The Development of a Full Field Three-Dimensional Microscale Flow Measurement Technique for Application to Near Contact Line Flows

The goal of this paper is to present details of the development of a new three-dimensional velocity field measurement technique which can be used to provide more insight into the dynamics of thin evaporating liquid films (not limited to just low heat inputs for the heat transfer) and which also could prove useful for the study of spreading and wetting phenomena and other microscale flows

A Catholic and Marianist Engineering Education

The School of Engineering at the University of Dayton (UD), a Catholic and Marianist University, boasts large enrollments of 1,300 undergraduate and 350 graduate students out of a total of 7,000 undergraduates and 3,000 graduate students. It also boasts a faculty very active in research, which, under the umbrella of the University of Dayton Research Institute, is funded at a level of $100 million per year. In the past decade, the University of Dayton has sought to better articulate the impact of its Catholic and Marianist traditions, and faculty have been challenged to embody these traditions. University mission statements and unit strategic plans have also evolved to make better connections. In this context, our paper explores the historical and present connections to these traditions, and then more importantly presents a vision for better integration of them into the education of our students. The visioning really represents an early foray into thinking about greater embodiment of mission into the engineering education at Catholic universities. Finally, we envision what a specific application of the principles to a course in thermodynamics would look like and consider extension to all engineering courses

Effects of thermocapillarity on an evaporating extended meniscus in microgravity

An analytical investigation of the effects of thermocapillarity on the flow field within and heat transfer from the extended meniscus region of a heated meniscus which is re-supplied by capillarity is presented. Microgravity conditions are considered. The analysis shows that even for extremely small temperature differences between the wall and the vapor (less than 1 mK) thermocapillary stresses at the liquid-vapor interface due to a non-uniform interfacial temperature drastically alters the flow field. At the same time, these stresses were shown to have only a slight effect on the heat transfer from the extended meniscus but increasing with an increasing temperature difference. Additionally, thermocapillary effects were shown to be sensitive to pore size. A criterion was established from a scaling analysis identifying the conditions necessary for thermocapillarity to affect the operation of capillary-pumped heat transport devices in microgravity. A critical Marangoni number and corresponding critical temperature difference between wall and vapor were identified

Carbon Nanoadditives to Enhance Latent Energy Storage of Phase Change Materials

Latent energy storage capacity was analyzed for a system consisting of carbon nanoparticlesdopedphase changematerials (PCMs). Three types of samples were prepared by doping shell wax with single wall carbon nanotubes(SWCNTs), multiwall CNTs, and carbon nanofibers. Differential scanning calorimetry was used to measure the latent heat of fusion. The measured values of latent heat for all the samples showed a good enhancement over the latent heat of pure wax. A maximum enhancement of approximately 13% was observed for the wax/SWCNT composite corresponding to 1% loading of SWCNT. The change in latent heat was modeled by using an approximation for the intermolecular attraction based on the Lennard-Jones potential. A theoretical model was formulated to estimate the overall latent energy of the samples with the variation in volume fraction of the nanoparticles. The predicted values of latent energy from the model showed good agreement with the experimental results. It was concluded that the higher molecular density of the SWCNT and its large surface area were the reasons behind the greater intermolecular attraction in the wax/SWCNT composite, which resulted in its enhanced latent energy. The novel approach used to predict the latent heat of fusion of the wax/nanoparticle composites has a particular significance for investigating the latent heat of PCM with different types of nanoparticle additives

Achieving Energy Justice in Low Income Communities: Creating a Community-Driven Program for Residential Energy Savings

The cost of residential energy the U.S. is unequally distributed, with low income households paying higher rates and spending 16.8% of their income on utility bills compared to 3.5% of all U.S. Residents.[1] Researchers have found that bringing the housing stock up to the efficiency of the median household would reduce excess energy cost by as much as 68%.[2] However, access to opportunities to reduce residential energy consumption and costs such as tax incentives and utility rebate programs tends to be biased toward wealthier, white homeowners. Additionally, low income residents are most likely to be renters, and residence owners have little incentive to improve the energy effectiveness of their properties. Beyond its economic benefits, energy efficiency is essential to reducing local environmental pollution from high-emissions energy sources and to reducing carbon emissions that contribute to global climate change, the direct and indirect harms of which are more likely to impact low income and non-white populations.[3] Our research explores methods of achieving energy justice in low income communities through a pilot study in the Twin Towers neighborhood of Dayton Ohio. By providing free wifi and smart thermostats, our pilot narrows the digital divide and provides immediate opportunities for residents to exercise more control over their energy use and learn more about how to further reduce their utility bills. Building on existing community resources and organizational capacity, we are developing a peer-to-peer education program with the goal of contributing to the long term eco-economic transformation of the Twin Towers neighborhood and developing a model for the replication of the program in other communities. We propose that engaging the community in the grassroots creation of a neighborhood energy savings initiative is a more effective approach - one that emphasizes energy justice rather than simply energy efficiency - than previous top-down efforts. [1] Drehobl, A., & Ross, L. (2016). “Lifting the High Energy Burden in America’s Largest Cities: How Energy Efficiency Can Improve Low Income and Underserved Communities.” American Council for an Energy Efficient Economy, Washington, DC. [2] Lin, J. (2018). “Energy Affordability and Access in Focus: Metrics and Tools of Relative Energy Vulnerability.” Behavior, Energy & Climate Change Conference. Behavior, Energy & Climate Change Conference, Washington, DC [3] Mohai, P., Pellow, D., & Roberts, J. T. (2009). Environmental Justice. Annual Review of Environment and Resources, 34(1), 405–430

