College Station, TX, United States
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Inagaki M.,Heat Transfer Research Inc. | Nagaoka M.,Heat Transfer Research Inc. | Horinouchi N.,Heat Transfer Research Inc. | Suga K.,Osaka Prefecture University
International Journal of Engine Research | Year: 2010

Large eddy simulation (LES) using a mixed-time-scale (MTS) subgrid-scale (SGS) model is applied to the intake flows in simplified internal combustion engine geometry. A modified colocated grid system is employed to obtain results as precise as possible and to perform calculations in a stable way with a central difference scheme for convective terms. The results are compared with corresponding experimental data and the Reynolds averaged Navier-Stokes (RANS) equation model results obtained using the low-Reynolds-number linear k- In addition, it is made clear that when the QUICK scheme is used in LES for the convective terms instead of the central difference scheme, the result obtained deteriorates owing to the numerical viscosity. The importance of the discretization method in practical LES is also confirmed. © IMechE 2010.


Shilling R.L.,Heat Transfer Research Inc.
Heat Transfer Engineering | Year: 2012

Fouling is a costly problem in heat exchanger design and operation. Over the past 20-30 years, design capabilities have advanced such that most fouling can be mitigated through effective design techniques. A design margin is added to the initial clean design in order to handle uncertainties in design and any deterioration in performance due to the reduced fouling that occurs in spite of good design practice. This article explains the advantages and disadvantages of three common methods for adding design margin to heat exchangers. It then introduces a new design margin method that combines the strengths of the previous three while avoiding their weaknesses. © 2012 Taylor and Francis Group, LLC.


Talapatra S.,Heat Transfer Research Inc. | Farrell K.,Heat Transfer Research Inc.
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2015

The ability to predict the liquid-gas two-phase flow regime and void fraction in exchangers and piping is a critical engineering requirement in the process industry. The distribution of the liquid and gas phases depend on many factors including flow conditions, physical properties of the two fluids, and geometry of the flow conduit. The problem of correctly predicting the two-phase distribution is of enormous complexity, and generalized correlations that adequately describe the flow regime and/or the void fraction have not been yet been developed even for the simplest of geometries. While Computational Fluid Dynamics codes that model two-phase flows exist, they are limited in their applicability and usually require a priori knowledge of the flow regime. In this part of a two paper series, we discuss the state-of-the-art in two-phase flow regime studies inside shell-and-tube heat exchangers, while in the second part, we will discuss two-phase flows inside piping. We have performed air-water tests inside a glass shelland- tube exchanger at HTRI, and by systematically varying various geometrical parameters, compiled the largest flow visualization database inside such exchangers. We have evaluated the best available flow regime maps available in the open literature, and shown how our results help enhance understanding of liquid-gas distribution inside heat exchangers. We have shown how, for a given flow rate, increasing the baffle spacing and reducing baffle-cut enhances two-phase separation. While these results are expected, they have never been quantified before. However, the use of flow visualization limits the liquid and gas phases to water and air mixtures, which limits the range of applicability. Shellside studies using various industrially relevant fluids such as hydrocarbon mixtures, steam water are planned, where non-visual flow regime detection techniques need to be applied. © 2015 by ASME.


Bouhairie S.,Heat Transfer Research Inc.
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2015

