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Performance Analysis of Two Alternative Hvac Systems for the Unt Zero Energy Lab

Description: This paper covers the simulation and comparison among three different HVAC (heating, ventilation & air conditioning)systems to achieve the goal of finding the most effective HVAC among these three in terms of human comfort, efficiency and cost considering North Texas climate. In the Zero Energy Lab at the University of North Texas, Denton, TX, the HVAC system of the building assembles with geothermal heat source. Here, water to water heat pump with radiant floor and water to air heat pump with air ducts provide heating & cooling of the building. In this paper electricity consumption, comfort, cost & efficiency analysis is done for the existing system using Energy Plus simulation software. Calibration of the simulated data of the existing system is done comparing with the actual data. Actual data is measured using 150 sensors that installed in Zero Energy Lab. After the baseline model calibration, simulation for ground source water to water heat pump, evaporative cooler with baseboard electric heater and water cooled electric chiller with baseboard electric heater (as a conventional system) is shown. Simulation results evaluate the life cycle cost (LCC) for these HVAC systems. The results of the comparison analysis among all the three HVAC systems show the most effective HVAC system among these three systems in North Texas weather. The results will make UNT Zero Energy lab a standard model towards a sustainable green future.
Date: August 2013
Creator: Hasib, Naimee
Partner: UNT Libraries

Sensitivity and Uncertainty Analysis of Occupancy-related Parameters in Energy Modeling of Unt Zero Energy Lab

Description: The study focuses on the sensitivity and uncertainty analysis of occupancy-related parameters using Energyplus modeling method. The model is based on a real building Zero Energy Lab in Discovery Park, at University of North Texas. Four categories of parameters are analyzed: heating/cooling setpoint, lighting, equipment and occupancy. Influence coefficient (IC) is applied in the sensitivity study, in order to compare the impact of individual parameter on the overall building energy consumption. The study is conducted under Texas weather file as well as North Dakota weather file in order to find weather’s influence of sensitivity. Probabilistic collocation method (PCM) is utilized for uncertainty analysis, with an aim of predicting future energy consumption based on history or reference data set. From the study, it is found that cooling setpoint has the largest influence on overall energy consumption in both Texas and North Dakota, and occupancy number has the least influence. The analysis also indicates schedule’s influence on energy consumption. PCM is able to accurately predict future energy consumption with limited calculation, and has great advantage over Monte Carlo Method. The polynomial equations are generated in both 3-order and 6-order, and the 6-order equation is proved to have a better result, which is around 0.1% compared with real value.
Date: August 2013
Creator: Xiong, Guangyuan
Partner: UNT Libraries

Effect of Dispersed Particles and Branching on the Performance of a Medium Temperature Thermal Energy Storage System

Description: The main objective of my thesis is to develop a numerical model for small-scale thermal energy storage system and to see the effect of dispersing nano-particles and using fractal-like branching heat exchanger in phase change material for our proposed thermal energy storage system. The associated research problems investigated for phase change material (PCM) are the low thermal conductivity and low rate of heat transfer from heat transfer fluid to PCM in thermal energy storage system. In this study an intensive study is carried out to find the best material for thermal storage and later on as a high conductive nano-particle graphite is used to enhance the effective thermal conductivity of the mixed materials. As a thermal storage material molten solar Salt (60% NaNO3+40%KNO3) has been selected, after that detailed numerical modeling of the proposed design has been done using MATLAB algorithm and following the fixed grid enthalpy method. The model is based on the numerical computation of 1-D finite difference method using explicit scheme. The second part of the study is based on enhancing the heat transfer performance by introducing the concept of fractal network or branching heat exchanger. Results from the numerical computation have been utilized for the comparison between a conventional heating system (with a simple single tube as a heat exchanger) and a passive PCM thermal energy storage system with branching heat exchanger using NTU-effectiveness method and charging time calculation. The comparison results show a significant amount improvement using branching network and mixing nano-particle in terms of heat transfer (13.5% increase in effectiveness of branching level-02 heat exchangers from the conventional one ), thermal conductivity (increased 73.6% with 20% graphite nano-particle mix with solid PCM), charging time (57% decrease of charging time for the effect of both the dispersion of Graphite nano-particle and branching heat exchange) and ...
Date: August 2013
Creator: Hasib, A. M. M. Golam
Partner: UNT Libraries