Estimating Smart Wi-Fi Thermostat-Enabled Thermal Comfort Control Savings for Any Residence

Nowadays, most indoor cooling control strategies are based solely on the dry-bulb temperature, which is not close to a guarantee of thermal comfort of occupants. Prior research has shown cooling energy savings from use of a thermal comfort control methodology ranging from 10 to 85%. The present research advances prior research to enable thermal comfort control in residential buildings using a smart Wi-Fi thermostat. Fanger\u27s Predicted Mean Vote model is used to define thermal comfort. A machine learning model leveraging historical smart Wi-Fi thermostat data and outdoor temperature is trained to predict indoor temperature. A Long Short-Term-Memory neural network algorithm is employed for this purpose. The model considers solar heat input estimations to a residence as input features. The results show that this approach yields a substantially improved ability to accurately model and predict indoor temperature. Secondly, it enables a more accurate estimation of potential savings from thermal comfort control. Cooling energy savings ranging from 33 to 47% are estimated based upon real data for variable energy effectiveness and solar exposed residences

Capillary Pumped Heat Transfer (CHT) Experiment

The operation of Capillary Pumped Loops (CPL's) in low gravity has generally been unable to match ground-based performance. The reason for this poorer performance has been elusive. In order to investigate the behavior of a CPL in low-gravity, an idealized, glass CPL experiment was constructed. This experiment, known as the Capillary-driven Heat Transfer (CHT) experiment, was flown on board the Space Shuttle Columbia in July 1997 during the Microgravity Science Laboratory mission. During the conduct of the CHT experiment an unexpected failure mode was observed. This failure mode was a result of liquid collecting and then eventually bridging the vapor return line. With the vapor return line blocked, the condensate was unable to return to the evaporator and dry-out subsequently followed. The mechanism for this collection and bridging has been associated with long wavelength instabilities of the liquid film forming in the vapor return line. Analysis has shown that vapor line blockage in present generation CPL devices is inevitable. Additionally, previous low-gravity CPL tests have reported the presence of relatively low frequency pressure oscillations during erratic system performance. Analysis reveals that these pressure oscillations are in part a result of long wavelength instabilities present in the evaporator pores, which likewise lead to liquid bridging and vapor entrapment in the porous media. Subsequent evaporation to the trapped vapor increases the vapor pressure. Eventually the vapor pressure causes ejection of the bridged liquid. Recoil stresses depress the meniscus, the vapor pressure rapidly increases, and the heated surface cools. The process then repeats with regularity

