Electrical-analogy network model of a modified two-phase thermofluidic oscillator with regenerator for low-grade heat recovery

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.

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

ASME 2010 4th International Conference on Energy Sustainability, Volume 1 ◽

10.1115/es2010-90089 ◽

2010 ◽

Cited By ~ 1

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.

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Applicability of Thermo-Acoustic Generators (TAGs) for Low Grade Heat Recovery and Power Generation

2018 8th International Conference on Power and Energy Systems (ICPES) ◽

10.1109/icpesys.2018.8626947 ◽

2018 ◽

Author(s):

R.K.A. Rathnayake ◽

M.M.I.D. Manthilake ◽

M.A. Wijewardane

Keyword(s):

Power Generation ◽

Heat Recovery ◽

Low Grade ◽

Low Grade Heat

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Feasibility Study of Low Grade Heat Recovery Rankine Cycle Using Ozone-Neutral Refrigerant

Volume 7: Education; Industrial and Cogeneration; Marine; Oil and Gas Applications ◽

10.1115/gt2008-51537 ◽

2008 ◽

Cited By ~ 4

Author(s):

W. Wayne Husband ◽

Asfaw Beyene

Keyword(s):

Heat Recovery ◽

Cost Benefit Analysis ◽

Cost Benefit ◽

Rankine Cycle ◽

Theoretical Models ◽

Photovoltaic System ◽

Working Fluid ◽

Low Grade ◽

Management Tools ◽

Low Grade Heat

The paper addresses the feasibility of ozone-neutral low grade heat recovery to produce power. The low grade heat source can either be industrial exhaust or solar radiation. Using a scroll expander as a basis for testing, theoretical models yielded a thermal efficiency of 11%, utilizing a non-toxic and non-hazardous working fluid. This project spanned research and development of a system from the comparison of several working fluids, modeling of a theoretical 10 kW unit, the sizing and selection of appropriate system components, and the development of project management tools, in support of its real world development. A cost benefit analysis of the theoretical system shows that solar heat recovery with ozone-neutral refrigerant is a viable option for power generation, at about 1/3 the cost of a comparable photovoltaic system.

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