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The Effects Of Fin Spacing And Tube Outer Diameter Of Evaporator On System Performance In Heat Pump Tumble Dryers, Cenk Onan, Serkan Erdem, Derya Burcu Özkan, Hasan Alpay Heperkan

International Refrigeration and Air Conditioning Conference

In heat pump tumble dryers, moisture separates from the laundry and leaves the dryer system at the evaporator. Moist air goes out the drum and enters the evaporator whose outer surface is below the dew point temperature. Air cools and then leaves its moisture. At the airside of the evaporator the wet surface develops and simultaneous heat-mass transfer occurs. Fin-and-tube heat exchangers are used as evaporators in household heat pump tumble dryers. In addition to optimum operating conditions, optimum evaporator geometry can significantly affect system performance. In this study, a model was developed for household heat pump tumble dryer. The …

Transient 1d Heat Exchanger Model For The Simulation Of Domestic Cooling Cycles Working With R600a, Erwin Berger, Martin Heimel, Stefan Posch, Raimund Almbauer, Martin Eichinger

International Refrigeration and Air Conditioning Conference

Generally, domestic refrigerators and freezers are running in non-continuous operation mode most of the time, which is a necessity to match cooling capacity to thermal loads. In currently available domestic appliances this matching is realized either by on/off or variable frequency control of the hermetic compressor, leading to a repetitive and transient change of the system state. On the other hand, if the runtimes of the compressor are longer because cooling capacity demand is high (e.g. pull down cycles, initial operation), steady state operating conditions might be reached. The cycling transients cause losses in system efficiency thus they should be …

Exergy And Energy Analysis Of Waste Heat Recovery Options For Cooling Capacity Production, Chantal Maatouk, Rayan Slim

International Refrigeration and Air Conditioning Conference

Electricity production in Lebanon stands at around 1.5 GW while the demand exceeds 2.5 GW at peak times and peak cooling demands, resulting in rationing cuts from between 3 to 20 hours a day which is the worst performance in the Middle East. Due to the country energy shortfall, a large number of small-scale backup generators is installed to address the electric and cooling needs. The proliferation of use of these backup generators presents an interesting potential for waste heat recovery in order to achieve additional power generation and cooling capacity production. This paper investigates two possible configurations for waste …

Theoretical And Experimental Research On Co2 Electrical Heating Pool Boiling Heat Transfer Outside A Horizontal Tube, Lan Li, Shengchun Liu, Jinghong Ning

International Refrigeration and Air Conditioning Conference

Numerical simulation on electrical heating pool boiling heat transfer with CO2 as refrigerant outside a horizontal tube is carried. A voltage-controlled heating method has been used in the experiment, with the advantages of good stability and adjustability of the experimental heat flux density. After a series of preliminary calculation and pre-work, numerical simulation is carried based on a software FLUENT. Bubble behaviors are observed, the distribution regularity of volume fraction of vapor is obtained and compared with the experimental results. The results show that numerical simulation and experimental results are in good agreement. Furthermore, by changing the heat flux density, …

Thermodynamic Analysis And Optimization Of Cascade Condensing Temperature Of A Co2(R744)/R404a Cascade Refrigeration System, Baris Yilmaz, Nasuh Erdonmez, Mustafa Kemal Sevindir, Ebru Mancuhan

International Refrigeration and Air Conditioning Conference

Synthetic refrigerants are widely used in refrigeration applications. However, it is shown that such refrigerants have negative impacts on the ozone layer of atmosphere. Recently, natural refrigerants such as carbon dioxide and various hydrocarbon compounds are proposed to replace synthetic refrigerants in the industrial refrigeration systems. Carbon dioxide is one of the most promising and environment-friendly refrigerant solution due to its thermo-physical properties, low ozone depletion value and low global warming potential. In this study thermodynamic analysis of a two stage sub-critical cascade refrigeration system using CO2 and R404a refrigerants in low temperature and high temperature cycles is presented. The …

Model Predictive Control Of Variable Refrigerant Flow Systems, Neera Jain, Daniel J. Burns, Stefano Di Cairano, Christopher R. Laughman, Scott A. Bortoff

