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Articles 1 - 20 of 20
Full-Text Articles in Architectural Engineering
A Generic Benchmark For A Mini-Split Heat Pump System, Yuchen Wang
A Generic Benchmark For A Mini-Split Heat Pump System, Yuchen Wang
Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research
Heating, Ventilation, and Air Conditioning (HVAC) accounts for half of the building energy consumption in the U.S where Mini-Split Heat Pumps (MSHPs) are an emerging type of HVAC system. Their utilization has greatly increased by 34% from 2009 to 2013 and high potential EER is recognized for MSHPs. However, there is limited research involving MSHPs systems, and there is no generic benchmark for system testing and modeling. The available simulation tools such as VapCyc, GreatLab, and CYCLE_D are either too complicated, difficult to access, or not freely available. Therefore, an accurate and public share generic benchmark is essential and will …
An Investigation Of Dx Cooling Coil Inherent Characteristics, Krittima Santiwattana
An Investigation Of Dx Cooling Coil Inherent Characteristics, Krittima Santiwattana
Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research
DX cooling coil (DCC) systems have dominated light commercial and household applications in the U.S for several decades. Approximately 14.5% of energy use is consumed by space cooling in commercial buildings, whereas 87% of households are installed with air-conditioners. Improper installation, poor design, and lack of optimized control/operations incur faults in HVAC systems causing 25% to 50% energy waste in a building. These consequences are subject to inefficient equipment modelling of which is developed from: (1) insufficient understanding in equipment characteristics, (2) uncertainties in testing environment and data, and (3) access and cost limitations. Therefore, in this thesis DCC inherent …
How Acoustics In California High Performance Schools Relate To Student Achievement, Devin K. Wong
How Acoustics In California High Performance Schools Relate To Student Achievement, Devin K. Wong
Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research
This research project seeks to determine if students attending K-12 schools meeting a minimum standard of high performance classroom conditions in the state of California do evidence higher scholastic achievement, based on publically available results on state-wide standardized tests. In three phases, a subset of 200+ schools applying for grants dedicated to building high performance schools over the past decade was correlated with an existing database of achievement scores for all public schools in California. The criteria utilized to specify high performance classrooms was provided by the California High Performance Initiative (HPI) Grant program. Academic achievement was evaluated on a …
Case Study Of Quantifying Energy Loss Through Ceiling-Attic Recessed Lighting Fixtures Through 3d Numerical Simulation, Ri Na, Shengmao Lin, Zhigang Shen, Linxia Gu
Case Study Of Quantifying Energy Loss Through Ceiling-Attic Recessed Lighting Fixtures Through 3d Numerical Simulation, Ri Na, Shengmao Lin, Zhigang Shen, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
Abstract Air leakage through recessed lighting fixtures has been identified as a common issue that causes extra energy consumption in residential buildings. However, few quantitative studies in this area were found. As such, a preliminary assessment of the magnitude of this type of energy loss was conducted by using three-dimensional (3D) transient computational fluid dynamics (CFD) models. A hypothetical layout of recessed lighting fixtures was designed with boundary conditions of four different seasons, which were obtained from recorded roof/attic temperature data sets. The results of the study indicate that leakage of recessed lighting fixtures could be a significant channel of …
Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang
Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang
Durham School of Architectural Engineering and Construction: Faculty Publications
A large number of non-native English speakers may be found in American classrooms, both as listeners and talkers. Little is known about how this population comprehends speech in realistic adverse acoustical conditions. A study was conducted to investigate the effects of background noise level (BNL), reverberation time (RT), and talker foreign accent on native and non-native listeners' speech comprehension, while controlling for English language abilities. A total of 115 adult listeners completed comprehension tasks under 15 acoustic conditions: three BNLs (RC-30, RC-40, and RC-50) and five RTs (from 0.4 to 1.2 s). Fifty-six listeners were tested with speech from native …
Design And Optimization Of Membrane-Type Acoustic Metamaterials, Matthew G. Blevins
Design And Optimization Of Membrane-Type Acoustic Metamaterials, Matthew G. Blevins
Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research
