scholarly journals Correction to: Parametric study and working fluid selection of modified combined power and refrigeration cycles (MCPRCs) using low-temperature heat sources

2018 ◽  
Vol 40 (2) ◽  
Author(s):  
Hadi Rostamzadeh ◽  
Hadi Ghaebi
Keyword(s):  
Low Temperature ◽  
Parametric Study ◽  
Working Fluid ◽  
Heat Sources ◽  
Temperature Heat ◽  
Working Fluid Selection ◽  
Selection Of

Combined Cycle for Power Generation and Refrigeration Using Low Temperature Heat Sources

2014 ◽  
Vol 3 (3) ◽  
pp. 34-56 ◽  
Author(s):  
Vijay Chauhan ◽  
P. Anil Kishan ◽  
Sateesh Gedupudi
Keyword(s):  
Power Generation ◽  
Low Temperature ◽  
Combined Cycle ◽  
Working Fluid ◽  
Heat Sources ◽  
Ambient Temperatures ◽  
Temperature Heat ◽  
Good Potential ◽  
Output Ratio ◽  
Operation Results

A combined refrigeration and power cycle, which uses ammonia-water as the working fluid, is proposed by combining Rankine and vapour absorption cycles with an advantage of varying refrigeration capacity to power output ratio. The study investigates the usage of low temperature heat sources for the cycle operation. Results of parametric analysis are presented, which show the scope for optimization. Results of thermodynamic optimization of the cycle for second law efficiency performed using genetic algorithm for different ambient temperatures are also presented. The cycle shows good potential for obtaining refrigeration and power generation.

A New Combined Power and Cooling Cycle for Low Temperature Heat Sources

2003 ◽  
Author(s):  
D. Y. Goswami ◽  
Gunnar Tamm ◽  
Sanjay Vijayaraghavan
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Waste Heat ◽  
Experimental System ◽  
Operating Conditions ◽  
Working Fluid ◽  
Second Law ◽  
Heat Sources ◽  
Vapor Generation ◽  
Temperature Heat

A new thermodynamic cycle has been developed for the simultaneous production of power and cooling from low temperature heat sources. The proposed cycle combines the Rankine and absorption refrigeration cycles, providing power and cooling in desired ratios to best suit the application. A binary mixture of ammonia and water is used as the working fluid, providing a good thermal match with the sensible heat source over a range of boiling temperatures. Due to its low boiling point, the ammonia-rich vapor expands to refrigeration temperatures while work is extracted through the turbine. Absorption condensation of the vapor back into the bulk solution occurs near ambient temperatures. The proposed cycle is suitable as a bottoming cycle using waste heat from conventional power generation systems, or can utilize low temperature solar or geothermal renewable resources. The cycle can be scaled to residential, commercial or industrial uses, providing power as the primary goal while satisfying some of the cooling requirements of the application. The cycle is under both theoretical and experimental investigations. Initial parametric studies of how the cycle performs at various operating conditions showed the potential for the cycle to be optimized. Optimization studies performed over a range of heat source and heat sink temperatures showed that the cycle could be optimized for maximum work or cooling output, or for first or second law efficiencies. Depending on the heat source temperatures, as much as half of the output may be obtained as refrigeration under optimized conditions, with refrigeration temperatures as low as 205 K being achievable. Maximum second law efficiencies over 60% have been found with the heat source between 350 and 450 K. An experimental system was constructed to verify the theoretical results and to demonstrate the feasibility of the cycle. The investigation focused on the vapor generation and absorption processes, setting up for the power and refrigeration studies to come later. The turbine was simulated with an equivalent expansion process in this initial phase of testing. Results showed that the vapor generation and absorption processes work experimentally, over a range of operating conditions and in simulating the sources and sinks of interest. The potential for combined work and cooling output was evidenced in operating the system. Comparison to ideally simulated results verified that there are thermal and flow losses present, which were assessed to make both improvements in the experimental system and modifications in the simulations to include realistic losses.

scholarly journals A Simple Method of Finding New Dry and Isentropic Working Fluids for Organic Rankine Cycle

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 480 ◽  
Author(s):  
Gábor Györke ◽  
Axel Groniewsky ◽  
Attila Imre
Keyword(s):  
Low Temperature ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Electricity Production ◽  
Working Fluid ◽  
Heat Sources ◽  
Simple Method ◽  
Working Fluids ◽  
Temperature Heat

One of the most crucial challenges of sustainable development is the use of low-temperature heat sources (60–200 °C), such as thermal solar, geothermal, biomass, or waste heat, for electricity production. Since conventional water-based thermodynamic cycles are not suitable in this temperature range or at least operate with very low efficiency, other working fluids need to be applied. Organic Rankine Cycle (ORC) uses organic working fluids, which results in higher thermal efficiency for low-temperature heat sources. Traditionally, new working fluids are found using a trial-and-error procedure through experience among chemically similar materials. This approach, however, carries a high risk of excluding the ideal working fluid. Therefore, a new method and a simple rule of thumb—based on a correlation related to molar isochoric specific heat capacity of saturated vapor states—were developed. With the application of this thumb rule, novel isentropic and dry working fluids can be found applicable for given low-temperature heat sources. Additionally, the importance of molar quantities—usually ignored by energy engineers—was demonstrated.

