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Architectural Engineering -- Faculty Publications

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Efficient Excitation Of Micro/Nano Resonators And Their Higher Order Modes, N. Jaber, M. A. A. Hafiz, S. N. R. Kazmi, M. H. Hasan, F. Alsaleem, S. Ilyas, M. I. Younis Jan 2019

Efficient Excitation Of Micro/Nano Resonators And Their Higher Order Modes, N. Jaber, M. A. A. Hafiz, S. N. R. Kazmi, M. H. Hasan, F. Alsaleem, S. Ilyas, M. I. Younis

Architectural Engineering -- Faculty Publications

We demonstrate a simple and flexible technique to efficiently activate micro/nano-electromechanical systems (MEMS/NEMS) resonators at their fundamental and higher order vibration modes. The method is based on the utilization of the amplified voltage across an inductor, L, of an LC tank resonant circuit to actuate the MEMS/NEMS resonator. By matching the electrical and mechanical resonances, significant amplitude amplification is reported across the resonators terminals. We show experimentally amplitude amplification up to twelve times, which is demonstrated to efficiently excite several vibration modes of a microplate MEMS resonator and the fundamental mode of a NEMS resonator.


Efficient Excitation Of Micro/Nano Resonators And Their Higher Order Modes, N. Jaber, M. A. A. Hafiz, S. N. R. Kazmi, M. H. Hasan, F. M. Alsaleem, S. Ilyas, M. I. Younis Jan 2019

Efficient Excitation Of Micro/Nano Resonators And Their Higher Order Modes, N. Jaber, M. A. A. Hafiz, S. N. R. Kazmi, M. H. Hasan, F. M. Alsaleem, S. Ilyas, M. I. Younis

Architectural Engineering -- Faculty Publications

We demonstrate a simple and flexible technique to efficiently activate micro/nano-electromechanical systems (MEMS/NEMS) resonators at their fundamental and higher order vibration modes. The method is based on the utilization of the amplified voltage across an inductor, L, of an LC tank resonant circuit to actuate the MEMS/NEMS resonator. By matching the electrical and mechanical resonances, significant amplitude amplification is reported across the resonators terminals. We show experimentally amplitude amplification up to twelve times, which is demonstrated to efficiently excite several vibration modes of a microplate MEMS resonator and the fundamental mode of a NEMS resonator.


Voltage And Deflection Amplification Via Double Resonance Excitation In A Cantilever Microstructure, Mohammad H. Hasan, Fadi Alsaleem, Abdallah Ramini Jan 2019

Voltage And Deflection Amplification Via Double Resonance Excitation In A Cantilever Microstructure, Mohammad H. Hasan, Fadi Alsaleem, Abdallah Ramini

Architectural Engineering -- Faculty Publications

Cantilever electrostatically-actuated resonators show great promise in sensing and actuating applications. However, the electrostatic actuation suffers from high-voltage actuation requirements and high noise low-amplitude signal-outputs which limit its applications. Here, we introduce a mixed-frequency signal for a cantilever-based resonator that triggers its mechanical and electrical resonances simultaneously, to overcome these limitations. A single linear RLC circuit cannot completely capture the response of the resonator under double resonance excitation. Therefore, we develop a coupled mechanical and electrical mathematical linearized model at different operation frequencies and validate this model experimentally. The double-resonance excitation results in a 21 times amplification of the voltage ...


Development Of A Model To Predict The Likelihood Of Complaints Due To Assorted Tone-In-Noise Combinations, Joonhee Lee, Lily M. Wang May 2018

Development Of A Model To Predict The Likelihood Of Complaints Due To Assorted Tone-In-Noise Combinations, Joonhee Lee, Lily M. Wang

Architectural Engineering -- Faculty Publications

This paper develops a model to predict if listeners would be likely to complain due to annoyance when exposed to a certain noise signal with a prominent tone, such as those commonly produced by heating, ventilation, and air-conditioning systems. Twenty participants completed digit span tasks while exposed in a controlled lab to noise signals with differing levels of tones, ranging from 125 to 1000 Hz, and overall loudness. After completing the digit span tasks under each noise signal, from which task accuracy and speed of completion were captured, subjects were asked to rate level of annoyance and indicate the likelihood ...


