• New & Renewable Energy
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• v.19 no.4
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• pp.61-71
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• 2023

The necessity of energy utilization using livestock manure has been proposed with the decrease in domestic agricultural land. Livestock manure solid fuel has been investigated as a promising energy resource owing to its convenient storage and use in agricultural and livestock fields. Additional electricity production is possible through the integration of a biomass combustion boiler with the organic Rankine cycle (ORC). In this study, a mathematical system model of the cattle manure solid fuel boiler integrated with the ORC was developed to analyze the components' performance under variable operating conditions. A sensitivity analysis was conducted to confirm the electrical efficiency of the ORC turbine and the applicability of this system. The minimum required waste heat recovery rate was derived considering the system marginal price and levelized cost of electricity of the ORC. The simulation results showed that, in Korea, more than 77.98% of waste heat recovery and utilization in ORC turbines is required to achieve economic feasibility through ORC application.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.1
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• pp.51-60
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• 2012

Optimization procedures of performance analysis for ORC(Organic Rankine Cycle) system are established to the characteristics of low temperature heat sources such as open-type and closed-type. Effective heat recovery and heat extraction related to maximum power of the cycle as well as heat quality and thermal efficiency must be considered in the case of the open-type low temperature heat source. On the other hand, in the case of the closed-type low temperature heat source, only thermal efficiency is important due to constant heat input. In this study, thermal efficiency and exergy efficiency representing a level of close to Carnot cycle are studied, as useful index for the optimization of the ORC system. To validate the results of cycle analysis, those are compared with appropriate experimental data of ORC system as a thermal efficiency point of view.

• The KSFM Journal of Fluid Machinery
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• v.18 no.5
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• pp.33-41
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• 2015

Organic Rankine cycle (ORC) has been used to generate electrical or mechanical power from low-grade thermal energy. Usually, this thermal energy is not supplied continuously at the constant thermal energy level. In order to optimally utilize fluctuating thermal energy, an axial-type turbine was applied to the expander of ORC and two supersonic nozzle were used to control the mass flow rate. Experiment was conducted with various turbine inlet temperatures (TIT) with the partial admission rate of 16.7 %. The tip diameter of rotor was to be 80 mm. In the cycle analysis, the output power of ORC was predicted with considering the load dissipating the output power produced from the ORC as well as the turbine efficiency. The predicted results showed the same trend as the experimental results, and the experimental results showed that the system efficiency of 2 % was obtained at the TIT of $100^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.377-385
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• 2015

This paper presents a thermodynamic performance analysis of regenerative organic Rankine cycle (ORC) using turbine bleeding to utilize low-grade finite thermal energy. Refrigerant R245fa was selected as the working fluid. Special attention is paid to the effects of the turbine bleeding pressure and the turbine bleed fraction on the thermodynamic performance of the system such as net power production and thermal efficiency. Results show that the thermal efficiency has an optimum value with respect to the turbine bleeding pressure and the net power production is lower than the basic ORC while the thermal efficiency is higher.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.2
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• pp.234-241
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• 2020

This paper presents a thermodynamic performance analysis of a combined cycle consisting of regenerative organic Rankine cycle (ORC) and liquefied natural gas (LNG) Rankine cycle to recover low-grade heat source and the cold energy of LNG. The mathematical models are developed and the system performances are analyzed in the aspect of thermodynamics. The effects of the turbine inlet pressure and the working fluid on the system performance such as the mass flow rates, heat transfers at heat exchangers, power productions at turbines, and thermal efficiency are systematically investigated. The results show that the thermodynamic performance of ORC such as net power production and thermal efficiency can be significantly improved by the regenerative ORC and the LNG cold energy.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.41-48
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• 2015

The performance characteristics of a scroll expander is the most important variable for the performance of organic Rankine cycle system. In this paper, the performance characteristics of a scroll expander was identified using 1kW class organic Rankine cycle system with various operating conditions. The ORC system is composed of an evaporator, a scroll expander, a condenser and a working fluid feed pump that uses R245fa as working fluid. The hot water temperature was controlled from $80^{\circ}C$ to $115^{\circ}C$ by the 50kW-class electric water-heater. The maximum isentropic efficiency of the scroll expander was measured about 77%, and the shaft power was measured from 0.5 kW to 1.8 kW according to heat source temperatures.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.64-70
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• 2015

Organic Rankine cycle (ORC) is an useful cycle for power generation system with low temperature heat sources ($80{\sim}400^{\circ}C$). Since the boiling point of operating fluid is low, the system is used to recover the low temperature heat source of waste heat energy. In this study, a ORC with R134a is applied to recover the waste energy of condenser of coal fired power plant. A system model is developed via Thermolib$^{(R)}$ under Simulink/MATLAB environment. The model is composed of a refrigerant heat exchanger for heat recovery from coal fired condenser, a drum, turbine, heat exchanger for ORC heat rejection, storage tank, water recirculation pump and water drip pump. System analysis parameters were heat recovery capacity, type of refrigerants, and types of turbines. The simulation model is used to analyze the heat recovery capacity of ORC power system. As a result, increasing the overall heat transfer coefficient to become the largest of turbine power is the most economical.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.839-845
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• 2021

In this study, it shows the efficiency of each refrigerant through simulation method for ORC (Organic Rankine Cycle) power generation that converts waste heat discarded by ship exhaust into electricity for the purpose of reducing CO₂ emission and increasing ship waste heat recovery. by Simulation was performed with waste heat from the exhaust gas which is relatively high temperature and cooling sea water which is relatively low temperature from ships. As a result of the sea water cooling ORC power generating system, efficiency of the working fluid with R717 is highest as a 2.86 % and the next working fluid is R152a, R134a, R143a and R125a.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.140-145
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• 2014

Exploitation of renewable energies is on the increase to mitigate the reliance on fossil fuels and other natural gases with rocketing prices currently due to the depletion of their reserves not to mention their diverse consequences on the environment. Divergently, there are lots of industries "throwing" heat at higher temperatures as by products into the environment. This waste heat can be recovered through organic Rankine systems and converted to electrical energy with a waste heat recovery organic Rankine cycle system (WHR-ORC). This study uses the annual average condenser effluent from Namhae power plant as heat source and surface seawater as cooling source to analyze a waste heat recovery organic Rankine cycle using the Aspen HYSYS simulation software package. Hydrocarbon mixtures are employed as working fluid and varied in a ratio of 9:1. Results indicate that Pentane/Isobutane (90/10) mixture is the favorable working fluid for optimizing the waste heat recovery organic Rankine cycle at the set simulation conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.4
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• pp.208-215
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• 2013

An experimental study of an ORC (Organic Rankine Cycle) system has been performed for small-scale applications in the range of a few kW for low-grade-recovery heat sources. The ORC system was equipped with a scroll expander. Experimental tests were carried out using this system, and showed good performance and reliability for the small-scale system. The effects of various operating conditions were selected as the main parameters for the performance of ORC system, such as the expander speeds and mass flow rates of R-134a for expander inlet temperatures ranging from $100^{\circ}C$ to $190^{\circ}C$, as well as the thermal power, thermal efficiency, expansion efficiency, and volumetric efficiency.