Analysis and Optimization of an Ammonia Based Transcritical Rankine Cycle for Power Generation

2008 ◽  
Author(s):  
Jahar Sarkar ◽  
Souvik Bhattacharyya
Keyword(s):  
Power Generation ◽  
Low Temperature ◽  
Thermal Efficiency ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Heat Sources ◽  
High Side ◽  
Water Based ◽  
Temperature Heat ◽  
Transcritical Rankine Cycle

This study presents the potential of ammonia as a working fluid in transcritical Rankine cycle for power generation using both high and low temperature heat sources. Higher heat capacity value and superior heat transfer properties of ammonia compared to water are the motivating factors behind its use as a working fluid. A thermodynamic analysis for the ammonia based transcritical Rankine cycle and its comparison with the water based Rankine cycle is presented. Analyses with several cycle modifications are also presented to study the thermal efficiency augmentation. It is observed that an optimum high side pressure exists for near critical operation. In case of low temperature heat sources such as solar energy or waste heat, where water based systems are not suitable, ammonia based Rankine cycle is applicable with attractive thermal efficiency, although cycle modification is not possible. The results with high temperature heat source such as boiler or nuclear reactor, where the turbine outlet is in superheated zone, show that simple ammonia systems yield lower efficiency than water, although a recompression cycle with regenerative heat exchangers exhibits higher efficiency than water. Significant thermal efficiency improvement can be achieved by increasing the high side cycle pressure. Recompression Rankine cycle can be a potential alternative with proper design measures taken to avoid toxicity and flammability.

Novel MEMS-Based Boiler Development for Low Temperature Applications

2009 ◽  
Author(s):  
K. Prather ◽  
H. Hemphill ◽  
I. Pjescic ◽  
C. Tranter ◽  
J. Dorton ◽  
...  
Keyword(s):  
Low Temperature ◽  
Evaporation Rate ◽  
Low Cost ◽  
Working Fluid ◽  
Heat Sources ◽  
Micro Fabrication ◽  
Capillary Action ◽  
Temperature Heat ◽  
Silicon Based ◽  
Temperature Applications

A novel MEMS-based boiler is fabricated and tested. The device is designed to operate from low-temperature heat sources using capillary action channels. The channels supply working fluid to the heated boiler surface, eliminating the need for traditional working fluid pumps. Two basic types of construction are evaluated. First, a more traditional silicon-based device is constructed and tested. Fabrication of the silicon boiler utilizes standard micro-fabrication practices. Second, a copper-based unit is fabricated and tested. Fabrication of the copper boiler focusses on low-cost techniques performed outside the scope of traditional micro-fab procedures. Results of these tests show the promise of non-traditional metals in low-temperature MEMS-based applications. The effectiveness of the copper boilers is shown to be 60% greater than their silicon counter parts. The copper-based prototypes exhibited a maximum evaporation rate for working fluid pumped across the boiling surface of 4.21 mg/sec.

Effect of Mixture R600a/R601a on Performance of Radial Turbine for Low Temperature Waste Heat

2017 ◽  
Author(s):  
Zemin Bo ◽  
Zhenkun Sang ◽  
Xiaojing Lv ◽  
Yiwu Weng
Keyword(s):  
Low Temperature ◽  
Output Power ◽  
Waste Heat ◽  
Aerodynamic Performance ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Optimal Composition ◽  
Radial Turbine ◽  
Temperature Heat ◽  
Selection Of

A 150kW organic working fluid radial turbine designed for the low temperature waste heat with temperature of 150 ∼ 200°C using R600a as working fluid was selected. Under the condition of same inlet temperature and rotational speed, the mixture R600a(iso-butane) / R601a(iso-pentane) with different compositions was adopted for the CFD numerical simulation to obtain the aerodynamic performance and the detailed flow of the organic working fluid radial turbine. The results show that the mixture R600a / R601a can broaden the output power range and increase the efficiency of the radial turbine compared with the pure working fluid. The output power of the organic working fluid radial turbine increases from 54.03kW to 129.6kW as the R600a composition increases from 0.1 to 0.9. The optimal composition of R600a / R601a was obtained for relatively higher efficiency of the organic working fluid radial turbine. The results can provide a reference for the selection of working fluid for radial turbine of the low temperature heat source.

Management of Low-Temperature Heat Source by ORC Aided by Additional Heat Source

2016 ◽  
Vol 831 ◽  
pp. 270-277
Author(s):  
Dariusz Mikielewicz ◽  
Jan Wajs ◽  
Michał Bajor ◽  
Elżbieta Żmuda
Keyword(s):  
Power Plant ◽  
Low Temperature ◽  
Heat Source ◽  
Waste Heat ◽  
Working Fluid ◽  
Heat Sources ◽  
Additional Heat ◽  
Low Pressure Turbine ◽  
Temperature Heat ◽  
Overall Efficiency

In the paper presented is a concept to utilize waste heat from the power plant with the aid of the low-temperature ORC cycle. The ORC system is heated from two heat sources, the first one being the flow rate of waste heat obtained from the exhaust gases. Subsequently, the working fluid in the cycle is additionally heated by the condensing steam from the low pressure turbine extraction points increasing in such way the level of temperature of working fluid before turbine to 120°C. Examination of the results enables to conclude that the overall efficiency of the cycle increased from =51.958% to =52.304%. That is due to the fact that additional heat enabled to evaporate more working fluid. The total generated power increased to the value of NelRU=915.85MWe, which corresponds to about 1.5% increase in power.

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