Digital Commons Network^™

Environmental Index For Real Time Feedback On Biowall Indoor Air Quality, William Hutzel, Hengyu Liu, Jun Ho Kim

International High Performance Buildings Conference

This paper describes an ongoing field evaluation of a simplified Environmental Index (EI) that provides a homeowner with an intuitive metric for assessing indoor air quality based on regular measurements of temperature, humidity, and Volatile Organic Compounds (VOC’s). These discrete measurements are used to compute an overall weighted score that correlates with the comfort and health of the living space. Although this environmental index is not a rigorous scientific computation, it is an initial point to improve residents’ understanding of Indoor Air Quality (IAQ) by providing active feedback. The context of this environmental index work is the Biowall, a living …

Review Of Humidity Effect On Humid Air-To-Water Condensation By A Cooling Surface For Atmospheric Water Harvesting, Gyeong Sung Kim, Tao Cao, Yunho Hwang

International Refrigeration and Air Conditioning Conference

Many atmospheric water harvesting technologies have been produced to mitigate water scarcity as an auxiliary source of water. These technologies may be described as direct and indirect water collection techniques. The direct method is to induce a phase-change turning from vapor to liquid on a cooling surface and generate condensate without interim processes. On the other hand, the indirect method has absorption or adsorption processes to take water from humid air before producing water. This paper focuses on the direct methods and discusses the effects of humidity and surface temperature on water generation rates and condensate droplet formation patterns in …

Enhanced Integer Permutation Based Genetic Algorithm For Optimization Of Tube-Fin Heat Exchanger Circuitry With Splits And Merges, Zhenning Li, Vikrant Aute

International Refrigeration and Air Conditioning Conference

Tube-fin heat exchangers (HXs) are widely used in air-conditioning and heat pump applications. The performance of these heat exchangers is strongly influenced by the refrigerant circuitry. Studies have proved that by optimizing the refrigerant circuitry, the performance of HXs can be significantly improved. In our previous research, an Integer Permutation based Genetic Algorithm (IPGA) was developed to obtain the optimal circuitry designs. Our previous research showed that IPGA demonstrates superior capability to obtain better refrigerant circuitries with lower computational cost than the other methods in literature. And the optimal circuitry designs obtained from IPGA are manufacturable with the available tooling. …

Promoting Equity By Scaling Up Summer Engineering Experiences: A Retrospective Reflection On Tensions And Tradeoffs, Walter C. Lee, David B. Knight, Monica E. Cardella

Journal of Pre-College Engineering Education Research (J-PEER)

A central challenge in engineering education is providing experiences that are appropriate for and accessible to underserved communities. However, to provide such experiences, we must better understand the process of offering a geographically distributed asset-based out-of-school program. This paper focuses on a collaborative research project that examined the broad implementation of the Summer Engineering Experiences for Kids (SEEK) program organized by the National Society of Black Engineers (NSBE). SEEK is a three-week summer program that engages participants in hands-on, team-based engineering design projects. NSBE’s goal is to make SEEK culturally sustaining, community-connected, and scalable. The purpose of this paper is …

Transnational Latinx Youths’ Workplace Funds Of Knowledge And Implications For Assets-Based, Equity-Oriented Engineering Education, Amy Wilson-Lopez, Jorge Acosta-Feliz

Journal of Pre-College Engineering Education Research (J-PEER)

Due to economic inequality in society, millions of Latinx high school youth work after-school jobs and summer jobs in order to provide additional income for their families. The purpose of this qualitative study, conducted with transnational Latinx youth, was to identify the engineering-related skills and bodies of knowledge they developed and applied while in different workplaces. This study is framed in complementary theories of funds of knowledge, Vygotskian theories of mediated action, and theories of resistant capital. Specifically, this study is based in the premise that youth can develop engineering-related funds of knowledge through tool-mediated, goal-directed activities jointly conducted with …

Elementary Teacher Adaptations To Engineering Curricula To Leverage Student And Community Resources, Jennifer L. Chiu, Sarah J. Fick, Kevin W. Mcelhaney, Nonye Alozie, Reina Fujii

Journal of Pre-College Engineering Education Research (J-PEER)

