Design, Analysis and Optimization of a Micro-CHP System Based on Organic Rankine Cycle for Ultralow Grade Thermal Energy Recovery

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Davide Ziviani ◽  
Asfaw Beyene ◽  
Mauro Venturini
Keyword(s):  
Heat Exchanger ◽  
Simulation Model ◽  
Thermal Energy ◽  
Energy Recovery ◽  
Organic Rankine Cycle ◽  
Residential Building ◽  
Rankine Cycle ◽  
Hot Water ◽  
Solar Thermal Energy ◽  
Chp System

This paper presents the results of the application of an advanced thermodynamic model developed by the authors for the simulation of Organic Rankine Cycles (ORCs). The model allows ORC simulation both for steady and transient analysis. The expander, selected to be a scroll expander, is modeled in detail by decomposing the behavior of the fluid stream into several steps. The energy source is coupled with the system through a plate heat exchanger (PHE), which is modeled using an iterative sub-heat exchanger modeling approach. The considered ORC system uses solar thermal energy for ultralow grade thermal energy recovery. The simulation model is used to investigate the influence of ORC characteristic parameters related to the working medium, hot reservoir and component efficiencies for the purpose of optimizing the ORC system efficiency and power output. Moreover, dynamic response of the ORC is also evaluated for two scenarios, i.e. (i) supplying electricity for a typical residential user and (ii) being driven by a hot reservoir. Finally, the simulation model is used to evaluate ORC capability to meet electric, thermal and cooling loads of a single residential building, for typical temperatures of the hot water exiting from a solar collector.

Application of an Advanced Simulation Model to a Micro-CHP ORC-Based System for Ultra-Low Grade Heat Recovery

2012 ◽  
Author(s):  
Davide Ziviani ◽  
Asfaw Beyene ◽  
Mauro Venturini
Keyword(s):  
Heat Exchanger ◽  
Simulation Model ◽  
Heat Recovery ◽  
Residential Building ◽  
Hot Water ◽  
Low Grade ◽  
Solar Thermal Energy ◽  
Working Medium ◽  
Cooling Loads ◽  
Low Grade Heat

This paper presents the results of the application of an advanced thermodynamic model developed by the authors for the simulation of Organic Rankine Cycles (ORCs). The model allows ORC simulation both for steady and transient analysis. The expander, selected to be a scroll expander, is modeled in detail by decomposing the behavior of the fluid stream into several steps. The heat source is coupled with the system through a plate heat exchanger, which is modeled using an iterative sub-heat exchanger modeling approach. The considered ORC system uses solar thermal energy for ultra-low grade heat recovery. The simulation model is used to investigate the influence of ORC characteristic parameters related to the working medium, hot reservoir and component efficiencies for the purpose of optimizing the ORC system efficiency and power output. Moreover, dynamic response of the ORC is also evaluated for two scenarios, i.e. (i) supplying electricity for a typical residential user and (ii) being driven by a hot reservoir. Finally, the simulation model is used to evaluate ORC capability to meet electric, thermal and cooling loads of a single residential building, for typical temperatures of the hot water exiting from a solar collector.

scholarly journals A Hot Water Split-Flow Dual-Pressure Strategy to Improve System Performance for Organic Rankine Cycle

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3345 ◽  
Author(s):  
Shiqi Wang ◽  
Zhongyuan Yuan
Keyword(s):  
Output Power ◽  
Thermal Energy ◽  
System Performance ◽  
Industrial Waste ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Inlet Temperature ◽  
Split Flow ◽  
Net Power Output

