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Experimental Study Of An Ejector Refrigeration System, Christopher Reddick, Yves Mercadier, Mohamed Ouzzane
Experimental Study Of An Ejector Refrigeration System, Christopher Reddick, Yves Mercadier, Mohamed Ouzzane
International Refrigeration and Air Conditioning Conference
The aim of the present work is to experimentally study the possibility of improving the energy efficiency of a vapour compression refrigeration system where a two-phase ejector replaces the expansion valve. A test bench using refrigerant R134a was designed and built which functions in both the conventional mode and in ejector mode. The primary nozzle of the ejector was equipped with a double throat, having an adjustable area for the first throat and a fixed area for the second throat. Experimental results showed an improvement of 11% in the coefficient of performance (COP) in ejector mode as compared with the …
A Departure Function-Based Method To Determine The Effect Of The Oil Circulation Ratio On The Performance Of Vapor Compression Refrigeration Systems, Moises Marcelino Neto, Jader Barbosa Jr.
A Departure Function-Based Method To Determine The Effect Of The Oil Circulation Ratio On The Performance Of Vapor Compression Refrigeration Systems, Moises Marcelino Neto, Jader Barbosa Jr.
International Refrigeration and Air Conditioning Conference
A method to estimate the performance of single-stage vapor compression refrigeration systems as a function of the oil circulation ratio is presented. The model is based on the Peng-Robinson equation of state and on the theory of departure functions to estimate the mixture enthalpy, entropy and specific volume as a function of pressure, temperature and mixture composition. The method is applied to a mixture of isobutane (R-600a) and alkyl benzene oil. Pressure-enthalpy diagrams are presented as a function of the oil circulation ratio. These are used in conjunction with a thermodynamic cycle analysis in which the behavior of overall performance …
Energy Efficiency Of Refrigeration Systems, Michael Arnemann
Energy Efficiency Of Refrigeration Systems, Michael Arnemann
International Refrigeration and Air Conditioning Conference
Energy efficiency plays an important role in the development and operation of refrigeration systems. The method of the VDMA 24247-2 2 “Energy efficiency of refrigeration systems – Requirements for the system design and the components” were recently published. The method will be described within this paper, with the focus on the graphical interpretation.
Comparison Of Equation-Based And Non-Equation-Based Approaches For Transient Modeling Of A Vapor Compression Cycle, Hongtao Qiao, Vikrant Aute, Reinhard Radermacher
Comparison Of Equation-Based And Non-Equation-Based Approaches For Transient Modeling Of A Vapor Compression Cycle, Hongtao Qiao, Vikrant Aute, Reinhard Radermacher
International Refrigeration and Air Conditioning Conference
Transient modeling methods can also be classified into two categories based on equation specifications. The first category of methods are non-equation based methods, in which one has to describe the underlying physics with fundamental equations, formulate residual equations and provide an algorithm to solve the underlying nonlinear equations. The second category of methods are equation based methods, wherein the engineer only has to specify the underlying physics, that holds for each time step, in the form of equations and use an established modeling platform or a solver which will handle the formulation and solution of underlying nonlinear differential algebraic equations. …
Modelica Based Transient Modeling Of A Flash Tank Vapor Injection System And Experimental Validation, Hongtao Qiao, Xing Xu, Vikrant Aute, Reinhard Radermacher
Modelica Based Transient Modeling Of A Flash Tank Vapor Injection System And Experimental Validation, Hongtao Qiao, Xing Xu, Vikrant Aute, Reinhard Radermacher
International Refrigeration and Air Conditioning Conference
The flash tank vapor injection cycle is widely used and has been proven effective for improving system performance compared with the conventional systems. A good control design for this type of cycle to make the system work properly under various operation conditions is a challenge and one often has to resort to experimental studies, which are time-consuming and costly. In this paper, a transient mathematical model for a flash tank vapor injection heat pump system with an economized scroll compressor is presented. The compressor model is a map-based model. The heat exchangers are modeled using the finite volume method. The …
Modeling And Simulation Of A Desiccant Assisted Brayton Refrigeration Cycle, Carlos E.L. Nobrega, Leandro Alcoforado Sphaier
Modeling And Simulation Of A Desiccant Assisted Brayton Refrigeration Cycle, Carlos E.L. Nobrega, Leandro Alcoforado Sphaier
International Refrigeration and Air Conditioning Conference
The phase-out of CFCs has shed a new light over natural refrigerants, which have null global warming potentials. Air would be a natural choice, and although the Brayton cycle usually exhibits a lower coefficient of performance when compared to vapor-compression systems of same capacity, it has been considered in applications other than aircraft cooling. These include gas separation, food processing and preservation, refrigerated containers and train air-conditioning. Price perspectives in the oil market also make the Brayton cycle an alternative to be considered as an option for automotive air conditioning. Even though the Brayton cycle is often employed in low …
Experimental Investigation And Mathematical Modeling Of Commercially Available R744 Compressors, Orkan Kurtulus, Burak Olgun, Emre Oguz
Experimental Investigation And Mathematical Modeling Of Commercially Available R744 Compressors, Orkan Kurtulus, Burak Olgun, Emre Oguz
International Refrigeration and Air Conditioning Conference
The vapor compression cycle using refrigerant CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) is widely used in refrigeration, air-conditioning and water heating industries. Utilization of these gases are prohibited by the Montreal Protocol. The critical temperature of carbon dioxide (CO2) is much lower than that of the other refrigerants, namely 31.06°C. The gas cooling process occurs at a constant pressure but at variable temperatures takes the place of the condensation process that occurs at both constant pressure and temperature. Domestic type refrigerators use smaller compressor capacities between 100 W to 300 W. Data on CO2 (R744) refrigeration cooling cycle applications and calorimetric …