Thermodynamic Study on Blends of Hydrocarbons and Carbon Dioxide as Zeotropic Refrigerants

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Sai C. Yelishala ◽  
Kumaran Kannaiyan ◽  
Ziyu Wang ◽  
Hameed Metghalchi ◽  
Yiannis A. Levendis ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Operating Conditions ◽  
Data Availability ◽  
Coefficient Of Performance ◽  
Heat Transfer Fluid ◽  
Alternative Refrigerants ◽  
Vapor Compression Refrigeration Cycle ◽  
Technical Interest ◽  
Carbon Dioxide Co2 ◽  
Low Global Warming Potential

Abstract Finding alternative refrigerants is of extreme importance to mitigate anthropogenic climate change. Among the next-generation refrigerants, hydrocarbons (HCs) are of technical interest because they are natural, efficient, have low global warming potential (GWP), and zero ozone depletion potential (ODP). However, their flammability impedes their widespread usage for fire-safety reasons. The present work investigated zeotropic mixtures of hydrocarbons with carbon dioxide (CO2) as refrigerants for a simple vapor-compression refrigeration cycle, since their flammability risks are lower than those of pure hydrocarbons. Refrigerants were selected utilizing various screening steps based on environmental effects (such as GWP, ODP, and toxicity), thermophysical properties (such as critical temperature, and boiling point), and mixture data availability. The thermodynamic analysis for these selected zeotropic mixtures was performed for a cycle with a constant temperature of energy (heat) transfer fluid in both the evaporator and the condenser/gas cooler. Subsequently, performance parameters like the coefficient of performance and volumetric refrigeration capacity were compared for each of these blends at different operating conditions, and thus, the most promising hydrocarbon mixtures with CO2 were identified. As a result, the following four hydrocarbons, individually blended with CO2, were favorable in performance: propylene, dimethyl ether, propane, and isobutane. Further analysis was performed to determine the non-dimensional exergy destruction by the various components of the cycle.

scholarly journals Exergetic performance analysis of low GWP alternative refrigerants for R404A in a refrigeration system

2021 ◽  
Author(s):  
Mehmet Altinkaynak
Keyword(s):  
Cooling System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Refrigeration System ◽  
Alternative Refrigerants ◽  
Condenser Temperature ◽  
Parametric Analyses ◽  
Low Global Warming Potential ◽  
Very High

Abstract According to the regulation of European Union laws in 2014, it was inevitable to switch to low global warming potential (GWP) fluids in the refrigeration systems where the R404A working fluid is currently used. The GWP of R404A is very high, and the potential for ozone depletion is zero. In this study, energetic and exergetic performance assessment of a theoretical refrigeration system was carried out for R404 refrigerant and its alternatives, comparatively. The analyses were made for R448A, R449A, R452A and R404A. The results of the analysis were presented separately in the tables and graphs. According to the results, the cooling system working with R448A exhibited the best performance with a coefficient of performance (COP) value of 2.467 within the alternatives of R404A followed by R449A and R452A, where the COP values were calculated as 2.419 and 2.313, respectively. In addition, the exergy efficiencies of the system were calculated as 20.62%, 20.22% and 19.33% for R448A, R449A and R452A, respectively. For the base calculations made for R404A, the COP of the system was estimated as 2.477, where the exergy efficiency was 20.71%. Under the same operating conditions, the total exergy destruction rates for R404A, R448A, R449A and R452A working fluids were found to be 3.201 kW, 3.217 kW, 3.298 kW and 3.488 kW, respectively. Furthermore, parametric analyses were carried out in order to investigate the effects of different system parameters such as evaporator and condenser temperature.

scholarly journals Parametric analysis of a combined ejector-vapor compression refrigeration cycle

2020 ◽  
Vol 15 (3) ◽  
pp. 398-408
Author(s):  
I Ouelhazi ◽  
Y Ezzaalouni ◽  
L Kairouani
Keyword(s):  
Current Model ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Entrainment Ratio ◽  
Constant Area ◽  
Vapor Compression Refrigeration Cycle ◽  
Vapor Compression Refrigeration

Abstract From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.

scholarly journals Energy Analysis of Vapor Compression Refrigeration Cycle Using a New Generation Refrigerants with Low Global Warming Potential

