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Heat transfer enhancement in shell-and-tube heat exchangers using porous media
, Article Heat Transfer Engineering ; Volume 36, Issue 3 , 2015 , Pages 262-277 ; 01457632 (ISSN) ; Afshin, H ; Farhanieh, B ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
A numerical simulation has been carried out to investigate the heat transfer enhancement in a shell-and-tube heat exchanger using a porous medium inside its shell and tubes, separately. A three-dimensional geometry with k-ε turbulent model is used to predict the heat transfer and pressure drop characteristics of the flow. The effects of porosity and dimensions of these media on the heat exchanger's thermal performance and pressure drop are analyzed. Inside the shell, the entire tube bundle is wrapped by the porous medium, whereas inside the tubes the porous media are located in two different ways: (1) at the center of the tubes, and (2) attached to the inner wall of the tubes. The results...
A new developed semi-full-scale approach to facilitate the CFD simulation of shell and tube heat exchangers
, Article Chemical Engineering Science ; Volume 245 , 2021 ; 00092509 (ISSN) ; Abdollahpour, M. S ; Hasanpour Matkolaei, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
The full-scale CFD simulations may not be recommended in preliminary steps of STHEs’ design and sensitivity analyses because of heavy computations. This work benefits from the sequential geometry repetitions in STHEs and presents a new semi-full-scale approach, which alleviates the need for full-scale simulation of STHEs. This approach first isolates the smallest zone, say block, which is sequentially repeated in the STHE domain. Second, this block is carefully simulated considering various thermal and flow working conditions. Third, the data collected from these CFD simulations are used to generate the required thermal and flow correlations for the chosen block at various working...
Heat Transfer Enhancement in Shell-and-Tube Heat Exchangers Using Porous Media
, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan (Supervisor) ; Afshin, Hossein (Supervisor)
Abstract
Heat transfer enhancement in heat transfer equipment, such as heat exchangers, has been widely studied. There are plenty of techniques to increase heat transfer in tubular heat exchangers. One of these techniques is applying a porous medium. These media have a great interface with fluids which can enhance the heat transfer rate. Meanwhile, the thermal conductivity of these media is usually greater than that of the studied fluid. Thus, by adding a kind of highly conductive porous insert to a heat exchanger, we are able to save the material used to construct the device and the space occupied by it.
Shell-and-tube heat exchangers are one of the most widely-used types of exchangers in...
Shell-and-tube heat exchangers are one of the most widely-used types of exchangers in...
Analysis and optimized design of a packaged liquid chiller (part I -Analytical modelling)
, Article 2005 ASME Summer Heat Transfer Conference, HT 2005, San Francisco, CA, 17 July 2005 through 22 July 2005 ; Volume 4 , 2005 , Pages 461-466 ; 0791847314 (ISBN); 9780791847312 (ISBN) ; Kargar, S ; Sharif University of Technology
2005
Abstract
The purpose of this work is to develop a physical simulation model for the purpose of studying the effect of various design parameters on the performance of a packaged liquid chiller. A computer model which simulates the steady-state cyclic performance of a vapor compression chiller is developed for the purpose of performing detailed physical design analysis of actual industrial chillers. The model can be used for optimizing design and for detailed energy efficiency analysis of packaged liquid chillers. The simulation model takes into account presence of all chiller components such as compressor, shell-and-tube condenser and evaporator heat exchangers, thermostatic expansion valve and...
Twisted bundle heat exchangers performance evaluation by CFD (CJ12/5054)
, Article International Communications in Heat and Mass Transfer ; Volume 39, Issue 10 , 2012 , Pages 1654-1660 ; 07351933 (ISSN) ; Farhadi, F ; Sharif University of Technology
Abstract
Shell and tube heat exchanger with single twisted tube bundle in five different twist angles, are studied using computational fluid dynamics (CFD) and compared to the conventional shell and tube heat exchanger with single segmental baffles. Effect of shell-side nozzles configurations on heat exchanger performance is studied as well. Heat transfer rate and pressure drop are the main issues investigated in the paper. The results show that, for the same shell-side flow rate, the heat transfer coefficient of heat exchanger with twisted tube bundle is lower than that of the heat exchanger with segmental baffles while shell-side pressure drop of the former is even much lower than that of the...
Heat Transfer Coefficient Prediction in Shell and Tube Heat Exchanger with Twisted Tube Bundle by CFD
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor)
Abstract
In this thesis, shell and tube heat exchanger with twisted tube bundle in 5 different twist angles is investigated using CFD commercial software, Fluent. A three dimensional unstructured grid has been employed to simulate the heat exchanger model. Optimum grid size is selected according to the level of accuracy required, optimum run time and the available computational resources. The method and simulation accuracy were verified by comparing simulation result with data from Bell-Delaware method. The RNG-K-ϵ method and second order discretization scheme for all variables are selected to model turbulent flow and solve the governing equations. Overall Heat transfer coefficient and pressure drop...
