Third Generation of Working Fluids for Advanced Refrigeration Heating and Power Generation Technologies

2020 ◽  
Vol 839 ◽  
pp. 51-56
Author(s):  
Oleg B. Tsvetkov ◽  
Igor V. Baranov ◽  
Yuriy A. Laptev ◽  
Alexander V. Sharkov ◽  
Vladimir V. Mitropov ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Global Warming ◽  
Chemical Industry ◽  
Montreal Protocol ◽  
Third Generation ◽  
Atmospheric Lifetime ◽  
Working Fluids ◽  
Hfc 134A ◽  
Organic Rankine Cycles

Since the 1987 Montreal Protocol, chlorinated refrigerants (CFCs and HCFCs) have been pointed out as responsible for the destruction of the ozone layer. The chemical industry has realized suitable replacement for CFC-12 and for HCFC-22 e.g. HFC-134a, HFC-404A, HFC-410A, HFC-507. This generation of refrigerants developed by the chemical industry can be characterized by the no ozone depleting potential and long atmospheric lifetime resulting in global warming potential. The contribution of the HFCs to the global warming brings up to discussion whether the HFCs should be considered as a transitional substance. Historically the use of natural and ecologically safe refrigerants was a strategy to eliminate environmental problems and avoid uncertainties with synthetic replacement fluids. Since ammonia is toxic, carbon dioxide provide high pressure, and the hydrocarbons are flammable, the general conclusion is often drawn that natural fluids gave safety problems. This paper will describe the possibilities of application as working fluids in low-temperature engineering refrigeration, heat pumping and organic Rankine cycles of the hydrofluoroolefins (HFOs) as third generation of synthetic working fluids.

Thermodynamic Analyses of Single Brayton and Combined Brayton–Rankine Cycles for Distributed Solar Thermal Power Generation

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
M. T. Dunham ◽  
W. Lipiński
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Thermal Power ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Working Fluids ◽  
Solar Thermal Power ◽  
Topping Cycle ◽  
Cycle Efficiency ◽  
Solar Thermal Power Generation

This paper reports theoretical efficiencies of single Brayton and combined Brayton–Rankine thermodynamic power cycles for distributed solar thermal power generation. Thermodynamic analyses are conducted with a nominal heat input to the cycle of 150 kW and component parameters for a 50 kWe gas microturbine for selected working fluids including air, Ar, CO2, He, H2, and N2 for the Brayton cycle and for the topping cycle of the combined system. Cycle parameters including maximum fluid temperature based on solar concentration ratio, pressure loss, and compressor/turbine efficiencies are then varied to examine their effect on cycle efficiency. C6-fluoroketone, cyclohexane, n-pentane, R-141b, R-245fa, and HFE-7000 are examined as working fluids in the bottoming segment of the combined cycle. A single Brayton cycle is found to reach a peak cycle efficiency of 15.31% with carbon dioxide at design point conditions. Each Brayton cycle fluid is examined as a topping cycle fluid in the combined cycle, being paired with six potential bottoming fluids, resulting in 36 working fluid configurations. The combination of the Brayton topping cycle using carbon dioxide and the Rankine bottoming cycle using R-245fa gives the highest combined cycle efficiency of 21.06%.

scholarly journals New Trends in the Conversion of CO2 to Cyclic Carbonates

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 479 ◽  
Author(s):  
Erivaldo J.C. Lopes ◽  
Ana P.C. Ribeiro ◽  
Luísa M.D.R.S. Martins
Keyword(s):  
Carbon Dioxide ◽  
Global Warming ◽  
Co2 Emissions ◽  
Chemical Industry ◽  
Reaction Mechanisms ◽  
Fine Chemicals ◽  
Cyclic Carbonates ◽  
Atom Economy ◽  
Carbon Dioxide Co2 ◽  
Meaningful Measure

This work concerns recent advances (mainly in the last five years) in the challenging conversion of carbon dioxide (CO2) into fine chemicals, in particular to cyclic carbonates, as a meaningful measure to reduce CO2 emissions in the atmosphere and subsequent global warming effects. Thus, efficient catalysts and catalytic processes developed to convert CO2 into different chemicals towards a more sustainable chemical industry are addressed. Cyclic carbonates can be produced by different routes that directly, or indirectly, use carbon dioxide. Thus, recent findings on CO2 cycloaddition to epoxides as well as on its reaction with diols are reviewed. In addition, indirect sources of carbon dioxide, such as urea, considered a sustainable process with high atom economy, are also discussed. Reaction mechanisms for the transformations involved are also presented.

scholarly journals Carbon Dioxide Capture and Support Technology and Contribution of India for the Planet Earth

2020 ◽  
pp. 247-252
Author(s):  
Pratap G. Patil
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Global Warming ◽  
Power Plants ◽  
Carbon Dioxide Capture ◽  
Ghg Emissions ◽  
Underground Storage ◽  
Power Sector ◽  
Gas Streams ◽  
Indian Scenario

The study is in the background of the present status of CO2 in atmosphere. Further the scope of the study is to know the development, feasibility of CCS technology and its implementation in India. The key objective of the research is “To study the importance and development of CCS technology in reducing the GHG emissions to restrain global warming”. In pursuing the above research objective, the study focused on the components of CCS technology with reference to power sector in detail so as to understand the feasibility of the concerned technologies; their applicability to the Indian scenario. The scope of CCS Technology aims to: • Enhancing efficiency of power plants by emerging technologies to reduce emission of CO2 per megawatt to reduce process load on capture technology; • Capturing and Separating CO2 from the gas streams emitted from combustion; • Transporting the captured CO2 to underground storage; In India upto 2050 there is no budgetary provision for CCS technology in spite of having major coal pro-duction and utilization of it for power generation

Nonflammable Low GWP Working Fluid for Organic Rankine Cycles

2014 ◽  
Author(s):  
Barbara Minor ◽  
Konstantinos (Kostas) Kontomaris ◽  
Bianca Hydutsky
Keyword(s):  
Global Warming ◽  
Electrical Power ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Vapor Pressures ◽  
Working Fluids ◽  
Environmentally Sustainable ◽  
Organic Rankine Cycles ◽  
Low Global Warming Potential ◽  
Ozone Depletion Potential

Regulatory pressure has been increasing globally to address the issue of climate change. In particular, there are plans to reduce the use of hydrofluorocarbon (HFC) based working fluids across many applications, as HFCs are forecast to be significant contributors to global warming in the future. Therefore, there is a need to find low global warming potential (GWP) fluids suitable for organic rankine cycles (ORCs) in those systems where HFCs have historically been preferred. These are usually systems that require a non-flammable working fluid. A new ORC working fluid, cis-1,1,1,4,4,4-hexafluoro-2-butene, also called DR-2 (cis-CF3CH=CHCF3) has been developed which is nonflammable with very low GWP of 8.9 and an ozone depletion potential (ODP) of zero because it contains no chlorine or other halogen atoms other than fluorine. DR-2 also has a favorable toxicity profile based on testing to date. DR-2 is thermally stable in the presence of lubricant and metals, air and oxygen up to the maximum temperature tested of 250°C. DR-2 has a boiling point of 33.4°C and a relatively high critical temperature of 171.3°C, which result in relatively low vapor pressures and high cycle energy efficiencies. It can enable more environmentally sustainable ORC platforms to generate electrical power from widely available heat at higher temperatures and with higher energy efficiencies than incumbent working fluids.

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