scholarly journals Numerical Analysis of Integral Characteristics for the Condenser Setups of Independent Power-Supply Sources with the Closed-Looped Thermodynamic Cycle

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Olga V. Vysokomornaya ◽  
Genii V. Kuznetsov ◽  
Pavel A. Strizhak

The mathematical model of heat and mass transfer processes with phase transition is developed. It allows analysis of integral characteristics for the condenser setup of independent power-supply plant with the organic Rankine cycle. Different kinds of organic liquids can be used as a coolant and working substance. The temperatures of the working liquid at the condenser outlet under different values of outside air temperature are determined. The comparative analysis of the utilization efficiency of different cooling systems and organic coolants is carried out.

2020 ◽  
Vol 92 (1) ◽  
pp. 10906
Author(s):  
Jeroen Schoenmaker ◽  
Pâmella Gonçalves Martins ◽  
Guilherme Corsi Miranda da Silva ◽  
Julio Carlos Teixeira

Organic Rankine Cycle (ORC) systems are increasingly gaining relevance in the renewable and sustainable energy scenario. Recently our research group published a manuscript identifying a new type of thermodynamic cycle entitled Buoyancy Organic Rankine Cycle (BORC) [J. Schoenmaker, J.F.Q. Rey, K.R. Pirota, Renew. Energy 36, 999 (2011)]. In this work we present two main contributions. First, we propose a refined thermodynamic model for BORC systems accounting for the specific heat of the working fluid. Considering the refined model, the efficiencies for Pentane and Dichloromethane at temperatures up to 100 °C were estimated to be 17.2%. Second, we show a proof of concept BORC system using a 3 m tall, 0.062 m diameter polycarbonate tube as a column-fluid reservoir. We used water as a column fluid. The thermal stability and uniformity throughout the tube has been carefully simulated and verified experimentally. After the thermal parameters of the water column have been fully characterized, we developed a test body to allow an adequate assessment of the BORC-system's efficiency. We obtained 0.84% efficiency for 43.8 °C working temperature. This corresponds to 35% of the Carnot efficiency calculated for the same temperature difference. Limitations of the model and the apparatus are put into perspective, pointing directions for further developments of BORC systems.


Author(s):  
Sebastian Bahamonde ◽  
Matteo Pini ◽  
Carlo De Servi ◽  
Antonio Rubino ◽  
Piero Colonna

Widespread adoption of renewable energy technologies will arguably benefit from the availability of economically viable distributed thermal power conversion systems. For this reason, considerable efforts have been dedicated in recent years to R&D over mini-organic Rankine cycle (ORC) power plants, thus with a power capacity approximately in the 3–50 kW range. The application of these systems for waste heat recovery from diesel engines of long-haul trucks stands out because of the possibility of achieving economy of production. Many technical challenges need to be solved, as the system must be sufficiently efficient, light, and compact. The design paradigm is therefore completely different from that of conventional stationary ORC power plants of much larger capacity. A high speed turbine is arguably the expander of choice, if high conversion efficiency is targeted, thus high maximum cycle temperature. Given the lack of knowledge on the design of these turbines, which depends on a large number of constraints, a novel optimal design method integrating the preliminary design of the thermodynamic cycle and that of the turbine has been developed. The method is applicable to radial inflow, axial and radial outflow turbines, and to superheated and supercritical cycle configurations. After a limited number of working fluids are selected, the feasible design space is explored by means of thermodynamic cycle design calculations integrated with a simplified turbine design procedure, whereby the isentropic expansion efficiency is prescribed. Starting from the resulting design space, optimal preliminary designs are obtained by combining cycle calculations with a 1D mean-line code, subject to constraints. The application of the procedure is illustrated for a test case: the design of turbines to be tested in a new experimental setup named organic rankine cycle hybrid integrated device (ORCHID) which is being constructed at the Delft University of Technology, Delft, The Netherlands. The first turbine selected for further design and construction employs siloxane MM (hexamethyldisiloxane, C6H18OSi2), supercritical cycle, and the radial inflow configuration. The main preliminary design specifications are power output equal to 11.6 kW, turbine inlet temperature equal to 300 °C, maximum cycle pressure equal to 19.9 bar, expansion ratio equal to 72, rotational speed equal to 90 krpm, inlet diameter equal to 75 mm, minimum blade height equal to 2 mm, degree of reaction equal to 0.44, and estimated total-to-static efficiency equal to 77.3%. Results of the design calculations are affected by considerable uncertainty related to the loss correlations employed for the preliminary turbine design, as they have not been validated yet for this highly unconventional supersonic and transonic mini turbine. Future work will be dedicated to the extension of the method to encompass the preliminary design of heat exchangers and the off-design operation of the system.


