• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.1
• /
• pp.105-111
• /
• 2020

The organic Rankine cycle (ORC) and the Kalina cycle system (KCS) are being considered as the most feasible and promising ways to recover the low-grade finite heat sources. This paper presents a comparative exergetical performance analysis for ORC and Kalina cycle using ammonia-water mixture as the working fluid for the recovery of low-grade heat. Effects of the system parameters such as working fluid selection, turbine inlet pressure, and mass fraction of ammonia on the exergetical performance are parametrically investigated. KCS gives lower lower exergy destruction ratio at evaporator and higher second-law efficiency than ORC. The maximum exergy efficiency of ORC is higher than KCS.

• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.6
• /
• pp.637-645
• /
• 2020

In this paper, entransy analysis is carried out for combined heat and power (CHP) generation system driven by low-grade heat source compared with energy and exergy analyses. The system consists of a regenerative organic rankine cycle (ORC) and an additional process heater in a series circuit. Special attention is paid to the effects of the turbine inlet pressure, source temperature, and the working fluid on the thermodynamic performance of the system. Results showed that the work efficiency of entransy is higher than that of energy but lower than that of exergy, wheress the process heat efficiency of entransy is lower than that of energy but higher than that of exergy. Entrance analysis showed the potential to complement the exergy analysis in the optimal design of the energy system.

• Transactions of the Korean hydrogen and new energy society
• /
• v.32 no.1
• /
• pp.77-85
• /
• 2021

In this paper, entransy analysis is carried out for combined heat and power (CHP) generation system driven by low-grade heat source compared with energy and exergy analyses. The system consists of an organic Rankine cycle (ORC) and an additional process heater in a parallel circuit. Special attention is paid to the effects of the source temperature, turbine inlet pressure, and the working fluid on the thermodynamic performance of the system. Results showed that the work efficiency of entransy is higher than that of energy but lower than that of exergy, wheress the process heat efficiency of entransy is lower than that of energy but higher than that of exergy. Entrancy analysis showed the potential to complement the exergy analysis in the optimal design of the energy system.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.5
• /
• pp.490-496
• /
• 2018

Recently, the power and refrigeration cogeneration based on Kalina cycle has attracted much attention for more efficient utilization of low-grade energy. This study presents a thermodynamic performance analysis of a cogeneration cycle of power and absorption refrigeration based on Kalina cycle. The cycle combines Kalina cycle (KCS-11) and absorption cycles by adding a condenser and an evaporator between turbine and absorber. The effects of ammonia mass fraction and separation pressure were investigated on the system performance of the system. Results showed that the energy utilization of the system could be greatly improved compared to the basic Kalina cycle.

• Clean Technology
• /
• v.20 no.3
• /
• pp.321-329
• /
• 2014

In this study, Indonesia low rank coal, which has moisture content of around 26%, is dried less than 5% by using a laboratory-scale (batch type) steam fluidized-bed dryer in order to produce the low-moisture, high rank coal. Normally, CCS (carbon capture and storage) process discharges $CO_2$ and steam mixture gas around $100-150^{\circ}C$ of temperature after regeneration reactor. The final purpose of this research is to dry low rank coal by using the outlet gas of CCS process. At this stage, steam is used as heat source for drying through the heat exchanger and $CO_2$ is used as fluidizing gas to the dryer. The experimental variables were the steam flow rate ranging from 0.3 to 1.1 kg/hr, steam temperature ranging from 100 to $130^{\circ}C$, and bed height ranging from 9 to 25 cm. The characteristics of the coal, before and after drying, were analyzed by a proximate analysis, the heating value analysis and particle size analysis. In summary, the drying rate of low rank coal was increased as steam flow rate and steam temperature increased and increased as bed height decreased.

• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.4
• /
• pp.363-371
• /
• 2020

Recently, the technologies to utilize the cold energy of liquefied natural gas (LNG) have attracted significant attention. In this paper, thermodynamic performance analysis of combined cycles consisting of ammonia Rankine cycle (AWR) and organic Rankine cycle (ORC) with LNG Rankine cycle to recover low-grade heat source and the cold energy of LNG. The mathematical models are developed and the effects of the important system parameters such as turbine inlet pressure, ammonia mass fraction, working fluid on the system performance are systematically investigated. The results show that the thermal efficiency of AWR-LNG cycle is higher but the total power production of ORC-LNG cycle is higher.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.5
• /
• pp.483-489
• /
• 2018

Recently proposed organic flash cycle (OFC) was shown to potentially improve power generation using low grade heat source. In this paper, a thermodynamic performance is carried out for a modified OFC employed double expansions. Effects of the selection of working fluid and the important system parameters such as the temperatures in flash evaporators on the system performance were extensively investigated. Results showed that the system performances are strongly influenced with the system parameters and selection of the working fluid, and the power generation can be increased compared to the basic OFC.

• Transactions of the Korean hydrogen and new energy society
• /
• v.27 no.5
• /
• pp.597-603
• /
• 2016

In this paper a comparative thermodynamics analysis is carried out for organic Rankine cycle (ORC) and ammonia-water Rankine cycle (AWRC) utilizing low-grade heat sources. Effects of the working fluid, ammonia concentration, and turbine inlet pressure are systematically investigated on the system performance such as mass flow rate, pressure ratio, turbine-exit volume flow, and net power production as well as the thermal efficiency. Results show that ORC with a proper working fluid shows higher thermal efficiency than AWRC, however, AWRC shows lower mass flow rate of working fluid and lower pressure ratio of expander than ORC.

• Transactions of the Korean hydrogen and new energy society
• /
• v.32 no.6
• /
• pp.649-655
• /
• 2021

The recently proposed Kalina based power and cooling cogeneration cycles (KPCCCs) have shown improvement in the energy utilization of the system compared to the basic Kalina cycle. This paper suggests a combined tri-cogeneration system for power, heating and cooling based on the Kalina cycle. And thermodynamic performances of the suggested system based on the first and second thermodynamic laws are parametrically investigated with respect to the ammonia mass fraction and the boiler pressure. Results showed that the thermodynamic performance of the system could be greatly improved compared to the former KPCCCs.

• Journal of the Korean Institute of Gas
• /
• v.18 no.2
• /
• pp.41-47
• /
• 2014

In this work a thermodynamic performance analysis is carried out for a combined cycle consisted of an organic Rankine cycle (ORC) and a LNG cycle. The combined system uses a low grade waste heat in the form of sensible energy and the LNG cold energy is used for power generation as well as for heat sink. The effects of the key parameters of th system such as turbine inlet pressure, condensation temperature and source temperature on the characteristics of system are throughly investigated. The simulation results show that the thermodynamic performance of the combined system can be significantly improved compared to the normal ORC which is not using the LNG cold energy.