Engineering Commons^™

Heat Transfer Modeling And Optimization Of A Carbonized Microvascular Solar Receiver, Taylor Brown

Boise State University Theses and Dissertations

Concentrating solar power is an emerging renewable energy source. The technology can collect and store thermal energy from the sun over long durations, generating electricity as needed at a later time. Current CSP systems are limited to a maximum operational temperature due to constraints of the working fluid, which limits the maximum possible efficiency of the system. One proposed pathway forward is to utilize a gas phase for the working fluid in the system such as supercritical carbon dioxide.

A composite gas phase modular receiver is being developed by researchers at Boise State University and the University of Tulsa. The …

Control Of The Degree Of Intensification And Convective Heat Exchange With Flow Of Liquids In Pipes With Turbulators, B.B. Babatullaev, E.T. Mavlonov, U.V. Mannanov, Kh.S. Nurmukhamedov, U.H. Sagdullaev

Chemical Technology, Control and Management

The article discusses the problem of controlling the degree of intensification of the absorption process of NH 3 purified brine and CO 2 ammoniated brine in the technology of soda ash production. It is known that the aforementioned gases upon contact with brine the reaction proceeds with liberation of a considerable quantitative via heat. Increasing temperatures s lead to reduced NIJ output and finished products. Timely control of the withdrawal requires maintaining the degree of intensification of the heat exchange process at a certain level while maintaining the ratio of the absorption and cooling zones of the absorption tower. To …

Material Properties And Heat Transfer Parameters In Compression Molding Of Glass Mat Thermoplastics, Cheng Xu

Electronic Thesis and Dissertation Repository

The compression molding of glass mat thermoplastics (GMT) allows high volume manufacture of composite parts with a short production cycle. Computer simulation is often used to assist process development and optimization. Reliable simulation depends on input of material property parameters and accurate prediction of heat transfer. This thesis developed experimental methods to characterize material property and heat transfer process parameters. Results were obtained by applying the methods to a selected commercial GMT sheet. Heat transfer coefficients including convection coefficients during pre-heating and transfer, as well as contact conductance at sheet-mold interface were estimated by a parameter-fitting approach. Viscoelastic parameters of …

Steady-State And Transient Study Of Flow Boiling In Microchannels With Microgrooves/Micronozzles, Congcong Ren

Theses and Dissertations

Microchannel flow boiling is one of the most desired cooling solutions for high power electronics. Owing to the high latent heat of vaporization, high heat fluxes can be achieved through phase-change heat transfer. However, the enhancements of (critical heat flux) CHF and heat transfer coefficient (HTC) are usually inhibited by the transitional flow patterns, which highly influence the liquid rewetting. In the past two decades, many techniques have been explored to enhance the liquid rewetting in microscale.

In this dissertation, four parallel micro-grooves fabricated on the bottom of five microchannels (W=200 μm, H=250 μm, L=10 mm) were designed to promote …

Using Schema Training To Facilitate Students' Understanding Of Challenging Engineering Concepts In Heat Transfer And Thermodynamics, Dazhi Yang, Ruth Streveler, Ronald L. Miller, Inanc Senocak, Jim Slotta

Educational Technology Faculty Publications and Presentations

Background: Chi and colleagues have argued that some of the most challenging engineering concepts exhibit properties of emergent systems. However, students often lack a mental framework, or schema, for understanding emergence. Slotta and Chi posited that helping students develop a schema for emergent systems, referred to as schema training, would increase the understanding of challenging concepts exhibiting emergent properties.

Purpose: We tested the effectiveness of schema training and explored the nature of challenging concepts from thermodynamics and heat transfer. We investigated if schema training could (a) repair misconceptions in advanced engineering students and (b) prevent them in beginning engineering students. …

The Use Of Three-Dimensional Conjugate Cfd To Enhance Understanding Of, And To Verify, Multi-Modal Heat Transfer In Dynamic Laboratory Test Walls, Rakshit D. Muddu, Timothy Patrick O'Leary, Ronan Hogan, Anthony James Robinson, Aimee Byrne

Articles

This work describes the use of conjugate computational fluid dynamics (C-CFD) to simulate controlled laboratory based dynamic heat transfer tests on building components. This study proposes that conjugate CFD simulation can be used to evaluate the influence of combined convective and conductive heat transfer in multi-state building components. To this end, a solid wall and cavity wall were tested with a Calibrated Hotbox and subject to variable temperature conditions leading to combined convective and conductive heat transfer. The varying temperature of the heat source was monitored and used as the input boundary condition in the simulation model, which included a …

