• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.142-142
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• 2003

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.702-708
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• 2017

The heat generation rate in a telecommunications cabinet keeps increasing due to the increased usage of mobile devices. Insufficient removal of the heat increases the cabinet temperature, which results in the malfunction of the electronic devices. In this study, tests were conducted on aluminum and plastic heat exchangers for cooling a telecommunications cabinet, and the results were compared with theoretical predictions. The aluminum heat exchanger comprised counter flow parallel channels with 4.5-mm pitch, and the plastic heat exchangers comprised cross or cross-counter flow triangular channels with 2.0-mm pitch. The volume of the cross flow heat exchanger was the same as that of the aluminum heat exchanger, and the volume of the cross-counter heat exchanger was 33% larger than that of the aluminum heat exchanger. The results show that the heat transfer rate is the highest for the cross-counter heat exchanger and lowest for the aluminum one. The temperature efficiency of the cross-counter heat exchanger was 56% higher than that of the aluminum one and 20% higher than that of the cross flow heat exchanger. The pressure drop of the cross-counter heat exchanger was approximately the same as that of the aluminum one. The heat exchange efficiency was the highest for the cross-counter heat exchanger and lowest for the cross flow heat exchanger. The theoretical analysis somewhat overestimated or underestimated the data.

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.41-41
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• 2006

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.148-149
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• 2012

• Proceedings of the SAREK Conference
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• 2005.06a
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• pp.79-79
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• 2005

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.50-50
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• 2007

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.27 no.3
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• pp.253-263
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• 1998

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2273-2278
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• 2007

Brazed Plate Heat Exchanger (BPHE) is a type of compact plate heat exchanger with parallel corrugated plates which are brazed together in series. Each plate hascorrugation called herringbone pattern. Inside a BPHE, hot fluid and cold fluid alternate its flow direction to establish counter current flow configuration. Two-phase flow heat transfer and pressure drop of R-22 in BPHE were experimentally measured in this study. In the present experiments, single-phase region and two-phase region coexist in a BPHE. Therefore, the inside of a BPHE have to be divided into single phase region and two phase region and analyzed accordingly. The results from the single phase flow analysis are then extended to the two phase flow analysis to correlate the condensation and evaporation heat transfer and pressure drop for the refrigerant R-22 in the BPHEs. Previous models for two- phase friction factor have been compared with the present experimental results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.987-995
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• 2003

The performance of a residential heating and cooling system with $CO_2$ is predicted by using a cycle simulation model. The simulations are conducted by varying design parameters and operating conditions. The efficiency of the transcritical cycle can be improved by utilizing the advantages in heat transfer characteristics of $CO_2$ and developing microchannel indoor and outdoor heat exchangers. For the designed system of this study, the predicted COP of the heat pump system is approximately 3.5 in the heating mode and 3.0 in the cooling mode. The predicted optimal discharge pressure for the heat pump system is approximately 11 MPa in the heating mode and 9 MPa in the cooling mode.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1129-1134
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• 2009

A numerical study has been conducted to investigate the effect of tube arrangement on the heat transfer and the pressure loss for cross flow heat exchangers. By defining a transverse deviation factor, ${\varepsilon}_t=l_T/S_T$, the flow pattern and the heat transfer characteristics are compared for selected ${\varepsilon}_t$ values of 0.0(in-lined), 0.1, 0.2, 0.3, 0.4, 0.5(staggered) by using a commercial software. Computational domain includes 1 pitch in the transverse direction and 5 pitches in the flow direction with due periodic boundary conditions.