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Showing 1 to 20 of 63 for “"vapor compression"”.
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Modeling and control of hybrid vapor compression cycles
… techniques, and control schemes for hybrid vapor compression cycles. Hybrid vapor compression cycles come in many possible configurations, but they all combine the power producing components of a conventional cycle with a thermal energy storage unit to provide increased operational …
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Potentials for COP increase in vapor compression systems
… different opportunities for COP increase in vapor compression systems: work recovery ejectors, condenser subcooling and increase of relative size of heat exchangers (HXs). Regarding work recovery ejectors, experimental results showed that the COP of the ejector system increased between 8.2% …
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Dynamic modeling, validation, and control for vapor compression systems
… process of model-based control design for vapor compression systems (VCSs), from nonlinear model development to linearization and control formulation. Addressing gaps in the previous literature, the equations behind each model and control approach are clearly stated and emphasis is placed …
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Model free real-time optimization for vapor compression systems
A vapor compression system's optimal input settings vary according to changes in environmental conditions. Tracking these optimal input trajectories can be challenging when insufficient information for a reliable system model is available. An alternative set of optimization approaches use system …
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Extremum seeking control of battery powered vapor compression systems for vehicles
… real-time energy optimization of battery powered vapor compression systems (VCS) for vehicles. Battery powered VCS are critical for maintaining passenger comfort in engine-off situations, and are especially important to long-haul truck drivers who sleep inside their vehicle overnight. However, one …
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Fault detection methods for vapor-compression air conditioners using electrical measurements
… 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 damage and are difficult to measure directly, a method for detecting this fault is proposed that only …
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A thermodynamics based analysis of exergy destruction in vapor compression cycle systems
In the last few decades, vapor-compression cycle systems (VCSs) have undergone many advances in actuation, allowing for variable aperture valves, variable speed compressors, and variable speed heat exchanger fans. Numerous efforts have been undertaken to quantify the energy efficiency of these …
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Dynamic modeling and multivariable control of vapor compression cycles in air conditioning systems
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.
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Commissioning of experimental facility for oil circulation rate measurements in a vapor compression system
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2024-03-01 without embargo terms
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Analysis and optimization of a dual-load vapor compression cycle using non-azeotropic refrigerant mixtures
… the use of intercooling with no decrease in evaporating pressure. The objective of this research was to investigate optimal pure refrigerant (R12 and R134a) and NARM (65% R22/35% R123 and 80% R22/20% R141b) refrigerator system configurations that minimized life-cycle cost.
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Dynamic modeling and control of transcritical vapor compression system for battery electric vehicle thermal management
… friendly and safe alternative. However, these vapor compression systems operate transcritical, thus requiring novel control techniques. This thesis develops a framework for architecture and control design of BEV subsystems. The foundation of this process is the development of multi-domain …
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TRANSIENT MODELING OF TWO-STAGE AND VARIABLE REFRIGERANT FLOW VAPOR COMPRESSION SYSTEMS WITH FROSTING AND DEFROSTING
… framework for the transient simulation of vapor compression systems. This framework contains a wide range of components and its modular nature enables an arbitrary cycle configuration to be analyzed. One of the highlights of this framework is the first-principles heat exchanger models with …
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Performance optimization of advanced vapor compression systems working with low-GWP refrigerants using numerical and experimental methods
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01
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Vortex control of two-phase refrigerant flow in nozzles and its application in ejector vapor compression cycles
… been measured. A 1D model for the estimation of vapor qualities in the initially subcooled flashing nozzle flow based on the measurement results was also developed. It was found that after the introduction of the inlet vortex to the initially subcooled flashing nozzle flow, the pressure drop …
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An integrated system of vapor-compression chiller and absorption heat pump: Experiment, modeling, and energy and economic evaluation
… an Integrated System of an Integrated Compression-Absorption Subcooling System (ICASS) Based upon the principle of subcooling effect, the ICASS can improve the efficiency of the cooling device but also achieve additional useful heating sources potentially used for space heating and …
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The performance of a reversible R744 vapor compression system with an internal heat exchanger in continuous frosting/ defrosting cycles
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01
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Design of a small-scale and off-grid water desalination system using solar thermal heating and mechanical vapor compression
… solar photovoltaics (PV) to power a mechanical vapor compression system, and is designed for low-cost and high output purification in a minimal footprint. The proposed system was analyzed in both transient warm up and steady state phases separately, and the results were combined to develop an …
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Experimental and numerical investigation of the design and control of vapor-compression systems with integration of two-phase ejectors for performance enhancement through expansion work recovery
… to improve the efficiency and capacity of vapor-compression refrigeration cycles by means of expansion work recovery has received significant attention in the past decade. Research has focused primarily on the design and performance of the ejector and the effect the ejector has on cycle …
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A quasi-steady modeling approach of a heat pump water heater system with experimental validation and analysis
… system, the dynamic interdependence between the vapor compression system and the water in the storage tank poses a modeling challenge for steady-state refrigeration system models. The aim of this project is to develop a model and methodology for coupling steady-state vapor compression system …
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Comparative study of advanced heat pumps
… are made to the more commonly applied vapor compression systems, including those using R-134a. The study examines the effect of thermal resistances between the device and the heat rejection or heat absorption space. A cool side temperature difference between 0 and …
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