A Dual-Source Organic Rankine Cycle (DORC) for Improved Efficiency in Conversion of Dual Low- and Mid-Grade Heat Sources

2009 ◽  
Author(s):  
F. David Doty ◽  
Siddarth Shevgoor
Keyword(s):  
Heat Source ◽  
Heat Input ◽  
Temperature Limit ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Low Grade ◽  
Heat Sources ◽  
Reaction Products ◽  
Pinch Point ◽  
Low Grade Heat

Detailed thermodynamic and systems analyses show that a novel hybrid cycle, in which a low-grade (and low-cost) heat source (340 K to 460 K) provides the boiling enthalpy and some of the preheating while a mid-grade source (500 K to 800 K) provides the enthalpy for the final superheating, can achieve dramatic efficiency and cost advantages. Four of the more significant differences from prior bi-level cycles are that (1) only a single expander turbine (the most expensive component) is required, (2) condenser pressures are much higher, (3) the turbine inlet temperature (even with a low-grade geothermal source providing much of the energy) may be over 750 K, and (4) turbine size is reduced. The latent heat of vaporization of the working fluid and the differences in specific heats between the liquid and vapor phases make full optimization (approaching second-law limits) impossible with a single heat source. When two heat sources are utilized, this problem may be effectively solved — by essentially eliminating the pinch point. The final superheater temperature must also be increased, and novel methods have been investigated for increasing the allowable temperature limit of the working fluid by 200 to 350 K. The usable temperature limit of light alkanes may be dramatically increased by (1) accommodating hydrogen evolution from significant dehydrogenation; (2) periodically or continually removing undesired reaction products from the fluid; (3) minimizing the fraction of time the fluid spends at high temperatures. Detailed simulation results are presented for the case where (1) the low-grade heat source (such as geothermal) is 400 K and (2) the mid-grade Concentrated Solar Power (CSP) heat source is assumed to be 720 K. For an assumed condensing temperature of 305 K and working fluid flow rate of 100 kg/s, preliminary simulations give the following: (1) low-grade heat input is 25 MWT; (2) mid-grade heat input is 24 MWT; (3) the electrical output power is 13.5 MWE; and (4) the condenser rejection is only 35 MWT. For comparison, with a typical bi-level ORC generating similar power from this geothermal source alone, the low-grade heat requirement would be ∼100 MWT.

scholarly journals Cool Steam Method for Desalinating Seawater

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2385
Author(s):  
Pedro Arnau ◽  
Naeria Navarro ◽  
Javier Soraluce ◽  
Jose Martínez-Iglesias ◽  
Jorge Illas ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Heat Source ◽  
Latent Heat ◽  
Heat Sink ◽  
Low Grade ◽  
Heat Sources ◽  
Working Pressure ◽  
Multi Stage ◽  
Heat Of Evaporation ◽  
Low Grade Heat

Cool steam is an innovative distillation technology based on low-temperature thermal distillation (LTTD), which allows obtaining fresh water from non-safe water sources with substantially low energy consumption. LTTD consists of distilling at low temperatures by lowering the working pressure and making the most of low-grade heat sources (either natural or artificial) to evaporate water and then condensate it at a cooler heat sink. To perform the process, an external heat source is needed that provides the latent heat of evaporation and a temperature gradient to maintain the distillation cycle. Depending on the available temperature gradient, several stages can be implemented, leading to a multi-stage device. The cool steam device can thus be single or multi-stage, being raw water fed to every stage from the top and evaporated in contact with the warmer surface within the said stage. Acting as a heat carrier, the water vapor travels to the cooler surface and condensates in contact with it. The latent heat of condensation is then conducted through the conductive wall to the next stage. Net heat flux is then established from the heat source until the heat sink, allowing distilling water inside every parallel stage.

scholarly journals Integrated Vapor Compression Chiller with Bottoming Organic Rankine Cycle and Onsite Low-Grade Renewable Energy