International Refrigeration and Air Conditioning Conference

Model Predictive Control (MPC) of vapor compression systems (VCSs) offers several advantages over conventional control methods (such as multivariable process control with selector logic) in terms of 1) the resulting closed-loop performance and 2) the control engineering design process. VCSs are multivariable systems and feature constraints on system variables and actuators that must be enforced during steady-state and transient operation. We present the design and validation of an MPC for a split ductless VCS. The design regulates room temperature with zero steady state error for unknown changes in the thermal load and enforces constraints on system variables such as compressor …

Standardized Polynomials For Fast Evaluation Of Refrigerant Thermophysical Properties, Vikrant Aute, Reinhard Radermacher

International Refrigeration and Air Conditioning Conference

Steady state and dynamic simulation and optimization are a key step in the design of heating, ventilation, air-conditioning and refrigeration (HVAC&R) systems. It is well known that the computation time in such simulations is dominated by the refrigerant thermophysical property calculations. These calculations generally involve calculating all thermophysical properties given one or two independent parameters. Refrigerant thermophysical properties are typically calculated using some fundamental equations of state (EOS). The NIST REFPROP database is an industrially accepted standard for EOS implementation. Due to the iterative nature of the EOS calculations in REFPROP, the computation time is significant and sometimes not acceptable …

Field Evaluation For Air-Source Transcritical Co2 Heat Pump Water Heater With Optimal Pressure Control, Bin Hu, Yongning He, Shouguo Wang, Feng Cao, Ziwen Xing

International Refrigeration and Air Conditioning Conference

Air-source transcritical CO2 heat pump water heater (ATHW) can supply hot water from 60 ? to 90 ? at high efficiency with environment-friendly refrigerant CO2 for commercial, residential and industrial applications. Several optimal discharge pressure correlations for transcritical CO2 heat pump have been proposed in the past few years, most of which are related to the ambient temperature, the evaporation temperature and the gas cooler outlet temperature. In an earlier study, the authors’ research group had presented a study on the dependency of the optimal discharge pressure on the ambient temperature and the hot water outlet temperature. In this study, …

A Comparison Of Transient Heat-Pump Cycle Simulations With Homogeneous And Heterogeneous Flow Models, Christopher R. Laughman

International Refrigeration and Air Conditioning Conference

This paper compares the effects of two different refrigerant flow modeling assumptions on the transient performance of vapor-compression heat pump cycles. These simulations are developed in the next-generation modeling language Modelica, which uses an acausal, equation-oriented approach to describe physical systems. The effect of the flow assumptions and specific slip ratio correlations on both the equilibrium operating point and the transient behavior of the cycle are demonstrated through these simulations. It is shown that equivalent simulations with different slip ratio correlations each have different equilibrium mass inventories, and that some aspects of the transient system behavior exhibits minor differences between …

Validation Of A Fault-Modeling Equipped Vapor Compression System Model Using A Fault Detection And Diagnostics Evaluation Tool, David P. Yuill, Howard Cheung, James E. Braun

International Refrigeration and Air Conditioning Conference

A methodology for evaluating the performance of fault detection and diagnostics (FDD) tools for unitary air-conditioners has been developed (Yuill and Braun 2013). The methodology uses laboratory measurements of systems with and without faults to test FDD tools’ effectiveness. A gray box modeling method capable of modeling systems with faults was developed by Cheung and Braun (2013a and 2013b) to provide input data, as an alternative to using laboratory data that had been collected. The simulation method was validated by direct comparison with experimental data, but a comparison of FDD evaluation results provides a more direct and useful validation of …

Kalman Filter-Based Fdd For An Air Handling Unit (Ahu), Timothy Mulumba, Afshin Afshari, Luiz Augusto Friedrich

International Refrigeration and Air Conditioning Conference

We propose to improve the energy efficiency of commercial HVAC systems by implementing a Kalman filter based fault detection and diagnosis (FDD) scheme to accurately identify certain categories of abnormal conditions that are the most prevalent in hot, humid climates like the UAE. The general approach used to deal with drift in system state includes the following tasks: 1) Determine possible model specifications, 2) Use a Kalman filter to determine time-varying parameters of the specified models, 3) Perform fault detection using a statistical process control and, 4) Perform fault diagnosis by formulating qualitative rules and comparing with those derived from …

Performance Of An R-410a Room Air Conditioner Modified For Use With R-1234ze, Charles Janicki, Konrad Hermann, John Neuman, Patrick Riley, Margaret M. Mathison

