CFD-Simulation of Oscillatory Flow Around the Heat Exchangers of Thermoacoustic Devices

2014 ◽  
Author(s):  
Olusegun M. Ilori ◽  
Xiaoan Mao ◽  
Artur J. Jaworski
Keyword(s):  
Heat Exchangers ◽  
Oscillatory Flow ◽  
Cfd Simulation ◽  
Waste Heat ◽  
Oil And Gas Industry ◽  
Cooling Power ◽  
Maximum Pressure ◽  
Curvature Radius ◽  
Computational Domain ◽  
Pressure Amplitude

Thermoacoustic systems rely on conversion between thermal and acoustic (i.e. mechanical) forms of energy. The technology lends itself to various applications such as waste heat recovery to produce useful electricity or cooling power or gas liquefaction and regasification in oil and gas industry. Detailed understanding of the fluid flow processes within the internal structures of thermoacoustic systems, especially the heat exchangers, is seen as one of the ways by which the performance of next generation of thermoacoustic systems can be improved. The current study uses 2-D computational fluid dynamics (CFD) model to perform numerical investigations of thermoacoustic heat exchangers placed in an oscillatory flow induced by a standing wave. The computational domain is chosen from a thermoacoustic rig that is built for characterisation of heat exchangers for thermoacoustic applications. Validation of the present numerical approach is first established. Then the numerical analysis is extended by modifying the geometrical and operating parameters. The geometrical parameter considered is the curvature radius of the aerodynamic shapes attached to the entrance and exit of gas channels of the heat exchangers, mainly to modify the flow characteristics. Cases are run for the drive ratios (i.e. the ratio of maximum pressure amplitude to the mean pressure) ranging from 0.3–3.0%. Turbulent model as suitable for thermoacoustic analysis is selected from the literature. Results are discussed based on velocity profiles and the pressure difference obtained as functions of phase angles in the acoustic flow cycle.

Numerical Study of Multistage Serial and Parallel Configurations of Thermoacoustic Engines

2016 ◽  
Vol 8 (2) ◽  
Author(s):  
Adnan Poshtkouhian Badi ◽  
Hamid Beheshti
Keyword(s):  
Fluid Dynamics ◽  
Low Temperature ◽  
Cfd Simulation ◽  
Waste Heat ◽  
Numerical Study ◽  
Initial Pressure ◽  
Heat Pumps ◽  
Published Data ◽  
Pressure Amplitude ◽  
Thermoacoustic Engines

The focus of this study is on serial and parallel configurations of a multistage thermoacoustic engines (TAE). Thermoacoustics integrates fluid dynamics, thermodynamics, and acoustics to explain the interactions existing between heat and sound. Considerable amounts of waste heat are released to the environment in everyday industrial processes. This waste heat cannot be reused due to its low temperature. One way for reusing some of this waste heat is to employ a thermoacoustic heat pump. TAEs can be driven by waste heat and are capable of supplying the power to drive the thermoacoustic heat pumps. However, due to the low temperature of this waste heat, single-stage TAEs cannot provide the required temperature lifts. Multistage TAEs are advantageous because they can provide sufficient temperature lifts. In this study, a computational fluid dynamics (CFD) simulation is carried out to understand the conversion process of heat to sound and study the nonlinear conjugation of unsteady heat release and acoustic disturbances. The two main parameters evaluated in this simulation are the initial pressure disturbance and the stack's temperature gradient. Their effects on actuating limit cycle oscillations are examined in a 2D numerical model. The numerical simulation results indicate that the pressure amplitude varies through alteration made in these mentioned parameters. The present numerical results are validated by previously published data.

scholarly journals Assessment of Aircraft Surface Heat Exchanger Potential

Aerospace ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 1 ◽  
Author(s):  
Hagen Kellermann ◽  
Anaïs Luisa Habermann ◽  
Mirko Hornung
Keyword(s):  
Heat Exchangers ◽  
Electric Propulsion ◽  
Waste Heat ◽  
Surface Heat ◽  
Cooling Power ◽  
Surface Cooling ◽  
Clear Trend ◽  
Order Of Magnitude ◽  
Hybrid Electric ◽  
The Impact

Providing sufficient cooling power for an aircraft will become increasingly challenging with the introduction of (hybrid-) electric propulsion. To avoid excessive drag from heat exchangers, the heat sink potential of the aircraft surface is evaluated in this study. Semi-empirical correlations are used to estimate aircraft surface area and heat transfer. The impact of surface heating on aircraft drag is qualitatively assessed. Locating surface heat exchangers where fully turbulent flow is present promises a decrease in aircraft drag. Surface cooling potential is investigated over a range from small regional aircraft to large wide body jets and a range of surface temperatures. Four mission points are considered: Take-off, hot day take-off, climb and cruise. The results show that surface heat exchangers can provide cooling power in the same order of magnitude as the waste heat expected from (hybrid-) electric drive trains for all sizes of considered aircraft. Also, a clear trend favouring smaller aircraft with regards to the ratio of available to required cooling power is visible.

scholarly journals A Three-Dimensional Numerical and Multi-Objective Optimal Design of Wavy Plate-Fins Heat Exchangers

