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Investigations Of Low Pressure Two-Phase Steam-Water Injector, Roman Kwidzinski, Dariusz Butrymowicz, Jaroslaw Karwacki, Marian Trela, Kamil Smierciew

International Refrigeration and Air Conditioning Conference

Vapor-liquid injector is a passive device in which thermal energy of vapor is used to compress and heat a cold liquid. In the past such injectors were used extensively for feeding water into boilers, especially of steam engines. Recently an interest in the two-phase injectors revived with new proposals of their application in thermal engineering, refrigeration and air conditioning. Low-pressure steam-water injectors may be applied as thermal driven liquid pump in absorption and steam ejection refrigeration systems. In this paper a close attention is paid to steam-water injectors in which superheated steam of relatively low pressure is the driving medium. …

Investigations Of Heat And Momentum Transfer In Vapor-Liquid Isobutane Injector, Kamil Smierciew, Dariusz Butrymowicz, Tomasz Przybylinski

International Refrigeration and Air Conditioning Conference

Renewable energy sources may be applied to drive refrigeration and air-conditioning systems, e.g. solar radiation, geothermal resources, heat derived from biomass or waste heat rejected form various thermal processes. In this case absorption refrigeration systems and ejection systems may be used for cooling applications. In both these systems the crucial problem is the development of a suitable liquid pump.  Energy consumption to drive these systems is not a major problem here as in most cases amount of energy required to drive a mechanical pump is a contribution of at most a few percent of the overall energy balance of …

Nutrition Education At First Glance, Allison G. Leffler Miss, Sarah O. Ulrich Miss

Williams Honors College, Honors Research Projects

This project is a community-based program conducted in a local community center, First Glance. It specifically worked with the Teen Mom and Young Mom programs as well as with their children in the Tiny Glancers program. Over the course of a year the authors planned, created, and implemented an interdisciplinary nutrition education unit with the objective of increasing their nutrition and health awareness while providing support in education fundamentals such as math skills and social-cultural awareness. The unit included pre-assessment surveys as well as round-table discussions with the participants to establish base knowledge, correlating yet age-appropriate lessons for the moms …

Hydroband: The Continuous Hydration Monitoring System, Karina E. Atkinson, Catherine P. Benedict

Williams Honors College, Honors Research Projects

Dehydration is defined as a mild, moderate, or extreme loss of water in the body. It can result in fever, muscle cramps, headaches, dizziness, or heat stroke in athletes. Ways to determine hydration levels include analysis of the urine, blood, or sweat, body weight changes, skin elasticity tests, and increases in core temperature. Patent search, research journals, and outside studies in the health and fitness market showed that a convenient and continuous hydration monitoring system was not available. Changes in core body temperature proved to be the quickest way to measure hydration levels. The HydroBand system is geared towards athletes …

Construction Of Polyurethane Fabric Nanocomposites For Use In Resistance Temperature Detectors-Effect Of Polyurethane Concentration, Multi-Walled Carbon Nanotubes, And Oxidant, Jordan M. Shaffer

Williams Honors College, Honors Research Projects

Current resistance temperature detectors (RTDs) are rigid and create pressure points when used in contact with the human body. The current RTDs can also not be used in confined areas like the inside of a prosthetic. The research done for this paper explores the possibility of creating a soft fabric like RTD that can accurately measure temperature. This RTD could be used in medical devices, be placed in prosthetic legs, and be worn for a long period of time creating no discomfort for the user. Polyurethane scaffolds were created through an electrospinning process and multiwalled carbon nanotubes were adhered to …

Diffusive Behavior Of Physically Cross-Linked Hydrogels, Morgan A. Stilke

Williams Honors College, Honors Research Projects

A hydrogel is a water swollen polymeric network that has the potential to transform a variety of biomedical applications because of its biocompatibility and water content. Unfortunately, hydrogels typically have poor mechanical robustness. The majority of the content is water, while the remaining structure consists of a physical network, a covalent network, or a combination of both, yielding strength and toughness. There are several strategies attempted to improve mechanical properties including double network hydrogels comprised of two interpenetrating networks: one being a highly crosslinked sacrificial network and the other being a weakly crosslinked network that maintains reversibility after deformation. However, …

Wavelet Transform Of Optical Conductivity Of Bi2sr2cacu2o8+X In The Normal And Superconducting State, Patrick Janovick

