scholarly journals Influence of evaporating rate on two-phase expansion in the piston expander with cyclone separator

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 2077-2088 ◽  
Author(s):  
Weifeng Wu ◽  
Qi Wang ◽  
Zhao Zhang ◽  
Zhijun Wu ◽  
Xiaotian Yang ◽  
...  
Keyword(s):  
Low Grade ◽  
Cyclone Separator ◽  
Expansion Process ◽  
Two Phase ◽  
Kalina Cycle ◽  
Thermodynamic Cycles ◽  
Heat Utilization ◽  
Inlet Stream ◽  
Organic Rankine Cycles ◽  
Low Grade Heat

The trilateral flash cycle shows a greater potentiality in moderate to low grade heat utilization systems due to its potentiality of obtaining high exergy efficiency, compared to the conventional thermodynamic cycles such as the organic Rankine cycles and the Kalina cycle. The main difference between the trilateral flash cycle and the conventional thermodynamic cycles is that the superheated vapor expansion process is replaced by the two-phase expansion process. The two-phase expansion process actually consists of a flashing of the inlet stream into a vapor and a liquid phase. Most simulations assume an equilibrium model with an instantaneous flashing. Yet, the experiments of pool flashing indicate that there is a flash evaporating rate. The mechanism of this process still remains unclear. In this paper, the flash evaporating rate is introduced into the model of the two-phase expansion process in the reciprocating expander with a cyclone separator. As such, the obtained results reveal the influence of evaporating rate on the efficiency of the two-phase expander.

scholarly journals Selection and optimization of pure and mixed working fluids for low grade heat utilization using organic Rankine cycles

Energy ◽  
2014 ◽  
Vol 73 ◽  
pp. 204-213 ◽  
Author(s):  
J.G. Andreasen ◽  
U. Larsen ◽  
T. Knudsen ◽  
L. Pierobon ◽  
F. Haglind
Keyword(s):  
Low Grade ◽  
Working Fluids ◽  
Heat Utilization ◽  
Organic Rankine Cycles ◽  
Low Grade Heat

scholarly journals Analysis and optimization of a modified Kalina cycle system for low-grade heat utilization

2021 ◽  
pp. 100121
Author(s):  
Mohammad Masrur Hossain ◽  
Niyaz Afnan Ahmed ◽  
Md Abid Shahriyar ◽  
M Monjurul Ehsan ◽  
Fahid Riaz ◽  
...  
Keyword(s):  
Low Grade ◽  
Kalina Cycle ◽  
Heat Utilization ◽  
Cycle System ◽  
Low Grade Heat

Modelling of a two-phase thermofluidic oscillator for low-grade heat utilisation: Accounting for irreversible thermal losses

2013 ◽  
Vol 106 ◽  
pp. 337-354 ◽  
Author(s):  
Roochi Solanki ◽  
Richard Mathie ◽  
Amparo Galindo ◽  
Christos N. Markides
Keyword(s):  
Low Grade ◽  
Two Phase ◽  
Low Grade Heat

Converting Low-Grade Heat Into Power Using a Supercritical Rankine Cycle With Zeotropic Mixture Working Fluid

2010 ◽  
Author(s):  
Huijuan Chen ◽  
D. Yogi Goswami ◽  
Muhammad M. Rahman ◽  
Elias K. Stefanakos
Keyword(s):  
Rankine Cycle ◽  
Phase Region ◽  
Working Fluid ◽  
Condensation Process ◽  
Heating Process ◽  
Low Grade ◽  
Two Phase ◽  
Working Fluids ◽  
Zeotropic Mixture ◽  
Low Grade Heat

A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power is proposed and analyzed in this paper. A supercritical Rankine cycle does not go through two-phase region during the heating process. By adopting zeotropic mixtures as the working fluids, the condensation process happens non-isothermally. Both of the features create a potential in reducing the irreversibility and improving the system efficiency. A comparative study between an organic Rankine cycle and the proposed supercritical Rankine cycle shows that the proposed cycle improves the cycle thermal efficiency, exergy efficiency of the heating and the condensation processes, and the system overall efficiency.