This paper addresses an important consideration for promoting equitable engineering instruction: understanding how teachers contextualize curricular materials to draw upon student and community resources. We present a descriptive case study of two 5th grade teachers who co-designed a Next Generation Science Standards (NGSS)-aligned curricular unit that integrated science, engineering, and computational modeling. The five-week project challenged students to redesign their school grounds to reduce water runoff and increase accessibility for students with disabilities. The teachers implemented the project with one Grade 5 class with a large proportion of students having individualized learning plans and cultural backgrounds minoritized in science, technology, …

The Life And Legacy Of William Rankine, Andy Pearson

International Refrigeration and Air Conditioning Conference

Professor William Rankine, who was born on July 5 1820, made a substantial contribution to the science of heat and power and his influence in refrigeration and air-conditioning is still apparent today. This paper gives a short overview of Rankine’s life and work and then considers how his legacy is relevant to the challenges facing refrigeration, air conditioning and heat pump engineers in the 21st century. These include system efficiency, expansion methods, alternative cycles and novel working fluids.

Comprehensive Modeling Of A Chemical Looping Heat Pump With A Reverse Fuel Cell, Junyoung Kim, Nelson A. James, James E. Braun, Eckhard A. Groll, Davide Ziviani

International Refrigeration and Air Conditioning Conference

HVAC, refrigeration, and water heating accounted for approximately 22 quads of primary energy consumed in the United States in 2018, according to US EIA. Most of HVAC&R industry still relies on vapor compression and heat-driven technologies. The development of highly efficient technologies that would significantly improve both COP and annual energy savings is an open challenge for the new decade. Among the novel technologies, the Chemical Looping Heat Pump (CLHP) combined with a reverse fuel cell has been modeled with estimates of a COP increase of over 20% relative to a conventional vapor compression (VC) cycle. However, limitations of simplified …

A Study On Computational Cost Reduction Of Simulations Of Phase-Change Material (Pcm) Embedded Heat Exchangers, Daniel Bacellar, Tanjebul Alam, Jiazhen Ling, Vikrant Aute

International Refrigeration and Air Conditioning Conference

Thermal storage can be implemented using Phase-Change Materials (PCM), which absorb significant latent heat with a relatively small temperature change. PCM phase-change processes are transient and are driven by thermal diffusion and natural convection – the latter, especially for melting process. Modeling and simulation of PCM heat exchangers (HX’s) is typically computationally intensive due to the relatively complex time-dependent physics. Most of the PCM modeling work in the literature uses high-order modeling tools such as Computational Fluid Dynamics (CFD) and Lattice-Boltzmann Method (LBM). For design purposes, the existing PCM modeling approaches are not practical, limiting researchers in their ability to …

Local Sensing And Personalized Thermal Comfort: Model-Predictive Vs Conventional Control Approaches, Hejia Zhang, Xiaoqi Liu, Seungjae Lee, Athanasios Tzempelikos

International High Performance Buildings Conference

Model-based and model predictive control (MPC) based on personalized thermal preferences has the potential to minimize energy consumption and guarantee occupant thermal comfort. This paper presents the implementation of personalized controls that satisfy personalized thermal preferences in private offices. Two control strategies, a simple PID control and a real-time model predictive control, were implemented through the Building Management System in two adjacent identical office spaces. In each office, monitoring and control of indoor thermal conditions was achieved either by using a conventional wall thermostat or by using a low-cost wireless local sensing network -both integrated with the building management system. …

A Practical Data-Driven Multi-Model Approach To Model Predictive Control: Results From Implementation In An Institutional Building, Etienne Saloux, Nunzio Cotrufo, José Candanedo

International High Performance Buildings Conference

Model-based Predictive Control (MPC) is an effective solution to improve building controls. It consists of the use of weather and occupancy forecasts along with a control-oriented model to predict the behaviour of the building a few hours or days ahead, and thus optimize the operation of its systems. Although the potential of MPC is widely recognized, and plentiful operational data is often available, the development of a model requires a great deal of effort, significant technical expertise and knowledge of building systems. The challenge of creating a model is a hurdle that makes the on-site implementation of MPC in buildings …

Cfd Simulation Of Laminar Film Condensation On A Vertical Surface, David Vilar, Elena Martín, Jaime Sieres

International Refrigeration and Air Conditioning Conference

Two-dimensional simulations of laminar film condensation on a vertical surface are presented. A modified version of the interFoam solver present in OpenFOAM was developed, in order to take into account for energy and mass transfer. The Volume of Fluid (VOF) method is used to track the vapor-liquid interface, with the effects of interfacial stress, gravity and surface tension being considered. Concerning the mass transfer model between phases, several models are used in the literature. Some authors have chosen empiric models, which incorporate some parameters that must be tuned by trial and error. The right estimate of those parameters is essential, …

