scholarly journals Thermodynamic Analysis of Working Fluids for a New “Heat from Cold” Cycle

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 808 ◽  
Author(s):  
Ilya Girnik ◽  
Mikhail Tokarev ◽  
Yuri Aristov
Keyword(s):  
Thermodynamic Analysis ◽  
Chemical Engineering ◽  
Activated Carbons ◽  
Maximum Temperature ◽  
Adsorption Potential ◽  
Working Fluids ◽  
Useful Heat ◽  
Heat Transformation ◽  
Transformation Systems ◽  
Made In

Adsorptive Heat Transformation systems are at the interface between thermal and chemical engineering. Their study and development need a thorough thermodynamic analysis aimed at the smart choice of adsorbent-adsorptive pair and its fitting with a particular heat transformation cycle. This paper addresses such an analysis for a new “Heat from Cold” cycle proposed for amplification of the ambient heat in cold countries. A comparison of four working fluids is made in terms of the useful heat per cycle and the temperature lift. The useful heat increases in the row water > ammonia ≥ methanol > hydrofluorocarbon R32. A threshold mass of exchanged adsorbate, below which the useful heat equals zero, raises in the same sequence. The most promising adsorbents for this cycle are activated carbons Maxsorb III and SRD 1352/2. For all the adsorptives studied, a linear relationship F = A·ΔT is found between the Dubinin adsorption potential and the driving temperature difference ΔT between the two natural thermal baths. It allows the maximum temperature lift during the heat generation stage to be assessed. Thus, a larger ΔT-value promotes the removal of the more strongly bound adsorbate.

scholarly journals Thermodynamic Analysis of Iron Ore Sintering Process Based on Biomass Carbon

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5988
Author(s):  
Mi Zhou ◽  
Zhenyu Yu ◽  
Panlei Wang ◽  
Huaqing Xie ◽  
Yongcai Wen ◽  
...  
Keyword(s):  
Thermodynamic Analysis ◽  
Iron Ore ◽  
Sinter Process ◽  
Great Influence ◽  
Pollutant Emissions ◽  
Coke Breeze ◽  
Maximum Temperature ◽  
Biomass Carbon ◽  
Metallurgical Properties ◽  
Pollutant Gases

The sinter process of iron ore with biomass carbon instead of coke breeze as fuel was investigated via thermodynamic analysis in this paper through a comparison of sinter composition indexes, metallurgical properties, and pollutant emissions. Straw charcoal was used in this paper, and its replacement does not adversely affect the composition index of iron ore, namely Fe, FeO, basicity, S, nor the metallurgical properties, namely reduction degradation index and reduction index. However, the replacement has a great effect on the emissions of pollutant gases, including SO2, NOx, CO, and CO2. The thermodynamic analysis result shows that emissions of pollutant gases produced in the sinter process significantly decrease by using straw charcoal instead of coke breeze in sinter. The sintering maximum temperature has a great influence on sintering technical indicators. The best sintering maximum temperature is between 1300 and 1400 °C, where sinter ore with high quality can be obtained.

scholarly journals Activated Carbons as Methanol Adsorbents for a New Cycle “Heat from Cold”

Fibers ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 51
Author(s):  
Ilya Girnik ◽  
Alexandra Grekova ◽  
Larisa Gordeeva ◽  
Yuri Aristov
Keyword(s):  
Performance Indicator ◽  
Activated Carbons ◽  
Carbon Powder ◽  
Pressure Jump ◽  
Multi Wall Carbon Nanotubes ◽  
Large Pressure ◽  
Useful Power ◽  
Useful Heat ◽  
And Storage ◽  
Fine Carbon

Activated carbons are widely used for sustainable technology of adsorptive transformation and storage of heat. Here, we analyze the applicability of twelve commercial carbons and an innovative carbonaceous composite “LiCl confined to multi-wall carbon nanotubes” (LiCl/MWCNT) for a new cycle “Heat from Cold” (HeCol). It has recently been proposed for amplification of low- temperature ambient heat in cold countries. The analysis is made in terms of the methanol mass exchanged and the useful heat generated per cycle; the latter is the main performance indicator of HeCol cycles. The maximum specific useful heat, reaching 990 and 1750 J/g, can be obtained by using carbon Maxsorb III and the composite, respectively. For these materials, methanol adsorption dynamics under typical HeCol conditions are experimentally studied by the large pressure jump method. Before making this analysis, the fine carbon powder is consolidated by either using a binder or just pressing to obtain larger particles (ca. 2 mm). The methanol desorption from the consolidated samples of Maxsorb III at T = 2 °C is faster than for LiCl/MWCNT, and the maximum (initial) useful power reaches (2.5–4.0) kW/kg sorbent. It is very promising for designing compact HeCol units utilizing the carbon Maxsorb III.

scholarly journals Thermodynamic Analysis and Optimization of Secondary Overheating Parameters in Turbo-Expander Plants on Low Boiling Working Fluids