Williams Honors College, Honors Research Projects

This paper compares the wavelet transform of the optical conductivity of Bi₂Sr₂CaCu₂O_8+x in both the normal and the superconducting state. The wavelet transforms of the normal and superconducting state are also compared with wavelet transforms of the Drude model as well as the Lorentz model. The wavelet transform of the collected data for Bi₂Sr₂CaCu₂O_8+x is similar in shape to the Drude model. The wavelet transform of the collected data in the normal state corresponds to the Drude model with a high scattering rate and the collected …

The Synergists: An Exploration Of Choreography, Media, And Science, Christine Howe

Williams Honors College, Honors Research Projects

Christine Howe

Major: BFA in Dance

Project Sponsor: Cydney Spohn Number of credits: 2

The Synergists: An Exploration of Choreography, Media, and Science

Abstract

This research project combined choreography, media, and science as a means to explore creative process. For this project, I created my own interpretation of mixing dance and multimedia elements through the use of video projection. I questioned how the use of video projection would affect my choreographic process and how the video and live performance would support each other to portray a cohesive idea. The scientific source of inspiration included neuron structure and synaptic function. Through …

Self-Learning Backlash Inverse Control Of Cooling Or Heating Coil Valves Having Backlash Hysteresis, Jie Cai, James E. Braun

International Refrigeration and Air Conditioning Conference

Valves are widely used in HVAC systems to regulate liquid flow rate, such as hot- and chilled-water valves utilized in cooling and heating coils. These valves are typically controlled with motorized actuators where significant backlash hysteresis might exist and the backlash magnitude mostly depends on the clearance of the manufactured gearbox. Due to the hysteresis effect, unsatisfactory tracking performance results when using a conventional PI controller. This paper proposes a self-learning backlash inverse control approach to mitigate the backlash effect with moderate modifications to a conventional PI control. In the proposed approach, a self-learning procedure is carried out at the …

Biomechanics Of Retinal Venous Pulsations As Indicators Of Intracranial Pressure, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

The origin of retinal venous pulsations remains an open problem in physiology and medicine; so too, their exact relationship to intracranial pressure. This study takes a mathematical modeling approach to explore details of blood flow through the eye to reveal the mechanism of pulsations. The intravaginal, intraneural, and intraocular segments of the retinal arteries and veins are modeled as connected resistive-capacitive segments. The analysis incorporates two critical mechanical properties of these small blood vessels, not heretofore studied, which become significant under conditions of negative transmural pressures: (1) dramatically reduced compliance during flattening and (2) cross-sectional shape change as internal volume …

Analysis Of Dynamic Stability Of Ejector Expansion Refrigeration System, Jianqiang Deng, Lixing Zheng, Fei Wang

International Refrigeration and Air Conditioning Conference

The stable operation of a system is restricted by the intrinsic characteristics, namely harmonious matching among and between structure parameters and operation parameters. In this paper, we put forward an analysis method of the dynamic stability of the refrigeration system based on the First Approximation Theory of Lyapunov Stability Theorem and the evaluation of stability margin. It is carried out by linearizing the governing equations and analyzing the eigenvalue form of coefficient matrix. And the minimum logarithmic decrement is calculated to represent the stability margin. Analyzing the stability of gas cooler confirms the consistency between the mathematical stability and the …

Proportional-Integral Extremum Seeking For Optimizing Power Of Vapor Compression Systems, Daniel J Burns, Christopher R. Laughman, Martin Guay

International Refrigeration and Air Conditioning Conference

Conventionally, online methods for minimizing power consumption of vapor compression systems rely on the use of physical models. These model-based approaches attempt to describe the influence of commanded inputs, disturbances and setpoints on the thermodynamic behavior of the system and the resultant consumed electrical power. These models are then used online to predict the combination of inputs for a measured set of thermodynamic conditions that both meets the heat load and minimizes power consumption. However, these models of vapor compression systems must contain nonlinear terms of sufficient complexity in order to accurately describe the region near the optimum operating point(s), …

Virtual Household Refrigerators At Steady-State And Transient Conditions. Numerical Model And Experimental Validation, Nicolas Ablanque, Carles Oliet, Joaquim Rigola, Carlos-David Pérez-Segarra

International Refrigeration and Air Conditioning Conference

The aim of the present work is to present a comprehensive validation of a numerical model to simulate vapor compression refrigeration systems at steady state and transient conditions. The model simulates both the refrigeration cycle itself and the refrigerated compartments network, based on a modular approach where each element of the system is solved independently by means of appropriate models, while the whole system is solved iteratively based on the links established between the elements. The methodology implemented to achieve the transient simulation of the whole system combines a steady-state approach for the refrigerating cycle loop with a transient approach …