Optimization Of Refrigerant Compositions For Low-Gwp Refrigerant Mixtures Using Segment-By-Segment Heat Exchanger And Detailed System Models, Zhenning Li, Bo Shen, Kyle Gluesenkamp

International Refrigeration and Air Conditioning Conference

The recently introduced hydrofluoroolefin (HFO) refrigerants, including R1234yf and R1234ze(E), have significantly lower global warming potentials (GWPs) than traditional hydrofluorocarbon (HFC) refrigerants like R410A. However, prior tests show that direct drop-in of pure R1234yf or R1234ze(E) into equipment designed for R410A results in a decrease in heat exchanger capacity and the system coefficient of performance. The primary reason is the lower in-tube heat transfer performance of R1234yf and R1234ze(E) compared with that of R410A. To address this issue, previous studies have mixed the mildly flammable HFC R32 with HFOs to improve system performance, with HFC R125 also added to suppress …

Alternate Refrigerants For Heat Pump Water Heater Applications- Opportunities And Challenges, Kashif Nawaz, Bo Shen, Ahmed Elatar, Van Baxter, Omar Abdelaziz

International Refrigeration and Air Conditioning Conference

Growing awareness of the potential environmental impacts of conventional refrigerants (CFCs and HFCs) has led to efforts to identify suitable alternative refrigerants for various heat pump applications with minimum environmental impact. This study is focused on the performance evaluation of various alternatives including hydrocarbon (HC), hydroflouroolefins (HFO), and CO2 as drop-in-replacement for R134a for heat pump water heating (HPWH). Fundamental thermophysical properties have been used to highlight the important performance characteristics of the systems when such fluids are deployed working medium. Key performance parameters such as unified energy factor, first hour rating and thermal stratification in the water tank are …

Measurement Of Condensation Heat Transfer And Pressure Drop For Zeotropic Mixture R-454c And Its Components R-32 And R-1234yf In A Horizontal Microfin Tubes, Ethan P. Matty, Brian M. Fronk

International Refrigeration and Air Conditioning Conference

This paper compares the condensation heat transfer and pressure drop for zeotropic refrigerant R454C and its individual components, R32 and R1234yf, in a horizontal microfin tube. The microfin tube has a 4 mm outer diameter, 0.18 mm wall thickness, and a surface area ratio of 1.56. HFOs and HFC/HFO blends like R454C have low global warming potential and can be alternatives to HFC refrigerants when retrofitting a system or producing new equipment. However, there is an additional mass transfer resistance present during phase change for a zeotropic mixture, which results in reduced heat transfer performance. Microfin tubes enhance heat transfer …

A Cfd Investigation Of The Suction Process In A Screw Compressor, Matt Cambio, Scott Branch, Alberto Scala, Jonathan Harrison

International Compressor Engineering Conference

Computational fluid dynamics (CFD) has been widely applied to screw compressors. CFD has allowed engineers to gain a better understanding of the complex flows that occur inside the screw compressor. In many cases, the details revealed are only possible with CFD compared to 1-D simulations. Both CFD and 1D can reduce development costs and as in this case, guide decisions on the choice of hardware to be tested. This paper presents the flow details of the suction process in a screw compressor and the effects on performance. The cases presented are a twin screw rotor set applied to two different …

Modeling Of The Nist Intelligent Building Agents Labratory, Adam Jacob Kopach

International High Performance Buildings Conference

The Intelligent Building Agents Laboratory (IBAL) at the National Institute of Standards and Technology (NIST) will be used to experimentally study control strategies within the realm of commercial building air-conditioning systems. A simulation software (Klein, 2020) model of the IBAL has been created to help guide the experiments in the IBAL and to provide a software-based method of evaluating control strategies implemented in this facility. This simulation model is composed of the various components comprising the IBAL HVAC system such as heating coils, cooling coils, fans and dampers that can accurately simulate the actual component behavior under transient and off-design …

Analysis Of Automated Fault Detection And Diagnostics Records As An Indicator Of Hvac Fault Prevalence: Methodology And Preliminary Results, Amir Ebrahimifakhar, David Yuill, Amanda Smith, Jessica Granderson, Eliot Crowe, Yimin Chen, Hayden Reeve

