A comparative study of the carbon dioxide transcritical power cycle compared with an organic rankine cycle with R123 as working fluid in waste heat recovery

2006 ◽  
Vol 26 (17-18) ◽  
pp. 2142-2147 ◽  
Author(s):  
Y. Chen ◽  
P. Lundqvist ◽  
A. Johansson ◽  
P. Platell
2021 ◽  
Vol 11 (5) ◽  
pp. 1984
Author(s):  
Ramin Moradi ◽  
Emanuele Habib ◽  
Enrico Bocci ◽  
Luca Cioccolanti

Organic Rankine cycle (ORC) systems are some of the most suitable technologies to produce electricity from low-temperature waste heat. In this study, a non-regenerative, micro-scale ORC system was tested in off-design conditions using R134a as the working fluid. The experimental data were then used to tune the semi-empirical models of the main components of the system. Eventually, the models were used in a component-oriented system solver to map the system electric performance at varying operating conditions. The analysis highlighted the non-negligible impact of the plunger pump on the system performance Indeed, the experimental results showed that the low pump efficiency in the investigated operating range can lead to negative net electric power in some working conditions. For most data points, the expander and the pump isentropic efficiencies are found in the approximate ranges of 35% to 55% and 17% to 34%, respectively. Furthermore, the maximum net electric power was about 200 W with a net electric efficiency of about 1.2%, thus also stressing the importance of a proper selection of the pump for waste heat recovery applications.


Author(s):  
Fredrik Ahlgren ◽  
Maria E. Mondejar ◽  
Magnus Genrup ◽  
Marcus Thern

Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.


2021 ◽  
Vol 143 (9) ◽  
Author(s):  
Md. Zahurul Haq

Abstract Organic Rankine cycle (ORC)-based waste heat recovery (WHR) systems are simple, flexible, economical, and environment-friendly. Many working fluids and cycle configurations are available for WHR systems, and the diversity of working fluid properties complicates the synergistic integration of the efficient heat exchange in the evaporator and net output work. Unique guidelines to select a proper working fluid, cycle configuration and optimum operating parameters are not readily available. In the present study, a simple target-temperature-line approach is introduced to get the optimum operating parameters for the subcritical ORC system. The target-line is the locus of temperatures satisfying the pinch-point temperature difference along the length of the heat exchanger. Employing the approach, study is carried out with 38 pre-selected working fluids to get the optimum operating parameters and suitable fluid for heat source temperatures ranging from 100 °C to 300 °C. Results obtained are analyzed to get cross-correlations between key operating and performance parameters using a heat-map diagram. At the optimum condition, optimal working fluid’s critical temperature and pressure, evaporator saturation temperature, effectivenesses of the heat exchange in the evaporator, cycle, and overall WHR system exhibit strong linear correlations with the heat source temperature.


Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1317 ◽  
Author(s):  
Guillermo Valencia Ochoa ◽  
Cesar Isaza-Roldan ◽  
Jorge Duarte Forero

The waste heat recovery system (WHRS) is a good alternative to provide a solution to the waste energy emanated in the exhaust gases of the internal combustion engine (ICE). Therefore, it is useful to carry out research to improve the thermal efficiency of the ICE through a WHRS based on the organic Rankine cycle (ORC), since this type of system takes advantage of the heat of the exhaust gases to generate electrical energy. The organic working fluid selection was developed according to environmental criteria, operational parameters, thermodynamic conditions of the gas engine, and investment costs. An economic analysis is presented for the systems operating with three selected working fluids: toluene, acetone, and heptane, considering the main costs involved in the design and operation of the thermal system. Furthermore, an exergo-advanced study is presented on the WHRS based on ORC integrated to the ICE, which is a Jenbacher JMS 612 GS-N of 2 MW power fueled with natural gas. This advanced exergetic analysis allowed us to know the opportunities for improvement of the equipment and the increase in the thermodynamic performance of the ICE. The results show that when using acetone as the organic working fluid, there is a greater tendency of improvement of endogenous character in Pump 2 of around 80%. When using heptane it was manifested that for the turbine there are near to 77% opportunities for improvement, and the use of toluene in the turbine gave a rate of improvement of 70%. Finally, some case studies are presented to study the effect of condensation temperature, the pinch point temperature in the evaporator, and the pressure ratio on the direct, indirect, and fixed investment costs, where the higher investment costs were presented with the acetone, and lower costs when using the toluene as working fluid.


2014 ◽  
Vol 575 ◽  
pp. 662-667
Author(s):  
Barghav Subramony Hariharan ◽  
Kaushik Suresh

Organic Rankine Cycles (ORC) is predominantly used in waste heat recovery applications because of their low temperature working range. The main efficiency enhancement operation in an Organic Rankine Cycle is reducing the pump work .The pump converts electrical energy to flow energy. This input reduced and output maintained at the same level gives us a more efficient waste heat recovery system. The pump work can also be achieved by using a material that has the ability to expand on heating and revert back to its original state on cooling. The expansion property of the material is used to compress and drive the operating fluid through the cycle. Material that was observed to possess such properties was Phase Change Material. Conventionally PCM were used as thermal storage to preheat the working fluid in an ORC but a novel idea is to make the PCM utilize the heat rejected from the condenser and do the pump work. This paper discusses the various desirable properties of PCM to perform pump work efficiently and also the general layout and working of ORC system using PCM. The working fluid selected is toluene


Author(s):  
Quazi E. Hussain ◽  
David R. Brigham

The Rankine cycle is used commercially to generate power in stationary power plants using water as the working fluid. For waste heat recovery applications, where the temperature is lower, water is typically replaced by a carefully selected organic fluid. This work is based on using the waste heat in an automobile to generate electricity using the Organic Rankine cycle (ORC) with R245fa (1, 1, 1, 3, 3 penta-fluoropropane) as the working fluid. The electricity thus generated can be used to drive the accessory load or charge the battery which in any case helps improve the fuel economy. A simple transient numerical model has been developed that is capable of capturing the main effects of this cycle. Results show that exhaust heat alone can generate enough electricity that is capable of bringing about an improvement to the fuel economy under transient drive cycle conditions. Power output during EPA Highway drive cycle is much higher than EPA City due to higher exhaust mass flow rate and temperature. Time needed to reach operating conditions or in other words, the warm-up time plays an important role in the overall drive cycle output. Performance is found to improve significantly when coolant waste heat is used in conjunction with the residual exhaust heat to pre-heat the liquid. A sizing study is also performed to keep the cost, weight, and packaging requirement down without sacrificing too much power. With careful selection of heat exchanger design parameters, it has been demonstrated that the backpressure on the engine can be actually lowered by cooling off the exhaust gas. This lower backpressure will further boost the fuel economy gained by the electricity produced by the Rankine bottoming cycle.


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