Performance Evaluation Of Peripheral-Finned Tube Evaporators Under Frosting Conditions, Marco Timmermann, Jader Barbosa

International Refrigeration and Air Conditioning Conference

The peripheral finned-tube (PFT) is a novel air-side geometry for compact heat exchangers. Previous studies (Pussoli et al., Int. J. Heat Mass Transfer 55, 2835–2843, 2012) dealt with the evaluation of the thermal-hydraulic performance of the PFT geometry under dry conditions (i.e., no frost or condensate formation on the air side). The present study is focused on quantifying the thermal-hydraulic perfomance of the PFT geometry under frosting conditions. PFT evaporators were tested in a closed loop wind tunnel calorimeter to quantify the influence of the tube wall temperature, air velocity and air psychrometric properties (temperature and relative humidity) on the …

Transient Modeling Of A Thermosiphon Based Air Conditioner With Compact Thermal Storage: Modeling And Validation, Rohit Dhumane, Yilin Du, Jiazhen Ling, Vikrant Aute, Reinhard Radermacher

International Refrigeration and Air Conditioning Conference

The Roving Comforter (RoCo) is an innovative personal thermal management technology currently being developed at the University of Maryland as part of Advanced Research Projects Agency – Energy (ARPA-e) project. Among several system configurations of RoCo, the paper focuses on a miniature battery-powered vapor compression cycle (VCC) system fitted on an autonomous robotic platform. The heat rejected from the condenser during its operation is stored in a compact phase change material (PCM) based heat storage device. The PCM can store only a limited amount of heat until it melts completely. The PCM heat exchanger needs to be designed so that …

Numerical Simulation On Forced Convection Cooling Of Horizontal Ionic Wind With Multi-Electrodes, Rong Li, Yijian He, Guangming Chen, Fengshuo Wen

International Refrigeration and Air Conditioning Conference

Enhancement ofheat transfer plays an important role in the cooling of electronic or refrigeration systems, and its characteristics could strongly affect the stability and performance of such systems. To enhance heat transfer, air cooling of forced convection remains one of the main solutions. For example, conventional rotary-fan air cooling is still dominant in many areas. However, with the increasing of heat generation in these systems, the limitation of the conventional rotary-fan air cooling is become more obvious. So, demands in novel air cooling technology become necessary, e.g., silent and high efficient air cooling. Recently, ionic wind, which has no moving …

Operation Analysis On Refrigeration System Combined With Heat Pipe, Haixia He, Wen Wang, Zhaogang Qi, Rui Zhuan, Qifan Gu

International Refrigeration and Air Conditioning Conference

In data center, telco equipment station and some central control rooms, there are some cases with cooling requirement all the year, their temperatures are usually controlled strictly whenever in summer or in winter. Moreover, due to clearness and safety requirement, the chiller should provide cooling water all the time even the outside environment is very cold. There had been some considerations about provide cooling capacity in cold climate with free environmental air by various heat exchangers directly. Without operating chillers, annual energy consumption on temperature control could be decreased. This paper proposed a system combined a chiller with an air-cooled …

Comparison Of Models For Calculation Of The Thermodynamic Properties Of Nh3-Co2-H2o Mixture, Vilborg Gudjonsdottir, Carlos Infante Ferreira

International Refrigeration and Air Conditioning Conference

Couple of models have been developed to calculate thermodynamic properties of NH3-CO2-H2O systems. These models are typically an equation of state for the vapor phase and an activity coefficient model for the liquid phase (Que & Chen, 2011). The activity coefficient models can be divided into three groups based on previous studies, Pitzer model, electrolyte Non Random Two Liquid (e-NRTL) model and extended UNIQUAC model. Que & Chen (2011) deem the e-NRTL model the model the most suitable for process modelling and simulations since it requires only binary interaction parameters and makes use of mole fraction concentration scale consistently for …

Heat Pumps Architecture Optimization For Enhanced Medium Temperature Geothermal Heat Use In District Heating, Matthildi Apostolou, Sahar Salame, Stéphanie Barrault, Assaad Zoughaib

