• Proceedings of the KSME Conference
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• 2002.08a
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• pp.615-618
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• 2002

Turbo-fan for ceiling cassette type air conditioner doesn't operate in general volute. It is operated by porous material, heat exchanger. Heat exchanger increases resistance of air conditioning system and disturbs exit-flow of impeller. Therefore it has some influences on impeller capacity. In this study, we want to how that influence of exchanger on impeller capacity for ceiling cassette type air conditioner. To research, we made circular case that didn't have asymmetric part unlike rectangular case. With and without heat exchanger we measured total pressure and static pressure of impeller and three-dimensional rear flow field From the result, a turbo fan , installed in the 35mm back of fan and operated in heat exchanger, experienced $2{\%}{\~}5{\%}$% total pressure loss over all flow rate. With heat exchanger impeller efficiency decrease as flow rate decrease when flow rate coefficient was below 0.18. Especially when flow rate coefficient was below 0.12, there was $20{\%}{\~}30{\%}$ decrease of impeller efficiency.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.1
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• pp.166-175
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• 1996

In recent years, air-conditioning units designed with higher efficiency and more compactness are required due to emphasis on energy efficiency in home electrical appliances. This trend in the air-conditioning industries has accelerated the development of improved heat exchanger with a better performance in heat transfer aspects. In this study, experiments were performed to investigate the shape and configuration of fins affecting on the performance of the conventional fin-and-tube type heat exchanger equipped in a commercial air conditioners. The geometry similtude method was employed to measure the heat transfer coefficient and pressure drop. Experimental results show that this method is very useful to analyze the heat transfer characteristics of the fin-and-tube type heat exchanger. It is also found that the slit fin has better performance than the conventional fin type in the air conditioners. The present results indicate that heat transfer from the fin si influenced by the parameters such as the forming area of the slit fin, the type of interrupted surfaces like a louver or slit, slit patterns and slit raised direction, and it also affects the overall heat exchanger performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.1018-1027
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• 2003

This study treats the analysis of the performance and the design of plume abatement wet/dry cooling tower with dry type heat exchanger using a numerical method. A two-dimensional analysis is performed using the finite volume method for mechanical draft counterflow and crossflow tower. For a coupling problem between water and air system, a turbulent two phase flow is considered. Effectiveness-NTU method is used for modeling of the dry type heat exchanger. The parameter change simulations of the outer wall shape, the relative flowrate of air, and attachment of an air mixer are performed to examine the effect on plume abatement. It is found that if the relative air flowrate ratio and the adequate air mixer type are chosen well in addition to the ratio of water to air flowrate, the loss of the cooling capacity and the additional cost are reduced and the plume is abated.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.2
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• pp.61-70
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• 2005

This study treats the numerical analysis of performance and design for plume abatement wet/dry cooling tower with a dry type heat exchanger. A two-dimensional analysis is performed using the finite volume method for mechanical draft counterflow and crossflow tower. For a coupling problem between water and air system, a turbulent two phase flow is considered. The Effectiveness-NTU method is used for modeling of the dry type heat exchanger. The parametric simulations such as the relative flowrate of air and attachment length of an air mixer are performed to examine the effect on plume abatement. It is found that if the relative air flowrate ratio and the adequate air mixer type are chosen well in addition to the ratio of water to air flowrate, the loss of cooling capacity and the additional cost are reduced and the plume is abated.

• New & Renewable Energy
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• v.16 no.4
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• pp.41-48
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• 2020

This study performed a single hole operation method using a balancing well-cross-mixed underground heat exchanger, and conducted thermal performance studies of an SCW-type underground heat exchanger using a two-well. The study attempted to change the existing operating method of the two adjacent SCW underground heat exchangers with one ball each. The SCW-type geothermal heat exchanger is considered to enable up to 20% of bleed discharge at maximum load, which makes groundwater usage unequal. The efficiency factor of the geothermal system was improved by constructing the discharged water by cross-mixing two balancing wells to prevent the discharge of groundwater sources and keep the temperature of the underground heat exchanger constant. As a result of the cooling and heating operation with the existing SCW heat exchange system and the balancing well-cross-mixed heat exchange system, the measured performance coefficient improved by 23% and 12% in cooling and heating operations, respectively. In addition, when operating with a balanced cross-mixing heat exchange system, it has been confirmed that the initial basement temperature is constant with a standard deviation of 0.08 to 0.12℃.

• 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.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.163-166
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• 2010

Numerical analysis is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver FLUENT. The fin-tube type of heat exchanger numerical calculation is conducted by changing the shape, number and material of fin shape of working fluid channel, etc in three-dimensional combustion field. Adjusted one-way constant velocity is used as the representative velocity of oscillating flow. The optimum design of heat exchanger considering the heat trasfer capability is suggested by using the calculation results.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.1
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• pp.53-60
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• 2003

Performance evaluation on thermal transport of a plate heat exchanger has been carried out. The $\varepsilon$-Ntu method is employed to evaluate the performance of a brazed type of plate heat exchanger. This problem is of particular interest in the design of a plate heat exchanger. The characteristics of heat transfer as well as pressure drop are studied in the wide range of Reynolds numbers in the cold side while that of hot side is fixed at 620. f-factor correlation in a plate heat exchanger is obtained from the pressure drop data. It is also found that the effectiveness of the plate heat exchanger is increased as the Ntu is increased.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.20 no.1
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• pp.75-83
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• 2024

In this study, high temperature design and integrity evaluation methodology have been developed for Type 316L stainless steel air-to-sodium heat exchanger which uses 700℃ sodium as coolant. Currently the only design rules that take creep effects into consideration explicitly for the 316L stainless steel subjected to high temperature in the creep range are French RCC-MRx, where elevated temperature designs are possible around 550℃. Absent design coefficients at high temperature were determined based on the material properties newly determined in previous studies, and high-temperature design evaluation methodologies were developed based on 3D finite element analyses on the 700℃ class heat exchanger. In addition, works were conducted on the web-based design evaluation program of HITEP_RCC-MRx including incorporation of material properties and design coefficients up to 700℃. Methodologies on high temperature design evaluations on Type 316L stainless steel high-temperature heat exchanger were suggested.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.4
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• pp.351-359
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• 1992

In order to improve the performance of heat exchanger, fluidized bed is often employed. The experiments are carried out in fluidized double pipe parallel flow heat exchanger in which finned tube is vertically immersed. And the heat transfer coefficients between the heated tube and fluidized bed of alumina beads(dp=0.41, 0.54, 0.65, 0.77mm) are calculated as a function of air fluidized velocity and pumping power. The effects of particle size, static bed height and pumping power on the heat transfer coefficients are investigated. And the heat transfer coefficients are compared with that of single phase forced convection heat exchanger. In particular, the heat transfer performance of each type heat exchanger is evaluated in relation to the pumping power.