Tag: RESEARCH
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Research Update: 2020 - Year in HTRI Research
February 09, 2021
After summarizing the results from HTRI Research over the past year, this webinar provides insights into how these results improve our technology and its use by HTRI members. Topics include prediction of hot air recirculation for air coolers, development of new non-Newtonian heat transfer correlations, modification of tubeside falling film heat...
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Research Update: Predicting Heat Transfer Coefficients with an Artificial Neural Network
June 30, 2020
Artificial neural networks (ANNs) allow the solution of hard problems such as determining important parameters affecting crude oil fouling analyzing operating data to troubleshoot heat exchangers developing correlations through multivariate nonlinear regression of complex data To evaluate a neural network model for heat transfer coefficients, we used a multilayer, feed-forward ANN...
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Research Update: Guidelines for Vertical Tubeside Thermosiphon Reboiler Turndown
May 28, 2020
Thermosiphon reboilers often pose challenges for column operations in refineries and chemical processing plants. Some challenges are related to turndown, when reboiler circulation rates or duties are lower than design conditions. The process industry uses various checklists and criteria, though most guidelines have little to no validating data backing them up....
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Research Update: 2019 – Year in HTRI Research
March 19, 2019
This webinar highlights the accomplishments of HTRI Research over the past year and describes how HTRI members can benefit from these developments. We briefly discuss airside studies with our air cooler unit, thermosiphon turndown results, lessons learned testing non-Newtonian fluids, insights from falling film experiments, heat transfer predictions with supercritical fluids,...
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Research Update: Natural-draft Testing on Air-cooled Heat Exchangers
December 12, 2019
To ensure reliable data collection, HTRI always seeks to improve test methods and incorporate innovative techniques. Recently installed at the Research & Technology Center, the Air-cooled Unit (ACU) has motivated us to develop better ways of collecting airside measurements for both forced- and natural-draft testing. Accurate measurements for natural-draft (fans off)...
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Research Update: 2018 - Year in HTRI Research
February 28, 2019
This webinar highlights the accomplishments of HTRI Research over the past year and describes how HTRI members can benefit from these developments. We briefly discuss airside studies with our air cooler unit, vacuum condensation experiments with hydrocarbon mixtures, new phase change methods for plate heat exchangers, subcooling with shellside condensation, and...
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Research Update: Shellside Vacuum Condensation with Mixtures
June 07, 2018
Condensation data were recently collected in the Low Pressure Condensation Unit (LPCU) using hydrocarbon mixtures. This recent set of data wraps up a multiyear research project to study shellside condensation under vacuum conditions. This webinar will focus on the latest results collected with hydrocarbon mixtures. High-speed videos are shown along with...
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Research Update: Identifying Ledinegg instability in a VTTR
July 20, 2017
In a vertical tubeside thermosiphon reboiler (VTTR), Ledinegg instability can occur when the tubeside pressure drop decreases with increasing flow rate. Theoretical analysis of two boundary conditions—constant heat flux and constant steam pressure—revealed that for either condition, Ledinegg instability can occur in a VTTR only when intube frictional pressure drop dominates...
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Research Update: Condensation of Immiscible Fluids
June 22, 2017
Condensation of immiscible fluid mixtures is a complex process. During condensation, three phases exist: one vapor phase and two liquid phases. HTRI conducted condensation experiments using a water/octane mixture outside plain tubes in the Low Pressure Condensation Unit (LPCU). Xist® predicted the experimental data with good agreement and high-speed videos showed...
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Research Update: Two-phase Flow Research - Key Findings and Impact
April 13, 2017
HTRI recently concluded research in the following topics: Vertical Upflow – pressure drop and void fraction Vertical Upflow – flow regime map Vertical Downflow – pressure drop and void fraction Vertical Downflow – flow regime The details of the research, results, and discussions have been published in HTRI research reports TPF-14,...
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F-24 Demonstration of RFU as Research Tool
March 27, 2017
In 2013 HTRI commissioned the Rotating Fouling Unit (RFU). With its smaller volume, shorter run duration, and faster turnaround, the RFU serves as a screening device for the High Temperature Fouling Units (HTFU-1 and HTFU-2) and is ideal for fouling impact studies on specific variables. Initial fouling tests and fouling impact...
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Research Update: Shellside Longitudinal Liquid-phase and Flow Boiling Heat Transfer for Vertical Plain Tube Bundles
January 19, 2017
Vertical shellside boiling is used for a variety of applications, including vertical thermosiphon reboilers where hot fluid must be on the tubeside steam generators/waste heat boilers, which use very hot or corrosive fluids as the heating medium vertical feed-effluent exchangers, whose vertical orientation prevents phase separation Ideal vertical shellside reboilers have...
