Derivation of an Anisotropic Model for the Pressure Loss Through a Heat Exchanger for Aero Engine Applications

2009 ◽  
Author(s):  
Kyros Yakinthos ◽  
Stefan Donnerhack ◽  
Dimitrios Missirlis ◽  
Olivier Seite ◽  
Paul Storm
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Pressure Loss ◽  
Pollutant Emissions ◽  
Experimental Measurements ◽  
Loss Model ◽  
Aero Engine ◽  
Porosity Model

We present an effort to model the pressure loss together with the heat transfer mechanism, in a heat exchanger designed for an integrated recuperative aero engine. The operation of the heat exchanger is focusing on the exploitation of the thermal energy of the turbine exhaust gas to pre-heat the compressor outlet air before combustion and to decrease fuel consumption and pollutant emissions. Two basic parameters characterize the operation of the heat exchanger, the pressure loss and the heat transfer. The derivation of the pressure loss model is based on experimental measurements that have been carried-out on a heat exchanger model. The presence of the heat exchanger is modeled using the concept of a porous medium, in order to facilitate the computational modeling by means of CFD. As a result, inside the integrated aero engine, the operation of the heat exchanger can be sufficiently modeled as long as a generalized and accurate pressure drop and heat transfer model is developed. Hence, the porosity model formulation should be capable of properly describing the overall macroscopic hydraulic and thermal behavior of the heat exchanger. The effect of the presence of the heat exchanger on the flow field is estimated from experimental measurements. For the derivation of the porous medium pressure loss model, an anisotropic formulation of a modified Darcy-Forchheimer pressure drop law is proposed in order to take into account the effects of the three-dimensional flow development through the heat exchanger. The heat transfer effects are taken also into account with the use of a heat transfer coefficient correlation. The porosity model is adopted by the CFD solver as an additional source term. The validation of the proposed model is performed through CFD computations, by comparing the predicted pressure drop and heat transfer with available experimental measurements carried-out on the heat exchanger model.

Best Strategies for the Development of a Holistic Porosity Model of a Heat Exchanger for Aero Engine Applications

2015 ◽  
Author(s):  
K. Yakinthos ◽  
D. Misirlis ◽  
Z. Vlahostergios ◽  
M. Flouros ◽  
S. Donnerhack ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Pressure Loss ◽  
Engine Performance ◽  
Operational Parameters ◽  
Tubular Heat Exchanger ◽  
Tube Heat Exchanger ◽  
Aero Engine ◽  
Porosity Model

In an attempt to manage CFD computations in aero engine heat exchanger design, this work presents the best strategies and the methodology used to develop a holistic porosity model, describing the heat transfer and pressure drop behavior of a complex profiled tubular heat exchanger for aero engine applications. Due to the complexity of the profile tube heat exchanger geometry and the very large number of tubes, detailed CFD computations require very high CPU and memory resources. For this reason the complex heat exchanger geometry is replaced in the CFD computations by a simpler porous medium geometry with predefined pressure loss and heat transfer. The present work presents a strategy for developing a holistic porosity model adapted for heat exchangers, which is capable to describe their macroscopic heat transfer and pressure loss average performance. For the derivation of the appropriate pressure loss and heat transfer correlations, CFD computations and experimental measurements are combined. The developed porosity model is taking into consideration both streams of the heat exchanger (hot and cold side) in order to accurately calculate the inner and outer pressure losses, in relation to the achieved heat transfer and in conjunction with the selected heat exchanger geometry, weight and operational parameters. For the same heat exchanger, RAM and CPU requirement reductions were demonstrated for a characteristic flow passage of the heat exchanger, as the porosity model required more than 80 times less computational points than the detailed CFD model. The proposed porosity model can be adapted for recuperation systems with varying heat exchanger designs having different core arrangements and tubes sizes and configurations, providing an efficient tool for the optimization of the heat exchangers design and leading to an increase of the overall aero engine performance.

Modeling an Installation of Recuperative Heat Exchangers for an Aero Engine

2010 ◽  
Author(s):  
Dimitrios Missirlis ◽  
Kyros Yakinthos ◽  
Olivier Seite ◽  
Apostolos Goulas
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Thermodynamic Cycle ◽  
Experimental Measurements ◽  
Exhaust Gas ◽  
Cfd Model ◽  
Pressure Losses ◽  
Aero Engine ◽  
Porosity Model