Clean Energy Infrastructure Educational Initiative

The Clean Energy Infrastructure Educational Initiative represents a collaborative effort by the University of Dayton, Wright State University and Sinclair Community College. This effort above all aimed to establish energy related programs at each of the universities while also providing outreach to the local, state-wide, and national communities. At the University of Dayton, the grant has aimed at: solidfying a newly created Master\u27s program in Renewable and Clean Energy; helping to establish and staff a regional sustainability organization for SW Ohio. As well, as the prime grantee, the University of Dayton was responsible for ensuring curricular sharing between WSU and the University of Dayton. Finally, the grant, through its support of graduate students, and through cooperation with the largest utilities in SW Ohio enabled a region-wide evaluation of over 10,000 commercial building buildings in order to identify the priority buildings in the region for energy reduction. In each, the grant has achieved success. The main focus of Wright State was to continue the development of graduate education in renewable and clean energy. Wright State has done this in a number of ways. First and foremost this was done by continuing the development of the new Renewable and Clean Energy Master\u27s Degree program at Wright State . Development tasks included: continuing development of courses for the Renewable and Clean Energy Master\u27s Degree, increasing the student enrollment, and increasing renewable and clean energy research work. The grant has enabled development and/or improvement of 7 courses. Collectively, the University of Dayton and WSU offer perhaps the most comprehensive list of courses in the renewable and clean energy area in the country. Because of this development, enrollment at WSU has increased from 4 students to 23. Secondly, the grant has helped to support student research aimed in the renewable and clean energy program. The grant helped to solidify new research in the renewable and clean energy area. The educational outreach provided as a result of the grant included activities to introduce renewable and clean energy design projects into the Mechanical and Materials Engineering senior design class, the development of a geothermal energy demonstration unit, and the development of renewable energy learning modules for high school students. Finally, this grant supported curriculum development by Sinclair Community College for seven new courses and acquisition of necessary related instrumentation and laboratory equipment. These new courses, EGV 1201 Weatherization Training, EGV 1251 Introduction to Energy Management Principles, EGV 2301 Commercial and Industrial Assessment, EGV 2351 LEED Green Associate Exam Preparation, EGV 2251 Energy Control Strategies, EGV Solar Photovoltaic Design and Installation, and EGV Solar Thermal Systems, enable Sinclair to offer complete Energy Technology Certificate and an Energy Management Degree programs. To date, 151 students have completed or are currently registered in one of the seven courses developed through this grant. With the increasing interest in the Energy Management Degree program, Sinclair has begun the procedure to have the program approved by the Ohio Board of Regents

Data Mining of Smart WiFi Thermostats to Develop Multiple Zonal Dynamic Energy and Comfort Models of a Residential Building

Smart WiFi thermostats have gained an increasing foothold in the residential building market. The data emerging from from these thermostats is transmitted to the cloud. Companies like Nest and Emerson Climate Technologies are attempting to use this data to add value to their customers. This overarching theme establishes the foundation for this research. This research seeks to utilize WiFi data from the Emerson Climate Technologies’ Helix test house to: develop a dynamic model to predict real time cooling demand and then apply this model to running ‘what-if’ thermostat scheduling scenarios with the ultimate goal of reducing energy use in the residence or responding to high demand events. The Helix residence, with two thermostat controlled zones for each floor, exists in a temperature/humidity controlled external environment, which can be controlled to simulate environmental conditions present in the hottest to coldest climates. A Design of Experiment approach was used to establish data needed for the model. The control variables in the experiments included: levels for the exterior environmental schedule and levels for the interior setpoint schedules for both zones. Simply, this data enabled data collection for constant or cyclical exterior environmental conditions and constant and scheduled interior setpoint conditions, not necessarily the same for each floor. From this data, a regression tree approach (Random Forest) was used to develop models to predict the room temperature as measured by each thermostat, as well as the cooling status for each zone. The models developed, when applied to validation data (e..g, data not employed in training the model) R2 values of greater than 0.95. Then, the models developed were utilized for various ‘What if’ scenarios. Two such scenarios were considered. The first looked at the possibility of using the model to estimate comfort in a demand response event, e.g., when the grid manager calls for demand reduction. In this case, the heat pump providing cooling would be powered off for some time. The second scenario sought to quantify the cooling savings from use of higher thermostat setpoint during simulated non-occupied periods and for different exterior temperature schedules. The ‘What if’ predictions are validated with experimental data, thus demonstrating the value of the data-driven, dynamic data solely from smart WiFi thermostat information

A Study of the Fundamental Operations of a Capillary Driven Heat Transfer Device in Both Normal and Low Gravity Part 1-Liquid Slug Formation in Low Gravity

Research has been conducted to observe the operation of a capillary pumped loop (CPL) in both normal and low gravity environments in order to ascertain the causes of device failure. The failures of capillary pumped heat transport devices in low gravity; specifically; evaporator dryout, are not understood and the available data for analyzing the failures is incomplete. To observe failure in these devices an idealized experimental CPL was configured for testing in both a normal-gravity and a low-gravity environment. The experimental test loop was constructed completely of Pyrex tubing to allow for visualization of system operations. Heat was added to the liquid on the evaporator side of the loop using resistance heaters and removed on the condenser side via forced convection of ambient air. A video camera was used to record the behavior of both the condenser and the evaporator menisci simultaneously. Low-gravity experiments were performed during the Microgravity Science Laboratory (MSL-1) mission performed onboard the Space Shuttle Columbia in July of 1997. During the MSL-1 mission, a failure mechanism, heretofore unreported, was observed. In every experiment performed a slug of liquid would form at the transition from a bend to a straight run in the vapor line. Ultimately, this liquid slug prevents the flow of vapor to the condenser causing the condenser to eventually dryout. After condenser dryout, liquid is no longer fed into the evaporator and it, too, will dry out resulting in device failure. An analysis is presented to illustrate the inevitable formation of such liquid slugs in CPL devices in low gravity