• New & Renewable Energy
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• v.20 no.3
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• pp.12-19
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• 2024

This study uses exergy analysis to evaluate the fuel-saving potential of a waste heat recovery unit (WHRU) integrated with an Organic Rankine Cycle (ORC) system for marine applications. Data from the training ship HANBADA of the Korea Maritime University and the general cargo ship BBC CAMPANA, including their operational routes and main engine loads, were used in this study. Simulations indicated that the WHRU system could save approximately 27.5 metric tons of fuel per voyage, equivalent to approximately 2.1% of the total fuel consumption. The WHRU system demonstrated a higher efficiency during long-distance voyages, significantly enhancing fuel savings. In addition, higher engine loads increased the exhaust gas thermal energy, thereby substantially improving the WHRU output. This study emphasizes the importance of evaluating the applicability of the ORC system for marine vessels by closely examining their operational patterns, navigation duration, and main engine load variability.

• Journal of Energy Engineering
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• v.5 no.1
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• pp.34-41
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• 1996

The heat of evaporation (cold energy) of LNG is the energy consumed in the production of LNG. This energy amounts to 14% of the NG. In Pyungtak LNG terminal, it is about 96 MW in 1993. In order to utilize the cold energy, the cold power generation systems are investigated: The Rankine cycle using the low temperature energy, the partial expansion cycle using the pressure energy, and the Linde process which is a combined cycle of the Rankine and the partial direct expansion cycle. The commercial simulator, ASPEN Plus, is used. The conceptual design data are obtained from the current facilities of the Pyungtak LNG terminal. The performances of three systems are evaluated. The amount of electric power ranges iron 3 MW to 6MW. The optimum energy efficiency is about 37%. The optimum design conditions are obtained for the partial direct expansion (PDE) cycle. The performance of the PDE cycle is supposed to be comparable to that of the Rankine cycle if the areas of the total heat exchanger of the both cycle are equal.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.5 no.1
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• pp.7-11
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• 2009

The purpose of this study is to investigate the performance of a water heat source cascade heat pump system R717(Ammonia) is used for a low-stage working fluid while R134a is for a high-stage. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. In this study, two experiments were carried out. One is a system starting test from the low load temperature of $10^{\circ}C$. The other is a system performance investigation over the R717 compressor capacity changes. Experimental results show that when it starts from the low load temperature, the suction temperature of the low-stage compressor is higher than that of a high-stage. The system performance increases when a water source temperature or a low-stage compressor rotational frequency goes higher.

• Journal of the Korean Solar Energy Society
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• v.37 no.2
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• pp.13-22
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• 2017

Two-step water splitting thermochemical cycle with $CeO_2/ZrO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2/ZrO_2$ foam device depending on heat recovery of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2/ZrO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. Resultantly, the quantity of hydrogen generation increased by 52.02% when the carrier gas of Thermal-Reduction step is preheated to $200^{\circ}C$ and, when the $N_2/steam$ is preheated to $200^{\circ}C$ in the Water-Decomposition step, the quantity of hydrogen generation increased by 35.85%. Therefore, it is important to retrieve the heat from the highly heated gases discharged from each of the reaction spaces in order to increase the reaction temperature of each of the stages and thereby increasing the quantity of hydrogen generated through this.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1497-1502
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• 2009

The present study has been conducted economic analysis of heat storage type ground source heat pump system(HSGSHP) and normal ground source heat pump (GSHP) and central boiler system with individual air conditioning facility which are installed at the same building in the shared an apartment house. Cost items, such as initial construction cost, annual energy cost and maintenance cost of each system are considered to analyze life cycle cost (LCC) and simple payback period (SPP) with initial cost different are compared. The initial cost is a rule to the Government basic unit cost of production. LCC applied present value method is used to assess economical profit of both of them. Variables used to LCC analysis are prices escalation rate and interest rate mean values of during latest 10 years. The LCC result shows that HSGSHP (1,351,000,000won) is more profitable than central boiler system with individual air conditioning facility by 86.7% initial cost. And SPP appeared 8.0 year overcome the different initial cost by different annual energy cost.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.507-514
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• 2002

A computation routine, capable of performing thermal design analysis of the triple-pressure bottoming system (heat recovery steam generator and steam turbine) of combined cycle power plants, is developed. It is based on thermal analysis of the heat recovery steam generator and estimation of its size and steam turbine power. It can be applied to various parametric analyses including optimized design calculation. This paper presents analysis results for the effects on the design performance of heat exchanger arrangements at intermediate and high temperature parts as well as steam pressures. Also examined is the effect of steam sources for deaeration on design performance.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.27-35
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• 1998

An experimental study was performed to investigate the optimum cycle of an inverter heat pump as a function of frequency. The performance of the inverter heat pump with the rated cooling capacity of 4,141 W(3,550kcal/h) was measured with a variation of frequency, indoor and outdoor temperature, and length of capillary tube in the psychrometric test room. As a base case, the inverter heat pump with the standard capillary length of l,000mm(optimum size for the frequency of 60Hz) and ASHRAE Test condition "A" was tested by varying frequency from 30Hz to 80Hz. Then, the optimum cycles were investigated by varying the length of capillary tube at each frequency level of 30, 60 and 80Hz. Based on the experimental data, the change of system characteristics between the optimum and the base case were analyzed for each selected frequency level. Generally, for low frequency level(30Hz), the longer length of the capillary tube compared with the standard size showed the higher energy efficiency ratio(EER), while for high frequency level(80Hz) the shorter length of the capillary tube showed the higher EER.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.48-60
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• 1999

An experimental study on the performance enhancement of a screw-compressor-type chiller with 100kW of nominal cooling capacity has been carried out. Performance test facility was developed to investigate the effects of a partial modification from the existing chiller on the performance. By replacing the existing shell-and -tube heat exchangers with plate heat exchangers, the cooling capacity is increased by 15~18% and the COP is also increased by 19~21% depending on the operation temperature range. Charging mixed refrigerant R22/R142b(80 : 20) instead of R22 into the chiller with plate heat exchangers improves the cooling capacity by 4% and the COP very largely by 30%. Each contribution of the plate evaporator, plate condenser, and mixed refrigerant to the performance enhancement is examined by analyzing the refrigeration cycle and the heat transfer processes. It is also shown that the chiller performance can be improved by adapting 2-stage-compression cycle using an economizer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.8
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• pp.545-552
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• 2017

In this research, numerical analysis was carried out on novel and existing fins, adjusted in terms of factors such as length, spacing, and angle, of a high-temperature heat exchanger for a 1 kW class Stirling engine, designed as a prime mover for a domestic cogeneration system. The performance improvement as a result of shape optimization was confirmed with numerical analysis by including the air preheater, which was not considered during optimization. However, a negative heat flux was observed in the cylinder head portion. This phenomenon was clarified by analyzing the exhaust gas and wall surface temperature of the combustion chamber. Furthermore, assuming an ideal cycle, the effects of heat transfer enhancement on the thermodynamic cycle and system performance were predicted.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.4
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• pp.444-451
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• 2009

The price increase of natural resources and the worldwide growth of LNG demand led to save the waste of Boil-Off Gas evaporating from cargo tanks of LNG carriers during navigation. As one of the efforts, a BOG reliquefaction system with BOG-to-BOG heat exchanging method was newly devised. This study was also discussed on the process details such as some features and advantages including comparisons with conventional BOG reliquefaction system, non BOG-BOG heat exchange type. The thermodynamic analysis for the system were also performed. Through the cycle simulation, the process efficiency of the BOG reliquefaction system BOG-BOG heat exchange was estimated to be increased up to 21%.