2021 ◽  
Vol 87 (2) ◽  
pp. 106-117
Author(s):  
Rabah Touaibi ◽  
Hasan Koten
Keyword(s):  
Global Warming ◽  
Global Warming Potential ◽  
Energy Analysis ◽  
Coefficient Of Performance ◽  
Cycle Performance ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Vapor Compression Refrigeration Cycle ◽  
Vapor Compression Refrigeration ◽  
Low Global Warming Potential

An energy analysis study carried out on a vapor compression refrigeration cycle using refrigerants with low global warming potential (GWP) of the Hydro-Fluoro-Olefin (HFO) type, in particular R1234yf and R1234ze fluids to replace HFC refrigerants . Computer code was developed using software for solving engineering equations to calculate performance parameters; for this, three HFC type fluids (R134a, R404A and R410A) were selected for a comparative study. The results showed that R1234ze is the best refrigerant among those selected for the mechanical vapor compression refrigeration cycle. The thermodynamic analysis showed the effect of the evaporator temperature (-22 °C to 10 °C) and the condenser temperature (30 °C to 50 °C) on the steam cycle performance. Compression refrigeration, including the coefficient of performance. The results showed that the HFO-R1234ze with low GWP gives the best coefficient of performance of 3.14 close to that of the R134a fluid (3.17). In addition, R1234ze is considered an alternative fluid to R134a for their ecological properties.

scholarly journals Simulation of the performance of alternative refrigerants in liquid chillers

2001 ◽  
Vol 215 (4) ◽  
pp. 429-441 ◽  
Author(s):  
I. N. Grace ◽  
S. A. Tassou
Keyword(s):  
Dynamic Models ◽  
Control Strategies ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
System Component ◽  
Alternative Refrigerants ◽  
Expansion Valve ◽  
Shell And Tube Evaporator ◽  
The Impact

The impact of refrigeration systems on the environment can be reduced by (a) the use of alternative refrigerants which are less harmful to the environment and (b) the optimization of systems and control strategies to deliver increased levels of energy efficiency. Mathematical modelling offers the opportunity to test the performance of systems under different operating conditions and with alternative refrigerants. Dynamic models allow comparison of both transient and steady state behaviour and this is of particular importance for liquid chillers since these systems can operate under transient conditions for long periods. This paper covers the development of a general dynamic model for the simulation of liquid chillers. Brief descriptions of the system component models are given, including a semihermetic reciprocating compressor and thermostatic expansion valve as well as a shell-and-tube evaporator and condenser. The paper demonstrates the application of the model to simulate the performance of a liquid chiller retrofitted with a range of alternative refrigerants. The performance of the system is determined in terms of cooling capacity, power consumption and coefficient of performance for a range of different operating conditions. The relative performance of each refrigerant is discussed and the preferred alternative identified for typical applications.

scholarly journals Offshore Power Plants Integrating a Wind Farm: Design Optimisation and Techno-Economic Assessment Based on Surrogate Modelling

Processes ◽  
2018 ◽  
Vol 6 (12) ◽  
pp. 249 ◽  
Author(s):  
Luca Riboldi ◽  
Lars Nord
Keyword(s):  
Carbon Dioxide ◽  
Power Plant ◽  
Wind Farm ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Oil Field ◽  
Total Carbon ◽  
Optimal Size ◽  
Surrogate Modelling ◽  
Carbon Dioxide Co2

The attempt to reduce the environmental impact of the petroleum sector has been the driver for researching energy efficient solutions to supply energy offshore. An attractive option is to develop innovative energy systems including renewable and conventional sources. The paper investigates the possibility to integrate a wind farm into an offshore combined cycle power plant. The design of such an energy system is a complex task as many, possibly conflicting, requirements have to be satisfied. The large variability of operating conditions due to the intermittent nature of wind and to the different stages of exploitation of an oil field makes it challenging to identify the optimal parameters of the combined cycle and the optimal size of the wind farm. To deal with the issue, an optimisation procedure was developed that was able to consider the performance of the system at a number of relevant off-design conditions in the definition of the optimal design. A surrogate modelling technique was applied in order to reduce the computational effort that would otherwise make the optimisation process unfeasible. The developed method was applied to a case study and the resulting optimal designs were assessed and compared to other concepts, with or without wind power integration. The proposed offshore power plant returned the best environmental performance, as it was able to significantly cut the total carbon dioxide (CO2) emissions in comparison to all the other concepts evaluated. The economic analysis showed the difficulty to repay the additional investment for a wind farm and the necessity of favourable conditions, in terms of gas and carbon dioxide (CO2) prices.