International High Performance Buildings Conference

Faults in commercial buildings can cause energy waste and other performance problems such as reduced occupant comfort, reduced equipment longevity, and increased noise. However, it is currently unknown how commonly faults occur in different equipment types. This paper describes a method to estimate the prevalence of faults in air handling units, air terminal units, and rooftop units and the use of three metrics for summarizing results. This method was developed by the authors as part of a study which includes data from several automated fault detection and diagnostics (AFDD) data providers, providing a large sample with a wide range of …

Fault “Auto-Correction” For Hvac Systems: A Preliminary Study, Guanjing Lin, Marco Pritoni, Yimin Chen, Christopher Weyandt, Raphael Vitti, Jessica Granderson

International High Performance Buildings Conference

A Fault Detection and Diagnostics (FDD) tool is a type of energy management and information system that is designed to continuously identify the presence of faults and efficiency improvement opportunities through a 1-way interface to the building automation system and application of automated analytics. It is estimated that 5-30% energy saving can be achieved by employing FDD tools and implementing efficiency measures based on FDD findings. Although the potential of this technology is high, actual savings are only realized when an operator takes an action to fix the problem. There is a subset of faults that can be potentially addressed …

Fault Detection And Diagnosis For Residential Hvac Systems Using Transient Cloud-Based Thermostat Data, Fangzhou Guo, Bryan P. Rasmussen

International High Performance Buildings Conference

Fault detection and diagnosis (FDD) using aggregated smart thermostat data is a relatively new research field, but one with immediate practical application to residential indoor climate control. This paper analyzes a cloud-based dataset which contains thermostat history records of nearly 370,000 distinct residential HVAC systems in the U.S. The large, diverse, and growing dataset enables novel methods for detecting and diagnosing faults on systems with limited sensor data. This paper proposes a statistics-based FDD method for non-variable speed heat pump and air conditioning units, and demonstrates the effectiveness with several case studies. The proposed method identifies systems within a similar …

The Thermodynamic Behavior Of Low-Gwp Zeotropic Mixtures On Water-Source Heat Pump Equipment, Saad Saleem, Craig R. Bradshaw

International Refrigeration and Air Conditioning Conference

Regulatory changes, aimed at mitigating climate change, are forcing air-conditioning and heat pump manufacturers to change refrigerants in their products, including all Water-Source Heat Pumps (WSHPs). These changes require substantive changes to WSHP equipment design in order to continue to deliver heat pumps that meet product specifications and energy efficiency regulations. Some of the proposed low-GWP refrigerants to replace R410A, such as R452B and R454A, are zeotropic mixtures of refrigerants. Zeotropes with a significant glide may be taken advantage of in the refrigerant-to-water heat exchanger in a WSHP to improve overall system efficiency. However, there is a potential to also …

Refuge Must Be Given: Eleanor Roosevelt, The Jewish Plight, And The Founding Of Israel, John F. Sears

Purdue University Press Books

Refuge Must Be Given details the evolution of Eleanor Roosevelt from someone who harbored negative impressions of Jews to become a leading Gentile champion of Israel in the United States. The book explores, for the first time, Roosevelt’s partnership with the Quaker leader Clarence Pickett in seeking to admit more refugees into the United States, and her relationship with Undersecretary of State Sumner Welles, who was sympathetic to the victims of Nazi persecution yet defended a visa process that failed both Jewish and non-Jewish refugees.

After the war, as a member of the American delegation to the United Nations, Eleanor …

The Canine-Campus Connection, Mary Renck Jalongo

New Directions in the Human-Animal Bond

A primary mission of universities is promoting student success and well-being. Many college and university personnel have implemented initiatives that offer students the documented benefits of positive human-animal interaction (HAI). Accumulating evidence suggests that assistance dogs, therapy dogs, and shelter dogs can support student wellness and learning. The best programs balance the welfare of humans and canines while assessing students’ needs and complying with all laws and regulations. Contributors to this edited volume have drawn upon research across many disciplines as well as their extensive practical experiences to produce a timely and valuable resource—for administrators and students. Whether readers are …