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Research Update: CFD Simulations of Forced Draft Air Coolers with Air Maldistribution
January 16, 2017
API-compliant air coolers are modeled in two- and three-dimensional computational fluid dynamics (CFD) simulations to see what improvements are needed in Xace® with regard to the airside maldistribution. We validated the CFD model using Xace base cases. We then used CFD to simulate non-ideal airside flow situations that can potentially affect...
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Research Update: Air-cooler Headers: Predicting Pressure Drop and Flow Distribution
January 16, 2017
Header flow maldistribution and pressure loss in air-cooled heat exchangers may significantly affect performance. Most relevant literature focuses on plate-fin and cylindrical channel headers for tubular heat exchangers. The flow in the header is affected by its internal geometry, the orientation of the nozzles on the header, and inlet flow velocity....
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Research Update: CFD Modeling of Offset Strip Plate-fin Exchanger with Vapor and Liquid Services
January 16, 2017
Compact plate-fin heat exchangers are widely used for electronics, aerospace, and automotive cooling because of the light weight and small size. The majority of open-literature data use air as the test fluid; thus, the application of the ensuing air-based methods to higher Prandtl number, liquid services is dubious. In some applications,...
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Research Update: Modeling Flow Distribution in Manifolds and Headers
January 16, 2017
In this webinar, we will discuss flow distribution and pressure drop for single T-junctions and manifolds by describing the T-junction resistance coefficients and how they vary with flow conditions and geometry describing manifold geometry and outlining the differential and discrete equation approaches for solving the flow distribution problem demonstrating which approach...
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Research Update: Maldistribution in Shellside Laminar Viscous Flow
January 16, 2017
Xist® can predict unexpected performances of shellside viscous fluids in laminar regimes, where thermal maldistribution is present. The heat transfer of viscous flows across vertical baffles is analyzed by CFD to determine impact of such non-uniformity. Maldistribution can be monitored using a viscosity-independent Richardson number. The Richardson relates the impact of...
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Research Update: Crossflow Mixed Convection Heat Transfer for Horizontal Tube Banks
January 16, 2017
This webinar reviews measurement of mixed convection heat transfer using liquids in crossflow over ideal horizontal plain and low-finned tube banks. We identify when natural convection may enhance or penalize crossflow heat transfer and recommend new calculations to improve HTRI software predictions....
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Research Update: Two-phase Pressure Drop across Changes in Cross-sectional Area
January 16, 2017
In this webinar, we describe pressure drop correlations and provide recommendations for their use. Many flow circuits include pipe diameter variations and piping components such as orifice plates, contractions, and expansions. Accurate prediction of the single- and two-phase pressure drops across these components is necessary to calculate the total pressure drop...
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Condensation Heat Transfer and Pressure Drop Measurement for Pure Hydrocarbons and Mixtures in Plain Tubes
January 16, 2017
In 2011, Professor Srinivas Garimella, the Hightower Chair and Professor and Founder/Director of the Sustainable Thermal Systems Laboratory (STSL) at the Georgia Institute of Technology in Atlanta, Georgia, USA, began work on a 3-1/2 year contract with HTRI entitled Condensation Heat Transfer and Pressure Drop of Propane. This project will conclude...
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Research Update: Sealing Device Application
January 16, 2017
During this webinar, we discuss the basics of sealing devices, including common practices and design guidelines. Further, we review the basic flow resistance equation for sealing strips used in Xist® Version 7 and compare the measured performances of HTRI research-scale heat exchanger using sealing strips to CFD and Xist predictions....
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Research Update: Applications of Crossflow Boiling Model to Low-finned Tube Bundles
January 16, 2017
This webinar reviews HTRI and literature boiling data outside low-finned tubes, compares HTRI flow boiling data across plan and low-finned tube bundles, examines and evaluates HTRI’s current boiling model, and describe a more simple and more accurate boiling model....
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Research Update: Pressure Drop of Vacuum Condensation in a Vertical Tube
January 16, 2017
This webinar discusses the status of HTRI vacuum condensation research plans, describes the current methods in Xchanger Suite®, and proposes a method to be implemented in future versions of Xchanger Suite....
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Research Update: Mixed Convection Heat Transfer in Horizontal Tubes
January 16, 2017
This webinar reviews mixed convection heat transfer measurements for liquid flow inside tubes, compares the performance of alternative correlations, and proposes an improved prediction method....
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Research Update: Predicting Phase Separation in Shell-and-Tube Heat Exchangers
January 16, 2017
Recent experiments performed in the Multi-purpose Visualization Unit (MVU) analyzed the dependence of shellside phase separation on exchanger geometry. During this webinar, we discuss the variation of the stratified to non-stratified transition boundary with exchanger geometry, applicable over a wide range of flow regime parameters....
