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

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.6
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• pp.413-420
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• 2011

Thermodynamic cycles using binary mixtures as working fluids offer a high potential for utilization of low-temperature heat sources. This paper presents a thermodynamic performance analysis of Goswami cycle which was recently suggested to produce power and cooling simultaneously and combines the Rankine cycle and absorption refrigeration cycle by using ammoniawater mixture as working fluid. Effects of the system parameters such as concentration of ammonia and turbine inlet pressure on the system are parametrically investigated. Results show that refrigeration capacity or thermal efficiency has an optimum value with respect to ammonia concentration as well as to turbine inlet pressure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.8
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• pp.439-447
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• 2009

Cogeneration system produces power as well as heat recovered from waste heat during power generation process. This system has higher energy efficiency than that of the power plant. In this study the optimal design for the cogeneration system with the increase of the capacity considering life cycle cost(LCC) analysis has been performed in the general facilities such as hotels and hospitals under the assumption of electricity cost of 95 won/kWh, the initial cost of cogeneration system of 1,500,000 won!kW and the value of 0.5${\sim}$1.0 in the ratio of heat to power. The optimal ratio of cogeneration capacity divided by average electricity load of facility was found out more than 0.5 in case of electricity cost with the increase of>30%, and the percentage of $CO_2$ reduction was about 9%. The most important factors in the economic analysis of cogeneration system was found out the electrity cost and the initial cost of cogeneration system. Also the ratio of heat to power at the value of>0.5 was not affected in the economy of cogeneration system, but was very important in the $CO_2$ reduction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.4
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• pp.248-257
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• 2010

An exhausted heat recovery system for a small gas engine cogeneration plant was investigated. The system was designed and built in a 300 kW class cogeneration demonstrative system. The basic performance was tested depending on load variation, and installed to a field site as a bottoming heat and power supply system. The exhaust gas heat exchangers (EGHXs) in shell-and-tube type and shell-and-plate type were tested. The entire efficiency of the cogeneration system was estimated between 85 to 90% under the 100% load condition, of which trend appears higher in summer due to the less thermal loss than in winter. Power generation efficiency and thermal efficiency was measured in a range of 31~33% and 54~57%, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.9
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• pp.657-662
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• 2012

The cogeneration system can operate at efficiencies greater than those achieved when heat and power are produced in separate. The optimal system can be determined by selecting the auxiliary system combined with cogeneration system. In the present study, economic investigation has been conducted with the cogeneration electric heat pump(EHP) system and the cogeneration absorption chiller(AC) system to install in a school dormitory. To analyze life cycle cost(LCC), cost items such as initial investment costs, annual energy costs and maintenance costs of each system have been considered. The initial investment cost is referred to the basis of estimated costs, and annual energy costs such as the electric power and gas consumption are based on the data in a school dormitory. LCC is evaluated with the present worth method. Considering investigated results, the initial investment cost of the cogeneration EHP system is more profitable about 24% than that of the cogeneration AC system. The energy cost of the cogeneration EHP system is more profitable about 8% than the cogeneration AC system. The LCC shows that the cogeneration EHP system is the most effective system in the school dormitory.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.697-703
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• 2003

Cogeneration is the simultaneous generation of heat and electricity in a single unit, and is a highly energy-efficient technology compared to the independent generation of both products. Therefore, cogeneration has been widely introduced in many countries for use in industrial, commercial and residential applications. However, there have been few models with an output of less than 100 kilowatt. In the present study, a spark ignited gas engine with electric generation output of 10 kilowatts was developed for micro cogeneration package. The gas engine shows 26.7% of electric generation efficiency, NOx emission less than 10 ppm at 13% oxygen, 82 dB of Noise level, and about 3 seconds of switching time from idling to nominal power.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.2
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• pp.71-78
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• 2009

Up until recently, the energy and the economic analysis of a cogeneration system have been implemented by a manual calculation that is based on monthly thermal loads of buildings. In this study, a cogeneration system modeling validation with a detail building energy simulation, eQUEST, for a building energy and cost prediction has been implemented. By analyzing the hourly building electricity and thermal loads, it enables users to decide proper cogeneration system capacity and to estimate more accurate building energy consumption. eQUEST also verified the energy analysis when the heat pump system is integrated with the cogeneration system. The mechanical system configuration benefits from the high efficiency heat pump system while avoiding the building electricity demand increase. Economic analysis such as LCC (Life Cycle Cost) method is carried out to verify economical benefits of the system by applying actual utility rates of KEPCO(Korea Electricity Power COmpany) and KOGAS(KOrea GAS company).

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.3
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• pp.141-147
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• 2004

Cogeneration has been widely introduced in many countries for use m industrial, commercial and residential applications. However, there have been few models with an output of less than 100kW. In the present study, a spark ignited gas engine with electric generation output of 10kW was developed for micro cogeneration package. Developed gas engine achieved following performance characteristics such as $26.7\%$ of electric generation efficiency, NOx emission less than 10 ppm at $13\%$ oxygen, 82 dB of noise level, and about 3 seconds of switching time from idling to nominal power.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.158-162
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• 2006

Micro gas turbine (MGT) has received attention recently as a small-scale distributed power source. Due to many advantages such as their small size, low maintenance cost and minimal vibrations during operation, they are expected to become widespread in a wide range of applications. The exhaust heat emitted by the MGT is in the form of an exhaust gas that is about $270^{\circ}C$ which is an extremely clean gas. Korea Gas Corporation (KOGAS) has researched performance characteristics of a cogeneration system combining 28kW class MGT and 13 USRT class absorption hot and chilled water generator in the local condition. The present results of this study can be summarized as follows: (1) in heating mode, the total efficiency of cogen. system is about $65\%$ and heating capacity is 33kW at 25kW MGP power (2) in cooling mode, COP is about 0.6 at 22kW MGT power.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.2
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• pp.242-249
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• 2020

The Kalina cycle (KC) is considered as one of the most efficient systems for recovery of low grade heat. Recently, Kalina based power and cooling cogeneration cycles (KPCCCs) have been suggested and attracted much attention. This paper presents an energy and exergy analysis of a recently suggested KPCCC with flexible loads. The cycle consists of a KC (KCS-11) and an aqua-ammonia absorption refrigeration cycle. By adjusting the splitting ratios, the cycle can be operated with four modes of pure Kalina cycle, pure absorption cooling cycle, Kalina-cooling parallel cycle, and Kalina-cooling series cycle. The effects of system variables and the operating modes on the energetic and exergetic performances of the system are parametrically investigated. Results show that the system has great potential for efficient utilization of low-grade heat source by adjusting loads of power and cooling.