scholarly journals Comparative Thermodynamic Analysis of Kalina and Kalina Flash Cycles for Utilizing Low-Grade Heat Sources

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3311 ◽  
Author(s):  
Kyoung Kim ◽  
Chul Han ◽  
Hyung Ko
Keyword(s):  
Mass Fraction ◽  
Power Production ◽  
Low Grade ◽  
Heat Sources ◽  
Kalina Cycle ◽  
Thermodynamic Performance ◽  
Locally Maximal ◽  
The Difference ◽  
Proposed Modification ◽  
Low Grade Heat

The Kalina flash cycle (KFC) is a novel, recently proposed modification of the Kalina cycle (KC) equipped with a flash vessel. This study performs a comparative analysis of the thermodynamic performance of KC and KFC utilizing low-grade heat sources. How separator pressure, flash pressure, and ammonia mass fraction affect the system performance is systematically and parametrically investigated. Dependences of net power and cycle efficiencies on these parameters as well as the mass flow rate, heat transfer rate and power production at the cycle components are analyzed. For a given set of separator pressure and ammonia mass fraction, there exists an optimum flash pressure making exergy efficiency locally maximal. For these pressures, which are higher for higher separator pressure and lower ammonia mass fraction, KFC shows better performance than KC both in net power and cycle efficiencies. At higher ammonia mass fraction, however, the difference is smaller. While the maximum power production increases with separator pressure, the dependence is quite weak for the maximum values of both efficiencies.

Organic Brayton Cycles with solid sorption thermal compression for low grade heat utilization

2014 ◽  
Vol 62 (1) ◽  
pp. 171-175 ◽  
Author(s):  
P. Dutta ◽  
P. Kumar ◽  
K.C. Ng ◽  
S. Srinivasa Murthy ◽  
K. Srinivasan
Keyword(s):  
Low Grade ◽  
Thermal Compression ◽  
Heat Utilization ◽  
Low Grade Heat

Low-Grade Heat Utilization Through Ultrasound-Enhanced Desorption of Activated Alumina/Water for Thermal Energy Storage

2020 ◽  
Author(s):  
Hooman Daghooghi Mobarakeh ◽  
Keshawa Bandara ◽  
Liping Wang ◽  
Robert Wang ◽  
Patrick E. Phelan ◽  
...  
Keyword(s):  
Water Vapor ◽  
Energy Storage ◽  
Thermal Energy ◽  
Input Power ◽  
Total Power ◽  
Low Grade ◽  
Ultrasonic Power ◽  
Activated Alumina ◽  
Heat Utilization ◽  
Low Grade Heat

Abstract Sorption thermal energy storage (TES) seems to be an auspicious solution to overcome the issues of intermittent energy sources and utilization of low-grade heat. Ultrasound-assisted adsorption/desorption of water vapor on activated alumina is proposed as a means of low-grade heat utilization through TES. The effects of ultrasonic power on the storing stage (desorption of water vapor) were analyzed to optimize the desorption and overall efficiencies. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, an approach of constant total (heat plus ultrasound) input power of 25 W was adopted. To measure the extent of the effectiveness of using ultrasound, ultrasonic-power-to-total power ratios of 0.2 and 0.4 were investigated and the results compared with those of no-ultrasound (heat only) at the same total power. The regeneration temperature and desorption rate were measured simultaneously to investigate the effects of ultrasonication on regeneration temperature and utilization of low-grade heat. The experimental results showed that using ultrasound facilitates the regeneration of activated alumina at both power ratios without increasing the total input power. With regard to regeneration temperature, incorporating ultrasound decreases the regeneration temperature hence justifying the utilization of low-grade heat for thermal energy purposes. In terms of overall energy recovery of the adsorption thermal storage process, a new metric is proposed to justify incorporating ultrasound and any other auxiliary energy along with low-grade heat.

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