International Refrigeration and Air Conditioning Conference

This paper presents the results of a senior design project that challenged a team of undergraduate students to reduce the environmental impact of a room air conditioner (RAC) by reducing its energy consumption and/or use of high-GWP refrigerants. Over the course of an academic year, the team was able to investigate, design, model, evaluate, and build a prototype improved RAC. The team began by reviewing literature on approaches that have been proposed to meet or exceed existing energy efficiency and refrigerant selection regulations. Based on these findings and the specified needs of the project sponsor, the team evaluated the appropriateness …

Shots In The Dark: The Presence Of Absence In Imaginative Literature (Iw), Gene Washington

English Faculty Publications

Western metaphysics and IW can be described as a search for "first" presences, not absences. With the exception of philosophers like Martin Heidegger, Jean-Paul Sartre, and Aristotle, writers like Lord Rochester (John Wilmot), Jonathan Swift and Philip Larkin, no one, to my knowledge, has taken absence as a "first" and consequently as also a "last." This essay is a modest attempt to open the door, if only a crack, for investigations into the metaphysics and meaning of absence as a means of creating, and understanding an interesting IW—from the perspective of the presence of absence as "first" and as "last."

Blast-Induced Tinnitus: A Combined Behavioral, Memri, And Electrophysiology Study, Jessica Pengyun Ouyang

Wayne State University Dissertations

ABSTRACT

BLAST-INDUCED TINNITUS: A COMBINED BEHAVIORAL, MEMRE, AND ELECTROPHYSIOLOGY STUDY

by

JESSICA OUYANG

May 2014 Advisor: Drs. Steve Cala & Jinsheng Zhang

Major: Physiology

Degree: Doctor of Philosophy

Tinnitus and hearing loss are the frequent auditory-related co-morbidities of blast trauma. The etiology of blast-induced tinnitus is also muddled by brain mechanisms associated with emotional and cognitive problems such as anxiety, memory loss, and depression. We set out to develop a realistic and ecologically valid model to address changes of cognitive status and psychological state that are associated with blast- induced tinnitus. In this study, 19 adult rats were randomly divided …

Pedestrian Head Protection During Car To Pedestrian Accidents: In The Event Of Primary Impact With Vehicle And Secondary Impact With Ground, Vishal Gupta

Wayne State University Dissertations

Current regulations for assessing pedestrian safety use a simplified test setup that ignores many real-world factors. In particular, the level of protection is assessed using a free-motion headform impacting the vehicle's hood at a fixed angle. As such, this test setup does not capture the effect due to the vehicle front-end profile, nor does it comprehend injury due to a possible secondary impact of the pedestrian's head with ground. This thesis aims to numerically simulate vehicle to pedestrian crashes to develop knowledge that may suggest ways to improve safety above and beyond the regulatory tests. Inputs to the simulations include …

Study On Endurance Of Flash Memory Ssds, Mochan Shrestha

Wayne State University Dissertations

Flash memory promises to revolutionize storage systems because of its massive performance gains, ruggedness, large decrease in power usage and physical space requirements, but it is not a direct replacement for magnetic hard disks. Flash memory possesses fundamentally different characteristics and in order to fully utilize the positive aspects of flash memory, we must engineer around its unique limitations. The primary limitations are lack of in-place updates, the asymmetry between the sizes of the write and erase operations, and the limited endurance of flash memory cells. This leads to the need for efficient methods for block cleaning, combating write amplification …

Static Extraction Of Dataflow Communication For Security, Laurentiu Radu Vanciu

Wayne State University Dissertations

The cost of security vulnerabilities in widely-deployed code such as mobile applications is high. As a result, many companies are using Architectural Risk Analysis (ARA) to find security vulnerabilities before releasing their applications. The existing analyses are focused on finding local coding bugs such as a hard-coded password, rather than architectural flaws such as bypassing the authentication component. During ARA, to find vulnerabilities that are architectural flaws, security architects use a forest-level view of the runtime architecture instead of reading the code. Unfortunately, such a view is often missing from the documentation or is inconsistent with the code.