This work presents the complete effort to model the presence of an integrated system of heat exchangers mounted in the exhaust nozzle of an aero engine which uses an alternative but more efficient thermodynamic cycle. The heat exchangers are operating as heat recuperators exploiting part of the thermal energy of the turbine exhaust gas to preheat the compressor outlet air before combustion and to reduce pollutants and fuel consumption. The presence of the heat exchangers enforces a significant pressure drop in the exhaust gas flow which can affect the overall efficiency of the thermodynamic cycle and the potential benefit of this technology. For this reason it is important to optimize the operation of the system of heat exchangers. The main target of this optimization effort is the minimization of the pressure losses for the same amount of heat transfer achieved. The optimization is performed with the combined use of experimental measurements and CFD methods. Since the CFD modeling is taking into consideration the overall geometry of the exhaust nozzle of the aero engine where the heat exchangers are mounted, the presence of the latter is unavoidably modeled with the use of a porosity model for practical reasons, having to do with CPU and memory requirements. The porosity model is taking into account the pressure drop and heat transfer behaviour of the heat exchangers and was developed and validated with the use of detailed experimental measurements. For the validation of the CFD model, isothermal experimental measurements carried out for laboratory conditions in a 1:1 model of a quarter of the exhaust nozzle of the aero engine, including four full-scale heat exchangers, were used. The CFD results were in good agreement with the experimental measurements and the same flow structures and problematic regions were detected. Thus, a complete 3-D CFD model of the overall exhaust nozzle of the aero engine was created and validated which at the next step formed the basis for the optimization of the overall aero engine installation for real engine operating conditions. The improved design of the aero engine installation presented decreased pressure losses in relation to the initial design and a more balanced mass flow distribution, showing the applicability of the overall methodology and its advantages for producing efficient engineering solutions for similar setups.

Numerical development of a heat transfer and pressure drop porosity model for a heat exchanger for aero engine applications

2010 ◽  
Vol 30 (11-12) ◽  
pp. 1341-1350 ◽  
Author(s):  
D. Missirlis ◽  
S. Donnerhack ◽  
O. Seite ◽  
C. Albanakis ◽  
A. Sideridis ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Numerical Development ◽  
Aero Engine ◽  
Porosity Model

The effect of heat transfer on the pressure drop through a heat exchanger for aero engine applications

2009 ◽  
Vol 29 (4) ◽  
pp. 634-644 ◽  
Author(s):  
C. Albanakis ◽  
K. Yakinthos ◽  
K. Kritikos ◽  
D. Missirlis ◽  
A. Goulas ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Aero Engine

scholarly journals Heat Transfer and Pressure Drop Characteristics of Angled Spiralling Tape Inserts in a Heat Exchanger Annulus

2001 ◽  
Author(s):  
H. Coetzee ◽  
L. Liebenberg ◽  
J. P. Meyer
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Single Phase ◽  
Experimental Measurements ◽  
Tube Heat Exchanger ◽  
Normal Tube

Abstract The purpose of this paper was to determine the single phase heat transfer and pressure drop characteristics of an angled spiralling tape inserted into the annulus of a tube-in-tube heat exchanger. Experimental measurements were taken on four setups: a normal tube-in-tube heat exchanger used as a reference and three heat exchangers with different angled spiralling tape inserts. From the results correlations were developed that can be used to predict the heat transfer and pressure drop characteristics. It was concluded that the angled spiralling tape inserts resulted in an increase in the heat transfer and pressure drop characteristics as can be expected.

Numerical simulation of the effect of baffle cut and baffle spacing on shell side heat exchanger performance using CFD

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Swanand Gaikwad ◽  
Ashish Parmar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Numerical Results ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Two Parameters

AbstractHeat exchangers possess a significant role in energy transmission and energy generation in most industries. In this work, a three-dimensional simulation has been carried out of a shell and tube heat exchanger (STHX) consisting of segmental baffles. The investigation involves using the commercial code of ANSYS CFX, which incorporates the modeling, meshing, and usage of the Finite Element Method to yield numerical results. Much work is available in the literature regarding the effect of baffle cut and baffle spacing as two different entities, but some uncertainty pertains when we discuss the combination of these two parameters. This study aims to find an appropriate mix of baffle cut and baffle spacing for the efficient functioning of a shell and tube heat exchanger. Two parameters are tested: the baffle cuts at 30, 35, 40% of the shell-inside diameter, and the baffle spacing’s to fit 6,8,10 baffles within the heat exchanger. The numerical results showed the role of the studied parameters on the shell side heat transfer coefficient and the pressure drop in the shell and tube heat exchanger. The investigation shows an increase in the shell side heat transfer coefficient of 13.13% when going from 6 to 8 baffle configuration and a 23.10% acclivity for the change of six baffles to 10, for a specific baffle cut. Evidence also shows a rise in the pressure drop with an increase in the baffle spacing from the ranges of 44–46.79%, which can be controlled by managing the baffle cut provided.

Sign in / Sign up

Export Citation Format

Share Document