• Journal of Institute of Control, Robotics and Systems
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• v.13 no.4
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• pp.365-370
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• 2007

This paper studies an automation problem of a heating, a ventilating, and an air conditioning (HVAC) for the development of smart space. The HVAC system is described by the fuzzy system for the stability analysis and the controller design. The linear matrix inequalities (LMIs) conditions are derived for the stabilization problem of the closed-loop system under the analog control. Also, it is required to digitally redesign the pre-designed the analog HVAC control system in order to accomplish the remote control via web. It is shown the this digital redesign problem can be converted to the convex optimization problem with the LMI constraints. An example is provided to show the effectiveness of the proposed method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.375-382
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• 2010

Ondol heating, a kind of radiant floor heating, is a main method used in housing units in Korea. Building energy simulation including ondol and relevant facilities has not been performed due to its complexity. For evaluating energy consumption and indoor temperature variation, a new method should be proposed. At the present work, a dynamic simulation on ondol heating was tried by combining TRNSYS and EES. Characteristic functions for a pump, hot water coils and a gas boiler were simultaneously solved by EES, and calculated flow rates and supply temperature of hot water were provided as inputs of the active layer of TYPE 56 in TRNSYS. The results by the simulation on a typical housing unit in Korea shows a good trend in a viewpoint of actual behavior of ondol heating.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.3
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• pp.130-142
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• 2018

We use heat pumps with thermal storage system to reduce peak usage of electric power during winters and summers. A heat pump stores thermal energy in a thermal storage tank during the night, to meet load requirements during the day. This system stabilizes the supply and demand of electric power; moreover by utilizing the inexpensive midnight electric power, thus making it cost effective. In this study, we propose a system wherein the thermal storage tank and heat pump are modeled using the TRNSYS, whereas the control simulations are performed by (i) conventional control methods (i.e., thermal storage priority method and heat pump priority method); (ii) region control method, which operates at the optimal part load ratio of the heat pump; (iii) load response control method, which minimizes operating cost responding to load; and (iv) dynamic programming method, which runs the system by following the minimum cost path. We observed that the electricity cost using the region control method, load response control approach, and dynamic programing method was lower compared to using conventional control techniques. According to the annual simulation results, the electricity cost utilizing the load response control method is 43% and 4.4% lower than those obtained by the conventional techniques. We can note that the result related to the power cost was similar to that obtained by the dynamic programming method based on the load prediction. We can, therefore, conclude that the load response control method turned out to be more advantageous when compared to the conventional techniques regarding power consumption and electricity costs.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2825-2827
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• 2000

In electric power industry. load balance has been one of the most fundamental and important management goals. Therefore. the strategy to achieve high quality load management now includes load balance besides the stabilization of electricity supply and quality management of electricity. Amongst many techniques of load management. direct load management has been actively studied and utilized to increase power facility and peak load suppression. Higher peak load situation is appeared during summer than during winter in Korea. and approximately 20% of the peak load is due to the load for air-conditioning. To cope with this peak load problem during summer KEPCO is performing a research project to develop a system to remotely control air-conditioning load using wireless communication. Currently, applicable facilities are limited to small-scale air-conditioning facility that has less than 2KW power capacity. This paper described the 1st year of efforts made in the study.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.103-111
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• 2006

To optimize the ventilation and smoke control systems in subway equipped with platform screen door, the technology to analyze the unsteady tunnel flow caused by running of train should be developed. The development of model experiment and numerical analysis technique with relation to unsteady flow of subway were presented. The pressure and air velocity changes in 1/20-scaling experiment unit were measured and results were comparied to those of 3-D unsteady numerical analysis applied with sharp interface method. The experimental and numerical results were quantitatively similar and it would be reasonable to apply sharp interface method to analyze the unsteady flow in subway equipped with platform screen door.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.1-13
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• 1998

The basic heat transfer process that occurs in a building can best be illustrated by an electrical circuit network. Present paper reports the dynamic simulation of annual energy consumption in an office building by the thermal resistance capacitance network method. Unsteady thermal behaviors and annual energy consumption in an office building were examined in detail by solving the simultaneous circuit equations of thermal network. The results are used to evaluate the accuracy of the modified BIN method for the energy consumption analysis of a large building. Present thermal resistance-capacitance method predicts annual energy consumption of an office building with the same accuracy as that of response factor method. However, the modified BIN method gives 15% lower annual heating load and 25% lower cooling load than those from the present method. Equipment annual energy consumptions for fan, boiler and chiller in the HVAC system are also calculated for various control systems as CAV, VAV, FCU+VAV and FCU+CAV. FCU+CAV system appears to consume minimum annual energy among them.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.343-350
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• 2012

The major goal of building energy management is to minimize the energy consumption while maintaining the comfortable environment condition. Nowadays building energy management to save HVAC energy and so on is the most critical issue for existing building service branch with high efficiency equipments and their optimal operation. The effects on the building energy savings of the building equipment retrofit and the improvement of its operation method, especially in the field of HVAC system, were analyzed in this study for domestic small and/or medium sized buildings. Over 8.8% of energy saving was achieved compared withe total energy consumption in commercial building. These results could be used for reasonable maintenance and efficient management of the various building service equipments and related systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.836-842
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• 2011

It has been shown that the air-conditioning system with slab cooling storage is effective in cutting peak load and utilizing nighttime electric power. The stochastic properties of internal heat generation which has great influence on the cooling load are examined in this paper. Based on the measured cooling load and electric power consumption in an office building with slab cooling storage, stochastic time series models to simulate these random processes are investigated. Furthermore, a calculated result by an optimal control method of thermal analysis taking into account the internal heat is compared with the measured cooling load.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.5
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• pp.446-475
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• 2000

Performance of a water-to-water multi-type heat pump system using R22 has been experimentally investigated. Total refrigerant flow rate was adjusted with a variable speed compressor and the refrigerant flow rate for two indoor units were controlled by electronic expansion valves. Evaporator outlet pressure of refrigerant and indoor unit outlet temperatures of secondary fluid were selected as controlled variables. Experiments were carried out for both cooling and heating modes using PID control method. Results show that the multi-type heat pump system can be adequately controlled by keeping control gains at certain levels for various operating conditions.

• Journal of Power System Engineering
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• v.20 no.6
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• pp.11-19
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• 2016

A variable speed refrigeration system(VSRS) has been received high attention for energy saving ability. This paper investigates effects of design factors such as membership function range and sampling time to control performances for systematical designing fuzzy logic controller of the VSRS. Some comparisons of control performance between the fuzzy and PI are conducted including comparative evaluation of robustness against noise by using computer simulations. The simulation results showed that the fuzzy is very useful design method for engineers in the industrial fields which have big noises system and deal with inherent nonlinear system like the VSRS.