Analyses Of Crowd-Sourced Sound Levels Of Restaurants And Bars In New York City, Gregory S. Farber, Lily M. Wang Feb 2018

Analyses Of Crowd-Sourced Sound Levels Of Restaurants And Bars In New York City, Gregory S. Farber, Lily M. Wang

Architectural Engineering -- Faculty Publications

For several decades, there has been a significant need to better educate the public about noise pollution. A small number of small-scale studies have focused on the sound levels of restaurants and their impact on health and hearing. There have also been an increasing number of media articles stating that eating and drinking venues are getting increasingly loud making it more difficult for people to connect with others in conversation. This study reports on an exploratory large-scale noise survey of sound levels of 2,376 restaurants and bars in New York City using a novel smart-phone application and categorized them ...


Comfort-Based Optimal Temperature Setpoint Calculation, Andrew Holthaus, Mostafa Rafaie, Fadi Alsaleem Jan 2018

Comfort-Based Optimal Temperature Setpoint Calculation, Andrew Holthaus, Mostafa Rafaie, Fadi Alsaleem

Architectural Engineering -- Faculty Publications

General practice in current building HVAC control is to select building temperature setpoints that comply with ASHRAE Standard 55. By meeting this standard, based on the PMV comfort model, 80% of building occupants should be satisfied with their thermal environment. However, unfortunately, this is rarely the case. One possible reason for this is the variation in occupant activity and clothing that are usually assumed default values using this standard. In this work, we present an iterative-based algorithm to solve this problem. The algorithm solves the PMV inverse model equation to determine the optimal temperature setpoint while inferring human activity level ...


Numerical Simulation Of Fault Impacts For Commercial Walk-In Freezers, Alireza Behfar, David P. Yuill Jan 2018

Numerical Simulation Of Fault Impacts For Commercial Walk-In Freezers, Alireza Behfar, David P. Yuill

Architectural Engineering -- Faculty Publications

Refrigeration systems can undergo many faults that could negatively affect their operation and performance. This paper describes a modeling process to simulate the fault impacts on the operation of a commercial walk-in freezer using semi-empirical models. These models often require less modeling effort than full forward models and could be used in scenarios where detailed information is missing, such as in field-measured systems. An important characteristic of a typical walk-in refrigeration system is the existence of a liquid-line receiver after the condenser, which significantly changes the behavior of the cycle, in comparison to a receiver-less system. Component models described in ...


Evaluation The Effect Of Washing On The Heat Transfer Capacity And Air-Side Flow Resistance Of Air Cooled Condensers, Mehdi Mehrabi, David Yuill Jan 2018

Evaluation The Effect Of Washing On The Heat Transfer Capacity And Air-Side Flow Resistance Of Air Cooled Condensers, Mehdi Mehrabi, David Yuill

Architectural Engineering -- Faculty Publications

17th International Refrigeration and Air Conditioning Conference at Purdue, July 9-12, 2018


Method For Radon Measurement In Residential Sewer Connections, David Yuill Jan 2018

Method For Radon Measurement In Residential Sewer Connections, David Yuill

Architectural Engineering -- Faculty Publications

Radon gas is the most deadly indoor air pollutant. In the US, it is responsible for over 20,000 deaths per year. Residential exposure is typically the largest portion of a person’s annual exposure, so a great deal of research has been done to understand the pathways that radon can follow to enter a house. Since radon emanates from the ground, it is present in high concentration in soil gas. Recent research on the vapor intrusion of volatile organic compounds from subsurface sources into a test house concluded that the sewer line is an important preferential pathway. Despite the ...


Utilizing Wearable Devices To Design Personal Thermal Comfort Model, Mostafa Rafaie, Mehari Tesfay, Fadi Alsaleem Jan 2018

Utilizing Wearable Devices To Design Personal Thermal Comfort Model, Mostafa Rafaie, Mehari Tesfay, Fadi Alsaleem

Architectural Engineering -- Faculty Publications

have confirmed that thermal comfort significantly depends on internal personal parameters such as metabolic rate, age, and health status. This is manifested as a difference in comfort levels between people residing under the same roof, and hence no general comprehensive comfort model satisfying everyone. Current and newly emerging advancements in state of the art wearable technology have made it possible to continuously acquired biometric information. This work proposes to access and exploit this data to build personal thermal comfort model. Relying on various supervised machine-learning methods, a personal thermal comfort model will be produced and compared to a general model ...


Localized Indoor Temperature Estimation Using Smartphone And Laptop Internal Sensors, Mostafa Rafaie, Mehari Tesfay, Fadi Alsaleem Jan 2018

Localized Indoor Temperature Estimation Using Smartphone And Laptop Internal Sensors, Mostafa Rafaie, Mehari Tesfay, Fadi Alsaleem

Architectural Engineering -- Faculty Publications

This paper investigates a mechanism in which indoor air temperature can be predicted using the temperature sensor on the battery and the CPU of smartphones or laptops, where data is easily accessible and ubiquitous. As a case study, several machine-learning methods were used to build models from a laptop data and the measured surrounding air temperature. The effects of the machine learning type and input feature size (by including other parameters such as CPU processing usage and battery charge percentage) on the model accuracy were investigated. The goal is to determine a set of feature combinations that can be used ...