International Refrigeration and Air Conditioning Conference

Use of geothermal heat in distric heating allows increasing the share of renewable energy use. However, in many cases, this share is limited by the district heating required temperature and seasonnal load variation. Heat pumps permit upgrading geothermal heat by increasing further the temperature while pumping residual heat from the network return. Therefore not only they substitute boilers for upgrading the temperature but also increase the capacity of the geothermal heat source by reducing the return temperature. This paper presents a methodology for heat pumps architecture optimization enhancing the use of geothermal heat. The methodology allows considering two optimisation objectives: …

Assessing Defrosting Performance On Hydrophilic, Hydrophobic, And Micro-Patterned Heat Transfer Surfaces, Nickolas C. Schmiesing, Andrew D. Sommers

International Refrigeration and Air Conditioning Conference

In this work, differences in drainage rates and defrosting effectiveness were explored for surfaces of differing wettability. Both patterned and non-patterned surfaces were explored. To date, six surfaces have been examined— an uncoated, untreated aluminum plate (Sample 1), an identical plate treated with a hydrophilic coating (Sample 2), a plate containing evenly-spaced micro-channels with no surface coating (Sample 3), a plate containing evenly-spaced micro-channels with a hydrophobic coating (Sample 4), and a surface containing a microstructural roughness gradient both with and without a hydrophobic surface coating (Samples 5 and 6). Cyclical tests containing frosting periods and defrosting periods were conducted …

Modelling Of An Automotive Multi-Evaporator Air-Conditioning System, Thomas Gillet, Emmanuelle Andrès, Amin El-Bakkali, Gérard Olivier, Vincent Lemort, Romuald Rullière, Philippe Haberschill

International Refrigeration and Air Conditioning Conference

With the arrival of plug-in hybrid electric vehicles (PHEV) and battery electric vehicles (BEV) with significant autonomy, battery cooling becomes a necessity in driving mode to ensure their durability and ability to charge rapidly. Â For these vehicles, the refrigerating system may be composed of two evaporators (for front and rear passengers) in order to afford cooled air in the cabin and a chiller or a built-in battery evaporator to cool down the traction battery. This kind of multi-evaporator air-conditioning system has a number of technological barriers that must be undone. They are related to the components sizing in a …

Modelling And Simulation Of A R744 Based Air Conditioning Unit, Mihir Mouchum Hazarika, Maddali Ramgopal, Souvik Bhattacharyya

International Refrigeration and Air Conditioning Conference

Studies show that the performance of transcritical R744 systems is highly sensitive to the high side pressure in the gas cooler. Hence use of appropriate strategy to control the high side pressure is essential to extract the best performance from these systems. In the present study, a R744 based air conditioning cycle with two expansion valves is considered for proper control of high side pressure and quality of refrigerant at evaporator exit. A system simulation model is developed for this cycle considering detailed model for each component. Both the gas cooler and evaporator considered here are crossflow heat exchangers with …

An Improved Approach For Modeling Plate Heat Exchangers Based On Successive Substitution In Alternating Flow Directions, Radia Eldeeb, Vikrant Aute, Reinhard Radermacher

International Refrigeration and Air Conditioning Conference

Finite volume modeling of plate heat exchangers is challenging in terms of computation time and robustness, especially in two-phase flow due to the coupling of pressure drop and heat transfer equations. Usually the entire heat exchanger is divided into segments and solved iteratively. Many thermophysical property calculations are required for each channel in each segment which is computationally expensive, especially with a high number of iterations. This led some models to employ pre-defined databases with many correction factors to overcome slow and unstable computation. In order to overcome this, an improved approach is developed for the analysis of plate heat …

Viscosity Correlations For Refrigerants And Other Working Fluids From Residual Entropy Scaling, Ian Bell, Arno Laesecke

International Refrigeration and Air Conditioning Conference

We apply a modified scaling of viscosity with residual entropy in a manner analogous to that proposed by Rosenfeld (1977). We consider the viscosity-entropy scaling for a reference fluid (refrigerant R124 (1-chloro-1,2,2,2- tetrafluoroethane) ), and demonstrate that the viscosity for many other refrigerants scales with residual entropy in a similar manner. Finally, we use a corresponding-states formalism with one adjustable parameter to obtain the viscosity in a non-iterative fashion for a number of refrigerants. The viscosities of the studied fluids are represented within average absolute deviations of 10%. The evaluation of the liquid viscosity from this formulation is approximately 40 …

A Review Of State Of The Art In Modeling Of Air-To-Refrigerant Heat Exchangers For Hvac&R Applications, Vikrant C. Aute