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6401
Author(s):  
Muhammad Tauseef Nasir ◽  
Michael Chukwuemeka Ekwonu ◽  
Javad Abolfazali Esfahani ◽  
Kyung Chun Kim
Keyword(s):  
Renewable Energy ◽  
Heat Source ◽  
Energy Input ◽  
Cooling Water ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Sensitivity Analyses ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Low Grade

The present study offers a scheme to improve the performance of existing large-scale chillers. The system involves raising the temperature of the chiller’s cooling water stream using renewable energy sources by incorporating an organic Rankine cycle (ORC). The thermal analysis was conducted by raising the temperature of one-third of the approximately 200 ton chiller’s cooling water. The investigation was considered for ORC evaporator inlet temperature of 90~120 °C by the step of 10 °C. Various working fluids for the different ORC evaporator inlet temperatures were examined. Sensitivity analyses conducted on the degree of superheating, degree of subcooling, condenser saturation temperature, pinch point temperature differences of the ORC evaporator and condenser, and the mass flowrates of the heating and cooling streams were also reported. Genetic algorithm was employed to carry out the optimization. The best options for the ORC working fluid at the heating source ORC evaporator inlet temperatures of 90 °C was found to be DME, presenting an improvement of 48.72% in comparison with the rated coefficient of performance (COP) value of the VCC, with a renewable energy input requirement of 710 kW. At the heat source temperatures of 100 °C and 110 °C, butene, which presented an improvement in the COP equal to 48.76% and 68.85%, respectively, with the corresponding renewable energy requirements of 789.6 kW and 852 kW, was found to be the ideal candidate. Meanwhile, at the heat source inlet temperature of 120 °C, R1233zd (E), representing an improvement of 140.88% with the renewable energy input of around 1061 kW, was determined to be the most favorable ORC working fluid candidate.

Working Fluid and Parametric Optimization of a Two-Stage ORC Utilizing LNG Cold Energy and Low Grade Heat of Different Temperatures

2017 ◽  
Author(s):  
Zhixin Sun ◽  
Shujia Wang ◽  
Fuquan Xu ◽  
Tielong Wang
Keyword(s):  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Cycle Performance ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Low Grade ◽  
Two Stage ◽  
Cold Energy ◽  
Low Grade Heat

Natural gas is considered as a green fuel due to its low environmental impact. LNG contains a large amount of cold exergy and must be regasified before further utilization. ORC (Organic Rankine Cycle) has been proven to be a promising solution for both low grade heat utilization and LNG cold exergy recovery. Due to the great temperature difference between the heat source and LNG, the efficiency of one-stage ORC is relatively small. Hence, some researchers move forward to a two-stage Rankine cycle. Working fluid plays a quite important role in the cycle performance. Working fluid selection of a two-stage ORC is much more challenging than that of a single-stage ORC. In this paper, a two-stage ORC is studied. Heat source temperatures of 100,150 and 200°C are investigated. 20 substances are selected as potential candidates for both the high and low Rankine cycles. The evaporating, condensing and turbine inlet temperatures of both Rankine cycles are optimized by PSO (Particle Swarm Optimization). The results show that the best combination for heat source temperature of 100°C is R161/R218 with the maximum exergy efficiency of 35.27%. The best combination for 150°C is R161/RC318 with the maximum efficiency of 37.84% and ammonia/ammonia with the maximum efficiency of 39.15% for 200°C. Fluids with intermediate critical temperature, lower triple point temperature and lower normal boiling temperature are good candidates.

scholarly journals System Design and Application of Supercritical and Transcritical CO2 Power Cycles: A Review

2021 ◽  
Vol 9 ◽  
Author(s):  
Enhua Wang ◽  
Ningjian Peng ◽  
Mengru Zhang
Keyword(s):  
Power Systems ◽  
Environmentally Friendly ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade ◽  
Heat Sources ◽  
Technological Advancement ◽  
Working Fluids ◽  
Power Cycles ◽  
Low Grade Heat

