scholarly journals Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC

2011 ◽  
Vol 32 (3) ◽  
pp. 57-70 ◽  
Author(s):  
Dariusz Mikielewicz ◽  
Jarosław Mikielewicz
Keyword(s):  
Power Plant ◽  
Low Temperature ◽  
Heat Source ◽  
Silicone Oil ◽  
Hot Water ◽  
Working Fluid ◽  
Preliminary Heating ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Steam Heat

Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC In the paper presented is a novel concept to utilize the heat from the turbine bleed to improve the quality of working fluid vapour in the bottoming organic Rankine cycle (ORC). That is a completely novel solution in the literature, which contributes to the increase of ORC efficiency and the overall efficiency of the combined system of the power plant and ORC plant. Calculations have been accomplished for the case when available is a flow rate of low enthalpy hot water at a temperature of 90 °C, which is used for preliminary heating of the working fluid. That hot water is obtained as a result of conversion of exhaust gases in the power plant to the energy of hot water. Then the working fluid is further heated by the bleed steam to reach 120 °C. Such vapour is subsequently directed to the turbine. In the paper 5 possible working fluids were examined, namely R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C the silicone oil MM showed the best performance, in all other cases the ethanol proved to be best performing fluid of all. Results are compared with the "stand alone" ORC module showing its superiority.

scholarly journals Design and experimental research on the combined flash-binary geothermal power generation system driven by low-medium temperature geothermal system

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 831-842
Author(s):  
Chao Luo ◽  
Jun Zhao ◽  
Yongzhen Wang ◽  
Hongmei Yin ◽  
Qingsong An ◽  
...  
Keyword(s):  
Power Generation ◽  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Geothermal Resource ◽  
Medium Temperature ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Variable Capacity

To match for the different temperature of the geothermal resource and strengthen the flexibility of organic Rankine cycle, a variable capacity power generation superstructure based on flash and organic Rankine cycle for geothermal energy was proposed. A combined flash-binary experimental prototype is newly established to investigate thermodynamic performance both on system and equipment in this paper. Pressured hot water is adopted as the extensive worldwide existed hydrothermal geothermal resource, eliminating the influence of the used heat transfer oil on evaporating process. The experimental results show that there is an optimal mass-flow rate of R245fa under the condition of different heat source temperature. Flash and binary power subsystem dominate the flash-binary power system, respectively, when the heat source temperature is 120? and 130?. The isotropic efficiency of modified compressor just between 0.2 and 0.25. The power output of per ton geofluid are 0.78 kWh/t and 1.31 kWh/t, respectively, when the heat source temperature are 120? and 130?. These results will predict the operation data of flash-binary power plant driven by the low-medium temperature geothermal water for construction in western of China.

Analysis of novel regenerative thermo-mechanical refrigeration system integrated with isobaric engine

2020 ◽  
pp. 1-27
Author(s):  
Ahmad K. Sleiti ◽  
Wahib Al-Ammari ◽  
Mohammed Al-Khawaja
Keyword(s):  
Heat Source ◽  
Environmental Effects ◽  
Power Efficiency ◽  
Waste Heat ◽  
Working Fluid ◽  
Refrigeration System ◽  
Cooling Systems ◽  
Working Fluids ◽  
Source Temperature ◽  
Heat Source Temperature

Abstract Refrigerants of the conventional cooling systems contribute to global warming and ozone depletion significantly, therefore it is necessary to develop new cooling systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. To address this, the present study introduces and analyzes a novel regenerative thermo-mechanical refrigeration system that can be powered by renewable heat sources (solar, geothermal, or waste heat). The system consists of a novel expander-compressor unit (ECU) integrated with a vapor compression refrigeration system. The integrated system operates at the higher-performance supercritical conditions of the working fluids as opposed to the lower-performance subcritical conditions. The performance of the system is evaluated based on several indicators including the power loop efficiency, the coefficient of performance (COP) of the cooling loop, and the expander-compressor diameters. Several working fluids were selected and compared for their suitability based on their performance and environmental effects. It was found that for heat source temperature below 100 °C, adding the regenerator to the system has no benefit. However, the regenerator increases the power efficiency by about 1 % for a heat source temperature above 130 °C. This was achieved with a very small size regenerator (Dr = 6.5 mm, Lr = 142 mm). Results show that there is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at heat source temperature Th=150 °C and cold temperature Tc1=40 °C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23 %, expander diameter of 53.12 mm, and compressor diameter of 75.4mm.

