scholarly journals Calculated and experimental evaluation heat pump distiller on pentane as working substance

2020 ◽  
Vol 324 ◽  
pp. 02007
Author(s):  
Gennady A. Ilyn ◽  
Ilya I. Malafeev ◽  
Vladimir B. Sapojnikov
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Recovery Phase ◽  
High Energy ◽  
Heat Pumps ◽  
Working Fluid ◽  
Vapor Compression ◽  
The Cost ◽  
Reliable Methods ◽  
High Temperature Vapor

One of the most common and reliable methods of water treatment is the method of thermal distillation. Despite the reliability of the method, its application is constrained by high energy intensity. The most effective way to reduce the cost of production of distillate is the use of thermal transformers, providing regenerate and heat recovery phase transformations of the distillate. The use of working fluid with the most favorable thermodynamic properties is of paramount importance for the creation of high efficiency thermotransformers. The work is considered working fluid for high-temperature heat pumps and the results of the calculation-experimental study of high-temperature vapor compression heat-pumping distiller on natural working substance n-pentan.

scholarly journals Thermodynamic competitiveness of high temperature vapor compression heat pumps for boiler substitution

Energy ◽  
2019 ◽  
Vol 182 ◽  
pp. 110-121 ◽  
Author(s):  
Riccardo Bergamini ◽  
Jonas Kjær Jensen ◽  
Brian Elmegaard
Keyword(s):  
High Temperature ◽  
Heat Pumps ◽  
Vapor Compression ◽  
High Temperature Vapor

scholarly journals Identification of Existing Challenges and Future Trends for the Utilization of Ammonia-Water Absorption–Compression Heat Pumps at High Temperature Operation

2021 ◽  
Vol 11 (10) ◽  
pp. 4635
Author(s):  
Marcel Ulrich Ahrens ◽  
Maximilian Loth ◽  
Ignat Tolstorebrov ◽  
Armin Hafner ◽  
Stephan Kabelac ◽  
...  
Keyword(s):  
High Temperature ◽  
Water Absorption ◽  
Industrial Sector ◽  
Heat Pumps ◽  
Working Fluid ◽  
Large Temperature ◽  
Future Trends ◽  
Ammonia Water ◽  
Starting Point ◽  
High Temperature Operation

Decarbonization of the industrial sector is one of the most important keys to reducing global warming. Energy demands and associated emissions in the industrial sector are continuously increasing. The utilization of high temperature heat pumps (HTHPs) operating with natural fluids presents an environmentally friendly solution with great potential to increase energy efficiency and reduce emissions in industrial processes. Ammonia-water absorption–compression heat pumps (ACHPs) combine the technologies of an absorption and vapor compression heat pump using a zeotropic mixture of ammonia and water as working fluid. The given characteristics, such as the ability to achieve high sink temperatures with comparably large temperature lifts and high coefficient of performance (COP) make the ACHP interesting for utilization in various industrial high temperature applications. This work reviews the state of technology and identifies existing challenges based on conducted experimental investigations. In this context, 23 references with capacities ranging from 1.4 kW to 4500 kW are evaluated, achieving sink outlet temperatures from 45 °C to 115 °C and COPs from 1.4 to 11.3. Existing challenges are identified for the compressor concerning discharge temperature and lubrication, for the absorber and desorber design for operation and liquid–vapor mixing and distribution and the choice of solution pump. Recent developments and promising solutions are then highlighted and presented in a comprehensive overview. Finally, future trends for further studies are discussed. The purpose of this study is to serve as a starting point for further research by connecting theoretical approaches, possible solutions and experimental results as a resource for further developments of ammonia-water ACHP systems at high temperature operation.

scholarly journals Externally Fired Combined Cycles (EFCC): Part B — Alternative Configurations and Cost Projections

1996 ◽  
Author(s):  
Stefano Consonni ◽  
Ennio Macchi
Keyword(s):  
High Temperature ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
High Efficiency ◽  
Complete Combustion ◽  
Economic Issues ◽  
Temperature Heat ◽  
Combined Cycles ◽  
Power Outputs ◽  
The Cost

Externally Fired Combined Cycles (EFCC) constitute one of the options allowing the use of “dirty” fuels like coal, biomass or waste in conjunction with modern, high efficiency gas turbines. This two-part paper discusses thermodynamic, technological and economic issues crucial to the successful realization of EFCCs. Part B discusses the cycle arrangement, its implications for the design and the cost of the high temperature heat exchangers, the effects of scale and the economic prospects. An “enhanced” configuration whereby the excess air sent to the combustor is limited to the minimum required for complete combustion can reach net LHV efficiencies above 50%, with relatively low high-temperature heat transfer surface requirements. Cost projections are hindered by the uncertainty on the cost of the high temperature heat exchangers. Estimates based on published and proprietary data collected by the authors indicate that EFCCs should be cost-competitive with IGCCs, especially at medium-low power outputs.

scholarly journals Performance Analysis and Working Fluid Selection for Single and Two Stages Vapor Compression Refrigeration Cycles

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1017
Author(s):  
Bahaa Saleh ◽  
Ayman A. Aly ◽  
Mishal Alsehli ◽  
Ashraf Elfasakhany ◽  
Mohamed M. Bassuoni
Keyword(s):  
Energy Efficiency ◽  
Environmental Impacts ◽  
High Energy ◽  
Working Fluid ◽  
Vapor Compression ◽  
Alternative Refrigerants ◽  
Two Stage ◽  
Azeotropic Mixtures ◽  
Vapor Compression Refrigeration ◽  
Two Stages