Impact Of Owners’ Early Decisions On Project Performance And Dispute Occurrence In Public Highway Projects, Sogand Hasanzadeh, Behzad Esmaeili, Ghada M. Gad, Douglas D. Gransberg Jan 2018

Impact Of Owners’ Early Decisions On Project Performance And Dispute Occurrence In Public Highway Projects, Sogand Hasanzadeh, Behzad Esmaeili, Ghada M. Gad, Douglas D. Gransberg

Architectural Engineering -- Faculty Publications

Disputes are common in the construction industry and lead to unnecessary cost and schedule overruns in projects. It is commonly believed that owners’ early decisions regarding the selection of delivery methods, procurement methods, and contract types impact the frequency and severity of project disputes; however, no previous study has empirically tested this hypothesis, particularly in highway public projects. Therefore, this study empirically investigated the impact of owners’ early decisions regarding project organization (i.e., delivery methods, procurement, and contract types) on performance measures (e.g., cost and schedule growth), specifically dispute performance metrics (e.g., frequency and severity of disputes ...


Simultaneous Electrical And Mechanical Resonance Drive For Large Signal Amplification Of Micro Resonators, M. H. Hasan, Fadi M. Alsaleem, N. Jaber, M. A. A. Hafiz, M. I. Younis Jan 2018

Simultaneous Electrical And Mechanical Resonance Drive For Large Signal Amplification Of Micro Resonators, M. H. Hasan, Fadi M. Alsaleem, N. Jaber, M. A. A. Hafiz, M. I. Younis

Architectural Engineering -- Faculty Publications

Achieving large signal-noise ratio using low levels of excitation signal is key requirement for practical applications of micro and nano electromechanical resonators. In this work, we introduce the double electromechanical resonance drive concept to achieve an order-of-magnitude dynamic signal amplification in micro resonators. The concept relies on simultaneously activating the micro-resonator mechanical and electrical resonance frequencies. We report an input voltage amplification up to 15 times for a micro-resonator when its electrical resonance is tuned to match the mechanical resonance that leads to dynamic signal amplification in air (Quality factor enhancement). Furthermore, using a multi-frequency excitation technique, input voltage and ...


Gas Collection, Haorong Li, Yanshun Yu, Daihong Yu Jun 2017

Gas Collection, Haorong Li, Yanshun Yu, Daihong Yu

Architectural Engineering -- Faculty Publications

A system includes a vessel configured to couple with a gas source for drawing gas into the vessel. The vessel is also configured to receive liquid. The system includes an over flow port in fluid communication with the environment external to the vessel. The overflow port is configured to separate gas within the vessel from the external environment. The system also includes an overflow conduit having an end within the overflow port so that when gas pressure within the vessel increases, liquid is received by the over flow conduit. Another system includes a tank defining an air space for receiving ...


How Tonality And Loudness Of Noise Relate To Annoyance And Task Performance” Noise Control Eng. J. 65(2), 71-82., Joonhee Lee, Jennifer M. Francis, Lily M. Wang Apr 2017

How Tonality And Loudness Of Noise Relate To Annoyance And Task Performance” Noise Control Eng. J. 65(2), 71-82., Joonhee Lee, Jennifer M. Francis, Lily M. Wang

Architectural Engineering -- Faculty Publications

Audible tones in noise generated by building mechanical equipment can be a leading cause of complaints from occupants. A number of metrics have been developed to quantify prominence of a tone, but previous work has shown that the impact of a certain tonality appears to vary with the level of the broadband noise signal. More work on how tonal signals of varying tonality, tone frequency and broadband noise levels relate to annoyance and task performance is needed. This paper investigates such relationships between current noise metrics, annoyance and task performance under assorted tonal noise conditions through subjective testing. Participants rated ...