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Research Update: Flow Boiling Heat Transfer across Plain Tube Bundles
January 16, 2017
This webinar will discuss flow boiling data across ideal plain tube bundles collected in the HTRI Multipurpose Boiling Unit and compiled from the literature. Our current method has four heat transfer mechanisms: nucleate boiling, convective boiling, thin liquid film conduction, and natural convection. It is complex with many correlation parameters and...
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Research Update: Analysis of NTIW Shellside Performance using CFD and Xist
January 16, 2017
This webinar will discuss Xist® and CFD predictions of three NTIW exchanger configurations – 2 baffle, 4 baffles, and 6 baffles. The discussion will focus on the contributions of crossflow and longitudinal flow on heat transfer, which is due to varied baffle spacing for the same baffle cut. During the webinar,...
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Research Update: Pressure Drop in Inclined Intube Downflow Condensation
January 16, 2017
Based on recent research, HTRI has developed a new pressure drop method for inclined cocurrent condensation. In this webinar, we discuss the effect of tube inclination on two-phase flow regimes and pressure drop. The performance of the existing inclined condensation pressure drop method is assessed against data, and an improved pressure...
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Research Update: Design and Construction of the Rotating Fouling Unit
January 16, 2017
HTRI currently runs fouling experiments on the High Temperature Fouling Unit (HTFU) which recirculates a 27 liter sample of crude for periods up to one month. As we plan to expand our crude oil fouling test program, we are investigating alternate test methods to screen crude oil fouling with smaller sample...
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Research Update: Evaluation of HTFS and HTRI Shellside Condensation Methods
January 16, 2017
Using available open literature sources and data from HTRI’s shellside condensation database, HTRI compared the predictions of horizontal shellside condensation correlations documented in HTFS™ reports and methods contained in HTRI Xchanger Suite®. The results show that HTFS methods slightly overpredict heat transfer coefficients for pure components and poorly predict heat transfer...
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Research Update: Modeling Flat Bundles in Kettle Reboilers
January 16, 2017
Engineers may design flat bundles in kettle reboilers by removing tuberows from round bundles to create a larger disengagement space. This webinar discusses application of the kettle reboiler circulation boiling model to flat bundles. It reviews calculations for the static driving head and maximum heat flux for flat bundles. We also...
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Research Update: A Review of Shellside Flow Regimes
January 16, 2017
This webinar provides a review of current HTRI, open literature, and HTFS research on shell flow regimes. The best available flow regime map will be identified, and focus areas of further research efforts will be discussed....
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Research Update: Quantitative Flow Visualization Techniques
January 16, 2017
Flow visualization describes the art of making visible what is invisible. Using flow visualization techniques, scientists like da Vinci, Reynolds, and Prandtl discovered some of the most fundamental concepts concerning wakes and boundary layers. The rapid evolution of affordable electro-optics and digital image processing during the last several decades has increased...
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Research Update: Condensation with Desuperheating
January 16, 2017
When superheated vapor enters a condenser, the vapor cannot condense until the sensible heat content is removed in a process called desuperheating. Reports CT-21 and CT-22 present experimental data, discuss the principles of pure components and mixture wet-wall desuperheating, and review available heat transfer models and correlations. These reports also propose...
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Research Update: Single-Phase Crossflow Methods
January 16, 2017
HTRI continues to improve its single-phase crossflow methods. We have completed a thorough review of heat transfer and pressure drop correlations for single-phase flow outside banks of plain- and low-finned tubes. This webinar highlights some of our findings and summarizes the performance of the improvements we are proposing for our correlations....
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Research Update: Condensation in Welded Plate Exchangers
January 16, 2017
Plate heat exchangers (PHEs) are well suited for applications that require compactness, low weight, and high efficiency. Traditional gasket-type PHEs are limited to a low range of pressures and temperatures. When operating pressures and temperatures exceed the range of a traditional gasket PHE, a welded-plate design is sometimes used. This webinar...
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Research Update: Non-Newtonian Flows in Heat Exchangers
January 16, 2017
HTRI has begun a research program dedicated to non-Newtonian flows. In order to discuss the plans for this research program, this webinar reviews the following items: the definition non-Newtonian fluids, the use apparent viscosity, focusing on power law fluids, how non-Newtonian flows affect pressure drop and heat transfer in heat exchangers...
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Research Update: Crude Oil Fouling
January 16, 2017
We begin this webinar with a definition of crude oil fouling and the difference between crude oil fouling and other types of fouling mechanisms. Following this review, we discuss fouling research at HTRI by describing the High Temperature Fouling Unit (HTFU), the research testing that we conduct, and the prediction models...
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