• Proceedings of the SAREK Conference
• /
• 2004.06a
• /
• pp.86-86
• /
• 2004

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.813-818
• /
• 2008

In order to reduce energy consumption, this study presents a way to energy reduction through energy-feedback which enables a household to self-recognize the need for energy reduction and respond to. The effect of this energy-feedback has been reported as $10{\sim}15%$ in average, and been actively investigated in abroad from 1970's while study in korea has been in its first step. In this study, examination on the cases of abroad study is made as it shows the effectiveness and applicability of energy feedback. And paradigms to consider for application to korea will be suggested anticipating the change of actions through energy feedback.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.76-81
• /
• 2007

The shopping center in underground passage increased for efficient space utilization in urban area. This study describes operation characteristics of all air type and hybrid type with local ventilation and fan coil unit fixed to ceiling. In order to compare energy saving, thermal environment and installation space, etc., integrated simulator with heat production and indoor distribution system is designed and constructed. Energy saving of the hybrid system is calculated as over 30% compared to conventional all air type. And also the results showed that humidity decreased about 6%, also indoor thermal distribution is improved as temperature variation of around $1^{\circ}C$.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.412-418
• /
• 2004

In this paper, a new distributed intelligent control module based on LonWorks fieldbus for air handling unit(AHU) of heating, ventilating and air-conditioning(HVAC) is proposed to replace with a conventional direct digital control(DDC) with 32 bit microprocessor. This article also addresses an Internet-based HVAC system architecture that combines Web technology and networking. The proposed control architecture has a excellent features such as highly compact and flexible function design, a low priced smart front-end and reliable performance with various functions. This also addresses issues in control network configuration, logical design of field devices by S/W tool, Internet networking and electronic element installation. Experimental results showing the system performance are also included in this paper.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.12 no.1
• /
• pp.21-29
• /
• 2004

This paper is to study the heat transfer performance of the copper-water heat pipe with screen wicks. Recently, the semiconductor capacity of an electronic unit becomes larger, but its size becomes much smaller. As a result, a high- performance cooling system is needed. Experimental variables are inclination angles, temperatures of cooling waters and the mesh number of screen wicks. The distilled water was used as a working fluid. Based on the experimental results, when the copper-water heat pipe of 6mm diameter is used at the top heat mode, the heat transfer performance of 100 mesh 2 layers heat pipe is better than that of 150 and 200 mesh. The thermal resistance of the two layers with the 100-mesh screen was 0.7-$0.8^{\circ}C$/W.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.17 no.7
• /
• pp.611-619
• /
• 2005

In a previous work of the authors, the heat and mass transfer in a desiccant rotor was analyzed theoretically through linearization assumptions and four dimensionless parameter groups dominating the dehumidification process were arranged. In this work is verified whether the four dimensionless parameters also play the dominant roles in more realistic situations where the nonlinear factors affect the heat and mass transfer. The results show that the dehumidification characteristics are closely similar to each other as long as the four dimensionless parameters have the same set of values while the rotor configurations and/or the operation conditions are different from each other. The four dimensionless parameters are $\Psi,\;\chi,\;\sigma$ and N, where $\Psi$ implies the average gradient of relative humidity lines in the psychrometric chart, $\chi$ the heat capacity of the rotor and $\sigma$ the sorption capacity of the rotor, and N implies the number of transfer unit.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.5
• /
• pp.313-320
• /
• 2011

For a steam Rankine cycle to recover waste heat from the exhaust gas of an Internal combustion engine, a swash plate type of expander as a power conversion unit has been designed. Numerical simulation has been carried out to estimate the performance of the designed expander. With the steam pressure and temperature of 35 bar and $300^{\circ}C$ at the expander inlet, respectively, the expander was estimated to produce the shaft power output of about 2.67 kW from the exhaust gas waste heat of 25.2 kW. The expander output increased almost linearly with the amount of exhaust gas waste heat in the range of from 5~40 kW, and the expander and Rankine cycle efficiencies showed gradual decreases in the ranges of 72.2%~69.5% and 10.8%~10.4%, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.24 no.8
• /
• pp.646-655
• /
• 2012

This study is intended to analyze the thermal performance and evaluate the applicability about non-duct type heat recovery ventilation system integrated with window. Eventually, economic analysis of the system is conducted according to building energy saving ratio of it. As results of the thermal performance, the U-factor of the window conducted on the basis of KS F 2278 appears to $1.8W/m^2K$, and the effective heat exchange efficiency of the ventilator conducted on the basis of KS B 6879 appears 49.95% for cooling, 66.89% for heating. In the applicability evaluated by TRNSYS 16, the caes of applying the heat recovery ventilator integrated with window is found to reduce the cooling or heating load by 2.9% or 13.5% than the non-ventilator case. The results of economic analysis taking a side of consumer is verified as the payback is 3 years, and the accumulated earning is 1,408,133 won in terms of '600,000 won/unit' for initial cost, 10 years for useful life of the system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.10
• /
• pp.679-686
• /
• 2007

The cooling load in winter season is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, a 4-room simultaneous heating and cooling heat pump system was designed and its performance was measured at each operating mode. The system used R-410A and adopted variable speed compressor. The problems on the designed system were analyzed and defined. In addition, the solutions of the problems were suggested to improve system efficiency and to obtain the stable operation.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.13 no.4
• /
• pp.14-20
• /
• 2017

Refrigerant having high global warming potentials will be phased out due to environmental protection issues. R410A has been widely used in geothermal heat pump. However, it has a little high GWP by 2088 value. One of the recommended substitute for R410A refrigerant is R452B which having a GWP by 698 value. In this paper, the heating and cooling performance of the water-to-water geothermal heat pump unit with R452B was experimentally investigated. The performance of the heat pump adopting R452B was also compared with the system applying R410A. The heating and cooling capacity of R452B heat pump system showed a slightly lower values within 2% comparing with R410A system. However, the R452B system's coefficient of performance was enhanced by 5.2% and 13.7% at heating and cooling mode, respectively.