• Journal of Power System Engineering
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• v.9 no.4
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• pp.18-23
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• 2005

The experimental investigation was carried out to evaluate the performance of air-to-air heat exchanger with rotating porous plates newly developed in this study. The rotating porous plates are mounted with an equal interval of 18 mm inside the heat exchanger where the hot and cold airs enter at opposite ends. When flowing in opposite directions by the separating plate installed in the center of the rotating porous plates, the airs give and receive the heat each other. The material of the porous plate is cooper and its thickness is 1.0 mm. Air flow rate is varied from 10 to 120 m3/h. From the experiment of air-to-air heat exchanger with the rotating porous plates, the heat exchange performance increased with the increase in RPM of the porous rotating discs at the conditions of the same air flow rate. The sensible heat exchange efficiency was maximum 60 to 70 percent, and enthalpy exchange efficiency 50 to 60 percent.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1101-1106
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• 2006

The water fluidized bed heat exchanger was installed to recover heat from paper mill hood exhaust air containing lot of moisture and also fouling contaminants. The hood exhaust air flow rate was about $110,000m^3/hr$ at $70^{\circ}C$. The commercial scale field test apparatus has been operated for 3 months. As a result of operation, total heat recovered was 2,380,000 kcal/hr and proportion of the latent heat to total heat was 74%. The annual energy saving was estimated as 450 million won.

• Journal of the Korean Solar Energy Society
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• v.26 no.1
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• pp.21-28
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• 2006

Changes in building construction methods and repairing of older buildings have reduced infiltration rate. Synthetic materials, release airborne particles and uneven healthy odor are increased. For preventing pollutants introduce fresh outdoor air into the building, simply letting fresh outdoor air into building, however, Is not a cost-effective way to ventilation. When additional ventilation is added to an existing HVAC system, the heating and cooling equipment, often cannot handle the increased load. A HRV provides a way to minimize in energy costs while introducing fresh air to a building. In this study, the economical research of HRV, made of three types of materials, are conducted. Heat recovering characteristics are studied at seasonal outdoor air conditions based on the outdoor air property condition at, Seoul in 2002. As a results, the average sensible effectiveness is 0.75 in the sensible heat exchanger and average total effectiveness is 0.65 in the total heat exchanger. The pay back period of the sensible heat exchangers are $3.2{\sim}3.5$ year and it of total heat exchanger is 2.2 years.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.651-656
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• 2006

A performance analysis model has been developed for fin-tube type heat exchanger for $CO_2$ heat pump. The model uses the tube-by-tube method Because air-side thermal resistance has a great portion among total thermal resistances, it is important to understand air-side heat transfer characteristics. The air-side heat transfer correlation has been proposed from experiments using water. The developed model was confirmed by experimental results and can be used for the performance analysis of heat exchanger.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.4
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• pp.1-7
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• 2014

This paper is performed to investigate of cooling effect and total enthalpy variation on EAHES(Earth-to-Air Heat Exchanger System) that is buried 3m depth and 60m length. Using EAHES, the reduction of the sensible heat is obviously but latent heat is showed increased trend. Although the outdoor average latent heat accounts for 53.2% of total enthalpy, latent heat of the exit air from EAHES was raised as 58%. For improving cooling effect of EAHES, it has to considered that how to remove the latent heat from EAHES.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.281-287
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• 2005

This study investigates the pressure drop and heat transfer characteristics of heat exchanger according to the combination of fin configuration and fin pitch of each row by the similitude experiments with the finned-tube geometry scaled as large as four times Finned-tube heat exchanger has 2 rows, and fin geometry consists of two cases, louver-louver and louver-slit. Fin pitch is varied with three types in each case, 6-6 mm, 8-8 mm and 8-6 mm. Results show that total heat transfer can be occurred evenly at each row by varying the fin pitch of 1st row and 2nd row. Heat transfer rate and pressure drop characteristics change according to the combination for fin geometry and fin pitch.

• Journal of Institute of Control, Robotics and Systems
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• v.1 no.2
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• pp.119-126
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• 1995

The purpose of this study is to develop the technique of energy recovery and energy saving by using the optimization of heat exchanger network synthesis. This article proposes a new method of determining the optimal target of a heat exchanger network synthesis problem of which data feature multiple pinch points. The system separation method we suggest here is to subdivide the original system into independent subsystems with one pinch point. The optimal cost target was evaluated and the original pinch rules at each subsystem were employed. The software developed in this study was applied to the Alko prosess, which is an alcohol production process, for the synthesis of heat exchanger network. It was possible to save about 15% of the total annual cost.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.769-775
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• 2008

The objective of this report is to determine the difference of thermal response that grouted two different materials, and compare the simulation result of the length of total ground heat exchanger length that using the ground thermal conductivity. And also to know heat exchange variation of ground heat exchanger temperature that measured with various test depth. The result shows that the test hole grouted with water permeable material got better thermal response than grouted with water impermeable material. However, with consideration of ingnore for the initial 12 hour data, the test hole grouted with impermeable material has larger thermal conductivity than the other. By former thermal conductivity, simulated data by engineering program shows only 3.4% difference or less. This result shows that ground thermal conductivity is not the main variables for the design program of ground heat exchanger. At the cooling or heating mode, base on the depth of -150m, the ground heat exchanger has best temperature at $-90{\sim}-60m$ and than getting worse because of entering water heat exchanged with leaving water in the same hole.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.299-306
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• 1996

This work presents an analytical model, so called modified LMTD method, to predict the thermal performance of finned-tube heat exchanger under frosting conditions. In this model, the total heat transfer coefficient and effective thermal conductivity of the frost layer were defined as a function of frost surface temperature. The surface temperature of the frost layer formed on the heat exchanger was calculated through the analysis of the heat and mass transfer process in the air and frost layer. To examine the validity of this analytical model, the computed results from the present model, such as heat transfer rate, frost mass and thickness of frost, were compared with the ones of the expermental work and LMED method.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.4
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• pp.17-26
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• 2001

Simulation was conducted using TRNSYS to evaluate the thermal performance of a facility. This facility has a condensing-type heat exchanger which is able to recover the latent energy for the purpose of reducing the heating energy in winter. The boiler and chiller are selected based on the annual peak loads and controlled to maintain the facility at the set temperature of 14~$17^\circ{C}$. Supplied energy by the boiler and recovered energy by the heat exchanger were calculated as a function of number of pass through heat exchanger, kind of fuel and hot water velocity. Simulation results show that about 20% of the total heating load can be recovered by the heat exchanger and the amount of latent heat is increasing with the number of pass. This means that the efficiency of the waste energy recovery system can be increased by using a condensing-type heat exchanger rather than a traditional sensible heat exchanger.