Study On The Methods For Predicting The Performance Of A Hybrid Solar-Assisted Ground-Source Heat Pump System, Zhaoyi Zhuang, Qiqi Zhu, Jian Song, Xin Zhang, Haorong Li Jan 2017

Study On The Methods For Predicting The Performance Of A Hybrid Solar-Assisted Ground-Source Heat Pump System, Zhaoyi Zhuang, Qiqi Zhu, Jian Song, Xin Zhang, Haorong Li

Architectural Engineering -- Faculty Publications

It is critical to find suitable setting parameters for designing a hybrid solar-assisted ground-source heat pump system in the practical engineering application, but the heat pump performance is unpredictable after many years of operation. This paper used 2000 sets of performance data collected from solar-assisted GSHP systems that keep operating over 20 years to simulate long term used heat pump with a professional software called GeoStar. Adopted the classification and regression tree (CART) method, the design of solar energy collector areas can be predicted. The multi-linear regression is also utilized to predict average monthly per meter borehole heat exchange. Seasonal ...


Research On The Cooling Characteristics In Building Interior Zones Using Displacement Ventilation System, Zhaoyi Zhuang, Yongbin Li, Qiqi Zhu, Jian Song, Haipeng An, Haorong Li Jan 2017

Research On The Cooling Characteristics In Building Interior Zones Using Displacement Ventilation System, Zhaoyi Zhuang, Yongbin Li, Qiqi Zhu, Jian Song, Haipeng An, Haorong Li

Architectural Engineering -- Faculty Publications

The outdoor low temperature fresh air can be used as a free cold source to eliminate waste heat for the building interior zones during the transition season and winter. This paper takes a project in Hunan as an example, and the project building interior zones is 25m×7m×3.9m(L×W×H). Using Fluent software to simulate the temperature field and velocity field both the interior and exterior zones of the engineering offices. The simulation results show that using the displacement ventilation system to take the outdoor air into inner rooms not only cooling but also improving the air ...


Social Sustainability Indicators In Mass Housing Construction, Ali Karji, Asregedew Woldesenbet, Mostafa Khanzadi Jan 2017

Social Sustainability Indicators In Mass Housing Construction, Ali Karji, Asregedew Woldesenbet, Mostafa Khanzadi

Architectural Engineering -- Faculty Publications

In the construction industry, buildings constitute more than half of the new construction built in the world. With the rapid growth of population in urban areas and high-energy consumption of buildings, considerable attention and efforts have been devoted to creating a sustainably built environment. As a result, various sustainable rating systems, principles and tools have been developed in recent years. This paper presents efforts underway for evaluation of sustainability in mass housing construction projects in the Middle East from a social aspect. The study reviews reports, guidelines and best practices at national and international levels to detect key sustainability indicators ...


Hvac System Remote Monitoring And Dagnosis, Jeffrey N. Arensmeier, Gregg M. Hemmelgarn, Fadi M. Alsaleem, Priotomo Abiprojo Jan 2017

Hvac System Remote Monitoring And Dagnosis, Jeffrey N. Arensmeier, Gregg M. Hemmelgarn, Fadi M. Alsaleem, Priotomo Abiprojo

Architectural Engineering -- Faculty Publications

A monitoring system for a heating, ventilation, and air conditioning (HVAC) system of a building includes a monitoring device installed at the building, a monitoring server located remotely from the building, and a review server. The monitoring device measures an aggregate current Supplied to components of the HVAC system and transmits current data based on the measured aggregate current. The monitoring server receives the transmitted current data and, based on the received current data, assesses whether failures have occurred in first and second components of the HVAC components. The monitoring server generates a first advisory in response to determining that ...


Performance And Energy Efficiency Analysis Of Data Center Cooling Plant By Using Lake Water Source, Li Ling, Quan Zhang, Liping Zeng Jan 2017

Performance And Energy Efficiency Analysis Of Data Center Cooling Plant By Using Lake Water Source, Li Ling, Quan Zhang, Liping Zeng

Architectural Engineering -- Faculty Publications

A cooling plant by using lake water source was proposed to cool the space in data centers. It combines free cooling technology and variable capacity technology to remove heat and reduce energy consumption effectively. In this paper, firstly, the control strategies for this cooling plant were proposed. Then, a detailed annual energy consumption model with considering the effect of the dynamic heat dissipation characteristics of servers, lake water temperature, outdoor weather conditions, and cooling plant thermal performance, will be established to evaluate the performance and energy efficiency of this cooling plant under different load factors. The results show the mode ...