One of the most common problems in noise control is the attenuation of low frequency noise. Typical solutions require barriers with high density and/or thickness. Membrane-type acoustic metamaterials are a novel type of engineered material capable of high low-frequency transmission loss despite their small thickness and light weight. These materials are ideally suited to applications with strict size and weight limitations such as aircraft, automobiles, and buildings. The transmission loss profile can be manipulated by changing the micro-level substructure, stacking multiple unit cells, or by creating multi-celled arrays. To date, analysis has focused primarily on experimental studies in plane-wave tubes …
The Effects Of Tones In Noise On Human Annoyance And Performance, Joonhee Lee
The Effects Of Tones In Noise On Human Annoyance And Performance, Joonhee Lee
Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research
Building mechanical equipment often generates prominent tones because most systems include rotating parts like fans and pumps. These tonal noises can cause unpleasant user experiences in spaces and, in turn, lead to increased complaints by building occupants. Currently, architectural engineers can apply the noise criteria guidelines in standards or publications to achieve acceptable noise conditions for assorted types of spaces. However, these criteria do not apply well if the noise contains perceptible tones. The annoyance thresholds experienced by the general population with regards to the degree of tones in noise is a significant piece of knowledge that has not been …
Quantification Of Time Varying Directivity Of Musical Instruments, Madeline A. Davidson
Quantification Of Time Varying Directivity Of Musical Instruments, Madeline A. Davidson
Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research
Static directivity patterns of musical instruments have been mapped somewhat extensively, but little research has been done in analyzing the directivity patterns of musical instruments over time as they play. Directivity patterns can be affected by variables such as instrument, frequency, dynamics, and style. This thesis proposes a set of quantification methods of time varying directivity, all derived from the maximum Directivity Index analyzed at consecutive short-duration time windows comprising the musical excerpt. The instrumental recordings used in this paper are taken in an anechoic chamber using either a 5, 13, or 32 multichannel setup. From the values of maximum …
Experimental Study On The Thermal Characteristics Of Micro Channel Separate Heat Pipe Respect To Different Filling Ratio, Li Ling, Quan Zhang, Yuebin Yu, Shuguang Liao, Zhengyong Sha
Experimental Study On The Thermal Characteristics Of Micro Channel Separate Heat Pipe Respect To Different Filling Ratio, Li Ling, Quan Zhang, Yuebin Yu, Shuguang Liao, Zhengyong Sha
Durham School of Architectural Engineering and Construction: Faculty Publications
A micro channel separate heat pipe (MCSHP) that can use natural cold energy was developed to reduce the cooling energy consumptions of telecommunications stations (TSs). Experimental investigations of exploring the optimal refrigerant filling ratio of MCSHP under different outdoor conditions and flow rates were presented. R22 was used as the working fluid. Various refrigerant filling ratios were tested in an enthalpy difference laboratory (EDL) in order to determine the optimal thermal performance for the exterior space temperature range from 8 °C to 23 °C and the air volume flow rate range from 1712 m3/h to 2980 m3/h. In addition, transient …
Case Study Of Quantifying Energy Loss Through Ceiling-Attic Recessed Lighting Fixtures Through 3d Numerical Simulation, Ri Na, Shengmao Lin, Zhigang Shen, Linxia Gu
Case Study Of Quantifying Energy Loss Through Ceiling-Attic Recessed Lighting Fixtures Through 3d Numerical Simulation, Ri Na, Shengmao Lin, Zhigang Shen, Linxia Gu
Durham School of Architectural Engineering and Construction: Faculty Publications
Air leakage through improperly installed recessed lighting fixtures has been identified as a common issue causing extra energy consumption of residential buildings. However, little quantitative study was found in this area. In this paper, a preliminary evaluation of the magnitude of such energy loss was conducted by numerical simulations using 3 dimensional transient computational fluid dynamics (CFD) model. A typical layout of recessed lighting fixtures was used in this case study with boundary conditions in four different seasons, which were obtained from past measured roof/attic temperature data sets. The results of the numerical simulations indicate that leakage of recessed lighting …
A Thermo-Activated Wall For Load Reduction And Supplementary Cooling With Free To Low-Cost Thermal Water, Yuebin Yu, Fuxin Niu, Heinz-Axel Guo, Denchai Woradechjumroen
A Thermo-Activated Wall For Load Reduction And Supplementary Cooling With Free To Low-Cost Thermal Water, Yuebin Yu, Fuxin Niu, Heinz-Axel Guo, Denchai Woradechjumroen
Durham School of Architectural Engineering and Construction: Faculty Publications