Heat Transfer and Pressure Drop Performance of Spiral Baffle Heat Exchangers
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor)
Abstract
In this work, a numerical investigation on shell side performance of a continuous helical baffle helixchanger along with smooth and helically ribbed tubes using CFD commercial code, Fluent, has been performed. The results of simulation for this type of exchanger were compared to a similar heat exchanger with segmental baffles. The geometries are created and meshed using Solidworks and Ansys Meshing softwares, respectively. Mesh generation is carried out using unstructured tetrahedral type elements. Element size (or number of elements) are chosen in such a manner that maintain accuracy and reliability of results in a reasonable run time. Simulation validation were carried out by comparison of...
Annual comparative performance and cost analysis of high temperature, sensible thermal energy storage systems integrated with a concentrated solar power plant
, Article Solar Energy ; Volume 153 , 2017 , Pages 153-172 ; 0038092X (ISSN) ; Taylor, R. A ; Nithyanandam, K ; Shafiei Ghazani, A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
The present study conducts a comprehensive comparative techno-economic analysis of some near-term sensible thermal energy storage (TES) alternatives to the ‘standard’ two-tank molten salt system for concentrated solar power (CSP) plants. As such, we conducted detailed, relative annual transient simulations for single-medium thermocline (SMT), dual-media thermocline (DMT), and shell-and-tube (ST) systems. To be consistent with recent literature, the DMT and ST systems use concrete with a porosity of 0.2 (e.g. where concrete occupies 80% of the system) as their low cost filler material. The systems were integrated into a validated 19.9 MWe Gemasolar CSP model, which has a solar multiple of...
Thermal and Hydrodynamic Analyses of Shell and Tube Heat Exchangers in Different Flow Regimes Using Semi-Full-Scale Simulation Approaches
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
One main problem in many numerical simulations is the lack of sufficient infrastructure data to precisely model and analyze the flow through complex geometries. Since experimental procedures are generally very expensive; and sometimes impossible, it becomes necessary to find alternative ways such as numerical approaches to predict the flow behavior through complex geometries. The heat exchangers can be categorized as geometries with complex configuration and apparently expensive to solve numerically. They are widely used in different industries including the aerospace. The restrictions in design and implementation of aviation’s heat exchangers have promoted the related companies to converge...
The effect of plugging of tubes on failure of shell and tube heat exchanger
, Article Engineering Failure Analysis ; Volume 104 , 2019 , Pages 545-559 ; 13506307 (ISSN) ; Chamani, M ; Kiyoumarsioskouei, A ; Mahmoudi, A. H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In shell and tube heat exchangers, deep cracks can occur in tube-to-tubesheet welding and repairing such cracks is an impossible task which makes these tubes totally out of service. To preserve the thermal and mechanical integrity of heat exchanger, a series of rods is passed through these tubes and then are welded to tubesheets from both ends. Due to the increased damages in the vicinity of plugged tubes, the effect of plugging the tubes in the surrounding tubes and tubesheet failure is investigated. To this end, using CFD analysis, the temperature and pressure were calculated throughout the heat exchanger and then, the deformations and stresses of the tubes and tubesheets were computed...
Effect of residual stress on failure of tube-to-tubesheet weld in heat exchangers
, Article International Journal of Engineering, Transactions A: Basics ; Volume 32, Issue 1 , 2019 , Pages 112-120 ; 17281431 (ISSN) ; Minaii, K ; Chamani, M ; Mahmoudi, A. H ; Sharif University of Technology
Materials and Energy Research Center
2019
Abstract
In a shell and tube heat exchanger, the failure of tube-to-tubesheet welds results in high-pressure water jet which erodes the refractory in front of the tubesheet. Finite element method was employed to simulate the welding process and post weld heat treatment (PWHT) to find the factors affecting the failure in tube-to-tubesheet weldments. Residual stresses in two different geometries of tube-to-tubesheet weldment were calculated through uncoupled thermal-structural analysis. The results showed that the values of residual stresses are higher in heat exchanger of site 1 than site 2 due to more weld passes and geometry of connection. Also, the maximum stress in site 1 occurs at the shellside...
Effect of residual stress on failure of tube-to-tubesheet weld in heat exchangers
, Article International Journal of Engineering, Transactions A: Basics ; Volume 32, Issue 1 , 2019 , Pages 112-120 ; 17281431 (ISSN) ; Minaii, K ; Chamani, M ; Mahmoudi, A. H ; Sharif University of Technology
Materials and Energy Research Center
2019
Abstract
In a shell and tube heat exchanger, the failure of tube-to-tubesheet welds results in high-pressure water jet which erodes the refractory in front of the tubesheet. Finite element method was employed to simulate the welding process and post weld heat treatment (PWHT) to find the factors affecting the failure in tube-to-tubesheet weldments. Residual stresses in two different geometries of tube-to-tubesheet weldment were calculated through uncoupled thermal-structural analysis. The results showed that the values of residual stresses are higher in heat exchanger of site 1 than site 2 due to more weld passes and geometry of connection. Also, the maximum stress in site 1 occurs at the shellside...