Heat - Pump System With Refrigerant Charge Diagnostics, Fadi M. Alsaleem, Gregg H. Hemmelgarn Jan 2017

Heat - Pump System With Refrigerant Charge Diagnostics, Fadi M. Alsaleem, Gregg H. Hemmelgarn

Architectural Engineering -- Faculty Publications

A heat-pump circuit may include an indoor heat exchanger, an outdoor heat exchanger, a compressor adapted to circulate a working fluid between the indoor and outdoor heat exchangers, and an expansion device disposed between the indoor and outdoor heat exchangers. A monitor for the heat-pump system may include a return-air temperature sensor, a supply-air temperature sensor, and a processor. The return-air temperature sensor may be adapted to measure a first air temperature of air upstream of the indoor heat exchanger. The supply-air temperature sensor may be adapted to measure a second air temperature of air down stream of the indoor ...


Research On Control Methods Of Roof Radiant Cooling System, Yongbin Li, Zhaoyi Zhuang, Qiqi Zhu, Jian Song, Haipeng An Jan 2017

Research On Control Methods Of Roof Radiant Cooling System, Yongbin Li, Zhaoyi Zhuang, Qiqi Zhu, Jian Song, Haipeng An

Architectural Engineering -- Faculty Publications

Taking the capillary ceiling radiation air conditioning system in radiation cooling Laboratory of comprehensive experimental building in Shandong Jianzhu University as an example, research the two different control methods which are room temperature control and water temperature control. The roof cooling model was established by using TRNSYS simulation software, two typical summer days were selected to explore the stability of the room temperature and the supply and return water temperature, research the comfort of human body and system energy consumption under two control methods. The results show that the indoor temperature of the two control methods can be stable at ...


Gas Generation, Haorong Li, Daihong Yu, Yanshun Yu Jan 2017

Gas Generation, Haorong Li, Daihong Yu, Yanshun Yu

Architectural Engineering -- Faculty Publications

A first system includes a feedstock load port and a feedstock discharge port. The first system also includes a tank configured to retain biomass feedstock for aerobic biodegradation. The first system further includes a mechanical ventilator in fluid communication with the tank. The mechanical ventilator is configured to supply air to facilitate the aerobic biodegradation of the biomass feedstock. The first system also includes an exhaust port configured to receive gas generated during the aerobic biodegradation. A second system includes a feedstock load port and a feedstock discharge port. The second system also includes a pressure vessel configured to retain ...


A Case Study Of Upper-Room Uvgi In Densely-Occupied Elementary Classrooms By Real-Time Fluorescent Bioaerosol Measurements, Chunxiao Su, Josephine Lau, Fang Yu Jan 2017

A Case Study Of Upper-Room Uvgi In Densely-Occupied Elementary Classrooms By Real-Time Fluorescent Bioaerosol Measurements, Chunxiao Su, Josephine Lau, Fang Yu

Architectural Engineering -- Faculty Publications

Recently, the requirement to continuously collect bioaerosol samples using shorter response times has called for the use of real-time detection. The decreased cost of this technology makes it available for a wider application than military use, and makes it accessible to pharmaceutical and academic research. In this case study, real-time bioaerosol monitors (RBMs) were applied in elementary school classrooms—a densely occupied environment—along with upper-room ultraviolet germicidal irradiation (UVGI) devices. The classrooms were separated into a UVGI group and a non-UVGI control group. Fluorescent bioaerosol counts (FBCs) were monitored on 20 visiting days over a four-month period. The classroom ...


Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang May 2016

Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang

Architectural Engineering -- 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 ...


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 Mar 2016

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

Architectural Engineering -- 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 ...


Case Study Of Quantifying Energy Loss Through Ceiling-Attic Recessed Lighting Fixtures Through 3d Numerical Simulation, Ri Na, Shengmao Lin, Zhigang Shen, Linxia Gu Jan 2016

Case Study Of Quantifying Energy Loss Through Ceiling-Attic Recessed Lighting Fixtures Through 3d Numerical Simulation, Ri Na, Shengmao Lin, Zhigang Shen, Linxia Gu

Architectural Engineering -- 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 ...


Normalized Effect Of Condenser Fouling And Refrigerant Charge On Performance Of Vapor Compression Air Conditioning Systems, Mehdi Mehrabi, David Yuill Jan 2016

Normalized Effect Of Condenser Fouling And Refrigerant Charge On Performance Of Vapor Compression Air Conditioning Systems, Mehdi Mehrabi, David Yuill

Architectural Engineering -- 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 Jan 2016

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

Architectural Engineering -- 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 ...


A Prediction Method For Overall Economic Value Of Fault Detection And Diagnostic Tools For Rooftop And Split Systems, David Yuill, James Braun Jan 2016

A Prediction Method For Overall Economic Value Of Fault Detection And Diagnostic Tools For Rooftop And Split Systems, David Yuill, James Braun

Architectural Engineering -- 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 ...