Empirical models of airflow and power consumption were developed for series and parallel variable air volume fan powered terminal units (FPTUs). An experimental setup and test procedure were developed to test the terminal units over typical operating ranges. The terminal units in this study used either an 8 in. (20.32 cm) or a 12 in. (30.48 cm) primary air inlet. All terminal units utilized electronically commutated motor (ECM) controllers. Data collected were compared against previous data collected for silicon controlled rectifier (SCR) units. Generalized models were developed for both series and parallel units, and compared against models developed for SCR units. In addition to the performance modeling, power factor and power quality data were also collected for each terminal unit. The power quality analysis included recording and analyzing harmonic distortion for current, voltage, and power up to the 25th harmonic. The total harmonic distortion (THD) was also recorded and presented. For the series terminal units, models were developed for fan airflow, fan power, and primary airflow. The models for fan airflow all had R2 values above 0.987. The models for fan power all had R2 values above 0.968. The models for primary airflow all had R2 values above 0.895. For the parallel terminal units, models were developed for leakage, fan airflow, fan power, and primary airflow. All of the leakage models had R2 values above 0.826. All of the fan airflow models had R2 values above 0.955. All of the fan power models had R2 values above 0.922. All of the primary airflow models had R2 values above 0.872. The real power THD was below 1.5 percent for both series and parallel FPTUs. The current THD ranged from 84 percent to 172 percent for series FPTUs and from 83 percent to 183 percent for parallel FPTUs. The voltage THD was below 1.4 percent for both series and parallel FPTUs. The performance models developed will help improve the accuracy of building energy simulation programs for heating, ventilation, and air conditioning (HVAC) systems utilizing ECM controlled FPTUs. Increasing the accuracy of these simulations will allow HVAC system designers to better optimize their designs for specific building types in a wide variety of climates.

This thesis proposes a methodology for determining sensitivity of building energy consumption of HVAC systems to sensor error. It is based on a series of simulations of a generic building, the model for which is based on several typical input parameters. There are a total of eight scenarios considered in this simulation. The simulation tool was developed based on Excel. The control parameters examined include room temperature, cold deck temperature, hot deck temperature, pump pressure, and fan pressure. All of the parameters considered are varied in order to analyze the sensitivity of building energy consumption to their variation. In this tool, different operation schedules for equipment, occupancy, and lighting are considered. By changing each control parameter, the sensitivity of energy use to sensor error is simulated, a regression model is generated, and the energy consumption change is expressed as a function of sensor error and outside air percentage. Two applications of this methodology are presented in this thesis. One is a SDVAV system and the other is a DDVAV system. The outside air percentage changes the trend of the sensor error curve. After the sensitivity study is discussed, some recommendations regarding the calibration intervals of the sensors are given.

It is a common problem that the cooling water loop in an HVAC or refrigeration plant is suffering from scaling, corrosion, and bacteria attacks, especially in an open-loop designs. The reason is that, through the open water loop, various kinds of contaminants were trapped and migrated along the water flow, causing condenser scaling, which in turn, leading to its poor thermal performances. The experiment conducted in this study revealed that each condenser temperature increase of 1 ¢J, accounts for a COP decrease of 2.4% to 2.8%.Serious scaling problem might even lead to system malfunction, and hazardous environmental problems. Conventionally, water-treatment in the condenser cooling water loop can be categorized into two parts, namely, the chemical and the physical methods. The chemical treatment is mainly performed by injecting chemicals, mostly acids, into the water loop so that it can circulate through the system and causing scales to peer off from the condenser tubes. In response to the cry of environmental protection, physical treatment has become increasingly important, which utilizes magnetic forces as the primary working principle. The main theme of this study is to validate this principle by full-scale experiments. The Zeta Rod system has been developed under the DLVO theory, with significant performance and is environmentally friendly. Experimental investigation has been performed in comparing the temperature differentials across a condenser, before and after the treatment. The result validated that it has increased from 3.9¢J to 4.2¢J and enhanced the thermal performances of the condenser accordingly.

In recent years, Green Building Promotion program has made a significant progress where 1359 cases have acquired the Green Building Candidate Certificate. Among them, 245 cases or 18% in total, eventually received the Green Building Label which is considered low and need to be improved. On the other hand, in United States where LEED is applied, the Commissioning, abbreviated as Commissioning, has been deemed as a Pre-Requisite Requirement for all LEED Projects. In ASHRAE design guides, Commissioning has been defined as a procedure through testing, adjusting, and balancing, to Perform in Conformity with the Design Intent. The goals of Owners, designers, and engineering contractors can all be integrated and optimized where design intent can be fulfilled with traceable records during the Commissioning process. Though Testing, Adjusting, Balancing, and Commissioning, building energy efficiency can be upgraded where energy savings and CO2 emission reduction can be obtained.

