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.

Experimental Study on the Organic Rankine Cycle Power System Adopting Dual Expanders in Parallel

2014 ◽  
Author(s):  
Eunkoo Yoon ◽  
Hyun Jun Park ◽  
Hyun Dong Kim ◽  
Kyung Chun Kim ◽  
Sang Youl Yoon
Keyword(s):  
Heat Source ◽  
Power System ◽  
Water Temperature ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Working Fluid ◽  
Electric Heater ◽  
Shaft Power ◽  
Scroll Expanders

This study aims to evaluate the performance of an organic Rankine cycle (ORC) power system adopting dual expanders in parallel by experiment. A dual-expander ORC system was designed to provide competitive advantages over a general single expander ORC system in typical applications with large thermal fluctuation of heat sources such as solar heat, marine waste heat, and etc. The ORC system consists of two scroll expanders installed in parallel, a hydraulic diaphragm type pump to feed and pressurize the working fluid, R-245fa, two plate heat exchangers for the evaporator and the condenser, and two generators with shaft power torque meters. The two scroll expanders were modified from two oil-free air scroll compressors, and were tested in the ORC loop with R245fa. The maximum isentropic efficiency of each expander was measured about 53%, and the shaft power was reached to about 2kW. The hot water was used as heat source, and the water temperature was controlled up to 150 °C by the 100 kW-class electric heater. A circulating air-cooled chiller was utilized for the control of the cooling water temperature. In order to determine the static performance of the system, efficiencies and shaft powers were measured with 130 °C heat source temperature. In addition, performance tests were conducted with various working fluid mass flow rates to control pressure ratios. The characteristics and total thermal efficiency of the dual parallel expander ORC system and optimal operating modes are addressed.

Generation of Electricity Utilizing Solar Hot Water Collectors and a Tesla Turbine

2009 ◽  
Author(s):  
Ryan Crowell
Keyword(s):  
Heat Exchanger ◽  
Flat Plate ◽  
Alternative Energy ◽  
Plate Heat Exchanger ◽  
Hot Water ◽  
Working Fluid ◽  
Solar Collectors ◽  
Gaseous State ◽  
Plate Heat ◽  
Ambient Temperatures

Threats of climate change and depleted petroleum supplies have prompted the need for eco-conscious alternative energy. This paper introduces a ground-breaking concept for harnessing the sun’s power that is significantly more efficient than existing systems. Solar collectors gather the electromagnetic radiation emitted by the sun and heat a propylene glycol to a high temperature that will then transfer the heat to a working fluid (Care30) through a plate heat exchanger. The Care30 then exits the heat exchanger in a gaseous state, and is passed through a Tesla turbine, which in turn rotates a shaft. The shaft is connected to a generator, which transforms the mechanical energy into electricity. The absorption efficiency of the solar collectors allows for mechanical loses while maintaining the overall efficiency at higher levels than any existing PV based system. Ambient temperatures drastically reduce the effectiveness of flat plate solar collectors, cooling the liquids inside before the heat can be efficiently consumed. In contrast, an evacuated tube collector maintains efficiency during such conditions. The collectors are insulated from ambient temperatures by the vacuum pressure inside the tube. A stainless steel flat plate heat exchanger is used to transfer the heat from the glycol/water solution to the refrigerant, which is sent to the turbine after it has been converted to its gaseous state. The solution also provides freeze protection in colder climates. A heat exchanger then cools the gas, returning it to its liquid state, which completes the cycle for the working fluid. The water used in the heat exchanger is then used as a supplementary heating source for the home, for domestic or radiant heating needs. As it is effective even in environments that compromise the functionality of existing PV systems, the proposed system responds effectively to the need for more efficient alternative energy sources.

scholarly journals The study of a seasonal solar CCHP system based on evacuated flat-plate collectors and organic Rankine cycle

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 915-924
Author(s):  
Guangtao Gao ◽  
Jing Li ◽  
Jingyu Cao ◽  
Honglun Yang ◽  
Gang Pei ◽  
...  
Keyword(s):  
Flat Plate ◽  
Thermal Efficiency ◽  
Residential Buildings ◽  
Lithium Bromide ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Outlet Temperature ◽  
Average Output ◽  
Autumn And Winter

