• Proceedings of the KSR Conference
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• 2003.10c
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• pp.358-362
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• 2003

Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of HVAC(Heating, Ventilating and Air-Conditioning} for double-deck train. The HVAC system is installed under the roof of carbody. In the lay-out of HVAC system, air duct must be installed to supply air to 1st and 2nd floor respectively. The standard k-epsilon turbulent models and SIMPLEC algorithm based on finite volume method are used to solve the physical HVAC model. To assure convergence, QUICK scheme for momentum equation and the first order upwind scheme for turbulent equations are used. From the results of simulation, the temperature and velocity magnitude are also distributed uniformly in the interior of passenger car.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.685-689
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• 2004

Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of HVAC(Heating, Ventilating and Air-Conditioning) for double' deck train. The HVAC system is installed under the roof of carbody. In the lay-out of HVAC system, air duct must be installed to supply air to 1st and 2nd floor respectively. The standard k-$\epsilon$ and LES models for turbulence and SIMPLE algorithm for pressure equation hased on finite volume method are used to solve the physic a] HVAC model. To assure convergence, QUICK scheme for momentum equation and the 2nd order upwind scheme for turbulent equations arc used. From the results of simulation, the temperature and velocity magnitude are also distributed uniformly in the interior of double-deck passenger car.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.379-387
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• 1998

HVAC systems are used to maintain comfort conditions in occupied spaces. Like rolling noise and aerodynamic noise, noise from the HVAC system of train increases interior noise level. For an appropriate interior noise level, it is necessary not to find noise sources and their propagation paths. Noise emission from the sources and propagation through the propagation paths should be regulated in order to reduce their effect to the interior noise level. In general, the main noise source in the HVAC system is blower which operates at high static pressure. This noise propagates through ducts which are directly connected to the residential area. Since the blower noise can be reduced only to some degree, it is necessary for the propagation paths to have enough noise attenuation. Acoustic properties of ducts are usually found by experimental methods but it is rather difficult and expensive to set up such test equipments. In this thesis, the design and the noise characteristics of TGV-K HVAC system are studied. Finite element method in accordance with experimental method is used to study the acoustic properties of TGV-K duct system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.2
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• pp.116-125
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• 2003

The new HVAC system to lower the conveyance energy and building height using IAV (Increasing Air Volume) technique is developed. IAV units which are equipped in each zone carry out air-conditioning and supply fresh air by induction of outdoor air in main duct. The design program which decides size of OAHU and IAV unit according to air conditioning load and fresh air demand of each zone is presented. The control system is developed to operate efficiently HVAC system and IAV unit, so that individual zone operation and well-deal with partial load and IAQ problem are possible. The new system is investigated in model building and makes more profit in conveyance energy, size of air conditioning facilities room and building height than VAV system. But in construction cost it is worse by about 15 per-centage.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.1
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• pp.31-43
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• 2005

The new HVAC system is developed to lower the conveyance energy and building height using IAV(Increasing Air Volume) technique. IAV units which are equipped in each zone carry out air-conditioning and supply fresh air by induction of outdoor air in main duct. The design program which decides size of OAHU and IAV unit according to air conditioning load and fresh air demand of each zone is presented. The control system is developed to operate efficiently HVAC system and IAV unit, so that individual zone operation and well-deal with partial load and IAQ problem are possible. The new system is investigated in model building and makes more profit in conveyance energy. size of air conditioning facilities room and building height than VAV system. But in construction cost it is worse by about 15 percentage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.999-1004
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• 2004

In this study, we identify contribution of structure-borne-noise of vehicle HVAC system using Multi-Dimensional spectral analysis (MDSA) method. Firstly, to identify the applicability of MDSA method, the case of HVAC system was modeled with four input / single output system. The four inputs which is given vibration data is composed of blower, evaporator, heater and duct. The single output is noise data from driver's seat. When the blower motor is operating, we analyze the contributions of four input / single output. As a result of experiment, we identify efficiency of systems modeled with four input / single output through ordinary coherence function (OCF) and multiple coherence function (MCF).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.4
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• pp.389-397
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• 1998

A loop duct system is often found in a VAV-HVAC(variable air volume heating, ventilating and air conditioning) design. It is known that the simple T-method is not be applicable to the loop duct system and cannot be used to calculate the flow rate and the pressure drop at each duct section of the loop duct system. In this paper, the extended T-method has been developed and it is found to be applicable to the loop duct system to which the simple T-method cannot be applied. The validity of the extended T-method has been verified by using to solve for a simple, ideal loop duct system for which there exists analytical solution. In addition, the extended T-method is employed to compute the loop duct system of a real building with an area of 380$m^2$. The results show that the computed flow rate at the exit differs from the designed flow rate by a range of -13.6~43.5 %. Consequently, three design factors must be adjusted in order that the flow rate may be balanced. These include the duct sizes, in terms of their lengths and diameters, the sub-duct locations and the positioning of damper which is found upstream of the exit duct.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.88-96
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• 2008

Effects of the duct inlet guide vane on the flowrate distribution characteristics of the defroster nozzle exit in a defrost duct system were investigated experimentally to design the optimum heating, ventilation and air conditioning (HVAC) system applied in an automotive compartment. A 3-dimensional hot-wire anemometer system was used to measure the velocity field in the vicinity of the defroster nozzle jet flow and the velocity distributions near the windshield interior surface. At first, two cases of with- and without-duct inlet guide vanes were considered as the test condition, and then three cases of the duct inlet guide vane were tested to determine the optimum guide vane shape and their positions. The arrangement of the duct inlet guide vanes has an effect on the improved flowrate distribution at the defroster nozzle exit and near the windshield interior surface. However, the application of the lots of guide vane to control the flow direction leads to increase the flow resistance, resulting in the decreased flowrate issuing from the defroster nozzle. The shape of the duct inlet guide vane affects not only the flowrate distribution between the driver side and the assistant driver side but also the reduction of the flow resistance in the defrost duct system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.2
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• pp.161-168
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• 2011

The heating, ventilating, air conditioning (HVAC) system is a very important part of an automotive vehicle: it controls the microclimate inside the passenger's compartment and removes the frost or mist that is produced in cold/rainy weather. In this study, the numerical analysis of the defrost duct in an HVAC system and the de-icing pattern is carried out using commercial CFX-code. The mass flow distribution and flow structure at the outlet of the defrost duct satisfied the duct design specification. For analyzing the de-icing pattern, additional grid generation of solid domain of ice and glass is pre-defined for conductive heat transfer. The flow structure near the windshield, streakline, and temperature fields clearly indicate that the de-icing capacity of the given defrost duct configuration is excellent and that it can be operated in a stable manner. In this paper, the unsteady changes in temperature, water volume fraction, and static enthalpy at four monitoring points are discussed.

• The Journal of the Acoustical Society of Korea
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• v.29 no.8
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• pp.497-503
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• 2010

In this paper, evaluation of noise reduction performance of HVAC system for ships by means of HVAC mock-up system is presented. Test is done for six different types of HVAC elements including room unit, silencer, etc. It is found that when diameter of silencer is small and air flow is large, flow noise degrades insertion loss. However, as diameter of silencer becomes larger, the effect of flow noise becomes smaller, and insertion loss up to 25 dB is measured. It is observed that insertion loss of diffuser type room unit is usually between zero and 10 dB, whereas that of the nozzle type room unit can be down to - 15 dB. In addition, it is shown that changing duct arrangement can reduce cabin noise by up to 2 dB, and providing same air flow to each room unit is crucial for generating less noise.