• Resources Recycling
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• v.24 no.2
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• pp.3-12
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• 2015

We researched characteristics of heat recovery rate and fouling according to structures and materials in heat exchangers like water preheater and air preheater. Economizer and air preheater have used in thermal electric power plant. we made small incinerator and heat exchangers to carry out simulated experiment. We observed fouling formation and change of heat recovery rate, combusting powdered coal for 24 hr. In economizer, fin tube type had the largest amount of fouling formation, followed by tube line type > pipe type > auto washing type according to structures. As heat recovery rate, fin tube showed highest recovery rate, followed by auto washing type > pipe type > tube line type. In air preheater, fin tube type had the largest amount of fouling formation, followed by fin plate type > pipe type > pipe type coated by teflon > pipe type coated by ceramic according to structures. And then, heat recovery rate showed the same oder.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.11a
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• pp.97-100
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• 2000

유동층 열교환기 (Fluidized Bed Heat Exchanger; FBHE) 는 온도 균일성이라는 유동층의 특징을 이용하여 적당한 전열면적을 갖는 열교환관을 층 내 설치하여 일정한 양의 열을 전열시키는 것으로, 최근 순환유동층 연소로의 scale-up 을 통한 열용량 증대와 함께 고온의 재순환물질로부터 열을 회수, 연소로의 온도제어 및 열회수율의 극대화를 얻고자 재순환부에 연결하여 사용하고 있다. 또한, 가압순환유동층의 개발과 더불어 유효열전달 면적의 증대를 통한 상대적인 연소로 소형화를 위해 채택되고 있다. 특히, 유동층 열교환기는 전체 공정에서 20-60% 의 열을 회수할 수 있어, 열전달에 있어 매우 중요한 역할을 차지한다.(중략)

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1780-1787
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• 1992

Experiments have been performed on the thermal behavior in a liquid saturated porous medium in a system to simulate a single well aquifer thermal energy storage system. The principal interests in this study are the combined effects of forced and natural convection. Significant buoyancy flow due to natural convection is developed quickly as the temperature difference between the injection and original aquifer temperature increases. Theoretical model under simplified assumptions (called simple buoyancy flow model in this study) has been developed. The results of this model agree well with the experiments. The effects of buoyancy flow on the recovery factor are also examined in this study.

• Journal of Energy Engineering
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• v.21 no.4
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• pp.393-397
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• 2012

In this study, an organic Rankine cycle(ORC) for gas engine waste heat recovery for industry has been constructed and a performance analysis test has been carried out. Shell & tube style heat exchanger has been equipped on an engine exhaust manifold in order to absorb heat of engine exhaust gas into the working fluid(refrigerant R134a). Under 60 kW of engine power output, about 63 kW of engine exhaust gas heat was discharged and the proportion of heat recovered was 68~73% while 43~46 kW of heat was absorbed into working fluid. Consequently rated power output of ORC was 4.6 kW while the ratio of rated power output to engine exhaust gas heat was 7.3%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.465-469
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• 2010

Air heater used in power plant helps increase the thermal efficiency of the boiler by recovering the heat from the boiler flue gas and thus preventing the loss of useful heat. This study investigates the effect of preventive maintenance on the performance of the air heater in a power plant. Performance indexes for the air heater are calculated to observe the changes in the performance and operation status of the air heater before and after preventive maintenance. The major performance indexes considered are temperature efficiency of the flue gas side, air leakage rate, heat recovery rate, heat transmission rate, and heat capacity ratio. The performance of the air heater is evaluated before and after preventive maintenance; our results show that all the abovementioned performance indexes are improved after the maintenance.

• Resources Recycling
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• v.5 no.3
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• pp.24-30
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• 1996

The computcr s~mulatiun model in vanaus s~nelllng process for melling waste cashhg sand was developed by using energy and malcrial balance concept. This modcl can prcdict the coal, flux and oxygen conaumptron and thc volume and temperature of off-gas The ~niljor critical varlablcs for smclting process can be crplained by using the analysis of energy and malc~ialb alance. Thc Innst lmportarlt variables lor smelting process were h i ~ hpo st-combust~anr atla, high heat transfer crficiency and refractory pratcclion lechnalogy. For saving encrg), in this smelting proccss, selection of caw marerials i.e coal, flus was important, cspacially ubi~go f low volatile coal was prufitahle.

• Journal of Energy Engineering
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• v.28 no.2
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• pp.47-54
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• 2019

As absorption type heat pump for waste heat recovery is installed in combined cycle power plant for Energy Service Company, performance test is implemented to confirm the operation data on partial load. The operation data changes according to the heat pump operation on partial load are as follows. Total heat output increases, because waste heat of closed cooling water and a portion of LP steam from HRSG is supplied. But electric power output of steam turbine is reduced, because LP steam to steam turbine is reduced. And heat output from HP district heater and LP district heater is reduced, because HP turbine exhaust steam to HP district heater and LP district heater is reduced. On partial load operation, turbine output reduction is higher than the base load operation. Therefore, on partial load, heat pump should be operated in consideration of the heat output increase and electric power output reduction.

• Journal of Energy Engineering
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• v.5 no.2
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• pp.115-122
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• 1996

Heat transfer characteristics of low temperature latent heat storage systems have been examined for the circular finned and unfinned tubes using Na$_2$B$_4$O$\_$7/10H$_2$O as a phase change material. In order to reduce the supercooling of PCM, 3 wt% of Na$_2$B$_4$O$\_$7/10H$_2$O was added as the nucleating agent and 2.2 wt% of acrylic acid sodium sulfate was used as the thickener. The heat storage vessel has dimension of 530 mm height, 74 mm 1.D. and inner heat transfer tube is 480 mm height and 13.5 mm O.D. Water was employed as the heat transfer fluid. During the heat recovery experiment, the heat recovery rate was affected by the flow rates and inlet temperature of heat transfer fluid. The enhancement of heat transfer by fins over the unfinned tube system was found to be negligible in the thin finned tube systems, whereas the heat transfer coefficient in the thick finned tube system is approximately 60% higher than that in the unfinned lobe system. The experimentally determined heat transfer coefficient for the unfinned tube and thick finned tube systems are 150-260 W/㎡$^{\circ}C$ and 230-530 W/㎡$^{\circ}C$, respectively. The fin efficiency based on the heat transfer coefficient and area increased by fins was found to be 0.05 and 0.26 for the thin and the thick finned tube systems.