• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.669-683
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• 1999

Heat dissipation in the domestic switching room has been gradually increased. Therefore, numerical study on the cooling characteristics of the telecommunication system in a switching room for three kinds of the air supply and return flow system was investigated to develop effective flow system. As a result, the cooling performance of the under floor air supply and overhead return flow system was the best.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.4
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• pp.252-261
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• 2001

Room air flow and temperature distribution was numerically investigated where a PAC(personal air conditioning) system was installed. The calculated results were compared with those from experiments. The effects of the important operation parameters such as the air flow rate, velocity, and temperature at the diffuser on the thermal performance of the system were studied. The possibility of energy saving using the PAC system was verified from the results, It was shown that the warm air from the diffuser could not spread over the whole task area if the inlet temperature was too high.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.3 no.3
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• pp.185-190
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• 1974

Floor panel heating system is popular in Korea as dwelling house heating system. There are two methods for keeping floor surface warm. One method is delivering warm air under the floor such as Roman Hypocaust and Korean traditional Ondol. The other method is imbedding hot water pipes into the concrete floor slab. This paper gives basic equations for steady and transient solutions of heat conduction from hurried pipes. For steady-state solution, fin Efficiency Method and Sink and Source Method were introduced. Sink and Source Method is applied to transient state and basic solution is given in the form of Exponential Integral Function. Numerical solutions can be solved easily by digital computer from these equations.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.472-483
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• 1997

An experimental facility consisting of two $3{\times}4.4{\times}3.8m$ rooms identical in construction is built. Each room has a control system and storage tank supplying hot water to the radiant floor heating system. The facility enables simultaneous comparision of two different control stratigies each implemented in a separate room. The operating performance of three kinds of flow control scheme is tested and compared in this study : (i) conventional on-off control based on feedback from room air temperature (ii) TPSC(two parameter switching control) (iii) TPOC(two parameter on-off control). Results show that TPSC and TPOC using room air and surface temperature sequentially as feedback signal to control hot water supply is the better temperature regulation scheme than conventional control based on feedback from only room air temperature. They are good candidates for the room with radiant floor heating system under continuous and intermittent heating mode.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.421-429
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• 2004

In Korea, the radiant heating system has been widely used as a residential heating method, which has been modernized to use hot water running into the tubes embedded in the floor structure. According to the recent improvement of living standard of residential buildings, the requirement of the thermal comfort and energy saving in heating system has been raised. Until now, the radiant floor heating system has been controlled by room thermostat installed in the living room, but for better thermal comfort, an individual room control method is adopted as an alternative. Therefore, it is necessary to evaluate the control performance between the current control method and the individual room control method. In this study, the control performance between the two systems is evaluated through the field experiment. And the control performances of room air temperature and energy performances are analyzed through the simulation using TRNSYS. Firstly, the simulations are performed in the various outdoor conditions and the flow rates and the simulation results are analyzed for the control performances. Also, to evaluate the energy performance, the simulations are performed under the operating conditions in which the set-point of the room air temperature is fixed or changed according to the schedule of occupancy, and the simulation results are analyzed between the two methods.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.866-871
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• 2006

Recently according to the fashion of well-being, the case study of under floor heating system type for residential space is increasing. Specially double slab floor system can make several roles as reducing the acoustic noises and also supplying fresh air through the gap. So in present study floor heating performance was examined with various location of the space in the case of floor supply air and ceiling supply air. In both cases return air went out through ceiling opening. As one of the result is that when using the heat pipe type floor heating system the temperature difference between supply and return water was $15.2^{\circ}C$, but in case of commercial type floor heating system the temperature difference was $5.3^{\circ}C$ when the supply water temperature was $50^{\circ}C$.

• International Journal of Air-Conditioning and Refrigeration
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• v.7
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• pp.91-100
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• 1999

This paper investigates ventilation characteristics of an environmental chamber simulating an under-floor air conditioning system for isothermal and cooling supply air conditions. The tracer gas sulfur-hexafluoride (SF$F_6$) was injected into a supply duct using step-up and step-down methods. Local mean and room mean ages were calculated from the concentrations measured at internal points and at the exhaust duct. The air change efficiency of the chamber has been found to be greater in cooling conditions than in isothermal conditions. Also the room air change efficiency is not significantly affected but slightly improved by the presence of a supply diffuser.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.105-112
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• 2007

Recently developed raised floor heating system is not only capable of basic function to reduce noise between floors, but also is a multi-functional floor heating system enabling natural ventilation. The procedure of this system for natural ventilation is to import outdoor air through bottom space of the floor heating system, circulate indoor space and discharge it out of ceiling. In winter, powerless natural ventilation is possible with buoyancy effect caused by temperature difference between outdoor and indoor. And it also allows saving of energy by importing pre-heated air in bottom space of the floor heating system. To evaluate ventilation performance of this system, on-site measurement was conducted in 2 test laboratories, and the nominal air change rate was satisfied as 0.4$\sim$0.8 h-1 under the condition of outdoor temperature $5^{\circ}C{\sim}-5^{\circ}C$, which was evaluated as highly possible to be applied as a natural ventilation system in multi-family houses.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.211-216
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• 2005

The authors carried out experiment, Computer Fluid Dynamics(CFD) and energy simulation of simulator. As a results of experiment and CFD, diffuser velocity is very important design factor for occupied zone air conditioning in Under Floor Air Distribution(UFAD) system. Then, in contrast to energy consumption of the Overhead system, the UFAD system could reduce 6.4% of the total energy because of occupied tone air conditioning. It concluded that tile UFAD system is more effective in energy Performance than the Overhead system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.9
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• pp.472-481
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• 2017

Radiant floor heating systems have been used as common heating supply systems in most residential buildings in Korea. Since the system uses a floor as thermal storage, proper control strategy should be adopted to avoid over-or under-heating problems. So far, studies related to control of the floor heating system have been conducted based on computer simulations. The active layer in TRNSYS is known for its usability as a floor heating system model and is integrated with the TRNSYS building model (Type 56). However, floor heating system simulations with the active layer are operated only if pre-defined minimum mass flow rate is ensured. This study proposes a simple RC (Resistance-Capacitance) model for radiant floor heating systems. Model parameters such as Rs and Cs are defined by optimization. The active layer, in this study, is used as the target system to search for optimal values. A TRNOPT optimization tool was used to conduct optimization under given simulation conditions. The RC model with optimal parameters are tested in other mass flow rates that were not used during optimization. Results reveal the RC model describes the active layer with successfully optimized model parameters. The RC model has fewer model limitations, and is expected to be used for various target systems, e.g. experimental data of a real radiant heating system.