Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 46 for “"Air-conditioning system"”.
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An air conditioning system for demonstration and research
… were to investigate the contemporary field of air conditioning in industry and education; to determine what equipment should be recommended for installation in the Mechanical Engineering Laboratory of the Virginia Polytechnic Institute; and to design the components and controls for a unit which …
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Potential of controlling subcooling in residential air conditioning system
… study of one way of improving residential air-conditioning (RAC) system performance by controlling subcooling. Instead of conventional superheat control at evaporator outlet, condenser subcooling is monitored and controlled and the corresponding effects on vapor-compression system …
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EnergyPlus Simulation of Single-Coil Twin-Fan Air Conditioning System
… the newly-developed Single-Coil Twin-Fan (SCTF) air conditioning system. The objectives of this project were to develop a customized module of the energy efficient SCTF system, validate the model using industry-accepted simulation verification methods, and implement the module in a program with …
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Operating strategies for economizer control in an air conditioning system
A typical economizer in an air conditioning system is investigated in this paper. New operating strategies of the economizer are proposed. An economizer consists of three coupled dampers--an outdoor air, a recirculation, and a discharge damper--controlled so that the amount of outdoor air may be …
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Supervisory Control of a Commercial Heating, Ventilating, and Air Conditioning System
… controllers to maximally utilize the control system framework currently used in the industry. Two different supervisory controller configurations were developed and compared with the existing normal mode of control. Results showed that superior performance could be obtained using the model …
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Design and development of a novel liquid desiccant air-conditioning system
The Direct Evaporative Closed Air Loop (DECAL) system is a novel high efficiency liquid desiccant air-conditioning (LDAC) system which runs primarily on thermal energy rather than electricity. It is designed for residential cooling in hot and humid climates where demand is growing rapidly and …
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Using Vibration Analysis to Determine Refrigerant Levels In an Automotive Air Conditioning System
… the amount of refrigerant (R-134a) in an air conditioning system of an automobile. In the research presented, vibration analysis is examined as a possible method to determine this R-134a amount. Initial laboratory tests were completed and experimental modal analysis methods were …
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Heating, ventilating and air-conditioning system energy demand coupling with building loads for office buildings.
… energy consumption. Heating, ventilating and air conditioning (HVAC) systems are the largest energy end use in the nondomestic sector, with energy consumption close to 50% of total energy consumption. Different HVAC systems have different energy requirements when responding to the same …
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Experimental and Analytical Investigation of a Two-Phase Ejector Used for Expansion Work Recovery in a Transcritical R744 Air-Conditioning System
… rejection pressure can be used to maximize the system performance. In addition, large throttling losses make R744 a suitable fluid for expansion work recovery. This study presents experimental and computational results obtained from a transcritical R744 air-conditioning system using a two-phase …
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Effect of oil in circulation on automotive A/C component and system performance
In Automotive air-conditioning system, oil is mixed with refrigerant and runs in the system. Although some amount of oil is beneficial to compressor to reduce compressor wear and prevent leakage, the existence of oil in circulation influences the performance of the air-conditioning system and …
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Off-peak cooling using phase change material
… path is illustrated by the development of an air conditioning system designed to displace power consumption in commercial buildings from peak to off-peak periods. The urban domestic utilities face their peak loads during the summer air conditioning season. The displacement of daytime air …
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Influence of passenger car air conditioner system thermostat level setting to fuel consumption and thermal comfort
… the day. Car users in Malaysia need in car air-conditioning system because the weather is hot and humid all year. Passenger adjusts the thermostat level (temperature knob setting) position to regulate the cold air temperature supplied to the cabin. By adjusting the thermostat, it affects the …
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Impact of advanced energy recovery system on light commercial building
… offices require large amounts of fresh air to maintain the indoor air quality as required by the building codes. This raises the energy costs of the buildings, especially when the number of occupants are large. In order to reduce the energy costs, traditionally, energy is recovered from …
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Experiment and simulation study on a novel, effective radiative cooing film
… portion of U.S. household use, and traditional air conditioning system poses a net heating effect to the global climate. Daytime radiative cooling (DRC) is a passive cooling method with zero energy consumption. It features a high ultraviolet visible near-infrared (UV-Vis-NIR) reflectivity and …
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A fundamental study of two-dimensional room ventilation flows under isothermal and non-isothermal conditions
Understanding room air distribution is essential to the design of a ventilation system and the control of room thermal and air quality conditions. To investigate the various aspects of room air distribution, a Room Ventilation Simulator was developed with several unique features: an outer room with …
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Fault detection methods for vapor-compression air conditioners using electrical measurements
… tested and validated on a commercially available air handler and duct system. In the second class of faults studied, liquid refrigerant, rather than vapor, enters the cylinder of a reciprocating compressor during operation. Since the higher cylinder pressures that result can cause substantial …
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New modeling and control solutions for integrated microgrid system with respect to thermodynamics properties of generation and demand
… of a combined cycle power plant, a building with air-conditioning system and a renewable source. This integrated model allows researchers to study microgrid stability while considering the physical behaviors of the generation and demand. Specifically, the model takes into account the slow dynamics …
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Reduction of excess fan power due to economizer damper pressure losses
An air conditioning system economizer, investigated in this thesis, consisted of three dampers, an outdoor air, a recirculation, and a discharge damper. The purpose of an economizer is to control the ratio of the outdoor air flow rate to the recirculation air flow rate. The dampers were opposed …
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Motor vehicle air-conditioning : utilising the exhaust gas energy to power an absorption refrigeration cycle
… from the motor car's exhaust gases to power an air-conditioning system. Thus the waste heat can be utilised and shaft power conserved by replacing the traditional compression refrigeration system, used for air-conditioning a motor car, with an absorption unit. The thesis deals with some …
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Nonlinear observer design using contraction theory with application to heat exchangers having varying phase transition
Thermo-fluid systems such as air conditioning and refrigeration systems are widely used in residential, commercial, and industrial applications. By the end of the 20th century, nearly 70 percent of U.S. households had air conditioning, and 99.5 percent had at least one refrigerator. Advanced …
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