This thesis …

Software Power Analysis And Optimization For Power-Aware Multicore Systems, Shinan Wang

Wayne State University Dissertations

Among all the factors in sustainable computing, power dissipation and energy consumption, arguably speaking, are fundamental aspects of modern computer systems. Different from performance metric, power dissipation is not easy to measure because hardware instrumentation is usually required. Yet as an indispensable component of a computer system, software becomes a major factor affecting power dissipation besides hardware energy-efficiency and power states. With detailed information on resource usage and power dissipation of an application/software, software developers will be able to leverage algorithms and implementations in order to produce power-efficient solutions. Hardware instrumentation, despite its accuracy, is costly and complicated to set …

The Impact Of Nested Testing On Experiment-Wise Type I Error Rate, Jack Sawilowsky

Wayne State University Dissertations

When conducting a statistical test the initial risk that must be considered is a Type I error, also known as a false positive. The Type I error rate is set by nominal alpha, assuming all underlying conditions of the statistic are met. Experiment-wise Type I error inflation occurs when multiple tests are conducted overall for a single experiment. There is a growing trend in the social and behavioral sciences utilizing nested designs. A Monte Carlo study was conducted using a two layer design. Five theoretical distributions and four real datasets taken from Micceri (1989) were used, each with five different …

In-Network Processing For Mission-Criticalwireless Networked Sensing And Control: A Real-Time, Efficiency, And Resiliency Perspective, Qiao Xiang

Wayne State University Dissertations

As wireless cyber-physical systems (WCPS) are increasingly being deployed in mission-critical applications, it becomes imperative that we consider application QoS requirements in in-network processing (INP). In this dissertation, we explore the potentials of two INP methods, packet packing and network coding, on improving network performance while satisfying application QoS requirements. We find that not only can these two techniques increase the

energy efficiency, reliability, and throughput of WCPS while satisfying QoS requirements of applications in a relatively static environment, but also they can provide low cost proactive protection against transient node failures in a more dynamic wireless environment.

We first …

Study Of Chaotic Ultrasound And Frequency Sweep Excitations In Sonic Ir Nde Technology, Ding Zhang

Wayne State University Dissertations

Sonic Infrared (IR) Imaging Nondestructive Evaluation (NDE) technology has shown inherent advantages, such as fast detection for all direction and all dimension flaws, for both metal and composite materials. The purpose of this dissertation is to study and investigate the physical process of two most important methods, frequency sweep excitation and chaotic excitation, to improve the defect detection ability of Sonic IR technology.

The tool used in our study is known as finite element analysis (FEA). According to test process of Sonic IR technology, some special technologies were developed in FEA simulation, such as creating cracks with flat contact surfaces …

On Ranked Approximate Matching Of Large Attributed Graphs, Mohammad Shafkat Amin

Wayne State University Dissertations

Many emerging database applications entail sophisticated graph based query manipulation, predominantly evident in large-scale

scientific applications. To access the information embedded in

graphs, efficient graph matching tools and algorithms have become of prime importance. Although the prohibitively expensive time

complexity associated with exact sub-graph isomorphism techniques has limited its efficacy in the application domain, approximate yet efficient graph matching techniques have received much attention due to their pragmatic applicability. Since public domain databases are noisy and incomplete in nature, inexact graph matching techniques have proven to be more promising in terms of inferring knowledge from numerous structural data repositories.

Contemporary …

A Study Of The Relationship Between Resilience And Job Satisfaction In Direct Care Workers Who Work With Traumatic Brain Injured Clients, Michele Terese White

Wayne State University Dissertations

The direct care worker occupation is a very fast and growing workforce. In fact, by the year 2016, it is estimated that it might be the largest workforce in the country. With the rapid growth come difficulties. One of those difficulties is a high turn over rate. Research shows that people that are resilient stay longer at a job versus those who are not resilient. Is there a relationship between resilience and job satisfaction? This research sought to determine if a relationship existed. The research delved into a particular field, traumatic brain injury. This research study attempted to determine if …

Interference Modeling And Control In Wireless Networks, Xin Che

Wayne State University Dissertations

With the successful commercialization of IEEE802.11 standard, wireless networks have become a tight-knit of our daily life. As wireless networks are increasingly applied to real- time and mission-critical tasks, how to ensuring real-time, reliable data delivery emerges as an important problem. However, wireless communication is subject to various dynamics and uncertainties due to the broadcast nature of wireless signal. In particular, co-channel interfer- ence not only reduces the reliability and throughput of wireless networks, it also increases the variability and uncertainty in data communication [64, 80, 77].