A Performance Analysis of Solar Chimney Passive Ventilation System in the Unt Zero Energy Lab

Description: The purpose of this investigation is to find out suitability of the solar chimney natural ventilation system in a Zero Energy Lab located at the University of North Texas campus, to figure out performance of the solar chimney. Reduction in the heating and ventilation and air conditioning energy consumption of the house has been also analyzed. The parameters which are considered for investigation are volumetric flow rate of outlet of chimney, the absorber wall temperature and glass wall temperatures. ANSYS FLUENT 14.0 has been employed for the 3-D modeling of the solar chimney. The dimensions of the solar chimney are 14’2” X 7’4” X 6’11”. The flow inside solar chimney is found to be laminar and the simulation results show that maximum outlet volumetric flow rate of about 0.12m3/s or 432 cfm is possible from chimney. The experimental velocity of chimney was found to be 0.21 m/s. Density Boussinesq approximation is considered for the modeling. Velocity and temperature sensors have been installed at inlet and outlet of the chimney in order to validate the modeling results. It is found that based on simulated volumetric flow rate that cooling load of 9.29 kwh can be saved and fan power of 7.85 Watts can be saved.
Date: August 2013
Creator: Talele, Suraj H.
Partner: UNT Libraries

Estimation of Aircraft Emissions for the Corpus Christi International Airport, Corpus Christi, Texas

Description: Commercial aviation is a vital part of the United States economy. It generates over $1 trillion annually, which is more than 5% of the U.S. GDP, and produces approximately 10 million jobs. Every year there is an increase in commercial air traffic. This is attributed to expanding trade between states and other countries, which requires larger amounts of cargo aircraft in operation, and also catering to the growing number of middle and upper class passengers who travel for business and pleasure purposes. A rise in commercial aviation leads to the use of more aviation fuel on a monthly and annual basis. This in turn leads to escalated levels of combustion by-products from jet and turbofan engines into the atmosphere. The negative effects of these by-products range from producing poor air quality and consequent health hazards to contributing to global warming. This study is aimed at assessing the impacts of aircraft emissions on the local air quality in Corpus Christi using the Emissions and Dispersion Modeling System. Flight data for the study was obtained from the Department of Transportation's Research and Innovative Technology Administration. Analyses of the emissions were compared on monthly, annual, engine type and airline provider bases. Climatic, economic and anthropogenic factors were identified in the analyses.
Date: May 2013
Creator: Thomas, Gregson Johann
Partner: UNT Libraries

Using a Multimodal Sensing Approach to Characterize Human Responses to Affective and Deceptive States

Description: Different ways to measure human affective and deceptive reactions to stimulus have been developed. One method is a multimodal approach using web camera, thermal imaging camera and physiological sensors data to extract different features in the human face (verbal and non-verbal behavior) such as breathing rate, heart rate, face temperature, skin conductance, eye tracking, language analysis and facial expressions among others. Human subjects from different ages and ethnicity were exposed to two different experiments were they watched videos (affection recognition) and others answered an interview session (deception recognition). With the data collected from videos (thermal and visual), different regions of interest (ROI) of the face were selected as well as the whole picture. The ROI were determined based on the most sensitive parts of the face where larger changes of temperature or other physiological features are recorded. It was also analyzed the language (written and spoken) in order to obtain the verbal modalities. The data has been compared among the subjects to determine whether the deceptive and affective reactions of a person can be predicted using multimodal approach. From the multiple data obtained, a characterization of reactions is proposed when subjects are exposed to different stimulus, positive or negative, as well as deceptive behavior and later on recognize if the person is happy, sad, nervous, anxious, telling the truth, lying etc. Using the multimodal approach we were able to predict automatically, with higher accuracy than the baseline, affective and deceptive states of a person. In the affective state recognition, the classifier software differentiated affective state versus neutral state with 92.85% accuracy. Then it differentiated Positive State, Negative State and Neutral State with 57.14% accuracy. Additionally, it differentiated Positive State versus Negative State with 73.21% accuracy. Finally, the classifier was able to predict Deceptive State (people lying) and Non Deceptive State ...
Date: May 2013
Creator: Narvaez-Valle, Alexis
Partner: UNT Libraries