The demands of cooling, heating and electricity in residential buildings are varied with seasons. This article presented a seasonal solar combined cooling heating and power (CCHP) system based on evacuated flat-plate collectors and organic Rankine cycle. The heat collected by evacuated flat-plate collectors is used to drive the organic Rankine cycle unit in spring, autumn and winter, and drive the double-effect lithium bromide absorption chiller in summer. The organic Rankine cycle condensation heat is used to yield hot water in spring and autumn, whereas supply heating in winter. The system thermodynamic performance was analyzed. The results show that the system thermal efficiency in spring, autumn and winter, ?sys,I, increases as organic Rankine cycle evaporation temperature, T6, and evacuated flat-plate collectors outlet temperature, T2, decrease. The maximum ?sys,I of 67.0% is achieved when T6 = 80?C and T2 =100?C. In summer, the system thermal efficiency, ?sys,II, increases first and then decreases with the increment of T2. The maximum ?sys,II of 69.9% is obtained at T2 =136?C. The system output performance in Beijing and Lanzhou is better than that in Hefei. The average output power, heating capacity, hot water and cooling capacity are 50-72 kWh per day, 989-1514 kWh per day, 49-57 ton per day and 1812-2311 kWh per day, respectively. The system exergy efficiency increases from 17.8-40.8% after integrating the organic Rankine cycle unit.

Optimization of Overcritical Organic Rankine Cycle

2016 ◽  
Vol 831 ◽  
pp. 306-315
Author(s):  
Qing Quan Wang ◽  
Sławomir Smoleń
Keyword(s):  
Numerical Method ◽  
Thermal Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Independent Variables ◽  
Hot Temperature ◽  
Working Fluid Selection ◽  
Two Independent Variables

This paper explores the optimization cases for overcritical Organic Rankine Cycle (ORC) in various situations. First the ORC optimization in terms of working fluid selection is discussed. In this case, thermal efficiencies for 10 different working fluids have been calculated under certain temperature frames and the results are compared. Second, overcritical optimization case in terms of variation of hot temperature and evaporation pressure is presented. In this overcritical ORC case, the influence of evaporation pressure on ORC thermal efficiency is studied by conducting a case study of R234a, and first 1-D freedom optimization case is discussed within the variation of evaporation pressure. 2-D freedom optimization is also considered, in which the two independent variables, hot temperature and evaporation pressure, are both varied within certain boundaries. This study employs numerical method for this 2-D problem and it is also presented in detail in the case study.

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.

Numerical Analysis of a Solar Organic Rankine Cycle (ORC) Unit With R245fa as Working Fluid

2012 ◽  
Author(s):  
Musbaudeen O. Bamgbopa ◽  
Eray Uzgoren
Keyword(s):  
Mass Flow ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Critical Parameters ◽  
Working Fluid ◽  
Flow Rates ◽  
Steady State Operation ◽  
Mass Flow Rates ◽  
Solar Field

This paper presents a solar Organic Rankine Cycle (ORC) for electricity generation; where a regression based approach is used for the working fluid. Models of the unit’s sub-components (pump, evaporator, expander and condenser) are also presented. Heat supplied by the solar field can heat the water up to 80–95 °C at mass flow rates of 2–12 kg/s and deliver energy to the ORC’s heat exchanger unit. Simulation results of steady state operation using the developed model shows a maximum power output of around 40 kWe. Both refrigerant and hot water mass flow rates in the system are identified as critical parameters to optimize the power production and the cycle efficiency.

scholarly journals Utilization of Indonesia’s Hot Spring Sources for Electricity using Kalina Cycle and Organic Rankine Cycle

2018 ◽  
Vol 31 ◽  
pp. 01002 ◽  
Author(s):  
Grano Prabumukti ◽  
Widodo Wahyu Purwanto
Keyword(s):  
Heat Source ◽  
Thermal Efficiency ◽  
Hot Springs ◽  
Hot Spring ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Power Capacity ◽  
Spring Temperature ◽  
Kalina Cycle