Research And Simulation Of Cross Flow Heat Exchanger, Chengyun Wu, Guangwen Wang, Geping Li, Xudong Xin

Journal of System Simulation

Abstract: Based on cell concept, the lumped parameter method was applied and the parameters in single heat exchanger cell were deduced. Thereafter 1, 4, 9,100 cells heat exchanger simulation model was set up and the simulation error and its influencing factors were analyzed. To simplify the algorithm and increase the calculation speed, as well as improve the accuracy of cross flow heat exchanger, the simplified heat exchanger model was proposed and reviewed. The research results show that the calculation of simplified heat exchanger is precise and the algorithm is simple. The model could be widely applied in cross flow heat …

Transient Thermal Modeling Of Bioprocessing Equipment, Cody M. Cummings

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Bioprocessing is leveraging cells to produce high value, lifesaving products. Precise environmental control is needed to maintain integrity of the bioprocessing production process. Temperature control requires both appropriate equipment choice and correct control parameter selection. To aid in the equipment selection process, enable better understanding of equipment capacity, and enable optimization of control parameters, a transient thermal model of both heat transfer characteristics and control systems was created in silico.

Numerical Simulation Of Hot And Cold Fluids Mixing In A Tee-Junction, Wenli Wei, Yunfei Hong, Shipeng Shao, Yuling Liu

Journal of System Simulation

Abstract: Flow and heat transfer model in tee junction was established and the 3D RNG k-ε turbulence model was completed to simulate the process of mixing and capture the information of velocity and temperature. The simulation results and measured data of the mean value of velocity and temperature were analyzed and compared, and are in a good agreement, which indicates that the RNG k-ε model combined with the heat transfer model can well simulate the hydraulic characteristics and heat transfer mechanism of hot and cold fluids in a tee junction. Furthermore, the upstream segment of a tee junction has two …

Jet Impingement Heat Transfer From Superheated, Superhydrophobic Surfaces, David Jacob Butterfield

Theses and Dissertations

Liquid jet impingement is a technique ubiquitously used to rapidly remove large amounts of heat from a surface. Several different regions of heat transfer spanning from forced convection to nucleate, transition, and film boiling can occur very near to one other both temporally and spatially in quenching or high wall heat flux scenarios. Heat transfer involving jet impingement has previously shown dependency both on jet characteristics such as flow rate and temperature as well as surface material properties. Water droplets are known to bead up upon contact with superhydrophobic (SH) surfaces. This is due to reduced surface attraction caused by …

Developing Highly Efficient Industrial Contact Heat Exchanger, Khoshim Shayimovich Bakhronov, Abdumalik Abduvahobovich Akhmatov, Yorkin Bakhodirovich Kadirov

Chemical Technology, Control and Management

The paper presents the results of an experimental study of the intensification of heat transfer of a swirling flow in a cylindrical channel with two tangential and axial swirlers. During the experiments, such parameters were measured as: air flow in front of the vortex apparatus; hot water consumption; pressure drop in the vortex apparatus; temperature of working media at the inlet to the apparatus and at the outlet of it. A method for intensifying the heat transfer process, which is based on swirling a gas stream by its tangential supply, has been developed and investigated. Experimental studies of the intensity …

Fluid Flow, Heat And Mass Transfer In Hot Dip Galvanizing Bath, Shouqun Sun, Zhongshuang Wei, Huayang Lu

Journal of System Simulation

Abstract: Zinc dross is produced inevitably as a metallurgical phenomenon of continuous hot galvanizing process, and the quality of galvanizing is affected. The phenomenon is closely related to the physical field of molten zinc and more surface defects are easily produced if the zinc dross removal process is improperly handled. By constructing a three-dimensional viscous standard k-ε two equation turbulence model, the fluid flow, heat and mass transfer law and the distribution regularities of flow vortex were obtained under the specific initial conditions and boundary conditions. The simulation results of the observation points are basically in agreement with the experimental …

Experimental Evaluation Of Heat Leak And Convective Heat Transfer In A Household Freezer., Catherine E. Berghuis

Electronic Theses and Dissertations

Heat leak into household refrigerated cabinets is a key driver affecting energy consumption and efficiency of the cooling system. Additionally, knowledge of heat transfer coefficients of internal surfaces is valuable in the development of cabinet and system level performance simulations. Several studies have examined heat leak of refrigeration units using heat flux sensors (HFS); however, no such studies have used heat flux measurements to derive convective heat transfer coefficients of the refrigerated unit walls. The goal of this study is to evaluate the use of HFS to quantify heat leak into a 490-liter freezer and determine the wall convective heat …