International Refrigeration and Air Conditioning Conference

Air-to-refrigerant heat exchangers are a key component in all air-conditioning, heat pump and refrigeration systems. The most common of types of air-to-refrigerant heat exchangers are tube-fin and microchannel heat exchangers. There has always been a great emphasis on understating the underlying physics and improving the performance of these heat exchangers. More recently, researchers have been investigating the use of small hydraulic diameter flow channels as well as novel heat transfer surfaces for use in such heat exchangers. The novel designs not only include shape optimized tubes, but also tube bundles with varying tube and fin geometries. In order to design …

A Study Of Microchannel Heat Exchanger Performance Associated With The Manufacturing Process, Hui Zhao, Sharat Raghunandanan, Stefan Elbel, Pega Hrnjak

International Refrigeration and Air Conditioning Conference

The increased demand for aluminum microchannel condensers in the HVAC&R industry imposes new challenges on the design and manufacturing processes. An aluminum microchannel heat exchanger typically contains three major components: headers, microchannel tubes and multi-louvered fins. The parts are assembled and joined together by a brazing process. To ensure high thermal performance of the brazed product, microchannel heat exchanger designers must carefully consider manufacturing issues related to the brazing process during the design stage. For example, in addition to proper sizing of the header manifolds, it is essential to determine the optimal insertion length of the microchannel tube into the …

Statistical Analysis Of The Effectiveness Of Seawalls And Coastal Forests In Mitigating Tsunami Impacts In Iwate And Miyagi Prefectures, Roshanak Nateghi, Jeremy D. Bricker, Seth D. Guikema, Akane Bessho

School of Industrial Engineering Faculty Publications

The Pacific coast of the Tohoku region of Japan experiences repeated tsunamis, with the most recent events having occurred in 1896, 1933, 1960, and 2011. These events have caused large loss of life and damage throughout the coastal region. There is uncertainty about the degree to which seawalls reduce deaths and building damage during tsunamis in Japan. On the one hand they provide physical protection against tsunamis as long as they are not overtopped and do not fail. On the other hand, the presence of a seawall may induce a false sense of security, encouraging additional development behind the seawall …

Heat Transfer Analysis In The Cylinder Of Reciprocating Compressor, Ján Tuhovcák, Jí?Í Hej?Ík, Miroslav Jícha

International Compressor Engineering Conference

Heat transfer inside the cylinder of reciprocating compressor causes decrease of volumetric efficiency. The reason is superheating of the working fluid from the cylinder walls, which are heated up by the compression process itself. Decreasing gas superheating is favorable not just for efficiency, but also for reliability of a compressor. Understanding heat transfer phenomenon inside the cylinder is necessary step for that. Nowadays there are several empirical correlation available in the literature, which are often used in simulation tools due to their easy-to-use properties and capability of providing fast results with solid accuracy compared to more complex numerical models for …

Application Of Single Blow Technique For Heat Transfer Measurement In Packed Bed Of Vegetables, Dariusz Butrymowicz, Adam Lapinski, Jerzy Gagan, Kamil Smierciew

International Refrigeration and Air Conditioning Conference

The non-invasive measurement of the mean heat transfer coefficient for the packed bed of fruits and vegetables may be thought as still open issue. There is a clear need for the assessment of heat transfer conditions for various types of fruits and vegetables in order to accurately predict the thermal load that is necessary to select refrigeration equipment for cold storage chamber. Additionally, there is significant development in numerical modeling of heat and mass transfer processes in cold storage chambers for fruits and vegetables which requires precise heat transfer description. The theoretical basis for the indirect measurement approach of heat …

Steady-State Numerical Simulation Of A Vapor Compression Heat Pump System As An Effective Method To Predict Its Performance, Zvonimir Jankovi?, Jaime Sieres Atienza, Fernando Cerdeira Pérez, Branimir Pavkovi?

International Refrigeration and Air Conditioning Conference

During the last two decades a strong driving force is directed to development of the simulation models and methodologies for vapor compression systems and its main components simulation. These models are highly useful as an effective method to predict the system performance and the thermodynamic processes of the vapor compression system under different operating conditions or different components’ properties. This paper presents the mathematical model of a reversible heat pump and numerical steady-state simulations with refrigerant R407C. Using the information from manufacturer data and real properties of scroll compressor, brazed plate heat exchangers and additionally built-in liquid-vapor heat exchanger, the …