A building envelope serves as a thermal barrier and plays an important role in determining the amount of energy used to achieve a comfortable indoor environment. Conventionally, it is constructed and treated as a passive component in a building thermal energy system. In this article, a novel, mini-tube capillary-network embedded and thermal-water activated building envelope is proposed to turn the passive component into active, therefore broaden the direct utilization of low-grade thermal energy in buildings. With this proposed approach, low-grade thermal water at a medium temperature close to the ambient environment can be potentially utilized to either counterbalance the thermal …
Student Absenteeism And The Comparisons Of Two Sampling Procedures For Culturable Bioaerosol Measurement In Classrooms With And Without Upper Room Ultraviolet Germicidal Irradiation Devices, Chunxiao Su, Josephine Lau, Shawn G. Gibbs
Student Absenteeism And The Comparisons Of Two Sampling Procedures For Culturable Bioaerosol Measurement In Classrooms With And Without Upper Room Ultraviolet Germicidal Irradiation Devices, Chunxiao Su, Josephine Lau, Shawn G. Gibbs
Durham School of Architectural Engineering and Construction: Faculty Publications
Upper room ultraviolet germicidal irradiance (UVGI) has been shown to reduce the concentration of bioaerosols in controlled chambers. However, there is a lack of experimental results on the reduction of bioaerosol concentrations by UVGI devices in actual uncontrolled buildings. This study was carried out in an American elementary school in the Midwest. Two sampling procedures were carried out in six selected classrooms with similar dimensions that were separated into two groups: (1) UVGI exposure group and (2) non-UVGI control group. Two-stage Tisch culturable impactors were utilized to collect airborne culturable bacteria and fungi. Monthly samples were collected during unoccupied period …
A Need For Evidence-Based And Multidisciplinary Research To Study The Effects Of The Interaction Of School Environmental Conditions On Student Achievement, Josephine Lau, Lily M. Wang, Clarence E. Waters, James A. Bovaird
A Need For Evidence-Based And Multidisciplinary Research To Study The Effects Of The Interaction Of School Environmental Conditions On Student Achievement, Josephine Lau, Lily M. Wang, Clarence E. Waters, James A. Bovaird
Durham School of Architectural Engineering and Construction: Faculty Publications
With funding from the U.S. Environmental Protection Agency’s (EPA) Healthy Schools initiative, a research team from the University of Nebraska– Lincoln (UNL) is currently working on establishing how environmental conditions in K-12 school buildings impact student scholastic achievement. The objectives of the research project are: (1) to study comprehensively the impacts of a wide set of indoor environmental factors (including indoor air quality, thermal, lighting and acoustic conditions) on student achievement; (2) to investigate how these environmental conditions interact with each other to impact student achievement; (3) to rank order the environmental variables in terms of their relative impact on …
Fault Detection And Diagnosis Process For Oversizing Design On Multiple Packaged Air-Conditioning Units, Denchai Woradechjumroen, Haorong Li, Thanapat Promwattanapakee
Fault Detection And Diagnosis Process For Oversizing Design On Multiple Packaged Air-Conditioning Units, Denchai Woradechjumroen, Haorong Li, Thanapat Promwattanapakee
Durham School of Architectural Engineering and Construction: Faculty Publications
Heating, ventilation, air-conditioning and Refrigeration (HVAC&R) systems are seldom designed or commissioned properly. The situation leads to abrupt or degradation faults resulting in inefficient energy uses, excessive energy consumption and high service costs. To solve these aforementioned problems, fault detection and diagnosis (FDD) is utilized to firstly detect any abnormal conditions of a system and then diagnoses and determines their causes. In order to apply this concept in HVAC oversizing designs, this paper proposes the state-of-art procedure of a FDD procedure for analyzing the inherently faulty design (oversizing) of multiple packaged air-conditioning units used to supply cooling for an open …
Development Of Coordination Control For Multiple Rooftop Units, Denchai Woradechjumroen, Haorong Li, Akekachai Deesiri
Development Of Coordination Control For Multiple Rooftop Units, Denchai Woradechjumroen, Haorong Li, Akekachai Deesiri
Durham School of Architectural Engineering and Construction: Faculty Publications
Rooftop Units (RTUs) have been widely applied in providing space heating and cooling for commercial buildings. In total, they serve over 60% of the commercial building floor space in the U.S. Even through the current control approaches of a RTU can maintain the zone temperature corresponding to a set point temperature, it performs inefficiently due to several factors such as limited sensing capability, non- coordinated local control, inherent oversizing effects and so on. In addition to unnecessary power consumptions, the current control and operation technology on RTUs also lead to the space humidity problem, equipment efficiency degradation, and premature failure. …
