• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.702-709
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• 2008

In this paper, the optimal thermal storage time of an air-conditioning system with slab thermal storage in office building was analyzed on the basis of the gradient method algorithm. The sum of room temperature deviation and heat extraction rate was set to the criterion function. It was calculated that four hours is the optimal thermal storage time under the standard evaluation criterion. Furthermore, some case studies were executed by controlling ratio of weight functions of room temperature deviation and heat extraction rate in criterion function. It is possible to design many kinds of optimal operation of an air-conditioning system with slab thermal storage by controlling ratio of the weight functions in criterion function.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.2
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• pp.106-114
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• 2001

The office environment of the building has been significantly changed and the office automation(OA) for productivity improvement and efficiency has proceeded. According to thee trends, the concept of office environment was transferred from conventional \"working space\" to \"living space\" or \"creative space\". Thus, occupants in office building have demanded more comfortable and advanced task environment. The objective of this paper is to evaluate the indoor environment of working space with personal air conditioning system using the measurements of environmental comfort parameters and the questionnaire survey of occupants、 thermal sensation response to the environment.n response to the environment.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.91-100
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• 2004

Energy efficiency evaluation method for a multi-type air conditioning system still has not been developed. In this study, analysis on capacity range and evaluating method of standards for air conditioners was conducted with world-wide Standards. It is not a proper approach to use the standards for residential air conditioner to multi type air conditioners. Some difficulties and problems are commented in this study with overview of the standards. Through the analytic research, an evaluating method for multi type air conditioner was suggested with Integrated Part Load Value (IPLV). The suggested concept for evaluating energy efficiency during part load condition considers building load pattern and operating hours of the system at different locations. Load was weighted in IPLV to consider not only the concept of occurrence of outdoor temperature such as bin method but also operation hours of the system. An experiment about the IPLV was conducted with variable air volume ducted type air conditioning system and multi-type system through modified code tester to give a glance at quantitative value of the IPLV.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.609-614
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• 2008

The heating and cooling performance of system multi-air conditioner under high-head and long-line conditions are experimentally investigated. The maximum head and tube length were 110 m and 1000 m, respectively. The experimental system was composed of 4 outdoor units with module systems, and 13 indoor units which were joined with the mode change unit by single-tube circuit. Field tests without indoor and outdoor temperature control were performed in a general office building with 22 different working conditions. Experimental results were prepared on the p-h diagram. Also the oil level in the compressor was normally maintained at the safety zone for the system multi-air conditioner with high-head and long-line conditions.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.67-75
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• 2007

This paper deals with the research for the effects of the operating parameters that could be used for a transcritical $CO_2$ mobile air-conditioning system on the cooling performance. The experimental conditions of the performance tests for a system and components such as a gas cooler and an evaporator were suggested to compare the performance of each with the standardized test conditions. And this research presents experimental results for the performance characteristics of a $CO_2$ mobile air conditioning system with various operating conditions such as different gas cooler inlet pressures and frontal air velocities/temperatures passing through an evaporator and a gas cooler. Experimental results show that the cooling capacity was more than 5kW and coefficient of performance (COP) was more than 2.1, also. Therefore, we checked that the mobile air-conditioning system using $CO_2$ has good performance compared to that using HFC-134a.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.435-440
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• 2009

For the effective control of a $CO_2$ air-conditioning system, the system high-side pressure algorithm, the indoor temperature algorithm, and the outdoor fan algorithm were developed. The system high-side pressure algorithm was composed of the setpoint algorithm, the reset algorithm, and the electronic expansion valve control algorithm. The indoor temperature algorithm was composed of the compressor control algorithm and the indoor fan control algorithm. These algorithms were tested by using mathematical models developed from the previous study. Results from the setpoint step change test and the disturbance test showed good control performances. Therefore, algorithms developed in this study may practically used for the control of a $CO_2$ air-conditioning system.

• Solar Energy
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• v.20 no.1
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• pp.91-96
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• 2000

This study was performed to find out how much experimental factors influence on regeneration performance in a solar air conditioning system. The experimental apparatus was set up in a climate-controlled chamber where temperature and humidity could be kept constant. In order. to investigate factors' influence on the regeneration performance of the solar air conditioning system, the model experiment was done using the 600mm $\times$ 600mm black painted aluminum regenerator. The design and analysis of experiment were done by the design of experiments, especially the table of orthogonal arrays. In order to find out how much experimental factors influence on regeneration performance, the table of orthogonal arrays $L_8(2^7)$ was used. According to the results, it was found that the most influential factor to affect regeneration performance was the concentration of LiCl solution. The next influential factors were a solar radiation, an air velocity, and the temperature of LiCl solution in order.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.22 no.4
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• pp.257-263
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• 1993

• Journal of Power System Engineering
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• v.20 no.2
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• pp.85-90
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• 2016

Coefficient of performance (COP) for two-stage compression system is investigated in this paper to develop seawater ice machine. The system performance is analyzed with respect to degrees of superheating and subcooling, condensing and evaporating temperatures, compression and mechanical efficiencies and mass flow ratio in an inter-cooler. The main results are summarized as follows : The COP of the system grows when the mass flow ratio, subcooling degree and evaporating temperature edge up. Contrariwise, the system performance descends in case that superheating degree and condensing temperature increase. The most effective factor for the COP is the mass flow rate ratio. Each refrigerant has different limitation for a value of the mass flow ratio in the inter-cooler because of difference in material property.