Planet rendering plays an important role in universe visualization and geographic visualization. The recent tools and methods allow better data acquisition, usually with very high resolution. However in computer graphics, there is always the limitation on the resolution of geometry and texture due to numerical imprecision. Not many applications can handle high resolution data effectively. This thesis introduces, Implicit Surface Scene, a level of detail scene management inspired by dynamic coordinate system and SCALEGRAPH™ which change over time depending on the current camera position relative to the planet surface. Our method is integrated into Uniview and allows Uniview to render high resolution planet geometry with dynamic texture composition and with a surface positioning system that does not suffer from precision issue.

abstract: Construction work is ergonomically hazardous, as it requires numerous awkward postures, heavy lifting and other forceful exertions. Prolonged repetition and overexertion have a cumulative effect on workers often resulting in work related musculoskeletal disorders (WMSDs). The United States spends approximately $850 billion a year on WMSDs. Mechanical installation workers experience serious overexertion injuries at rates exceeding the national average for all industries and all construction workers, and second only to laborers. The main contributing factors of WMSDs are ergonomic loads and extreme stresses due to incorrect postures. The motivation for this study is to reduce the WMSDs among mechanical system (HVAC system) installation workers. To achieve this goal, it is critical to reduce the ergonomic loads and extreme postures of these installers. This study has the following specific aims: (1) To measure the ergonomic loads on specific body regions (shoulders, back, neck, and legs) for different HVAC installation activities; and (2) To investigate how different activity parameters (material characteristics, equipment, workers, etc.) affect the severity and duration of ergonomic demands. The study focuses on the following activities: (1) layout, (2) ground assembly of ductwork, and (3) installation of duct and equipment at ceiling height using different methods. The researcher observed and analyzed 15 HVAC installation activities among three Arizona mechanical contractors. Ergonomic analysis of the activities using a postural guide developed from RULA and REBA methods was performed. The simultaneous analysis of the production tasks and the ergonomic loads identified the tasks with the highest postural loads for different body regions and the influence of the different work variables on extreme body postures. Based on this analysis the results support recommendations to mitigate long duration activities and exposure to extreme postures. These recommendations can potentially reduce risk, improve productivity and lower injury costs in the long term. / Dissertation/Thesis / M.S. Construction 2011

The thesis deals with the concepts of trams which are used for public transport in Prague and especially about solution of the ventilation system, heating and air conditioning. Here are described the most used principles of ventilation in the cab and in the passenger saloon. In the individual chapters, there are materials for design of air condition consequent from the standards and recommendations of the producers themselves. Air conditioning unit HVAC (Heating, ventilating and air conditioning) for the saloon passengers, including trams 15T cooling circuit is designed from these data. The unit is designed to fallen power required compared to the present. This is possible by the reversibility of the cooling circulation, which operates as a heat pump in the winter. In conclusion of thesis is stated measurements on existing air conditioning 15T. Measurements should verify that the unit has the necessary cooling performance. Design of HVAC unit and measurements are universal for any modern low-floor tram.

An energy modeling software was used to analyze the current building configuration and simulations were performed in an attempt to redesign the current HVAC system of an educational building to improve the energy efficiency of the building, exceed current building code requirements, and meet the building's cooling and heating load. The different HVAC systems simulated were: Dual Air Duct, Variable-Air Volume (VAV), and Dedicated Outdoor Air Systems (DOAS). Each system was modeled in four operation schedules including: current system operation, fan control, lighting control, and lighting and fan control. These operation schedules are to represent how efficient the building would be in different controlled settings. Results were obtained regarding the energy requirements of the different HVAC systems. For the educational building both VAV and DOAS systems offer 48.8% and 57.9%, respectively, in annual savings in energy use, achieved by adding controls to the lights and fans of both systems reducing energy consumed by ventilation fans. The time of a simple payback period for a new VAV and DOAS system is 10.2 and 9.35 years, respectively, and may remove any considerations to implement a new HVAC system. Based on these findings, educational buildings using Dual Duct should consider using DOAS systems.

abstract: The concept of this thesis came up as a part of the efforts being devoted around the world to reduce energy consumption, CO2 emissions, global warming and ozone layer depletion. In the United States, HVAC units in residential buildings consumed about 350 billion kWh in 2017 [1],[2]. Although HVAC manufacturers are investing in new technologies and more efficient products to reduce energy consumption, there is still room for further improvement. One way of reducing cooling and heating energy in residential buildings is by allowing the centralized HVAC unit to supply conditioned air to only occupied portions of the house by applying smart HVAC zoning. According to the United States Energy Information Administration [3], the percentage of houses equipped with centralized HVAC units is over 70%, which makes this thesis applicable to the majority of houses in the United States. This thesis proposes to implement HVAC zoning in a smart way to eliminate all human errors, such as leaving the AC unit on all day, which turns out to be causing a serious amount of energy to be wasted. The total amount of energy that could be saved by implementing the concepts presented in this thesis in all single-family houses in the U.S. is estimated to be about 156 billion kWh annually. This amount of energy reduction is proportional to the electricity bills and the amount of dollars paid annually on energy that is technically being wasted. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2018

Smart home automation is the dwelling bridge of smart grid technology, as it integrates the modern home appliances power consumption information over communication networks in the smart grid system. Among all the appliances, Heating, Ventilation and Cooling (HVAC) systems is one of the most primary concerns. Since a great amount of power consumption is contributed by these HVAC systems. Traditionally, HVAC systems run at a fixed schedule without automatic monitoring and control systems, which causes load variation, fluctuations in the electricity demand and inefficient utility operation. In this thesis, we propose a Finite State Machine (FSM) system to model the air condition working status to acquire the relationship between temperature changing and cooling/heating duration. Finally, we introduce the Zigbee communciation protocol into the model, the performance analysis of the impact of end-to-end delay over HVAC systems is presented.