Analysis of a solar assisted micro-cogeneration ORC system (original) (raw)
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Preliminary thermal analysis of a solar assisted micro- cogeneration system
In this work, three solar assisted thermodynamic cycles for a microcogeneration system are studied. The thermodynamic cycles are based on the organic Rankine cycle (ORC) and the operating temperatures of solar thermal collectors are 80ºC, 100ºC-150ºC and 200º-250ºC, for cycles 1, 2 and 3, respectively. Several researchers have investigated the application and performance of ORCs. They have shown that organic fluids can be used to generate power using low-temperature energy sources (solar or waste heat). The main work objective is the modelling of the selected cycles for optimisation according to the temperature range.
Global Journal of Energy Technology Research Updates, 2014
In this paper, we analyze characteristics of a small Combined Heat and Power (CHP) system based mainly on Organic Rankine Cycle (ORC) and heating plant in actual series connection regarding the low-temperature heat carrier heated by purely solar flat collector field. Simultaneously and for specific power production, comparison of this layout with stand-alone ORC, and with the traditional ORC-CHP imposing gain of condenser heat for heating aims, in second step, has been conducted. For evaluation, energetic and design criteria have been determined opposite the heating effects and also temperatures of the heat source and sink. The simulations addressed interesting optimization ratios till 24 % for the power unit throughout this series CHP utility versus single power generation at the same conditions tested. Moreover, the high heat source temperatures and CHP ratios improve the performance of the overall series plant, while the high supply and return temperatures have negative effects. Finally, the ORC-CHP scheme handled here highlights distinctive exploitation aspects and more suitability in wide range of application in comparison to yielding the hightemperature condensation heat of ORC, especially at low ambient temperatures, high supply and heat source temperatures. So, it can be advised to be adopted instead of the two other strategies.
2019
This paper proposes the configuration of an Organic Rankine Cycle (ORC) coupled to a 13 solar domestic hot water system (SDHWS), with the purpose of analyzing the cogeneration 14 capacity of the system. A simulation of the SDHWS was conducted at different temperatures, 15 observing its performance to determine the amounts of useable heat generated by the solar 16 collector; thus, from an energy balance, the amount of heat that may be used by the ORC could be 17 determined. The working fluid that would be suitable for the temperatures and pressures given in 18 the system were selected. The best fluid for the given conditions of superheated vapor at 120 °C 19 and 604 kPa and a condensation temperature of 60 °C and 115 kPa was acetone. The main 20 parameters for the expander thermodynamic design that may be used in such ORC were obtained 21 with the possibility of generating 443 kWh of annual electric energy, with 6.65 % global efficiency 22 of solar to electric power, or an overall ef...
This paper proposes the configuration of an Organic Rankine Cycle (ORC) coupled to a solar domestic hot water system (SDHWS) with the purpose of analyzing the cogeneration capacity of the system. A simulation of the SDHWS was conducted at different temperatures, observing its performance to determine the amounts of useable heat generated by the solar collector; thus, from an energy balance point of view, the amount of heat that may be used by the ORC could be determined. The working fluid that would be suitable for the temperatures and pressures in the system was selected. The best fluid for the given conditions of superheated vapor at 120 • C and 604 kPa and a condensation temperature of 60 • C and 115 kPa was acetone. The main parameters for the expander thermodynamic design that may be used by the ORC were obtained, with the possibility of generating 443 kWh of annual electric energy with 6.65% global efficiency of solar to electric power, or an overall efficiency of the cogeneration system of 56.35% with a solar collector of 2.84 m 2 .
This paper proposes the configuration of an Organic Rankine Cycle (ORC) coupled to a solar domestic hot water system (SDHWS), with the purpose of analyzing the cogeneration capacity of the system. A simulation of the SDHWS was conducted at different temperatures, observing its performance to determine the amounts of useable heat generated by the solar collector; thus, from an energy balance, the amount of heat that may be used by the ORC could be determined. The working fluid that would be suitable for the temperatures and pressures given in the system were selected. The best fluid for the given conditions of superheated vapor at 120 °C and 604 kPa and a condensation temperature of 60 °C and 115 kPa was acetone. The main parameters for the expander thermodynamic design that may be used in such ORC were obtained with the possibility of generating 443 kWh of annual electric energy, with 6.65 % global efficiency of solar to electric power, or an overall efficiency of the cogeneration s...
Analysis of a micro-cogeneration system using hybrid solar/gas collectors
International Journal of Low-Carbon Technologies, 2006
The use of solar thermal collectors for electricity production is a way to contribute to the Portuguese objective of reaching 39% of electricity production from renewable energy sources, until 2010. This is also in accordance with the objectives of the European Union and the Kyoto Protocol. The system in analysis is powered by solar energy and supplemented by a natural gas boiler, specially for periods when solar radiation is low. Use of the system would result in significant savings in primary energy consumption and a reduction in CO2 emissions to the environment. The solar collectors are of the heat pipe type and hybrid: they act as a boiler economizer, as boiler exhaust gases circulate below the absorber plate, increasing the energy input and collector efficiency. The behaviour of a combined heat and power cycle producing 6 kW of electricity was simulated. The heat rejected in the cycle condenser can be used for space/water heating or cooling of buildings. Several refrigerants have been considered for the cycle and methanol presented the best performance. The contribution of solar energy (solar fraction) was evaluated for the climatic data of Lisbon (Portugal), for two applications: a pool complex and an office building. The energy and economic potential of the system was compared to the conventional alternative.
