constant curvature spiral-coil heat exchanger. The combined performance of VSE is excellent when the cone angle is 15 deg.

The Potential Danger of Fire in Gas Turbine Heat Exchangers

1969 ◽  
Author(s):  
C. F. McDonald
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Engine Operation ◽  
Exhaust Heat ◽  
The Subject ◽  
Gas Turbine Cycle

Increased emphasis is being placed on the regenerative gas turbine cycle, and the utilization of waste heat recovery systems, for improved thermal efficiency. For such systems there are modes of engine operation, where it is possible for a metal fire to occur in the exhaust heat exchanger. This paper is intended as an introduction to the subject, more from an engineering, than metallurgical standpoint, and includes a description of a series of simple tests to acquire an understanding of the problem for a particular application. Some engine operational procedures, and design features, aimed at minimizing the costly and dangerous occurrence of gas turbine heat exchanger fires, are briefly mentioned.

Thermal Optimization of Exhaust-Based Thermoelectric Generator

2013 ◽  
Vol 743-744 ◽  
pp. 88-93 ◽  
Author(s):  
Ya Dong Deng ◽  
Shan Chen ◽  
Xun Liu
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
High Performance ◽  
Thermoelectric Generator ◽  
Thermal Characteristics ◽  
Interface Temperature ◽  
Cfd Simulations ◽  
Exhaust Heat ◽  
Internal Structures ◽  
Plate Shape

The potential for automotive exhaust heat based thermoelectric generator (TEG) has been increased with continuously advances in thermoelectric technology. The thermal performance of the heat exchanger in exhaust-based TEG was analyzed. In terms of interface temperature and thermal uniformity, the thermal characteristics of the heat exchangers with different internal structures, materials and thicknesses were discussed. CFD simulations and infrared experiments on a high-performance production engine with a dynamometer were carried out. It was proved that the plate-shape heat exchanger made of brass with internal baffles and the thickness of 3mm, obtained a relatively optimal thermal performance, and it will help to improve the thermal performance of the TEG.

Exhaust Heat Recovery Unit Equipped With Nanofluid and Helical Tapes, a Solution for Cleaner Energy Production

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
M. Sheikholeslami ◽  
A. Arabkoohsar ◽  
M. Jafaryar
Keyword(s):  
Nusselt Number ◽  
Heat Exchanger ◽  
Environmental Impacts ◽  
Flue Gas ◽  
Heat Recovery ◽  
Internal Combustion Engines ◽  
Waste Heat ◽  
Physical Parameters ◽  
Twisted Tape ◽  
Exhaust Heat

Abstract In internal combustion engines (ICE), a major part of the generated energy via burning the fuel is wasted. The cooling fluid controlling the temperature, the reclaimed hot gases for reducing the environmental impacts, and the hot combustion productions leaving the engine from the exhaust are the main origins of energy waste in such a machine. Waste heat recovery and flue gas condensation are the methods by which the overall efficiency of a thermal engine is enhanced, and its environmental impacts are mitigated. In this paper, the utilization of the exhaust waste energy of ICE by using a heat exchanger with nanofluid and helical tape, in order to augment the thermal performance of the engine and reduce its environmental impact, is investigated numerically. In this heat exchanger, the flue gas of the engine at high temperature and H2O-CuO nanofluid are considered as the primary and secondary working fluids, and the twisted tape makes the flow further disturbed so that a larger overall heat transfer coefficient is obtained. The finite volume method has been applied to scrutinize the impacts of Reynolds number as well as the twisting-tape turns number on the operation and performance of the tube. As such, suitable correlations for the prediction of some of the thermos-physical parameters of the problem (such as Nusselt number and Darcy factor) are extracted regarding the obtained data. The results of the study reveal that Nusselt number is higher for larger numbers of the tape turn and higher Reynolds numbers, while a lower friction factor is achieved as the number of the turns is reduced.

Heat Transfer and Pressure Drop Investigations of the Compact Exhaust Heat Exchanger With Twisted Tape Inserts for Automotive Waste Heat Utilization

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Dhruv Raj Karana ◽  
Rashmi Rekha Sahoo
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Internal Heat ◽  
Decisive Role ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Exhaust Heat

Abstract Thermoelectric-based waste heat recovery is a competent technique to reduce the exhaust emissions and fuel consumption of automobiles. Thermal and hydraulic characteristics of the exhaust heat exchanger plays a decisive role in the extent of waste heat recovery from the exhaust gas. In this study, the exhaust heat exchanger having twisted tape inserts is proposed to increase the internal heat transfer coefficient. The dimensionless Nusselt number and friction factor were evaluated experimentally for different designs of the twisted tapes. The experiments were performed for the Reynolds number in the range 2300–25000. The considered geometric parameters of the twisted rib explored were the pitch fraction, twist fraction, and slope. The obtained results were compared to reveal the best feasible design of the twisted tape. The maximum net thermohydraulic efficiency factor achieved for the system in the present analysis is 1.93. With the use of twisted tapes, the area of the exhaust heat exchanger can be greatly reduced for the same power output as flat geometry. This would help for the integration of the waste heat recovery with the engine, where the space available is very limited.

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