Thermal Characterization of Austenite Stainless Steel (304) and Cnt Films of Varying Thickness Using Micropipette Thermal Sensors

Description: Thermal transport behavior of austenite stainless steel stripe (304) and the carbon nano-tubes (CNTs) films of varying thickness are studied using a micropipette thermal sensor. Micropipette sensors of various tip sizes were fabricated and tested for the sensitivity and reliability. The sensitivity deviated by 0.11 for a batch of pipette coated under same physical vapor deposition (PVD) setting without being affected by a tip size. Annealing, rubber coating and the vertical landing test of the pipette sensor proved to be promising in increasing the reliability and durability of the pipette sensors. A micro stripe (80µm × 6µm × 0.6µm) of stainless steel, fabricated using focused ion beam (FIB) machining, was characterized whose thermal conductivity was determined to be 14.9 W/m-K at room temperature. Similarly, the thermal characterization of CNT films showed the decreasing tendency in the thermal transport behavior with the increase in the film thickness.
Date: May 2013
Creator: Dangol, Ashesh
Partner: UNT Libraries

Using a Multimodal Sensing Approach to Characterize Human Thermal Comfort Level

Description: A method to distinguish human level of comfort has been developed by using a thermal camera, physiological sensors, and a surroundings sensor. The method has successfully collected data from hominal facial features, breathing rate, skin temperature, room temperature, blood volume pressure, relative humidity, and air velocity. Participants from all genders and races were involved in two sessions of a human comfort experiment including a psychology survey session. The variables, such as room temperature and clothing are controlled to maintain steady test conditions. The region of interest was determined by body temperature and facial temperature as registered by the thermal imaging camera. To experience different levels of discomfort, participants were required to perform two different activities. The first session included an activity on the air resistance elliptical and the second session required the subjects to remain steady in front of a fan. The data was subsequently compared on all subjects to determine whether human discomfort and comfort can be predicted by using various approaches. The parameters of discomfort and comfort were simulated to characterize human levels of comfort. According to arrangement of correlation among thermal comfort responses, blood volume pressure, skin temperature, respiration, and skin conduction, we are be able to predict discomfort and comfort affective states.
Date: December 2013
Creator: Wicaksono, Cakra Aditya
Partner: UNT Libraries

Characterization of Viscoelastic Properties of a Material Used for an Additive Manufacturing Method

Description: Recent development of additive manufacturing technologies has led to lack of information on the base materials being used. A need arises to know the mechanical behaviors of these base materials so that it can be linked with macroscopic mechanical behaviors of 3D network structures manufactured from the 3D printer. The main objectives of my research are to characterize properties of a material for an additive manufacturing method (commonly referred to as 3D printing). Also, to model viscoelastic properties of Procast material that is obtained from 3D printer. For this purpose, a 3D CAD model is made using ProE and 3D printed using Projet HD3500. Series of uniaxial tensile tests, creep tests, and dynamic mechanical analysis are carried out to obtained viscoelastic behavior of Procast. Test data is fitted using various linear and nonlinear viscoelastic models. Validation of model is also carried out using tensile test data and frequency sweep data. Various other mechanical characterization have also been carried out in order to find density, melting temperature, glass transition temperature, and strain rate dependent elastic modulus of Procast material. It can be concluded that melting temperature of Procast material is around 337°C, the elastic modulus is around 0.7-0.8 GPa, and yield stress is around 16-19 MPa.
Date: December 2013
Creator: Iqbal, Shaheer
Partner: UNT Libraries

Multi-year Operation Effect of Geothermal Heat Exchanger on Soil Temperature for Unt Zero Energy Lab