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao
Keyword(s):  
Heat Exchangers ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Basis Functions ◽  
Approximation Model ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Multi Objective Genetic Algorithm ◽  
Colburn Factor ◽  
Heat Exchange Efficiency

This paper presents a method for optimizing wavy plate-fin heat exchangers accurately and efficiently. It combines CFD simulation, Radical Basis Functions (RBF) with multi-objective optimization to improve the performance. The optimization of the Colburn factor j and the friction coefficient f is regarded as a multi-objective optimization problem, due to the existence of two contradictory goals. The approximation model was obtained by Radical Basis Functions, and the shape of the heat exchanger was optimized by multi-objective genetic algorithm (MOGA). The optimization results showed that j increased by 17.62% and f decreased by 20.76%, indicating that the heat exchange efficiency was significantly enhanced and the fluid structure resistance reduced. Then, from the aspects of field synergy and tubulence energy, the performance advantage of the optimized structure was further confirmed.

scholarly journals Efficient storage and recovery of waste heat by phase change material embedded within additively manufactured grid heat exchangers

2021 ◽  
Vol 181 ◽  
pp. 121846
Author(s):  
Maryam Roza Yazdani ◽  
Alpo Laitinen ◽  
Valtteri Helaakoski ◽  
Lorant Katona Farnas ◽  
Kirsi Kukko ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Heat Exchangers ◽  
Waste Heat ◽  
Efficient Storage ◽  
Change Material

Development of Heat Exchanger Fouling Model and Preventive Maintenance Diagnostic Tool

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
H. Zabiri ◽  
V. R. Radhakrishnan ◽  
M. Ramasamy ◽  
N. M. Ramli ◽  
V. Do Thanh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Predictive Model ◽  
Diagnostic Tool ◽  
Preventive Maintenance ◽  
Heat Exchangers ◽  
Waste Heat ◽  
A Priori ◽  
Transfer Efficiency ◽  
Heat Transfer Efficiency

The Crude Preheat Train (CPT) is a set of large heat exchangers which recover the waste heat from product streams back to preheat the crude oil. The overall heat transfer coefficient in these heat exchangers may be significantly reduced due to fouling. One of the major impacts of fouling in CPT operation is the reduced heat transfer efficiency. The objective of this paper is to develop a predictive model using statistical methods which can a priori predict the rate of the fouling and the decrease in heat transfer efficiency in a heat exchanger in a crude preheat train. This predictive model will then be integrated into a preventive maintenance diagnostic tool to plan the cleaning of the heat exchanger to remove the fouling and bring back the heat exchanger efficiency to their peak values. The fouling model was developed using historical plant operating data and is based on Neural Network. Results show that the predictive model is able to predict the shell and tube outlet temperatures with excellent accuracy, where the Root Mean Square Error (RMSE) obtained is less than 1%, correlation coefficient R2 of approximately 0.98 and Correct Directional Change (CDC) values of more than 90%. A preliminary case study shows promising indication that the predictive model may be integrated into a preventive maintenance scheduling for the heat exchanger cleaning.

scholarly journals PROTECTION AGAINST CORROSION OF THE TECHNOLOGICAL EQUIPMENT OF THE OIL REFINING ENTERPRISE

2020 ◽  
Vol 2020 (1) ◽  
pp. 23-24
Author(s):  
Vladislav Bichevin ◽  
Nina Sosnovskaya
Keyword(s):  
Heat Exchangers ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Oil Refining ◽  
Heat Recovery Boiler ◽  
Technological Equipment ◽  
Slowing Down ◽  
Process Heat ◽  
Recovery Boiler

A method for slowing down the corrosion of heat exchangers in the T-104 and T102 heat recovery boiler blocks is considered. PK-1 Aminate was selected as the most suitable inhibitor for process heat exchangers of the waste heat recovery boiler unit

Resonator Optimization and Studying the Effect of Drive Ratio on the Theoretical Performance of a 10-W Cooling Power Thermoacoustic Refrigerator

2015 ◽  
Vol 23 (03) ◽  
pp. 1550020 ◽  
Author(s):  
B. G. Prashantha ◽  
M. S. Govinde Gowda ◽  
S. Seetharamu ◽  
G. S. V. L. Narasimham
Keyword(s):  
Dynamic Pressure ◽  
Optimization Procedure ◽  
Cooling Power ◽  
Pressure Amplitude ◽  
Performance Simulation ◽  
Resonator Design ◽  
Working Principle ◽  
Simulation Results ◽  
Theoretical Performance ◽  
Thermoacoustic Refrigerator

This paper deals with the basic insight of thermoacoustic refrigeration concepts, and the working principle, history and the role of linear thermoacoustic theory in designing a thermoacoustic refrigerator system are discussed. Resonator design optimization procedure for a 10W cooling power thermoacoustic refrigerators is discussed. The optimized resonator designs proposed in this paper are found to be efficient compared to published resonator designs. The effects of drive ratio on the theoretical performance by varying dynamic pressure amplitude from 0.2 bar to 0.4 bar in the steps of 0.05 bar on the optimized resonator designs are discussed. Performance simulation results for the optimized resonator designs using DeltaEC software are discussed. Simulation results are in agreement with theoretical results.

Sign in / Sign up

Export Citation Format

Share Document