• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.375-378
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• 2011

This study is intended to realize an intelligent controller using fuzzy control algorithms in order to recycle energy by recycling the waste water heat discharged by waste water heat collection boilers. Using waste water inflow temperature changes and waste water inflow amount changes as parameters, we present characteristic curves of the number of compressors being operated at fixed speeds and the temperature of hot water being discharged. We propose an intelligent controller that determines the optimum number of compressors being operated at fixed speeds in real time by measuring changes in the temperature and amount of waste water inflows in order to minimize the number of compressors being operated at fixed speeds relative to the waste water load flowing into the waste water heat collection boiler.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.15 no.4
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• pp.362-371
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• 1986

In the normal Refrigeration process, the condensation heat of refrigerant s not been used because of its low-temperature waste heat. To recover the condensation waste heat of R-12 refrigerator, a drying and hot water system was designed and experimented. The results obtained were summarized as follows: 1. As the temperature a temosphere was increased, the temperature of discharge gas of compressor was increased. And the temperature was $80-84^{\circ}C$ for air condensing type and was $68-71^{\circ}C$ for water condensing type during summer. 2. The condensation waste heat could be obtained up to $50-55^{\circ}C$ of drying heat-source and Hot water in summer. In this case, recovered rate was about $73\%$. And the more temperature of drying Heat-source and Hot water were increased, the more a recovered rate were decreased. 3. When comparing drying characteristics of Agro-products in dryer of waste heat utilization and Hot air, there was no quality difference in products. But drying time of the former was 3 Hours longer than the latter. 4. The condensation waste heat of compressor could be applied into the drying of marine products, the predrying of agro-products and making hot water. And showed high possibility of the waste heat using in low-temperature storage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.2
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• pp.57-62
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• 2017

The heat transfer performance of a multi-heat-source fluidized bed heat exchanger was analyzed. The fluidized bed heat exchanger examined in this study can simultaneously recover the waste heat from gas, water vapor, and hot water. The effects of waste water flow rate, gas flow rate, and cooling water flow rate were examined to find their experimental correlations with the heat transfer coefficient. A computer program using the correlations was developed in this study to predict the thermal performance of the fluidized bed heat exchanger. The calculated heat transfer rates of gas, water vapor, waste water, and cooling water were compared with the measured values. It was found that the error of the calculated values was less than 12%.

• 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.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.201-204
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• 2015

Recently, energy excessive consumption and environmental pollution are the social issued. The most efficient way to solve both energy excessive consumption and environmental pollution is existing combustion system improved. This study was part of the assume and commercial used existing waste heat recovery condensing boiler to low emission performance for exhaust gas recirculation(EGR) and thermal efficiency rise by applying the condensed water recirculation(CWR) conducted. The researchers applied the EGR and CWR develop a new concept for the condensed water recirculation waste heat recovery condensing boiler. Waste heat recovery condensing boiler applied to the condensed water recirculation thermal efficiency of the same conditions was increased by about 4.8~5.5% and pollution emission also decreased.

• Journal of Environmental Science International
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• v.12 no.6
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• pp.583-591
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• 2003

The research on potential energy was conducted to conserve the high-exergy energy like primary energy and utilize waste heat from sewage. From the Point of view in using the waste heat, the energy Potential of waste water from the model house was simulated. From the results, when the heated water was supplied to the model house side in order to put unused energy to Practice use, heated water had higher energy Potential than unheated water, which was due to the discharge of most of unused energy. The possessing heat capacity of sewage from heated water was increased to 40-70 percents in comparison with that from the unheated water. Therefore, it can be used as energy source for improving coefficient of performance of heat pumps. By adopting the multiple heat pump into a model house, It showed that the possessing heat capacity of sewage was reduced. It was also found that the heat was recovered as energy source fur multiple heat pump in a model house.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.187-197
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• 1996

A computer program for thermal design analysis has been developed to predict the operating characteristics and performance of an absorption heat pump to recover $30{\sim}40^{\circ}C$ of waste hot water. The effects of heat transfer area of the system components, temperature and mass flow rate of heat transfer medium, and solution circulation rate on the system performance are investigated in detail. The results obtained indicate that the COP is increased with a decrease in the temperature of driving steam and with an increase in the temperature of waste hot water while the COP is little affected by the variation of a hot water temperature. It is also found that the heating output is increased with an increase in the temperature of waste hot water and driving steam as well as with a decrease in the temperature of hot water. The simulation results are also compared with the experimental results for a periodic operation of the system and obtained a satisfactory agreement.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.10
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• pp.811-816
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• 2002

Waste heat exhausted from seven types of the domestic industry was surveyed, which include food, fibre, paper & wood, chemical, ceramics, metalworking and others. The databases of waste heat for each industry were made by using ACCESS software of Microsoft, and data were analyzed to get correlation between waste heat and purchase energy. The volume of usable waste heat is estimated to be 9,169,000 TOE in the year of 2000, when the minimum available temperature is set as $100^{\circ}C$ for waste gas, $30^{\circ}C$ for hot water and $100^{\circ}C$ for steam considering the condition of waste heat exhausting facilities and surroundings. This volume of waste heat is approximately 11.9 percent of the purchase energy of the domestic industry.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1171-1178
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• 1992

An experiment was performed to describe the heat and mass transfer occurring between hot waste gas and cold water through direct contact in a direct contact heat exchanger. This model was then used to obtain an equation of overall heat transfer coefficent based on heat exchanger volume. The diffusion heat transfer rate is 2-3 times larger than the convection heat transfer rate as results of condensation of the water vapor contained in the waste gas. The boiler efficiency increases over 10%.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.2
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• pp.73-81
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• 2003

The performance of heat exchanger using oscillating heat pipe (OHP) for low temperature waste heat recovery was evaluated. OHP used in this study was made from low finned copper tubes connected by many turns to become the closed loop of serpentine structure. The OHP heat exchanger was formed into shell and tube type. R-22 and R-141b were used as the working fluids of OHP with a fill ratio of 40 vol.%. Water was used as the working fluid of shell side. As the experimental parameters, the inlet temperature difference between heating and cooling water and the mass velocity of water were changed. The mass velocity of water was changed from 30 kg/$m^2$s to 92 kg/$m^2$s. The experimental results showed that the heat recovery rate linearly increased as the mass velocity and the inlet temperature difference of water increased. Finally, the performance of OHP heat exchanger was evaluated by $\varepsilon$-NTU method. It was found that the effectiveness would be 80% if NTU were about 1.5.