Water-Ammonia Cycles for the Utilization of Low Temperature Geothermal Resources

2015 ◽  
Author(s):  
Daniele Fiaschi ◽  
Giampaolo Manfrida ◽  
Lorenzo Talluri
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Source ◽  
Unit Cost ◽  
Heat Capacities ◽  
Hot Water ◽  
Saturated Steam ◽  
Working Fluid ◽  
Evaporator Temperature ◽  
Power Cycle

The research deals with the possibility of effective exploitation of low temperature geothermal energy resources, which are generally much more widespread worldwide compared to conventional high temperature ones, typically available only in limited areas of the Earth. The basic idea is the application of an advanced binary cycle, only thermally coupled to the primary endogen heat source. The selected reference-power cycle is the well-known Kalina, which gives the possibility of optimizing the matching between heat capacities of the geothermal fluid (i.e. typically hot water or saturated steam) and the cycle working fluid, which is a non azeotropic NH3-H2O mixture with variable vaporization temperature at a fixed pressure. The heat transfer diagrams of the main Kalina heat exchangers, namely the condenser and the evaporator, are analysed with the aim of minimizing the irreversibilities related to the heat transfer. At different fixed NH3-H2O composition and condenser pressures, the evaporator pressure shows an efficiency optimizing value between 40 and 55 bar, generally increasing at higher condenser pressure. At fixed geothermal heat source temperature, condenser/evaporator pressures and working mixture composition, the cycle efficiency increases with increasing evaporator temperature, because of the reduction in the approach temperature difference between the geothermal and the working fluid. Higher efficiencies are found at higher NH3 concentrations. The proposed Water-Ammonia power cycle is further enhanced introducing a chiller (thus making the power cycle a CCP unit), thanks to the properties of the fluid mixture downstream the absorber, through an intermediate heat exchanger between the condenser and the evaporator. Mainly due to the better matching of heat capacities between the geothermal and the working fluid, the proposed power cycle offers the possibility of interesting improvements in electrical efficiency compared to traditionally proposed binary cycles using ORCs, at fixed temperature level of the heat source. In the investigated proposal, values of electric efficiency between 15 and 20% are found. An economic analysis is presented, demonstrating that the CCP system is able to produce electricity at decreased unit cost with respect to the power-only unit.

scholarly journals Exergy Analysis of Two-Stage Organic Rankine Cycle Power Generation System

Entropy ◽  
2020 ◽  
Vol 23 (1) ◽  
pp. 43
Author(s):  
Guanglin Liu ◽  
Qingyang Wang ◽  
Jinliang Xu ◽  
Zheng Miao
Keyword(s):  
Heat Source ◽  
Organic Rankine Cycle ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Two Stage ◽  
Working Fluids ◽  
Source Temperature ◽  
Split Ratio ◽  
Heat Source Temperature ◽  
Stage System

Organic Rankine cycle (ORC) power generation is an effective way to convert medium and low temperature heat into high-grade electricity. In this paper, the subcritical saturated organic Rankine cycle system with a heat source temperature of 100~150 °C is studied with four different organic working fluids. The variations of the exergy efficiencies for the single-stage/two-stage systems, heaters, and condensers with the heat source temperature are analyzed. Based on the condition when the exergy efficiency is maximized for the two-stage system, the effects of the mass split ratio of the geothermal fluid flowing into the preheaters and the exergy efficiency of the heater are studied. The main conclusions include: The exergy efficiency of the two-stage system is affected by the evaporation temperatures of the organic working fluid in both the high temperature and low temperature cycles and has a maximum value. Under the same heat sink and heat source parameters, the exergy efficiency of the two-stage system is larger than that of the single-stage system. For example, when the heat source temperature is 130 °C, the exergy efficiency of the two-stage system is increased by 9.4% compared with the single-stage system. For the two-stage system, analysis of the four organic working fluids shows that R600a has the highest exergy efficiency, although R600a is only suitable for heat source temperature below 140 °C, while other working fluids can be used in systems with higher heat source temperatures. The mass split ratio of the fluid in the preheaters of the two-stage system depends on the working fluid and the heat source temperature. As the heat source temperature increases, the range of the split ratio becomes narrower, and the curves are in the shape of an isosceles triangle. Therefore, different working fluids are suitable for different heat source temperatures, and appropriate working fluid and split ratio should be determined based on the heat source parameters.