2021 ◽  
Vol 64 (2) ◽  
pp. 164-177
Author(s):  
A. V. Ovsyannik ◽  
V. P. Kliuchinski
Keyword(s):  
Heat Exchanger ◽  
Thermodynamic Analysis ◽  
Critical Pressure ◽  
Steam Superheater ◽  
Working Fluid ◽  
Exergetic Efficiency ◽  
Working Fluids ◽  
Secondary Steam ◽  
Turbo Expander ◽  
Expander Cycle

The paper presents a thermodynamic analysis of secondary overheating in turbo-expander plants on low-boiling working fluids. The possibility of optimizing the parameters of the working fluid in a secondary stem superheater has been studied. The research was carried out for two typical turbo-expander cycles: with a heat exchanger at the outlet of the turbo-expander, intended for cooling an overheated low-boiling working fluid, and without a heat exchanger. Cycles in T–s coordinates were constructed for the studied schemes. The influence of pressure and temperature in the intermediate superheater on the exergetic efficiency of the turbo-expander unit was studied. Thus, the dependences of the exergetic efficiency and losses on the elements of the turbo-expander cycle are obtained when the temperature of the working fluid changes and pressure of the working fluid not changes in the intermediate superheater, and when the pressure changes and the temperature does not change. As a low-boiling working fluid, the ozone-safe freon R236EA is considered, which has a “dry” saturation line characteristic, zero ozone layer destruction potential, and a global warming potential equal to 1370. It has been determined that increasing the parameters of the low-boiling working fluid in front of the low-pressure turbo expander (regardless of the scheme of the turbo expander cycle) does not always cause an increase in the exergetic efficiency. Thus, overheating of the working fluid at a pressure exceeding the critical pressure causes a positive exergetic effect, but for each temperature there is an optimal pressure at which the efficiency will be maximum. At a pressure below the critical pressure, overheating leads to a decrease in the exergetic efficiency, and the maximum exergetic effect is achieved in the absence of a secondary steam superheater. All other things being equal, a turbo-expander cycle with a heat exchanger is more efficient than without it over the entire temperature range and pressure of the low-boiling working fluid under study.

A probability form of the diffusion equation and its use to describe the distribution of the solid phase particle concentrations in a mechanically agitated charge

1986 ◽  
Vol 51 (9) ◽  
pp. 1910-1924 ◽  
Author(s):  
Vladimír Kudrna ◽  
Marie Sýsová ◽  
Ivan Fořt
Keyword(s):  
Markov Process ◽  
Diffusion Equation ◽  
Incompressible Liquid ◽  
Chemical Engineering ◽  
Solid Phase ◽  
Phase Particle ◽  
Local Concentration ◽  
Diffusion Term ◽  
Solid Phase Particle ◽  
Made In

An attempt is made in this paper to describe the solid particle motion in a flowing (agitated) incompressible liquid on the assumption that this motion may be considered as a diffusion Markov process. It is shown that such a procedure leads to a relation which differs from the diffusion equation commonly used in chemical engineering by the form of diffusion term. The expression proposed, unlike the relation usually used, makes it possible to describe the local concentration extremes of solid phase in the charge mixed.

scholarly journals Experimental and Techno-Economic Analysis of Solar-Geothermal Organic Rankine Cycle Technology for Power Generation in Nepal

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Suresh Baral
Keyword(s):  
Power Generation ◽  
Heat Source ◽  
Power Output ◽  
Solar Collector ◽  
Hot Spring ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Working Fluids

The current research study focuses on the feasibility of stand-alone hybrid solar-geothermal organic Rankine cycle (ORC) technology for power generation from hot springs of Bhurung Tatopani, Myagdi, Nepal. For the study, the temperature of the hot spring was measured on the particular site of the heat source of the hot spring. The measured temperature could be used for operating the ORC system. Temperature of hot spring can also further be increased by adopting the solar collector for rising the temperature. This hybrid type of the system can have a high-temperature heat source which could power more energy from ORC technology. There are various types of organic working fluids available on the market, but R134a and R245fa are environmentally friendly and have low global warming potential candidates. The thermodynamic models have been developed for predicting the performance analysis of the system. The input parameter for the model is the temperature which was measured experimentally. The maximum temperature of the hot spring was found to be 69.7°C. Expander power output, thermal efficiency, heat of evaporation, solar collector area, and hybrid solar ORC system power output and efficiency are the outputs from the developed model. From the simulation, it was found that 1 kg/s of working fluid could produce 17.5 kW and 22.5 kW power output for R134a and R245fa, respectively, when the geothermal source temperature was around 70°C. Later when the hot spring was heated with a solar collector, the power output produced were 25 kW and 30 kW for R134a and R245fa, respectively, when the heat source was 99°C. The study also further determines the cost of electricity generation for the system with working fluids R134a and R245fa to be $0.17/kWh and $0.14/kWh, respectively. The levelised cost of the electricity (LCOE) was $0.38/kWh in order to be highly feasible investment. The payback period for such hybrid system was found to have 7.5 years and 10.5 years for R245fa and R134a, respectively.

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