Description: Ground source heat pump (GSHP) uses earth’s heat to heat or cool space. Absorbing heat from earth or rejecting heat to the earth, changes soil’s constant temperature over the multiple years. In this report we have studied about Soil temperature change over multiple years due to Ground loop heat exchanger (GLHE) for Zero Energy Research Laboratory (ZØE) which is located in Discovery Park, University of North Texas, Denton, TX. We did 2D thermal analysis GLHP at particular Depth. For simulation we have used ANSYS workbench for pre-processing and FLUENT ANYS as solver. TAC Vista is software that monitors and controls various systems in ZØE. It also monitors temperature of water inlet/outlet of GLHE. For Monitoring Ground temperatures at various depths we have thermocouples installed till 8ft from earth surface, these temperatures are measured using LabVIEW. From TAC Vista and LabVIEW Reading’s we have studied five parameters in this report using FLUENT ANSYS, they are; (1) Effect of Time on soil Temperature change over Multi-years, (2) Effect of Load on soil temperature change over Multi-years, (3) Effect of Depth on soil temperature change over Multi-years, (4) Effect of Doubling ΔT of inlet and outlet of GLHE on soil temperature change over multi-years and (5) Effect on soil temperature change for same ZØE Laboratory, if it’s in Miami, Florida. For studying effect of time on soil temperature change for multi-years, we have varied heating and cooling seasons. We have four cases they are Case A: GSHP always “ON” (1) 7 months cooling and 5 month cooling and (2) 257 days are cooling and 108 days heating. Case B: GSHP “OFF” for 2 months (1) 7 months cooling and 3 months heating and (2) 6 months cooling and 4 month heating. For Studying Effect of Load on soil temperature change over multi-years, we ...
Date: December 2013
Creator: Walikar, Vinayak P.
Partner: UNT Libraries

Investigation of an Investment Casting Method Combined with Additive Manufacturing Methods for Manufacturing Lattice Structures

Description: Cellular metals exhibit combinations of mechanical, thermal and acoustic properties that provide opportunities for various implementations and applications; light weight aerospace and automobile structures, impact and noise absorption, heat dissipation, and heat exchange. Engineered cell topologies enable one to control mechanical, thermal, and acoustic properties of the gross cell structures. A possible way to manufacture complex 3D metallic cellular solids for mass production with a relatively low cost, the investment casting (IC) method may be used by combining the rapid prototyping (RP) of wax or injection molding. In spite of its potential to produce mass products of various 3D cellular metals, the method is known to have significant casting porosity as a consequence of the complex cellular topology which makes continuous fluid's access to the solidification interface difficult. The effects of temperature on the viscosity of the fluids were studied. A comparative cost analysis between AM-IC and additive manufacturing methods is carried out. In order to manufacture 3D cellular metals with various topologies for multi-functional applications, the casting porosity should be resolved. In this study, the relations between casting porosity and processing conditions of molten metals while interconnecting with complex cellular geometries are investigated. Temperature, and pressure conditions on the rapid prototyping – investment casting (RP-IC) method are reported, thermal stresses induced are also studied. The manufactured samples are compared with those made by additive manufacturing methods.
Date: August 2013
Creator: Kodira, Ganapathy D.
Partner: UNT Libraries

Optical Transparent Pmma Composite Reinforced By Coaxial Electrospun Pan Hollow Nanofibers

Description: Electrospinning has been recognized as an efficient technique for the fabrication of polymer fibers. These electrospun fibers have many applications across a broad range of industries. In this research, optical transparent composites were successfully fabricated by embedding polyacrylonitrile (PAN) hollow nanofibers into poly (methyl methacrylate) (PMMA) matrix. The hollow PAN nanofibers were prepared by coaxial electrospinning. The PAN was used as the shell solution, and the mineral oil was used as the core solution. The resulting fibers were then etched with octane to remove the mineral oil from the core. The hollow PAN fibers were then homogeneously distributed in PMMA resins to fabricate the composite. The morphology, transmittance and mechanical properties of the PAN/PMMA composite were then characterized with an ESEM, TEM, tensile testing machine, UV-vis spectrometer and KD2 Pro Decagon device. The results indicated that the hollow nanofibers have relatively uniform size with one-dimensional texture at the walls. The embedded PAN hollow nanofibers significantly enhanced the tensile stress and the Young's modulus of the composite (increased by 58.3% and 50.4%, respectively), while having little influence on the light transmittance of the composite. The KD2 Pro device indicated that the thermal conductivity of the PMMA was marginally greater than the PAN/PMMA composite by 2%. This novel transparent composite could be used for transparent armor protection, window panes in vehicles and buildings, and airplane windshield etc.
Date: May 2013
Creator: Antoine, Donley
Partner: UNT Libraries