The organic Rankine cycle (ORC) is widely used to recover industrial waste heat. For an ORC system using industrial waste hot water as a heat source, a novel hot water split-flow dual-pressure organic Rankine cycle (SFD-ORC) system is developed to improve the performance of the ORC. The maximum net power output was selected to compare three ORC systems, including basic ORC (B-ORC), conventional dual-pressure ORC (CD-ORC) and SFD-ORC. A genetic algorithm (GA) was used to optimize the parameters to search the maximum net power output of ORCs. The maximum net output power was taken as the standard of performance evaluation. The results show that, under the same hot water inlet temperature condition, the optimal hot water outlet temperature of B-ORC is much higher than that of CD-ORC and SFD-ORC, which indicates that less thermal energy could be utilized to convert to power in B-ORC. The optimal hot water temperature at the outlet of evaporator 1 in SFD-ORC is higher than that in CD-ORC, which means SFD-ORC could make more efficient use of the high-grade thermal energy of hot water. The SFD-ORC could obtain the highest net output power under the optimal parameter conditions, followed by the CD-ORC system, while the B-ORC has the lowest net output power. Moreover, with the increase in the hot water inlet temperature, the advantage of SFD-ORC becomes increasingly obvious. When the hot water inlet temperature is 90 °C, the net output power of SFD-ORC at is 6.22% higher than that of CD-ORC. The net output power of SFD-ORC at 130 °C increases to 9.7% higher than that of CD-ORC. The SFD-ORC presents better system performance and has great engineering application potential.

Experimental study on Organic Rankine cycle for low grade thermal energy recovery

2016 ◽  
Vol 94 ◽  
pp. 221-227 ◽  
Author(s):  
Wenhao Pu ◽  
Chen Yue ◽  
Dong Han ◽  
Weifeng He ◽  
Xuan Liu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Thermal Energy ◽  
Energy Recovery ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Low Grade

scholarly journals Features Design of Organic Rankine Cycle

2019 ◽  
pp. 733-745
Author(s):  
Denis I. Karabarin ◽  
Sergei A. Mihailenko
Keyword(s):  
Thermal Energy ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Body Type ◽  
Design Features ◽  
Effective Technology ◽  
Comparison And Analysis

This article discusses the design features of plants operating on the principle of organic Rankine cycle. Firstly, the choice of organic Rankine cycle as the most effective technology for utilization of low-potential heat by comparison and analysis with other technologies is justified. Secondly, the technique of selection and calculation of the installations working on the principle of an organic Rankine cycle, taking into account features of a choice of a working body, type of the expander, and also a configuration is offered. Third, an example of the calculation of the prototype of such a 4 kW unit operating on the thermal energy of hot water from the boiler, the simulation of which is performed in the program SmoWeb, the results of which it was designed. Fourth, the design for this technology takes

Development and Validation of an Advanced Simulation Model for ORC-Based Systems

2012 ◽  
Author(s):  
Davide Ziviani ◽  
Asfaw Beyene ◽  
Mauro Venturini
Keyword(s):  
Heat Exchanger ◽  
Simulation Model ◽  
System Modeling ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Low Grade ◽  
Key Characteristics ◽  
Low Grade Heat ◽  
Development And Validation ◽  
Power Generation Systems

Low-grade heat recovery from solar or geothermal energy may be an eco-friendly resource for electric and thermal energy recovery. The Organic Rankine Cycle (ORC) is one of the main candidates to exploit low-temperature heat sources, otherwise difficult to access using conventional power generation systems. In this paper, an advanced thermodynamic model of an ORC is developed, with the final aim to optimize ORC conversion efficiency, especially for micro-CHP applications. First, a thorough review of issues related to ORC system modeling is presented by analyzing the state-of-the-art experience and advancements. Subsequently, an advanced simulation model is developed, by taking advantage of all the key characteristics of the models presented in the literature. The simulation model is developed in Matlab®/AMESim® environment, which allows system modeling both for steady and transient analysis. The heat source is coupled with the system through a plate heat exchanger, which is modeled using an iterative sub-heat exchanger modeling approach. A scroll expander, modeled in detail by decomposing the behavior of the fluid stream into several steps, is used to extract the useful work. Finally, model predictions for the evaporator and the expander are validated against both numerical and experimental data published in literature. The simulation model of the entire ORC system is also validated against literature data taken on a test bench.

scholarly journals Optimal design of compact organic Rankine cycle units for domestic solar applications

2014 ◽  
Vol 18 (3) ◽  
pp. 811-822 ◽  
Author(s):  
Luca Barbazza ◽  
Leonardo Pierobon ◽  
Alberto Mirandola ◽  
Fredrik Haglind
Keyword(s):  
Heat Exchanger ◽  
Water Temperature ◽  
Flat Plate ◽  
Thermal Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Working Fluid ◽  
Solar Collectors ◽  
Allowable Temperature

