• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.815-820
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• 2011

A scroll expander was designed for an energy converter from waste heat of IC engine coolant to useful shaft work. The scroll expander is to run in a Rankine cycle which receives heat energy transferred from engine coolant circulation cycle. The working fluid was Ethanol. For axial compliance, a back pressure chamber was provided on the rear side of the orbiting scroll. Lubrication oil was delivered by a positive displacement type oil pump driven by the shaft rotation. Performance analysis on the scroll expander showed that the expander efficiency was 63.4%. It extracts shaft power of 0.6 kW out of engine coolant waste heat of 17.5 kW, resulting in the Rankine cycle efficiency of 3.43%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.5
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• pp.90-95
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• 2019

This study aims to gain the design data through the process design of the organic Rankine cycle, which can produce 250kW of electric power through waste heat recovery. In this study, a simulation was conducted using APSEN HYSYS to make the model for the process design of the 250kW-class waste heat recovery system. For the thermodynamic model, the test was conducted with hot water as the heat source, the water steam as the cooling water for the cooler, and the refrigerant R245FA in the cycle. In the final design, it was expected and found from the simulation that the cycle efficiency was 12.62% and that 250kW of power was produced considering the margin of 80%.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.637-645
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• 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
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• v.32 no.1
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• pp.77-85
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• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.403-410
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• 2020

This paper focuses on the design of a 12-kW small-scale supercritical CO₂ test loop. A theoretical study, stabilization, and optimization of carbon dioxide were carried out with the application of a solar heat source based on solar thermal data in Pohang. The thermodynamic cycle of the test facility is a Rankine cycle (transcritical cycle), which contains liquid, gas, and supercritical CO₂. The system is designed to achieve 6.98% efficiency at a maximum pressure of 12 MPa and a maximum temperature of 70℃. In addition, the optimum turbine inlet temperature and pressure were calculated to increase the cycle efficiency, and the application of an internal heat exchanger (IHX) was simulated. It was found that the maximum efficiency increases to 18.75%. The simulation confirmed that the efficiency of the cycle is 6.7% in May and 6.26% in June.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.2
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• pp.69-73
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• 2016

Recently, automotive engineers have paid much attention to waste heat recovery technology as a possible means to improve the thermal efficiency of an automotive engine. A large displacement gasoline engine is generally a V-type engine. It is not cost effective to install two superheaters at each exhaust manifold for the heat recovery purposes. A single superheater could be installed as close to the exhaust manifold as possible for the higher recovery efficiency; however, only half of exhaust gas can be used for heat recovery. On the contrary, the exhaust temperature is decreased for the case where the superheater is installed at a junction of two exhaust tail pipes. With the fact in mind, the optimum position of a single superheater was investigated using simulation models developed from a commercial software package (i.e. AMESim). It was found that installing the superheater near the exhaust manifold could recover 3.8 kW more from the engine exhaust despite utilizing only half of the exhaust mass flow. Based on this result, the optimum layout of an automotive waste heat recovery system was developed and proposed in this paper.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.81-91
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• 2013

A novel design process of a parallel multi-flow type air-cooled condenser of a dual-loop waste heat recovery system with Rankine steam cycles for improving the fuel efficiency of gasoline automobiles has been investigated focusing on reduction of the pressure drop inside the micro-tubes. The low temperature condenser plays a role to dissipate heat from the system by condensing the low temperature loop working fluid sufficiently. However, the refrigerant has low evaporation temperature enough to recover the waste from engine coolant of about $100^{\circ}C$ but has small saturation enthalpy so that excessive mass flow rate of the LT working fluid, e.g., over 150 g/s, causes enormously large pressure drop of the working fluid to maintain the heat dissipation performance of more than 20 kW. This paper has dealt with the scheme to design the low temperature condenser that has reduced pressure drop while ensuring the required thermal performance. The number of pass, the arrangement of the tubes of each pass, and the positions of the inlet and outlet ports on the header are most critical parameters affecting the flow uniformity through all the tubes of the condenser. For the purpose of the performance predictions and the parametric study for the LT condenser, we have developed a 1-dimensional user-friendly performance prediction program that calculates feasibly the phase change of the working fluid in the tubes. An example is presented through the proposed design process and compared with an experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1101-1105
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• 2014

Ocean Thermal Energy Conversion(OTEC) which uses the temperature difference between warm surface sea-water and cold deep sea-water to produce electric power is the promising technology. OTEC is able to be utilized as the $CO_2$ reducing technology by using the consistent temperature differential, while the system efficiency is very low. Thus, the design and development of a efficient turbine is essential to improve the system efficiency for OTEC. In this study, a 100kW-class radial inflow turbine using R32 was designed for OTEC and this turbine's performance was estimated by analysis of CFD. According as the simulation results, turbine's geometry was corrected. The radial inflow turbine satisfying the requirements is designed by the repeated attempts.

• New & Renewable Energy
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• v.18 no.2
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• pp.73-81
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• 2022

This study was aimed at designing a condenser, as a component of the organic Rankine cycle system for ships. The condenser was manufactured through press molding to achieve a bent shape to enhance the heat transfer performance, considering the shape of the heat transfer plate used in a brazing plate heat exchanger. The heat transfer plate was made of copper-nickel alloy. The required heat transfer rate for the condenser was 110 kW, and the maximum number of layers was set as 25, considering the characteristics of high-temperature brazing. Computational fluid dynamics techniques were used to perform the thermal fluid analysis, based on the ANSYS CFX (v.18.1) commercial program. The heat transfer rate of the condenser was 4.96 kW for one layer (width and length of 0.224 and 0.7 m, respectively) of the heat transfer exchanger. The fin efficiency pertaining to the heat transfer plate was approximately 20%. The heat flow analysis for one layer of the heat exchanger plate indicated that the condenser with 25 layers of heat transfer plates could achieve a heat transfer rate of 110 kW.

• Clean Technology
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• v.23 no.4
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• pp.441-447
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• 2017

The economic analysis for the power plant developed in the conceptual design phase is becoming more important and, research on process optimization for process development that meets the target economic is actively carried out. In the filed of power generation systems, economic assessment methods to predict the levelized cost of electricity (LCOE) has been widely applied for comparing economic effect quantitatively. In this paper, the platform that design criteria of key component required to optimize economic of power cycle can be calculated reversely was established roughly and design criteria of the key equipment (Compressor, turbine, heat exchanger) required to meet the target LCOE (the LCOE of supercritical steam Rankine cycle) was derived when the supercritical $CO_2$ power cycle is applied to the coal-fired power plant.