Development Of A Matlab Gui To Assist The Active Comprehension Of Biomedical Transport Phenomena Using A Visual Aid, Pranav Suri

Biomedical Engineering Undergraduate Honors Theses

Studies show that inductive teaching methods for Biomedical Transport Phenomena greatly benefit from an accompanying visual aid. The following project aimed to develop a MATLAB GUI application that illustrates steady-state heat transfer with a graph and heat map using user-defined boundary conditions and numerical parameters. The application was evaluated using a survey that first familiarized the user with the GUI by running through heat transfer exercises, then allowed the user to experiment with the application, and finally asked users about their experiences using a questionnaire. The responses indicate that the GUI was received positively overall, and that a MATLAB component …

Thermal Contact Resistance Measurement And Related Uncertainties, Amanda Elizabeth Stark

Mechanical & Aerospace Engineering Theses & Dissertations

Thermal contact resistance is an important parameter in detailed thermal analysis and design of aerospace systems. The ability to determine thermal contact resistance reliably can have a significant impact on the fidelity of thermal models—particularly for space applications. The 2004 NASA Langley Research Center thermal contact resistance test apparatus has been employed to evaluate two methods for inferring estimated interface surface temperatures so that thermal contact resistance can be calculated more accurately. The traditional method of extrapolation is a steady-state approach, while the new method utilizes inverse heat transfer techniques to account for inherent unsteadiness in these quasi-steady-state measurements. The …

Modeling Nonlinear Heat Transfer For A Pin-On-Disc Sliding System, Brian A. Boardman

Theses and Dissertations

The objective of this research is to develop a numerical method to characterize heat transfer and wear rates for samples of Vascomax® 300, or Maraging 300, steel. A pin-on-disc experiment was conducted in which samples were exposed to a high-pressure, high-speed, sliding contact environment. This sliding contact generates frictional heating that influences the temperature distribution and wear characteristics of the test samples. A two-dimensional nonlinear heat transfer equation is discretized and solved via a second-order explicit finite difference scheme to predict the transient temperature distribution of the pin. This schematic is used to predict the removal of material from the …

Seventh-Grade Students' Use Of Heat Transfer Conceptions During An Engineering Design-Based Stem Integration Curriculum, Emilie A. Siverling, Tamara J. Moore

Integrated Engineering Department Publications

As the integration of STEM becomes increasingly important in pre-college education, it is important to study models of STEM integration. One model, engineering design-based STEM integration, has shown promising results in terms of student science content learning. This study’s purpose was to explore one student team’s use of heat transfer conceptions as they participated in an engineering design-based STEM integration curriculum. A case study research design, along with procedures from qualitative content analysis, were used to identify scientific and alternative conceptions that the seventh-grade students communicated during the unit. The main result is that the students spoke and wrote about …

Hybrid Phase-Change Lattice Boltzmann Simulation Of Vapor Condensation On Vertical Subcooled Walls, Wandong Zhao, Yuan Gao, Ruijie Li, Songgang Qiu, Yin Zhang, Ben Xu

Mechanical Engineering Faculty Publications and Presentations

Saturated vapor condensation on homogenous and heterogeneous subcooled walls is presented in this study by adopting a hybrid phase-change multiple-relaxation-time Lattice Boltzmann model. The effects of wall wettability on the condensation process, including droplets’ growth, coalescence and falling, and the influence of vapor flow to condensation are investigated. The results demonstrate that the heat fluxes around the triple-phase contact lines are higher than that in other cold areas in homogeneous subcooled walls, which actually indicates the fact that filmwise condensation is preventing the continuous condensation process. Furthermore, the dropwise condensation can be formed more easily on the heterogeneous surface with …

The Influence Of Porous Media Heterogeneity On Smouldering Remediation, Jiahao Wang

Electronic Thesis and Dissertation Repository

Smouldering remediation is a promising technique for destroying organic contaminants in soil. Forced airflow is vital to supporting the smouldering reaction and to propagate it through the contaminated zone. This research focuses on investigating the effects of permeability heterogeneity on smouldering. A series of unique column experiments, combined with numerical model simulations, were conducted. The results suggest that smouldering can successfully propagate through layers in series despite more than a 1000:1 permeability contrast. However, extinction can occur in the finer layer when smouldering propagates through layers in parallel with a permeability ratio above 3:1. Extinction may occur due to insufficient …