Optimum Heat Source Temperature and Performance Comparison of LiCl–H2O and LiBr–H2O Type Solar Cooling System

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Bhargav Pandya ◽  
Vinay Kumar ◽  
Jatin Patel ◽  
V. K. Matawala
Keyword(s):  
Heat Source ◽  
Cooling System ◽  
Performance Comparison ◽  
Design Parameters ◽  
Working Fluid ◽  
Absorption System ◽  
Solar Absorption ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Optimum Heat

This comprehensive investigation has been executed to compare the thermodynamic performance and optimization of LiCl–H2O and LiBr–H2O type absorption system integrated with flat-plate collectors (FPC), parabolic-trough collectors (PTC), evacuated-tube collectors (ETC), and compound parabolic collectors (CPC). A model of 10 kW is analyzed in engineering equation solver (ees) from thermodynamic perspectives. Solar collectors are integrated with a storage tank which fueled the LiCl–H2O and LiBr–H2O vapor absorption system to produce refrigeration at 7 °C in evaporator for Gujarat Region of India. The main objective includes the evaluation and optimization of critical performance and design parameters to exhibit the best working fluid pair and collector type. Optimum heat source temperature corresponding to energetic and exergetic aspects for LiCl–H2O pair is lower than that of LiBr–H2O pair for all collectors. Simulation shows that FPC has lowest capital cost, exergetic performance wise PTC is optimum, and ETC requires lowest collector area. On the basis of overall evaluation, solar absorption cooling systems are better to be powered by ETC with LiCl–H2O working fluid pair.

scholarly journals Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype

2019 ◽  
Vol 9 (15) ◽  
pp. 3024 ◽  
Author(s):  
Chinedu K. Unamba ◽  
Paul Sapin ◽  
Xiaoya Li ◽  
Jian Song ◽  
Kai Wang ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Electric Heater ◽  
Part Load ◽  
Source Temperature ◽  
Heat Source Temperature

Several heat-to-power conversion technologies are being proposed as suitable for waste-heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter technology has demonstrated the highest efficiencies at small and intermediate scales and low to medium heat-source temperatures and is considered a suitable option for WHR in relevant applications. However, ORC systems experience variations in performance at part-load or off-design conditions, which need to be predicted accurately by empirical or physics-based models if one is to assess accurately the techno-economic potential of such ORC-WHR solutions. This paper presents results from an experimental investigation of the part-load performance of a 1-kWe ORC engine, operated with R245fa as a working fluid, with the aim of producing high-fidelity steady-state and transient data relating to the operational performance of this system. The experimental apparatus is composed of a rotary-vane pump, brazed-plate evaporator and condenser units and a scroll expander magnetically coupled to a generator with an adjustable resistive load. An electric heater is used to provide a hot oil-stream to the evaporator, supplied at three different temperatures in the current study: 100, 120 and 140 ∘ C. The optimal operating conditions, that is, pump speed and expander load, are determined at various heat-source conditions, thus resulting in a total of 124 steady-state data points used to analyse the part-load performance of the engine. A maximum thermal efficiency of 4.2 ± 0.1% is reported for a heat-source temperature of 120 ∘ C, while a maximum net power output of 508 ± 2 W is obtained for a heat-source temperature at 140 ∘ C. For a 100- ∘ C heat source, a maximum exergy efficiency of 18.7 ± 0.3% is achieved. A detailed exergy analysis allows us to quantify the contribution of each component to the overall exergy destruction. The share of the evaporator, condenser and expander components are all significant for the three heat-source conditions, while the exergy destroyed in the pump is negligible by comparison (below 4%). The data can be used for the development and validation of advanced models capable of steady-state part-load and off-design performance predictions, as well as predictions of the transient/dynamic operation of ORC systems.

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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