Incipient Fascism: Black Radical Perspectives, Alberto Toscano

CLCWeb: Comparative Literature and Culture

The sordid twilight of the Trump presidency raised the stakes of the debate on fascism. While much of the discussion has been magnetised by the legitimacy of analogies with the 1930s, this article argues that a rich and complex tradition of Black radical critique of right-wing authoritarianism provides a vital resource for thinking through the problem of US fascism beyond analogy – beginning with the DuBoisian insight that a racial fascism forged by chattel slavery and settler-colonialism anticipated the ascendancy of European fascisms. The article homes in on Black radical theories of fascism developed in the wake of the movements …

Factors Influencing Student Stem Learning: Self-Efficacy And Outcome Expectancy, 21st Century Skills, And Career Awareness, Jung Han, Todd R. Kelley, J. Geoff Knowles

Technology Leadership and Innovation Faculty Publications

Social, motivational, and instructional factors impact students’ outcomes in STEM learning and their career paths. Based on prior research and expectancy-value theory, the study further explored how multiple factors affect students in the context of integrated STEM learning. High school STEM teachers participated in summer professional development and taught integrated STEM to students during the following school year, where scientific inquiry, biomimicry, 3D printing technology, and engineering design were integrated as instructional strategies. Surveys were conducted to measure teacher self-efficacy and outcome expectancy. Student STEM attitudes (self-efficacy and expectancy-value beliefs), 21st century skills, STEM career awareness, and STEM knowledge achievement …

Clima Y Café = Climate & Coffee: Adapting Together To Climate Change In Colombia (2020/2021 Engaged Activities), Jessica Eise

Brian Lamb School of Communication Working Papers

*Clima y Café* is a research-informed information and communication project to help Colombian coffee farmers adapt to climate change. It is participatory and practices tailored, collaborative activities that seek to (1) support farmers with targeted information, resources and solutions, (2) draw attention to their needs and (3) inspire and motivate change in local, regional, national and international communities. This report contains outreach activities supporting the social, engaged scholarship component of *Clima y Café *during the academic calendar year of 2020/202. Activities included podcast and radio segments, a photography exhibition, tailored WhatsApp videos, printed posters and calendars, Facebook Live meetings and …

Challenges Faced By Persons With Disabilities Using Self-Service Technologies, Dana Boucher, Neeti Dave, Steven Dedomenic, Kirsten Frey, Morgan Goetz, Charles Gomez, Emily Hamman, Kevin Hitch, Jonah Jordan, Wahaj Khan, Jakob Larsen, Caleb Macadaeg, Justin Macneill, Christina Mangione, Adriene Mannas, Kristen Martin, Madison Myers, Rujuta Patel, Shiv Patel, Brian Peterson, Kaitlyn Roberts, Zachary Sanders, Devin Shah, Ryley White, Kirsten Wozniak, Lindsay Wright, Clarisse Zigan, Justan Zommers, Bradley S. Duerstock

Undergraduate Coursework

Foreseeable game changing solutions to SSTs will allow for better universal access by better implementing features that are easy and intuitive to use from the inception. Additional robotic advancements will allow for better and easier delivery of goods for consumers. Improvements to artificial intelligence will allow for better communication through natural language and alternative forms of communication. Furthermore, artificial intelligence will aid consumers at SSTs by remembering the consumers preferences and needs. With all foreseeable game changing solutions people with disabilities will be consulted when new and improved SSTs are being developed allowing for the SST to maximize its potential.

Optimization Of An Embedded Phase Change Material Cooling Strategy Using Machine Learning, M. Bhatasana, A. M. Marconnet

CTRC Research Publications

No abstract provided.

Refuge Must Be Given: Eleanor Roosevelt, The Jewish Plight, And The Founding Of Israel, John F. Sears

Purdue University Press Book Previews

Refuge Must Be Given details the evolution of Eleanor Roosevelt from someone who harbored negative impressions of Jews to become a leading Gentile champion of Israel in the United States. The book explores, for the first time, Roosevelt’s partnership with the Quaker leader Clarence Pickett in seeking to admit more refugees into the United States, and her relationship with Undersecretary of State Sumner Welles, who was sympathetic to the victims of Nazi persecution yet defended a visa process that failed both Jewish and non-Jewish refugees.

After the war, as a member of the American delegation to the United Nations, Eleanor …

The Canine-Campus Connection: Roles For Dogs In The Lives Of College Students, Mary Renck Jalongo

Purdue University Press Book Previews

No abstract provided.