Alternative Refrigerants for Solar Absorption Air-Conditioning

2019 ◽  
Vol 28 (01) ◽  
pp. 2050001
Author(s):  
Nihel Chekir ◽  
Ali Snoussi ◽  
Ammar Ben Brahim
Keyword(s):  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Hydrocarbon Mixture ◽  
Water Mixture ◽  
Air Conditioner ◽  
Alternative Refrigerants ◽  
Solar Absorption ◽  
Air Conditioners ◽  
A Value ◽  
Circulation Ratio

Three hydrocarbons are considered as refrigerants for solar absorption air-conditioner. The cooling plant is composed essentially of the absorption chiller and the solar system is simulated with three working pairs: propane/octane, butane/octane and iso-butane/octane. Results are compared to those of ammonia/water mixture at the same fixed operating conditions and assumptions. The main advantages of the investigated refrigerants are their similar cooling effect compared to ammonia with a coefficient of performance reaching 0.63 and their relatively low working pressures. Nevertheless, the circulation ratio for hydrocarbon mixture is higher compared to ammonia. Propane/octane working mixture seems to be suitable for solar absorption air-conditioners with some particular precautions. The heat required to drive the absorption system is provided by evacuated tubes solar collectors of 90[Formula: see text]m2, a value in agreement with commercialized solar absorption air-conditioner operating with ammonia.

scholarly journals Experimental Analysis and Optimization of an R744 Transcritical Cycle Working with a Mechanical Subcooling System

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3204 ◽  
Author(s):  
Daniel Sánchez ◽  
Jesús Catalán-Gil ◽  
Ramón Cabello ◽  
Daniel Calleja-Anta ◽  
Rodrigo Llopis ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Critical Temperature ◽  
Computational Model ◽  
Experimental Analysis ◽  
Experimental Tests ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Liquid Heat

In the last century, the refrigerant R744 (carbon dioxide) has become an environmentally friendly solution in commercial refrigeration despite its particular issues related to the low critical temperature. The use of transcritical cycles in warm and hot countries reveals the necessity of adopting different configurations and technologies to improve this specific cycle. Among these, subcooling methods are well-known techniques to enhance the cooling capacity and the Coefficient of Performance (COP) of the cycle. In this work, an R600a dedicated mechanical subcooling system has been experimentally tested in an R744 transcritical system at different operating conditions. The results have been compared with those obtained using a suction-to-liquid heat exchanger (IHX) to determine the degree of improvement of the mechanical subcooling system. Using the experimental tests, a computational model has been developed and validated to predict the optimal subcooling degree and the cubic capacity of the mechanical subcooling compressor. Finally, the model has been used to analyze the effect of using different refrigerants in the mechanical subcooling unit finding that the hydrocarbon R290 and the HFC R152a are the most suitable fluids.

scholarly journals Selection of optimal fluid for refrigeration cycles

2020 ◽  
Vol 1 (2) ◽  
pp. 021-036
Author(s):  
Ayman G. A. Essa ◽  
Adil A. Mohamed
Keyword(s):  
Molecular Design ◽  
Industrial Applications ◽  
Optimization Techniques ◽  
Molecular Structures ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Alternative Refrigerants ◽  
Aspen Hysys ◽  
Vapor Compression Refrigeration Cycle ◽  
Selection Of

Refrigeration and air-conditioning play an important role in our life and industrial applications. They have great impact on our life. They have also contributed to the world’s major environmental issues like ozone layer depletion and global warming. Common refrigerants such as CFCs and HCFCs which are working as fluid in refrigeration cycles have unfavorable environmental impacts and this has brought about concerns and regulations prohibiting their production and use as refrigerants by the year 2030. The development of different refrigerants over time took place based on safety and environmental impact issues. This paper, presents the selection of optimal working fluids for Vapor-Compression Refrigeration Cycle (VCRs) based on computer aided molecular design (CAMD) and process optimization techniques. The resulting methodology utilizes from CAMD for the generation of optimum working fluid candidates. Candidates were evaluated as alternative refrigerants for the R134a refrigerating system through simulation using Aspen Hysys V8.0, with restricted by priority coefficient of performance COP, environmental and safety criteria. Ethyl trifluoromethyl ether 1,1,1-TrifluoroButane (new refrigerant) shows a good environmental and toxicity data also have high COP, 4.5, 2.7 respectively and were favored amongst the studied refrigerants as the choice alternative refrigerants to replace R134a. The methodology systematically identified conventional molecular structures that enable optimum VCRs process performance.