The petroleum and petrochemical industries continually seek mechanical methods to improve heat transfer in shell-andtube heat exchangers. Tube bundle inserts are popular mechanical devices that help improve performance. The increase in the tubeside heat transfer coefficient by the insert allows for a decrease in required shellside flow length, assuming single tube pass. The flow length reduction allows for designing higher velocities and subsequent shellside shear rates, to help reduce crude oil fouling potential. This work presents some of HTRI's ongoing experimental measurements and preliminary Computational Fluid Dynamics (CFD) simulations. CFD visualization of swirl flow dynamics and heat transfer inside the augmented tube provides insight on complex flow physics, which is misunderstood. Heat Transfer Research, Inc. (HTRI) collected experimental data for in-tube single-phase flow using twisted tape inserts in the Tubeside Single-Phase Unit (TSPU) situated in the Research and Technology Center (RTC). Our data will be used to calibrate ANSYS FLUENT CFD simulations of a tube with a twisted tape swirl insert. We first performed plain tube simulations and compared the heat transfer results with open literature measurements, for validation. We will modify the CFD tube model to have a swirl flow insert, and compare numerical results against open literature experimental data of diabatic single-phase swirl flow. In future, we will compute heat transfer (heating and cooling) and pressure drop for tube insert configurations at laminar and turbulent Reynolds numbers from 3000 to 500000. The range of tubeside Reynolds numbers required the use of the laminar, transition, and Realizable k-epsilon turbulence models with scalable wall functions. This study describes some of the mechanisms behind turbulent swirl flow augmentation inside a tube, as well as the limitations of conventional in-tube heat transfer correlations applied to swirl flow inserts. © 2015 by ASME.


Bouhairie S.,Heat Transfer Research Inc.
Chemical Engineering Progress | Year: 2012

Some of the steps that need to be followed to select the appropriate baffle for shell-and-tube heat exchangers are discussed. Baffles play a crucial role in regulating shellside fluid flow and improving heat transfer between shellside and tubeside process fluids. It is essential to remember that baffles are available in a range of shapes and sizes, and the most common among these is the segmental baffle. The Tubular Exchanger Manufacturers Association, Inc., (TEMA) provides design guidelines for segmental baffles. TEMA baffles can be single- or multi-segmental, or tube support plates, while tube support plates are used in the no-tubesin-window (NTIW) design to ensure that all baffles support every tube, eliminating tubes with long unsupported spans. TEMA standards also specify that the minimum spacing between segmental baffles need to be the larger of one-fifth of the shell inside diameter or 51 mm.


Talapatra S.,Heat Transfer Research Inc. | Farrell K.,Heat Transfer Research Inc.
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2014

The detailed flow inside a shell-and-tube exchanger remains an open area of research, despite its relevance to the heat exchanger industry. We present some of our recent efforts in this field based on Particle Image Velocimetry (PIV) experiments within a transparent shell-and-tube exchanger (TSTX) at the Research and Technology Center at HTRI. The single-phase flow in the window region of the TSTX is resolved by mapping the two-dimensional velocity field in multiple planes. Different shell-side geometries were tested. Time-averaged results indicate flow patterns that are different from the idealized flow assumptions that form the conceptual basis of commercially available shell-side flow solvers. Copyright © 2014 by ASME.


Shilling R.L.,Heat Transfer Research Inc.
Chemical Engineering Progress | Year: 2012

Tube inserts are useful tools that improve tubeside performance in heat exchangers. The best insert type and design for a particular application depends on flow conditions and fluid properties. Inserts that augment single-phase heat transfer use one or more of the four distinct mechanisms to compensate for boundary layer effects, static mixing, boundary layer interruption, swirl flow, and displaced flow. Static mixing is the physical interchange of fluid particles to different locations in the flow stream by mechanical means. At higher Graetz numbers, the thickness of the laminar boundary layer can easily be reduced by boundary layer interruption inserts. It trips the boundary layer, causing it to thin to its minimum thickness, which enhances heat transfer. Displaced flow inserts increase heat transfer by blocking the flow area farthest from the tube wall, which creates higher velocities along the tube wall heat transfer surface.


Trademark
Heat Transfer Research Inc. | Date: 2016-05-18

Computer software for the design and performance evaluation of heat transfer equipment.


Trademark
Heat Transfer Research Inc. | Date: 2010-01-12

Computer software for the design and performance evaluation of heat transfer equipment.


Trademark
Heat Transfer Research Inc. | Date: 2015-04-09

Computer software for evaluating the performance and efficiency of heat transfer equipment and thermal processing equipment. Consulting services in the fields of energy consumption and usage conservation to improve the energy efficiency of heat transfer and thermal processing equipment. Technical consultation in the field of heat transfer and thermal processing equipment, namely, testing and evaluation of the equipment to improve its performance and efficiency.

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