Improving energy efficiency and reducing carbon emissions are crucial for the technological advancement of power systems. Various carbon dioxide (CO2) power cycles have been proposed for various applications. For high-temperature heat sources, the CO2 power system is more efficient than the ultra-supercritical steam Rankine cycle. As a working fluid, CO2 exhibits environmentally friendly properties. CO2 can be used as an alternative to organic working fluids in small- and medium-sized power systems for low-grade heat sources. In this paper, the main configurations and performance characteristics of CO2 power systems are reviewed. Furthermore, recent system improvements of CO2 power cycles, including supercritical Brayton cycles and transcritical Rankine cycles, are presented. Applications of combined systems and their economic performance are discussed. Finally, the challenges and potential future developments of CO2 power cycles are discussed. CO2 power cycles have their advantages in various applications. As working fluids must exhibit environmentally-friendly properties, CO2 power cycles provide an alternative for power generation, especially for low-grade heat sources.

scholarly journals Investigations of prototype ejection refrigeration system driven by low grade heat

2018 ◽  
Vol 70 ◽  
pp. 03002 ◽  
Author(s):  
Dariusz Butrymowicz ◽  
Jerzy Gagan ◽  
Kamil Śmierciew ◽  
Michał Łukaszuk ◽  
Adam Dudar ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Heat Source ◽  
Air Conditioning ◽  
Thermal Capacity ◽  
Low Grade ◽  
Heat Sources ◽  
Refrigeration System ◽  
Gas Emission ◽  
Low Grade Heat ◽  
System Operating

One of possibilities of reduction of F-gas emission is application of low grade heat to drive the refrigeration systems as well as application of natural or low warming impact working fluids. The own experimental investigation of the ejection refrigeration system operating with refrigerant R-1234zeE are presented and discussed. The system is driven with low grade heat source of temperature below 70°C and thermal capacity approximately 90 kW. The experiments covered the effect of condensation, evaporation and generation temperatures on the capacity and thermal efficiency of the ejection refrigeration system operating for the air-conditioning purposes. Obtained results demonstrated that the proposed system may be thought as the promising heat driven refrigeration system with application of low grade motive heat sources.

scholarly journals Thermodynamic investigation of organic Rankine cycle energy recovery system and recent studies

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2679-2690 ◽  
Author(s):  
Ozlem Boydak ◽  
Ismail Ekmekci ◽  
Mustafa Yilmaz ◽  
Hasan Koten
Keyword(s):  
Phase Change ◽  
Low Temperatures ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Energy Resources ◽  
Working Fluid ◽  
Low Grade ◽  
Heat Sources ◽  
Water Steam ◽  
Low Grade Heat

Recently, new environment-friendly energy conversion technologies are required for using energy resources valid to power generation. Accordingly, low-grade heat sources as solar heat, geothermal energy, and waste heat, which have available temperatures ranging between 60 and 200?C, are supposed as applicants for recent new generation energy resources. As an alternative energy source, such low-grade heat sources usage generating electricity with the help of power turbine cycles was examined through this study. Such systems have existing technologies applicable at low temperatures and a compact structure at low cost, however, these systems have a low thermal efficiency of the Rankine cycles operated at low temperatures. An organic Rankine cycle is alike to a conventional steam power plant, except the working fluid, which is an organic, high molecular mass fluid with a liquid-vapor phase change, or boiling point, at a lower temperature than the water-steam phase change. The efficiency of an organic Rankine cycle is about between 10% and 20%, depending on temperature levels and availability of a valid fluid.