Assessment And Improvement Of Computational Fluid Dynamics Methods For Separated Turbulent Flows At Low Reynolds Numbers, Tom Mancuso

Dissertations, Master's Theses and Master's Reports

This study investigates the accuracy of Computational Fluid Dynamics (CFD) models to predict heat transfer in turbulent separated flows at low Reynolds numbers. A novel improvement of a Scale Adaptive technique is also presented. A spectrum of turbulence models is used to simulate flow and heat transfer of two geometries; fully developed flow through a staggered tube bank and a square prism in cross flow. Experimental data for both local heat transfer and velocity data are available in the literature for these cases and have been used extensively evaluate various CFD methods. Six unsteady models were used and the results …

Heat Exchanger, Chance Linarez

All Undergraduate Projects

A water jet cutting machine can cause excess heat and humidity within a closed building, while also making it more difficult for the user to pick material off the cutting table. Water temperatures can reach as high as 150 degrees Fahrenheit in the tank. A system that would reduce the temperature of the water in a water jet tank would be beneficial for the occupants in the room in providing a better more comfortable work environment. Data was collected while the machine was in use. The data includes; temperature of water leaving the nozzle, the rate of change of tank …

An Evaluation Of Ground-Freezing Methods In The Zone Of Discontinuous Permafrost, Northwest Territories, Elzbieta Mastej Ms

Theses and Dissertations (Comprehensive)

Northwestern Canada is one of the most rapidly warming regions on Earth. The southern limit of the discontinuous permafrost zone is highly sensitive to small climatic fluctuations and presently experiencing a rapid landscape change due to accelerated permafrost thaw, which is further exacerbated by anthropogenic disturbances such as seismic exploration. Recent research has begun to examine both natural and mechanical approaches to minimize permafrost loss, although the utility of such methods in peatland environments is not well understood. This study explored the efficiency of natural and artificial ground cooling processes in a peatland environment by evaluating snow exclusion and thermosyphon …

Thermal-Hydraulic Performance In A Microchannel Heat Sink Equipped With Longitudinal Vortex Generators (Lvgs) And Nanofluid, Basel Al Muallim, Mazlan A. Wahid, Hussain A. Mohammed, Mohammed Kamil, Daryoush Habibi

Research outputs 2014 to 2021

In this study, the numerical conjugate heat transfer and hydraulic performance of nanofluids flow in a rectangular microchannel heat sink (RMCHS) with longitudinal vortex generators (LVGs) was investigated at different Reynolds numbers (200-1200). Three-dimensional simulations are performed on a microchannel heated by a constant temperature with five different configurations with different angles of attack for the LVGs under laminar flow conditions. The study uses five different nanofluid combinations of Al2O3 or CuO, containing low volume fractions in the range of 0.5% to 3.0% with various nanoparticle sizes that are dispersed in pure water, PAO (Polyalphaolefin) or ethylene glycol. The results …

Energy Conservation And Heat Transfer Enhancement For Mixed Convection On The Vertical Galvanizing Furnace, Dan Mei, Yuzheng Zhu, Xuemei Xu, Futang Xing

Mechanical & Aerospace Engineering Faculty Publications

The alloying temperature is an important parameter that affects the properties of galvanized products. The objective of this study is to explore the mechanism of conjugate mixed convection in the vertical galvanizing furnace and propose a novel energy conservation method to improve the soaking zone temperature based on the flow pattern and heat transfer characteristics. Herein, the present study applied the k-ε two-equation turbulence model to enclose the Navier-Stokes fluid dynamic and energy conservation equations, and the temperature distributions of the steel plate and air-flow field in the furnace were obtained for six Richardson numbers between 1.91 ⋅ 10^{5 …}

Thermal Atomization Due To Boiling During Droplet Impingement On Superhydrophobic Surfaces, Preston Todd Emerson

Theses and Dissertations

Superhydrophobic (SH) surfaces are characterized by their extraordinary water repellent qualities. When water comes in contact with these surfaces, it beads up and rolls around. This phenomenon is due partially to surface chemistry which promotes weak adhesive forces between liquid and solid. However, micro- and nanoscale surface roughness also plays a crucial role by trapping air beneath the liquid, reducing liquid-solid contact. Many advantages of these surfaces have been identified, including drag reduction and self-cleaning properties, and the body of research regarding them has grown rapidly over the past few decades.This thesis is concerned with water droplets impinging superheated, superhydrophobic …