• Journal of Biosystems Engineering
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• v.8 no.2
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• pp.49-61
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• 1983

U shape multitube heat exchanger was equipped in the flue to recover the exhaust heat from the boiler system. The fluids of the exhaust heat recovery equipment were the flue gas as the hot fluid, and the water as the cold fluid. The flow geometry of the fluids was cross flow - two pass, the hot fluid being mixed and the cold fluid unmixed. The results of the theoretical and the experimental analysis and the economic evaluation are summarized as follows. 1) The heat exchanger effectiveness and the temperature efficiency of the hot fluid were about 35% when the fuel consumption rate was 140 - 150 L/15min. The temperature efficiency for the cold fluid ranged from 3.0% to 4.5%. The insulation efficiency ranged from 85% to 98%, which was better than the KS air preheater insulation efficiency of 90%. 2) The relationship between the fuel consumption rate, F, and the outlet temperature, $T_{h2}$, of the flue gas from the heat exchanger was $T_{h2}$ = 0.927F + 110. In order to prevent the low temperature corrosion from the coagulation of $SO_3$, it is necessary to maintain the fuel consumption rate above 82 L/15min. 3) The ratio of the exhaust heat from the boiler system to the total energy consumption was about 14.5%. With the installation of the exhaust heat recovery equipment, the energy recovery ratio to the exhaust heat was about 25%. Accordingly, about 3.6% of the total fuel consumption was estimated to be saved. 4) Economic analysis indicated that the installation of the exhaust heat recovery equipment was feasible to save the energy, because the capital reocvery period was only 10 months when the fuel consumption rate was 80 L/15min. 4 months when it was 160 L/15min. 5) Based on the theoretical and the experimental analysis, it was estimated to save the energy of about 18 million Won per year, if four heat exchangers are installed in a factory. 6) A further study is recommended to identify the relationship among the flow rate of the exhaust gas, the size of the heat exchanger and the capacity of the air preheater. For a maximum heat recovery from the exhaust gas an automatic control system is required to control the flow rate of the cold fluid depending on the boiler load.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.2
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• pp.102-110
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• 1993

An isothermal analysis was conducted to develop the design tool of an aquifer thermal energy storage system. Taejeon aquifer was chosen for the analysis, and the variation of FRE(Fluid Recovery Efficiency) with respect to the aquifer natural velocity and thermal load were investigated. The analysis results were compared with those of ATESSS(Aquifer Thermal Energy Storage System Simulator) and agreed within 2% of discrepancy. It is recommended, based on the result of this study, that the system may be suitable for a large volume of hot or chill thermal energy storage system, such as for district heating or cooling.

• 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％.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.21-29
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• 2012

A dual 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 (HT loop) only recovers the heat of the exhaust gas. A low temperature loop (LT loop) recovers the residual heat from the HT loop, the coolant heat and the remaining exhaust gas heat. The two separate loops are coupled with a heat exchanger. This paper has dealt with a layout of the dual loop system, the review of the working fluids, and the design of the cycle. The design point and the target heat recovery of the HT boiler, a core part of a HT loop, have been presented. The prototype of the HT boiler was evaluated by experiment. For the performance evaluation of the HT boiler, inlet temperature of the HT boiler working fluid was set equal to the temperature degree of sub-cool of $5^{\circ}C$ at the condensing pressure. The exit condition was the degree of super-heat set at $5^{\circ}C$. The characteristics of the HT boiler such as heat recovery and pressure drops of fluids were evaluated with varying flow rates and inlet temperatures of exhaust gas under various evaporating pressure conditions.

• The KSFM Journal of Fluid Machinery
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• v.12 no.2
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• pp.46-51
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• 2009

Recently, microturbines have received attention as a small-scale distributed power generator. Since the exhaust gas carries all of the heat release, generating hot water is usual method of heat recovery from microturbine CHP (combined heat and power) systems. The power of microturbines decreases as ambient temperature increases. This study predicted micoturbine power boost by injecting hot water generated by heat recovery. Influence of injecting water at two different locations was examined. Water injection improves power, but efficiency depends much on the injection location. Injecting water at the compressor discharge shows a much higher efficiency than the combustor injection. However, the combustor injection may have as much available cogeneration heat as the dry operation, while the available heat in the compressor discharge injection is much smaller than the dry operation.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.27-35
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• 2017

The amount and quality of waste heat from a resource recovery facility were measured. The temperature of exhaust gas was $176.6^{\circ}C$ and the amount of that was 13.8 kg/s. This research designed a waste heat recovery system whose working fluid is R-245fa. It simulated three study cases as follows. In simulation of a basic ORC system, the turbine power output and thermal efficiency were respectively 96.56 kW, 14.3%. In simulation of a superheater connection, 0.09% of efficiency could be improved due to the increase of enthalpy by overheating of working fluid, but the obtained output was decreased with 16.58kW because of the decrease of working fluid mass. In simulation of a process heater connection, efficiency was increased up to 38.51%.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.76-81
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• 2012

In recent, there are tremendous efforts to apply co-generation concept in automobile to improve its thermal efficiency. The co-generation is basically a simple Rankine Cycle that uses the waste heat from the engine exhaust and coolant for heat source. In spite of developed nano technology and advance material science, the bulky co-generation system is still a big concern in automotive application. Therefore, the system should be effectively designed not to add much weight on the vehicle, but the capacity of the waste heat recovery should be still large. With such a goal in mind, the system thermal efficiency was investigated in terms of the system operation condition and working fluid. This paper provides a direction for the optimal design of the automotive co-generation system.

• Korean Journal of Computational Design and Engineering
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• v.17 no.1
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• pp.54-61
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• 2012

In this paper, we performed numerical analysis to improve the heat exchange efficiency of wasted heat recovery ventilator which has a delivery and a exhaustion fan. One of the most important design factors that affect the efficiency of heat exchange is uniform counter-flow between inbound and outbound air flows. We had simulated several types of porous plates which were installed at air intake area. With plate having 45 degrees of installation angle and 15 mm diameter holes which are uniformly arranged, we can generate a uniform air flows at the area of porous media where inbound and outbound air flows are cross over. In addition, we installed a duct to reduce vortex flows at the outlet and to discharge exhaust airs rapidly. By using the proposed numerical assessment, we expect the improvement of the heat exchange efficiency of ventilator.

• Particle and aerosol research
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• v.19 no.3
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• pp.77-87
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• 2023

We present the development of a wetcyclone sampler designed for the sampling of airborne bacteria. The wetcyclone design involves a combination of two traditional cyclone shapes and computational fluid dynamics (CFD) analysis to validate its effectiveness in terms of pressure drop and collection efficiency. The wetcyclone exhibits a collection efficiency of over 90% for bacteria, specifically targeting Staphylococcus aureus. Additionally, the wetcyclone enables continuous bioaerosol sampling using a liquid medium (deionized water), demonstrating a concentration ratio exceeding >105 and a stable microbial recovery rate of 81.9%. The application of real-time quantitative polymerase chain reaction (qPCR) and the colony counting method ensures precise measurement of the concentration ratio and microbial recovery rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.58-66
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• 2011

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(HT loop) is a system to recover the waste heat from the exhaust gas, a low temperature loop(LT loop) is for heat recovery from the engine coolant cold relatively. This paper has dealt with a layout of a LT loop system, the review of the working fluids, and the design of the cycle. The design point and the target heat recovery of the LT boiler, a core part of a LT loop, has been presented and analytically investigated. Considering the characteristics of the cycle, the basic concept of the LT boiler has been determined as a shell-and tube type counterflow heat exchanger, the performance characteristics for various design parameters were investigated.