• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.4
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• pp.46-54
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• 2019

In this study, the performance of a shell and tube heat exchanger (STHE) and welded plate heat exchanger (WPHE) was measured experimentally. The pass numbers of the STHE was changed by 1, 2 and 4. As a result, the WPHE showed 2.1 times higher heat exchange capacity than that of the STHE. In case of pressure drop, the STHE with 1 and 2 pass number has a lower pressure drop than the WPHE, while the STHE with 4 pass presented higher pressure drop than the WPHE. The performance index considering the heat exchange capacity and pump consumption power, showed in oder of STHE_Pass1 > STHE_Pass2 > W PHE > STHE_Pass4 under the same flow rate. Therefore, when the WPHE was designed optimally under same operating condition with STHE, the maintenance fee and space can be reduced effectively by using the WPHE.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.3
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• pp.13-20
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• 2021

The capacity optimization of the heat exchanger of the TEM dehumidifier was performed through numerical analysis. If the ratio of the size of heat exchangers on the cold and hot surfaces of the TEM is not appropriate, the larger the size of the heat exchanger results the lower performance and efficiency. Optimizing the ratio of heat exchangers on the cold surface of TEM can improve the performance and the efficiency compared to when the ratio is 50%. The optimal proportion of cold surface heat exchangers is inversely proportional to the sum of the size of the heat exchangers on the cold and hot surfaces. When the optimum ratio of cold surface heat exchanger was applied, the larger the sum of size of the two heat exchangers results the greater the improvement of the performance and efficiency, compared to when the ratio of cold surface heat exchangers is 50%.

• 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.16 no.4
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• pp.340-348
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• 2004

The air and refrigerant side heat transfer performances are key parameters to improve heat transfer efficiency of the heat exchanger including the fan performance. Design of the fins, treatment of the tube inside, tube diameter and tube array effect heat transfer performance of the heat exchanger. The heat exchanger is used as a condenser at cooling mode and used as an evaporator at heating mode in the heat pump system. The heat pump system uses R410A as the refrigerant. The heat exchangers are consisted with 7 mm diameter tubes with slit-type fins. The study was conducted with variation of arrangement of the refrigerant path and air flow rate and refrigerant pressure drop and heat transfer rate were measured with a code tester. The capacity of the 3 path heat exchanger is more efficient than 2 or 4 path heat exchangers in heating or cooling modes.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.124-132
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• 2007

The main objective of this work is to investigate the characteristics of a heat pump system for fuel cell electric vehicle (FCEV). The present heat pump system adopts an electrically driven compressor running with R134a and uses the heat from the fuel cell stack as the heat source for the exterior heat exchanger. The experimental work has been done with various operating conditions such as different compressor speeds, fuel cell stack coolant temperatures and flow rates. The heating capacity was measured to be from 4 to 10 kW at $-20^{\circ}C$ ambient temperature, and the outlet temperature of interior heat exchanger was up to $70^{\circ}C$. After 30 seconds from start-up, the system reached a steady state and the heating capacity of 6.8 kW was acquired, and after 90 seconds, the air outlet temperature of interior heat exchanger became $35^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.10 no.1
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• pp.19-26
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• 1999

The effectiveness of a double-tube heat exchanger has been investigated experimentally. This problem is of particular interest in the design of the heat exchanger in a hydrogen liquefaction system. Temperature, pressure, and mass flow rate for hydrogen were measured both in inner tube and in annulus of a double-tube heat exchanger. The effectiveness could be evaluated from the measured temperature and mass flow rate. It is found that the effectiveness increases with an increase in the heat transfer area of a double-tube heat exchanger and with a decrease of the heat capacity ratio. But the increase rate of the effectiveness decreased with a decrease of the heat capacity ratio. Therefore, it is presented that a criterion for selecting the heat exchanger length and heat capacity ratio to obtain the effectiveness required in a hydrogen liquefaction system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.7
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• pp.293-298
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• 2016

A three-dimensional (3D) numerical model of the vertical ground-coupled heat exchanger is useful for analyzing the modern ground source heat pump system. Furthermore, a detailed description of the inner side of the exchanger allows to account for the effects of the thermal capacity. Thus, both methods are included in the proposed numerical model. For the ground portion, a FDM (Finite Difference Method) scheme has been applied using the Cartesian coordinate system. Cylindrical grids are applied for the borehole portion, and the U-tube configuration is adjusted at the grid, keeping the area and distance unchanged. Two sub-models are numerically coupled at each time-step using an iterative method for convergence. The model is validated by a reference 3D model under a continuous heat injection case. The results from a periodic heat injection input show that the proposed thermal capacity model reacts more slowly to the changes, resulting in lower borehole wall temperatures, when compared with a thermal resistance model. This implies that thermal capacity effects may be important factors for system controls.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.525-530
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• 2008

In the present study, the cooling performances of the air-conditioner applied the fin-tube and aluminum PF heat exchangers have been experimentally investigated by using the calorimeter. The experiment is carried out in the conditions of the standard temperature and the low temperature. Fin type of PF heat exchanger is a triangler and squarer form. PF heat exchanger has smaller refrigerant weight and larger capacity and COP han the fin-tube heat exchanger. The performance of PF-2 heat exchanger with the squarer in is more excellent than that of PF-1 heat exchanger with the triangler fin. The high pressure of PF heat exchanger decreases about 7%, compared to the fin-tube heat exchanger. Also, CSPF of the fin-tube and PF heat exchanger is evaluated.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.73-81
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• 2008

Intercooling and aftercooling are required in order to operate air compressor, these are conducted through air-cooled or water-cooled heat exchangers. This study aims to find more suitable type of heat exchanger as a water-cooled intercooler of air compressor. Comparative performance evaluation among fin-tube heat exchanger and shell-and-tube (S&T) heat exchanger having various tubes such as circular tube, spiral tube, and internally finned tube was conducted. Thermal-hydraulic performance of each heat exchanger type is evaluated in terms of temperature drop and pressure drop. The comparisons show that shell-and-tube heat exchangers may have similar and larger heat transfer capacity to the fin-tube heat exchanger if tube diameter is reduced and multiple pass is adopted. For these cases, however, compressed air pressure drop in shell-and-tube heat exchanger become much larger than that in fin-tube heat exchanger.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.67-75
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• 2009

Recently, the higher capacity waste heat recovery PDC clean ventilation system has a tendency which is increasing due to the excellent energy reduction in factory, big building, and so on. This system was developed to complement the room environment which is deteriorated. However, the researches and technologies about this system were not well studied. Specially, the characteristic for heat exchanger element used to this system were not well known. Therefore, this study was carried out to evaluate the mechanical properties of the heat exchanger element as the core parts compose of this system. From results, tensile strength and elongation of the plate type heat exchanger element had about 10.11~14.32 kgf/$mm^2$ and 8.0~16.2%, respectively.