Solar Thermal Organic Rankine Cycle For Micro-Generation
The conceptual design of an Organic Rankine Cycle (ORC) driven by solar thermal energy is developed for the decentralized production of electricity of up to 50 kW. Conventional Rankine Cycle uses water as the working fluid whereas ORC uses organic compound as the working fluid and it is particularly suitable for low temperature applications. The ORC and the solar collector will be sized according to the solar flux distribution in the Republic of Yemen for the required power output of 50 kW. This will be a micro power generation system that consists of two cycles, the solar thermal cycle that harness solar energy and the power cycle, which is the ORC that generates electricity. As for the solar thermal cycle, heat transfer fluid (HTF) circulates the cycle while absorbing thermal energy from the sun through a parabolic trough collector and then storing it in a thermal storage to increase system efficiency and maintains system operation during low radiation. The heat is then transferred to the organic fluid in the ORC via a heat exchanger. The organic fluids to be used and analyzed in the ORC are hydrocarbons R600a and R290.
E3S Web of Conferences, 2021
Suitability to off-design operation, applicability to combined thermal and electrical generation in a wide range of low temperatures and pressures and compliance with safety and environmental limitations qualify small-scale Organic Rankine Cycle plants as a viable option for combined heat and power generation in the residential sector. As the plants scale down, the electric and thermal output maximization has to account for issues, spanning from high pump power absorption, compared to the electric output of the plant, to intrinsically low plant permeability induced by the expander, to the intermittent availability of thermal power, affected by the heat demand for domestic hot water (DHW) production. The present paper accounts for a flat-plate solar thermal collector array, bottomed by an ORC unit featuring a sliding vane expander and pump and flat-plate heat exchangers. A high-temperature buffer vessel stores artificially heated water – electric heaters, simulating the solar collect...
SECOND INTERNATIONAL CONFERENCE ON MATERIAL SCIENCE, SMART STRUCTURES AND APPLICATIONS: ICMSS-2019, 2019
The aim of this work is to present a dynamic model of an innovative small-scale trigeneration system implemented by means of TRNSYS. The modelled system is composed of a solar field, a low-temperature micro-Organic Rankine Cycle plant (ORC) and an adsorption chiller (AC). In particular, the main innovation of the model is the utilization of a micro-ORC machine and adsorption chiller implemented on TRNSYS by user-defined types that use experimental performance data obtained by a full characterization of ORC and AC prototypes, implemented at University of Bologna and at CNR-ITAE respectively. The considered micro-ORC system is driven by a reciprocating piston expander prototype, made of three radial cylinders with total displacement of 230 cm 3. The other components are two brazed plate heat exchangers as evaporator and recuperator, a prototypal gear pump and a shell-and-tube condenser. The adopted working fluid is HFC-134a, suitable for heat source temperature up to 100 °C and characterized by a global warming potential (GWP) equal to 1430. The adsorption chiller prototype is characterized by an innovative architecture, employing 3 adsorbers connected to a single evaporator and condenser and by the use of hybrid adsorbers, realized embedding microporous Silica Gel loose grains into aluminium flat tube heat exchangers, previously coated with the Mitsubishi AQSOA FAM Z02 sorbent. The cooling machine has a nominal capacity of 4.4 kWc. Both the AC and ORC prototypes can be driven by low grade thermal energy (<90°C) from waste heat, industrial processes or renewable energy sources. The model realized is easily adaptable to any other plant by redefining the different subsystems of the desired technology and, in conclusion, this study has highlighted the promising characteristics of ORC and AC technologies in tri-generative configuration, with a 63% of global efficiency.
Experimental investigation of an ORC system for a micro-solar power plant
2014
Because of the depletion of fossil fuels and global warming issues, the world energy sector is undergoing various changes towards increased sustainability. Among the different technologies being developed, solar energy, and more specifically CSP (Concentrated Solar Power) systems are expected to play a key role to supply centralized loads and off-grid areas in the medium-term. Major performance improvements can be achieved by implementing advanced control strategies accounting for the transient and random nature of the solar heat source. In this context, a lab-scale solar power plant has been designed and is under construction for experimental purposes and dynamic analysis. The test rig includes an Organic Rankine Cycle (ORC) unit, a field of parabolic trough collectors and a thermal energy storage system. This paper presents the results of an experimental campaign conducted on the ORC module alone. This power unit, designed for a 2.8 kW net electrical output, consists of two scroll expanders in series, an air-cooled condenser, a recuperator, a volumetric pump and an oil-heated evaporator. The ORC engine is constructed using standard mass manufactured components from the HVAC industry, this practice reducing considerably the system cost. The overall unit performance and components effectiveness are presented in different operating conditions and relevant empirical correlations are derived to be implemented in a steady state model of the ORC unit.