Organic Rankine cycle turbogenerators are a promising technology to transform the solar radiation harvested by solar collectors into electric power. The present work aims at sizing a small-scale organic Rankine cycle unit by tailoring its design for domestic solar applications. Stringent design criteria, i. e., compactness, high performance and safe operation, are targeted by adopting a multi-objective optimization approach modeled with the genetic algorithm. Design-point thermodynamic variables, e. g., evaporating pressure, the working fluid, minimum allowable temperature differences, and the equipment geometry, are the decision variables. Flat plate heat exchangers with herringbone corrugations are selected as heat transfer equipment for the preheater, the evaporator and the condenser. The results unveil the hyperbolic trend binding the net power output to the heat exchanger compactness. Findings also suggest that the evaporator and condenser minimum allowable temperature differences have the largest impact on the system volume and on the cycle performances. Among the fluids considered, the results indicate that R1234yf and R1234ze are the best working fluid candidates. Using flat plate solar collectors (hot water temperature equal to 75 ?C), R1234yf is the optimal solution. The heat exchanger volume ranges between 6.0 and 23.0 dm3, whereas the thermal efficiency is around 4.5%. R1234ze is the best working fluid employing parabolic solar collectors (hot water temperature equal to 120 ?C). In such case the thermal efficiency is around 6.9%, and the heat exchanger volume varies from 6.0 to 18.0 dm3.

Solar Thermal Energy

2018 ◽  
Author(s):  
E. L. Wolf
Keyword(s):  
Solar Cells ◽  
Thermal Energy ◽  
Fossil Fuel ◽  
Rankine Cycle ◽  
Carnot Cycle ◽  
The Sun ◽  
Solar Thermal Energy ◽  
Heat Engines ◽  
Direct Use ◽  
Fossil Fuel Energy

The Sun’s spectrum on Earth is modified by the atmosphere, and is harvested either by generating heat for direct use or for running heat engines, or by quantum absorption in solar cells, to be discussed later. Focusing of sunlight requires tracking of the Sun and is defeated on cloudy days. Heat engines have efficiency limits similar to the Carnot cycle limit. The steam turbine follows the Rankine cycle and is well developed in technology, optimally using a re-heat cycle of higher efficiency. Having learned quite a bit about how the Sun’s energy is created, and how that process might be reproduced on Earth, we turn now to methods for harvesting the energy from the Sun as a sustainable replacement for fossil fuel energy.

scholarly journals Effect of Twisted Fin Array in a Triple-Tube Latent Heat Storage System during the Charging Mode

2021 ◽  
Vol 13 (5) ◽  
pp. 2685
Author(s):  
Mohammad Ghalambaz ◽  
Jasim M. Mahdi ◽  
Amirhossein Shafaghat ◽  
Amir Hossein Eisapour ◽  
Obai Younis ◽  
...  
Keyword(s):  
Energy Storage ◽  
Heat Exchanger ◽  
Latent Heat ◽  
Thermal Energy ◽  
Heat Storage ◽  
Hot Water ◽  
Melting Time ◽  
Latent Heat Storage ◽  
Tube Heat Exchanger ◽  
Storage Rate

This study aims to assess the effect of adding twisted fins in a triple-tube heat exchanger used for latent heat storage compared with using straight fins and no fins. In the proposed heat exchanger, phase change material (PCM) is placed between the middle annulus while hot water is passed in the inner tube and outer annulus in a counter-current direction, as a superior method to melt the PCM and store the thermal energy. The behavior of the system was assessed regarding the liquid fraction and temperature distributions as well as charging time and energy storage rate. The results indicate the advantages of adding twisted fins compared with those of using straight fins. The effect of several twisted fins was also studied to discover its effectiveness on the melting rate. The results demonstrate that deployment of four twisted fins reduced the melting time by 18% compared with using the same number of straight fins, and 25% compared with the no-fins case considering a similar PCM mass. Moreover, the melting time for the case of using four straight fins was 8.3% lower than that compared with the no-fins case. By raising the fins’ number from two to four and six, the heat storage rate rose 14.2% and 25.4%, respectively. This study presents the effects of novel configurations of fins in PCM-based thermal energy storage to deliver innovative products toward commercialization, which can be manufactured with additive manufacturing.

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