Working Fluid Dependence on Source Temperature for Organic Rankine Cycles

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Hugo Darío Pasinato
Keyword(s):  
Performance Indicator ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Low Grade ◽  
Working Fluids ◽  
Source Temperature ◽  
Operation Conditions ◽  
Organic Rankine Cycles ◽  
Low Grade Heat ◽  
Selection Of

Abstract This paper presents the results of numerical simulations of organic Rankine cycles (ORCs) for low-grade heat source temperature in the range of 373–653 K for 20 working fluids. The goal of the study is to determine the importance of the level of the source temperature in the selection of working fluids and operation conditions. As a performance indicator, a function of the net power, the internal and external exergy efficiencies, and the exergy efficiency of the evaporator is used. The results show that there is a strong correlation between the level of the source temperature and the critical temperature, between the expander inlet temperature and the source temperature, and between the expander inlet pressure and the critical pressure of the working fluids tested. The study shows that once the source temperature level is known, it is possible to select the working fluid and the conditions at the expander entrance.

An Innovative Falling Film Evaporative Cooling With Recirculation Driven by Low-Grade Heat

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
S. He ◽  
R. Z. Wang ◽  
Z. Z. Xia ◽  
B. Tian ◽  
L. W. Wang
Keyword(s):  
Heat Transfer ◽  
Evaporative Cooling ◽  
Hot Water ◽  
Working Fluid ◽  
Small Scale ◽  
Inlet Temperature ◽  
Low Grade ◽  
Falling Film ◽  
Film Evaporator ◽  
Low Grade Heat

A falling film evaporator integrated with a recirculation tube driven by low-grade heat has been proposed to achieve a more compact and reliable system, which can be easily integrated into small-scale systems. An experimental study of the evaporative cooling of such an innovative falling film evaporator is presented. Water was used as the working fluid. The results are compared with published data for systems using mechanical pumps to circulate the fluid. Experimental investigation showed that the evaporative heat transfer coefficient of 6770–6870 W/m2 K can be achieved when the inlet temperature of the falling fluid is 29°C and the hot water entry temperature is 70°C. Detailed investigation on the effects of the driving heat source temperature and the inlet temperature of the hot water on the liquid film cooling mechanism was investigated. The results showed that for such a system, the effect of the falling film inlet temperature is more pronounced as compared with the other two parameters. Comparisons with traditional falling film evaporator with a mechanical pump indicated that the proposed integrated evaporator is more compact, reliable, and cost effective without impairing the heat transfer performance.

Experimental and Numerical Simulation for Thermal Investigation of Oscillating Heat Pipe Using VOF Model

2020 ◽  
Vol 38 (1A) ◽  
pp. 88-104
Author(s):  
Anwar S. Barrak ◽  
Ahmed A. M. Saleh ◽  
Zainab H. Naji
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Heat Input ◽  
Cfd Simulation ◽  
Working Fluid ◽  
Maximum Deviation ◽  
Inlet Temperature ◽  
Maximum Heat ◽  
Oscillating Heat Pipe ◽  
Vof Model

This study is investigated the thermal performance of seven turns of the oscillating heat pipe (OHP) by an experimental investigation and CFD simulation. The OHP is designed and made from a copper tube with an inner diameter 3.5 mm and thickness 0.6 mm and the condenser, evaporator, and adiabatic lengths are 300, 300, and 210 mm respectively.  Water is used as a working fluid with a filling ratio of 50% of the total volume. The evaporator part is heated by hot air (35, 40, 45, and 50) oC with various face velocity (0.5, 1, and 1.5) m/s. The condenser section is cold by air at temperature 15 oC. The CFD simulation is done by using the volume of fluid (VOF) method to model two-phase flow by conjugating a user-defined function code (UDF) to the FLUENT code. Results showed that the maximum heat input is 107.75 W while the minimum heat is 13.75 W at air inlet temperature 35 oC with air velocity 0.5m/s. The thermal resistance decreased with increasing of heat input. The results were recorded minimum thermal resistance 0.2312 oC/W at 107.75 W and maximum thermal resistance 1.036 oC/W at 13.75W. In addition, the effective thermal conductivity increased due to increasing heat input.  The numerical results showed a good agreement with experimental results with a maximum deviation of 15%.

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