2020 ◽  
Author(s):  
M. T. Nitsas ◽  
I. P. Koronaki

Abstract The objective of this paper is the thermodynamic analysis of a solar powered Organic Rankine Cycle (O.R.C.) and the investigation of potential working fluids in order to select the optimum one. A dynamic model for a solar O.R.C. with a storage tank, which produces electricity is developed. The mathematical model includes all the equations that describe the operation of the solar collectors, the storage tank, the Rankine Cycle and the feedback between them. The model runs for representative days throughout the year, calculating the net produced energy as a function of the selected evaporation temperature for every suitable working fluid. Above that, the temporal variation of the systems’ temperatures, collectors’ efficiency and net produced power, for the optimum organic fluid and evaporation temperature are presented.


2011 ◽  
Vol 383-390 ◽  
pp. 6071-6078
Author(s):  
E. H. Wang ◽  
H. G. Zhang ◽  
B. Y. Fan ◽  
H. Liang ◽  
M. G. Ouyang

Energy saving and environment protection are two important issues that today’s automobile industry must emphasize. Lots of heat energy waste with the exhaust gas when the engine is running. If this part of waste heat can be recovered, the energy efficiency will be improved. Thus plenty of energy can be saved and the global warming also can be reduced. In this paper, the organic Rankine cycle whose working fluid was R245fa was studied. It was adopted to recover the gasoline engine waste heat. The mathematical model of the organic Rankine cycle was built up in Matlab to search the optimized working condition. The pinch analysis method was used to analyze the outlet temperature of the exhaust gas. The results indicate that organic Rankine cycle is a good way to recover the gasoline engine waste heat, especially in the high load conditions. The temperature of the exhaust gas can be apparently decreased.


Author(s):  
Mauro Reini

In recent years, a big effort has been made to improve microturbines thermal efficiency, in order to approach 40%. Two main options may be considered: i) a wide usage of advanced materials for hot ends components, like impeller and recuperator; ii) implementing more complicated thermodynamic cycle, like combined cycle. In the frame of the second option, the paper deals with the hypothesis of bottoming a low pressure ratio, recuperated gas cycle, typically realized in actual microturbines, with an Organic Rankine Cycle (ORC). The object is to evaluate the expected nominal performance parameters of the integrated-combined cycle cogeneration system, taking account of different options for working fluid, vapor pressure and component’s performance parameters. Both options of recuperated and not recuperated bottom cycles are discussed, in relation with ORC working fluid nature and possible stack temperature for microturbine exhaust gases. Finally, some preliminary consideration about the arrangement of the combined cycle unit, and the effects of possible future progress of gas cycle microturbines are presented.


2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Fayrouz El hamdani ◽  
Sébastien Vaudreuil ◽  
Souad Abderafi ◽  
Tijani Bounahmidi

Abstract Concentrating solar power (CSP) technology is one of the promising options to generate green energy. However, the cost of kWhe produced is relatively high compared with fossil resources and can be reduced by integrating a cogeneration system exploiting waste energy. In this study, a technico-economic evaluation of a 1 MWe CSP plant with a condensation heat (85 °C) is investigated. The temperature constraint is set to meet the thermal separation needs of the draw solution of a forward osmosis desalination process. The purpose of this study focuses on the factors involved in reducing the cost per kWhe, which are the selection of the organic fluid used in the organic Rankine cycle and the appropriate choice of the solar multiple (SM) according to the appropriate storage hours (SH) maximizing the CSP thermal efficiency. The performance of different organic fluids was compared, based on the calculation of the thermodynamic cycle efficiency. The cyclopentane was retained for its reduced cost. Operating with this fluid, a sensitivity analysis was realized to test the effect of the solar multiple and storage hours on the power plant. It allows us to conclude that different appropriate combination between storage hours and solar multiple can be chosen, for the needs of our project, we opt for 8 h and 1.85, respectively. Thus, in this case, the cost of kWh was found to be 23.95¢.


2015 ◽  
Vol 36 (2) ◽  
pp. 85-103 ◽  
Author(s):  
Szymon Mocarsk ◽  
Aleksandra Borsukiewicz-Gozdur

AbstractThe paper presents a literature review on the topic of vapour power plants working according to the two-phase thermodynamic cycle with supercritical parameters. The main attention was focused on a review of articles and papers on the vapour power plants working using organic circulation fluids powered with low- and medium-temperature heat sources. Power plants with water-steam cycle supplied with a high-temperature sources have also been shown, however, it has been done mainly to show fundamental differences in the efficiency of the power plant and applications of organic and water-steam cycles. Based on a review of available literature references a comparative analysis of the parameters generated by power plants was conducted, depending on the working fluid used, the type and parameters of the heat source, with particular attention to the needs of power plant internal load.


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