Indonesia posses 40% of the world's geothermal energy sources. The existence of hydrothermal sources is usually characterized by their surface manifestations such as hot springs, geysers and fumarole. Hot spring has a potential to be used as a heat source to generate electricity especially in a rural and isolated area. Hot springs can be converted into electricity by binary thermodynamic cycles such as Kalina cycle and ORC. The aim of this study is to obtain the best performances of cycle configuration and the potential power capacity. Simulation is conducted using UNISIM software with working fluid and its operating condition as the decision variables. The simulation result shows that R1234yf and propene with simple ORC as desired working fluid and cycle configuration. It reaches a maximum thermal efficiency up to 9.6% with a specific turbine inlet pressure. Higher temperature heat source will result a higher thermal efficiency‥ Cycle thermal efficiency varies from 4.7% to 9.6% depends on source of hot spring temperature. Power capacity that can be generated using Indonesia’s hot spring is ranged from 2 kWe to 61.2 kWe. The highest capacity located in Kawah Sirung and the least located in Kaendi.

scholarly journals Performance comparison of the solar-driven supercritical organic Rankine cycle coupled with the vapour-compression refrigeration cycle

Clean Energy ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 476-491
Author(s):  
Yunis Khan ◽  
Radhey Shyam Mishra
Keyword(s):  
Thermal Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Coefficient Of Performance ◽  
Solar Irradiation ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Exergy Destruction ◽  
Cogeneration System ◽  
Vapour Compression

Abstract In this study, a parametric analysis was performed of a supercritical organic Rankine cycle driven by solar parabolic trough collectors (PTCs) coupled with a vapour-compression refrigeration cycle simultaneously for cooling and power production. Thermal efficiency, exergy efficiency, exergy destruction and the coefficient of performance of the cogeneration system were considered to be performance parameters. A computer program was developed in engineering equation-solver software for analysis. Influences of the PTC design parameters (solar irradiation, solar-beam incidence angle and velocity of the heat-transfer fluid in the absorber tube), turbine inlet pressure, condenser and evaporator temperature on system performance were discussed. Furthermore, the performance of the cogeneration system was also compared with and without PTCs. It was concluded that it was necessary to design the PTCs carefully in order to achieve better cogeneration performance. The highest values of exergy efficiency, thermal efficiency and exergy destruction of the cogeneration system were 92.9%, 51.13% and 1437 kW, respectively, at 0.95 kW/m2 of solar irradiation based on working fluid R227ea, but the highest coefficient of performance was found to be 2.278 on the basis of working fluid R134a. It was also obtained from the results that PTCs accounted for 76.32% of the total exergy destruction of the overall system and the cogeneration system performed well without considering solar performance.

scholarly journals Análisis termodinámico del intercambiador de calor de un sistema ORC para el aprovechamiento de calor residual en procesos industriales

2019 ◽  
pp. 27-33
Author(s):  
Uzziel Caldiño-Herrera ◽  
Delfino Cornejo-Monroy ◽  
Shehret Tilvaldyev ◽  
José Omar Dávalos-Ramírez
Keyword(s):  
Energy Source ◽  
Heat Exchanger ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Industrial Process ◽  
Rankine Cycle ◽  
Energy System ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Working Fluid

In this paper we present the implementation of a system based on organic Rankine cycle coupled to a heat discharge of an industrial process. Waste heat is used as an energy source input to the system, which uses this energy to evaporate an organic fluid and expand it in a turbine, where mechanical power is produced. The system consists of 4 processes and the heat exchanger is specially analyzed. According to the availability of heat energy, the heat exchanger was designed to achieve the maximum efficiency in the energy system. Likewise, the maximum thermal efficiency of the ORC system is calculated as a function of the available energy, the energy source temperature and the available mass flow rate. By these calculations, the working fluid and the suitable operating conditions were selected through a thermodynamic analysis.

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