Screening for alternative refrigerants with high energy efficiency and low environmental impacts is one of the highest challenges of the refrigeration sector. This paper investigates the performance and refrigerant screening for single and two stages vapor compression refrigeration cycles. Several pure hydrocarbons, hydrofluorocarbons, hydrofluoroolefins, fluorinated ethers, and binary azeotropic mixtures are proposed as alternative refrigerants to substitute R22 and R134a due to their environmental impacts. The BACKONE equation of state is used to compute the thermodynamic properties of the candidates. The results show that the maximum coefficients of performance (COP) for single and two stage cycles using pure substances are achieved using cyclopentane with values of 4.14 and 4.35, respectively. On the other side, the maximum COP for the two cycles using azeotropic mixtures is accomplished using R134a + RE170 with values of 3.96 and 4.27, respectively. The two-stage cycle presents gain in COP between 5.1% and 19.6% compared with the single-stage cycle based on the used refrigerant. From the obtained results, among all investigated refrigerants, cyclopentane is the most suitable refrigerant for the two cycles from the viewpoint of energy efficiency. However, extra cautions should be taken due to its flammability.

scholarly journals Problems of sodium using in pulsating heat pipe made from fused silica

2018 ◽  
Vol 207 ◽  
pp. 04004
Author(s):  
Radovan Nosek ◽  
Tatiana Liptáková ◽  
Libor Trško ◽  
Zuzana Kolková ◽  
Milan Malcho ◽  
...  
Keyword(s):  
High Temperature ◽  
Heat Pipe ◽  
Alkali Metals ◽  
High Efficiency ◽  
Fused Silica ◽  
Operating Conditions ◽  
Liquid Sodium ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
High Temperature Reaction

You Heat pipe is a high efficiency heat transfer element, depends on the evaporation, condensation and circulation of inside working fluid. The working fluid of a high temperature pulsating heat pipe is generally alkali metals, and sodium heat pipe can operate in range of 500-1100°C. In order to investigate terminal velocity of working fluid, the glass pulsating heat pipe was produced for experimental purposes. The experiment was carried out, in order to simulate real operating conditions in range of 500-1100°C. Sudden boiling of liquid sodium (b.p. = 883°C at 1 atm) inside the all quartz-made heat pipe results in high-temperature reaction of sodium vapour with the inner wall surface. The reaction became more aggressive with increasing vapour temperature and resulted in heat pipe explosion. The evaluation of damage character is analysed in this paper.

Development of a Cascade Elastocaloric Regenerator

2019 ◽  
Author(s):  
Nehemiah Emaikwu ◽  
David Catalini ◽  
Jan Muehlbauer ◽  
Yunho Hwang ◽  
Ichiro Takeuchi ◽  
...  
Keyword(s):  
Solid State ◽  
Energy Use ◽  
Environmentally Friendly ◽  
High Energy ◽  
Heat Pumps ◽  
Vapor Compression ◽  
Regenerative Heat ◽  
Pump Design ◽  
Surface Areas ◽  
Elastocaloric Effect

Abstract Heat pumps based on the vapor compression cycle account for a significant portion of energy use around the world. However, growing demands for energy efficient and environmentally friendly technologies have created a need for new space conditioning approaches. Novel systems which use elastocaloric material have shown potential to replace traditional vapor compression due to high energy efficiency and use of environmentally friendly, solid-state refrigerants. The solid-state refrigerants exhibit the elastocaloric effect, a phenomenon that occurs when metal alloys experience stress-induced reversible phase transformations resulting in latent heat release or absorption. Prototypes built in the Center for Environmental Energy Engineering have utilized the active elastocaloric regeneration (AER) operating method to develop high temperature gradients between the ends of a regenerative heat exchanger made of tubular elastocaloric material. Though this schema significantly increases the temperature span developed by elastocaloric cooling devices, the current heat pump design leads to temperature degradation as a result of conduction along the length of the tubes in the regenerator. The novel regenerator concept presented in this work mitigates that issue by using short, thermally insulated tubes layers which also enables fluid flow over external surface areas of the material.

High-Temperature Liquid-Fluoride-Salt Closed-Brayton-Cycle Solar Power Towers

2006 ◽  
Vol 129 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Charles W. Forsberg ◽  
Per F. Peterson ◽  
Haihua Zhao
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Solar Power ◽  
Heat Storage ◽  
Solar Furnace ◽  
Working Fluid ◽  
Fluoride Salt ◽  
Power Cycle ◽  
Solar Power Tower ◽  
The Cost

Liquid-fluoride-salt heat transfer fluids are proposed to raise the heat-to-electricity efficiencies of solar power towers to about 50%. The liquid salt would deliver heat from the solar furnace at temperatures between 700°C and 850°C to a closed multireheat Brayton power cycle using nitrogen or helium as the working fluid. During the daytime, hot salt may also be used to heat graphite, which would then be used as a heat storage medium to make night-time operations possible. Graphite is a low-cost high-heat-capacity solid that is chemically compatible with liquid fluoride salts at high temperatures. About half the cost of a solar power tower is associated with the mirrors that focus light on the receiver, and less than one-third is associated with the power cycle and heat storage. Consequently, increasing the efficiency by 20–30% has the potential for major reductions in the cost of electricity. Peak temperatures and efficiencies of current designs of power towers are restricted by (1) the use of liquid nitrate salts that decompose at high temperatures and (2) steam cycles in which corrosion limits peak temperature. The liquid-fluoride-salt technology and closed Brayton power cycles are being developed for high-temperature nuclear reactors. These developments may provide the technology and industrial basis for an advanced solar power tower.

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