Cognitive Radio For Smart Grid With Security Considerations, Khaled Shuaib, Ezedin Barka, Nedaa Al Hussien, Mohammed Abdel-Hafez, Mahmoud Alahmad
Cognitive Radio For Smart Grid With Security Considerations, Khaled Shuaib, Ezedin Barka, Nedaa Al Hussien, Mohammed Abdel-Hafez, Mahmoud Alahmad
Durham School of Architectural Engineering and Construction: Faculty Publications
In this paper, we investigate how Cognitive Radio as a means of communication can be utilized to serve a smart grid deployment end to end, from a home area network to power generation. We show how Cognitive Radio can be mapped to integrate the possible different communication networks within a smart grid large scale deployment. In addition, various applications in smart grid are defined and discussed showing how Cognitive Radio can be used to fulfill their communication requirements. Moreover, information security issues pertained to the use of Cognitive Radio in a smart grid environment at different levels and layers are …
Compressor Having A Control And Dagnostic Module, Hung M. Pham, Fadi M. Alsaleem
Compressor Having A Control And Dagnostic Module, Hung M. Pham, Fadi M. Alsaleem
Durham School of Architectural Engineering and Construction: Faculty Publications
An apparatus includes a Voltage sensor, a current sensor, and a controller. The Voltage sensor measures Voltage values of alternating current power Supplied to a capacitor. The capaci tor is electrically coupled to a compressor. The current sensor measures current values of the alternating current power. The controller is configured to receive the Voltage values and the current values. The controller is configured to determine a first power factor value based on at least one of the voltage values and at least one of the current values. The controller is configured to selectively detect a first capacitor fault in response …
A Prediction Method For Overall Economic Value Of Fault Detection And Diagnostic Tools For Rooftop And Split Systems, David Yuill, James Braun
A Prediction Method For Overall Economic Value Of Fault Detection And Diagnostic Tools For Rooftop And Split Systems, David Yuill, James Braun
Durham School of Architectural Engineering and Construction: Faculty Publications
Fault detection and diagnostics (FDD) tools for air-conditioning application may perform well or poorly, but it is difficult to characterize this performance in a meaningful way. Some recently proposed evaluation techniques have provided various statistics to characterize FDD performance, but these results can be difficult for a potential adopter of FDD to understand. A new method of characterizing FDD performance by predicting the overall economic value of the FDD tool is proposed in this paper. It is applicable to FDD tools intended for air-cooled unitary airconditioners, such as rooftop units (RTU) and split systems. The method gives an estimated dollar …
Normalized Effect Of Condenser Fouling And Refrigerant Charge On Performance Of Vapor Compression Air Conditioning Systems, Mehdi Mehrabi, David Yuill
Normalized Effect Of Condenser Fouling And Refrigerant Charge On Performance Of Vapor Compression Air Conditioning Systems, Mehdi Mehrabi, David Yuill
Durham School of Architectural Engineering and Construction: Faculty Publications
Several laboratory experiments have studied the effect of faults on vapor compression cycle air-conditioning systems. There has been a particular focus on refrigerant charge variation, which is believed to be quite common in air conditioners, and a lesser focus on heat exchanger fouling. The majority of the published results evaluate the fault effects on particular system operating parameters in one unit. For example, the effect on capacity and efficiency are typically evaluated. The results differ from one study to the next. The current paper summarizes the effects for all of the results available in the literature for condenser fouling and …
Fault Diagnosis Of Refrigerant Charge Based On Pca And Decision Tree For Variable Refrigerant Flow Systems, Jiangyan Liu, Huanxin Chen, Jiangyu Wang, Guannan Li, Haorong Li, Wenju Hu
Fault Diagnosis Of Refrigerant Charge Based On Pca And Decision Tree For Variable Refrigerant Flow Systems, Jiangyan Liu, Huanxin Chen, Jiangyu Wang, Guannan Li, Haorong Li, Wenju Hu
Durham School of Architectural Engineering and Construction: Faculty Publications
Variable refrigerant flow (VRF) systems are easily subjected to performance degradation due to refrigerant leakage, mechanical failure or improper maintenance after years of operation. Ideal VRF systems should equip with fault detection and diagnosis (FDD) program to sustain its normal operation. This paper presents the fault diagnosis method for refrigerant charge faults of variable refrigerant flow (VRF) systems. It is developed based on the classification and regression tree (CART) algorithm. Data of the experimental VRF system is used to test the advantages of the CART method. Results show that the decision tree can achieve desirable diagnosis efficiency on undercharge faults, …