• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.80-84
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• 2011

The cycle performance of closed ocean thermal energy conversion (OTEC) system with 50 kW gross power was evaluated to obtain the basic data for the optimal design of OTEC using waste heat such as solar power, discharged heat from condenser of power plant. The basic thermodynamic model for OTEC is Rankine cycle, and the surface seawater and deep seawater were used for the heat source of evaporator and condenser, respectively. The cycle performance such as efficiency, heat exchanger capacity, etc. was analyzed on the variation of temperature increase by waste heat. The cycle efficiency increased and necessary capacity of evaporator and condenser decreased under 50kW gross power with respect to the temperature increase of working fluid. Also, when the temperature increase is about $13.5^{\circ}C$, the heat which can be used is generated. By generator with 0.9 effectiveness under the simulated condition, the cycle efficiency was improved approximately 3.0% comparing with the basic cycle.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.11a
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• pp.299-304
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• 2003

Heat regenerator occupied by regenerative materials improves thermal efficiency of regenerative combustion system through the recovery of sensible heat of exhaust gases. By using one-dimensional two-phase fluid dynamics model, the unsteady thermal flow of regenerators with spherical particles were numerically analyzed to evaluate performance of ratio of waste heat recovery and temperature efficiency and to suggest optimized conditions of heat regenerator. It is predicted that exhaust gases temperature at regenerator outlet of 3.5$\times$10$^{6}$ kcal/hr heat regenerator is even lower than design condition and ratio of waste heat recovery is 75.8％.

• Clean Technology
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• v.2 no.2
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• pp.100-125
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• 1996

After recycle of spent materials has been optimised, there remains a proportion of waste which must be dealt with in the most environmentally friendly manner available. For materials such as municipal waste, clinical waste, toxic waste and special wastes such as tyres, incineration is often the most appropriate technology. The study of incineration must take a process system approach covering the following aspects: ${\bullet}$ Collection and blending of waste, ${\bullet}$ The two stage combustion process, ${\bullet}$ Quenching, scrubbing and polishing of the flue gases, ${\bullet}$ Dispersion of the flue gases and disposal of any solid or liquid effluent. The design of furnaces for the burning of a bed of material is being hampered by lack of an accurate mathematical model of the process and some semi-empirical correlations have to be used at present. The prediction of the incinerator gas phase flow is in a more advanced stage of development using computational fluid dynamics (CFD) analysis, although further validation data is still required. Unfortunately, it is not possible to scale down many aspects of waste incineration and tests on full scale incinerators are essencial. Thanks to a close relationship between SUWIC and Sheffield Heat&Power Ltd., an extended research programme has been carried out ar the Bernard Road Incinerator plant in Sheffield. This plant consists of two Municipal(35 MW) and two Clinical (5MW) Waste Incinerators which provide district heating for a large part of city. The heat is distributed as hot water to commercial, domestic ( >5000 dwelling) and industrial buildings through 30km of 14" pipes plus a smaller pipe distribution system. To improve the economics, a 6 MW generator is now being added to the system.

• Journal of Environmental Impact Assessment
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• v.4 no.2
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• pp.59-70
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• 1995

The solution-state of a reclaimed waste would be known to the method in using an analysis for seepage. But it is not the best method in the huge landfill reclaimed all kinds of the waste at random. Especially in case of the landfill called the Nan Gi-do located along the Han-river, it is difficult to judge the generative seepage to be flowed in to the Han-river. So to plan the effective stabilization on a landfill, it is very useful survey method using the Landsat TM image. Operating a heat-distribution analysis with the Landsat TM image, in case of a landfill not having definite data, we would assume the reclaimed sections of the waste to judge a solution-speed late comparatively such as a industry waste or a harmful waste through the heat change.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.47-48
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• 2014

This study is to hydration property of low carbon type recycled cement from waste cementitious powder and cement raw materials. Waste cementitious powder possible to low carbon type recycled cement in small part of additive materials. Also, low carbon type recycled cement using waste cementitious powder is suitable for low heat type cement.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.1091-1095
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• 2005

This study is performed to develop a tripple-tube exchanger which can improve the system efficiency. Three different tube diameters are compacted by one body(tripple-tube) to recover waste heat from heat exchanging among the fluids. With this, the tripple-tube shows higher cooling capacity than the double-tube after comparing between those two systems. The results of this study are basic data to design the optimum tripple-tube heat exchanger.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.5
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• pp.368-376
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• 2001

Performance of heat exchanger was evaluated to heat exchanger using oscillating heat pipe for waste heat recovery of low temperature. Oscillating heat pipe used in this study was formed to the closed loop of serpentine shapes using copper tubes. Heat exchanger was formed to shell and tube type and composed of low finned tube. R-22 and R-141b were used to the working fluids of tube side and their charging ratio was 40%. And, water was used to the working fluid of shell side. As the experimental parameters, the inlet temperature difference of heating and cooling part of secondary fluid and the mass velocity of secondary fluid were used. The mass velocity of secondary fluid was changed from 90 kg/$m^2s\; to\;190 kg/m^2$s from the experimental results, heat recovery rate was linearly increased to the increment of the mass velocity of secondary fluid and the inlet temperature difference of secondary fluid. Finally, the performance of heat exchanger was evaluated by using $\varepsilon$-NTU method. It was found that NTU was about 1.5 when effectiveness was decided to 80%.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.957-966
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• 1996

An attempt was made to measure the availability of waste heat, released from the cooling system of a small engine, which can be utilized for grain drying. An engine powered flat-bed rough rice dryer was constructed and the performance of the dryer with available engine-waste heat was analyzed for 10 , 20, 30 and 40 cm rough rice bulk depths with a constant dryer base area of 0.81$m^2$/min. The waste heat was sufficient to increase the drying air temperature 7 to 12$^{\circ}C$ at an air flow rate of 8.8 to 5.7㎥/min, while the average ambient temperature and relative humidity were 24$^{\circ}C$ and 70%. The minimum energy requirement was 3.26 MJ/kg of water removed in drying a 40 cm deep grain bed in 14h. A forty to fifty centimeter deep grained seems to be optimum in order to avoid over-drying in the top layers. On the basis of minimum energy requirement (3.26 MJ/kg ) , an estimation was made that the waste heat harvest from an engine of a power range of 1 to 10.5PS can dry about 0.1 to 1 metric on of rough rice from 23% to 15% m.c. (w.b) in 12 h at an average ambient temperature and relative humidity of $25^{\circ}C$ and 80%, respectively. The engine-waste heated grain dryer can be used in the rural areas of non industrialized countries where electricity is not available.

• New & Renewable Energy
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• v.9 no.4
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• pp.32-39
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• 2013

A 2-loop waste heat recovery system with Rankine steam cycles for the improvement of fuel efficiency of gasoline vehicles has been investigated. A high temperature loop is used to recover waste heat from exhaust gas and a low temperature loop is used to recover waste heat from cold engine coolant. This paper has dealt with a layout of low temperature loop system, the review of the velocity contours through numerical analysis. According to the result of analysis, the designed heat exchanger. And comparing with flow analysis results, LT Boiler is safe to operation.