scholarly journals Looking for Energy Losses of a Rotary Permanent Magnet Magnetic Refrigerator to Optimize Its Performances

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4388 ◽  
Author(s):  
Angelo Maiorino ◽  
Antongiulio Mauro ◽  
Manuel Gesù Del Duca ◽  
Adrián Mota-Babiloni ◽  
Ciro Aprea
Keyword(s):  
Heat Load ◽  
Eddy Currents ◽  
Extensive Study ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Heat Transfer Fluid ◽  
Fluid Distribution ◽  
Energy Losses ◽  
Rotary Valve ◽  
Magnetic Refrigerator

In this paper, an extensive study on the energy losses of a magnetic refrigerator prototype developed at University of Salerno, named ‘8MAG’, is carried out with the aim to improve the performance of such a system. The design details of ‘8MAG’ evidences both mechanical and thermal losses, which are mainly attributed to the eddy currents generation into the support of the regenerators (magnetocaloric wheel) and the parasitic heat load of the rotary valve. The latter component is fundamental since it imparts the direction of the heat transfer fluid distribution through the regenerators and it serves as a drive shaft for the magnetic assembly. The energy losses concerning eddy currents and parasitic heat load are evaluated by two uncoupled models, which are validated by experimental data obtained with different operating conditions. Then, the achievable coefficient of performance (COP) improvements of ‘8MAG’ are estimated, showing that reducing eddy currents generation (by changing the material of the magnetocaloric wheel) and the parasitic heat load (enhancing the insulation of the rotary valve) can lead to increase the COP from 2.5 to 2.8 (+12.0%) and 3.0 (+20%), respectively, and to 3.3 (+32%), combining both improvements, with an hot source temperature of 22 °C and 2 K of temperature span.

scholarly journals Investigation and Analysis of R463A as an Alternative Refrigerant to R404A with Lower Global Warming Potential

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1514
Author(s):  
Piyanut Saengsikhiao ◽  
Juntakan Taweekun ◽  
Kittinan Maliwan ◽  
Somchai Sae-ung ◽  
Thanansak Theppaya
Keyword(s):  
Carbon Dioxide ◽  
Global Warming ◽  
Transport Properties ◽  
Global Warming Potential ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Fourth Generation ◽  
Operating Pressure ◽  
Thermodynamic And Transport Properties ◽  
Carbon Dioxide Co2

This research presents the development of R463A refrigerant, a nonflammable refrigerant that was retrofitted to replace R404A. R463A is primarily composed of hydrofluorocarbons/hydrocarbons/carbon dioxide (HFCs/HCs/CO2), and has global-warming potential (GWP) of 1494. It is a nonazeotropic mixture of R32 (36%), R125 (30%), R134a (14%), R1234yf (14%), and R744 (6%). R463A is composed of polyol ester oil (POE), and it is classified as a Class A1 incombustible and nontoxic refrigerant. R463A has a higher cooling capacity (Qe) than that of R404A, as it is composed of hydrofluorocarbons (HFCs) R32 and carbon dioxide (CO2) R744, and has lower GWP than that of R404A due to the use of hydrofluoroolefins (HFOs) from R1234yf. The results of this research showed that R463A can be retrofitted to replace R404A due to its composition of POE, Class A1 incombustibility, and lower toxicity. The properties of R463A and R404A, as analyzed using national institute of standards and technology (NIST) reference fluid thermodynamic and transport properties database (REFPROP) software and NIST vapor compression cycle model accounting for refrigerant thermodynamic and transport properties (CYCLE_D-HX) software, are in accordance with the CAN/ANSI/AHRI540 standards of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI). The normal boiling point of R463A was found to be higher than that of R404A by 23%, with a higher cooling capacity and a 63% lower GWP value than that of R404A. The critical pressure and temperature of R463A were found to be higher than those of R404A; it can be used in a high-ambient-temperature environment, has higher refrigerant and heat-rejection effects, and has lower GWP than that of R404A by 52% due to the HFOs from the R1234yf component. The cooling coefficient of performance (COPc) of R463A was found to be higher than that of R404A by 10% under low-temperature applications. R463A is another refrigerant option that is composed of 7% carbon dioxide (CO2), and is consistent with the evolution of fourth-generation refrigerants that contain a mixture of HFCs, HFOs, HCs, and natural refrigerants, which are required to produce a low-GWP, zero-ozone-depletion-potential (ODP), high-capacity, low-operating-pressure, and nontoxic refrigerant.

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