A basis of interference control is the interference model which \emph{predicts} whether a …

Teak: A Novel Computational And Gui Software Pipeline For Reconstructing Biological Networks, Detecting Activated Biological Subnetworks, And Querying Biological Networks., Thair Judeh

Wayne State University Dissertations

As high-throughput gene expression data becomes cheaper and cheaper, researchers are faced with a deluge of data from which biological insights need to be extracted and mined since the rate of data accumulation far exceeds the rate of data analysis. There is a need for computational frameworks to bridge the gap and assist researchers in their tasks. The Topology Enrichment Analysis frameworK (TEAK) is an open source GUI and software pipeline that seeks to be one of many tools that fills in this gap and consists of three major modules. The first module, the Gene Set Cultural Algorithm, de novo …

Energy Efficiency Analysis And Optimization For Mobile Platforms, Grace Metri

Wayne State University Dissertations

The introduction of mobile devices changed the landscape of computing. Gradually, these devices are replacing traditional personal computer (PCs) to become the devices of choice for entertainment, connectivity, and productivity. There are currently at least 45.5 million people in the United States who own a mobile device, and that number is expected to increase to 1.5 billion by 2015.

Users of mobile devices expect and mandate that their mobile devices have maximized performance while consuming minimal possible power. However, due to the battery size constraints, the amount of energy stored in these devices is limited and is only growing by …

The Modulation Of Mucosal Immune Markers, Urs, And Psychological Parameters Following Acute And Chronic Exercise, Carole Ann Sloan

Wayne State University Dissertations

The purpose of this dissertation was to evaluate changes in two antimicrobial markers, upper respiratory symptom (URS) variables, and mood state following participation in an acute (N = 93) and chronic (N = 88) observational study of college aerobic exercise, yoga exercise, and non-exercise classes.

METHODS: Unstimulated whole saliva was collected pre/post-acute (50 minutes) and pre/midpoint/post-chronic (12 weeks) during the study period. Saliva was analyzed for salivary immunoglobulin A (SIgA) and salivary alpha amylase (SAA) using protocols and assay kits by Salimetrics, upper respiratory symptoms (URS) were evaluated using the Wisconsin Upper Respiratory Symptom Survey (WURSS), and mood states were …

Validity Of The Educator Evaluation Instrument In The State Of West Virginia, Carla Howe

Wayne State University Dissertations

In the state of West Virginia, the educator evaluation system was implemented in 2010 as part of a comprehensive system of support to increase teacher effectiveness and student learning. As part of the system, the Educator Evaluation Instrument was developed to measure teachers' effectiveness. This study was conducted to determine whether the Educator Evaluation Instrument was valid for use in measuring effectiveness.

A hierarchical confirmatory factor analysis (HCFA) was conducted on the scores from the demonstration year. The data were not normal, nor was good model fit established based on the current model. Because good model fit could not be …

Parameter Identification And Fault Detection For Reliable Control Of Permanent Magnet Motors, Dusan Vukosav Progovac

Wayne State University Dissertations

The objective of this dissertation is to develop new fault detection, identification, estimation and control algorithms that will be used to detect winding stator fault, identify the motor parameters and optimally control machine during faulty condition. Quality or proposed algorithms for Fault detection, parameter identification and control under faulty condition will validated through analytical study (Cramer-Rao bound) and simulation. Simulation will be performed for three most applied control schemes: Proportional-Integral-Derivative (PID), Direct Torque Control (DTC) and Field Oriented Control (FOC) for Permanent Magnet Machines. New detection schemes forfault detection, isolation and machine parameter identification are presented and analyzed. Different control …

Vehicle Lane Departure Prediction Based On Support Vector Machines, Alhadi Ali Albousefi

Wayne State University Dissertations

Advanced driver assistance systems, such as unintentional lane departure warning systems, have recently drawn much attention and R & D efforts. Such a system will assist the driver by monitoring the driver or vehicle behaviors to predict/detect driving situations (e.g., lane departure) and alert the driver to take corrective action. In this dissertation, we explored utilizing the nonlinear binary support vector machine (SVM) technique and the time series of vehicle variables to predict unintentional lane departure, which is innovative as no machine learning technique has previously been attempted for this purpose in the literature. Furthermore, we developed a two-stage training …