• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2304-2309
• /
• 2008

The objectives of this paper are to study the characteristics of heat transfer and pressure drop of the micro channel heat exchangers using diffusion bonding technology. Four types of heat exchangers are designed and manufactured, which are straight type, long dot type, splited wavy type and straight double side type. Heat transfer and pressure drop performance of each heat exchangers are measured in various operating conditions, and compared each other. The results show that the $(j/f)^{1/3}$ performance of splited wavy type and long dot type increases about 10.3% and 6.1% at the Reynolds number 470 compared to that of straight type, respectively. On the other hand, $(j/f)^{1/3}$ performance of straight double side type decreases 19.7%.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.15 no.3
• /
• pp.97-103
• /
• 2006

The development of a heat exchanger production model based on the microlamination technology and it's economic efficiency is addressed. A microchannel production model is proposed for the high-volume production. The microlamination system is made up of lamina patterning, laminae sorting and laminae bonding. A cost estimation model is developed based on the hewn cycle time and capital equipment costs. An economic efficiency analysis is performed to determine the cost drivers under the different market and product scenarios. The result of the economic efficiency analysis indicated that the device size and the production rate have a great effect on the overall manufacturing cost of microlamination devices. And it can be concluded that the microlamination should focus on bonding larger laminae and reducing both cycle time and warpage.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.04a
• /
• pp.127-129
• /
• 2011

In the building, controlling temperature is main concern for maintaining fresh environment. To control temperature, phase change material(PCM) can be used as a medium that keeps temperature in certain level. PCM has its own phase change temperature. PCM melts/solidifies while absorbing/releasing the heat. Because of the advantage, PCM can be applied to a air-PCM heat exchanger. In this study, the air-PCM heat exchanger was designed based on the system requirements and experimental analysis was conducted to study on the performance of the heat exchanger.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.1090-1095
• /
• 2009

The purpose of this study is to determine the performance characteristics for the micro-channel gascooler with various operating conditions. The performance of four kind of HX models were analyzed and optimized with the variation of refrigerant inlet temperature, air velocity, outdoor temperature. As a result, Model B showed the maximum capacity and high performance could be maintained for wide operating conditions. Beside, the micro-channel heat exchanger could be appled to $CO_2$ system appropriately because of a small pressure drop and high heat transfer rate.

• Proceedings of the SAREK Conference
• /
• 2004.11a
• /
• pp.123-123
• /
• 2004

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.11
• /
• pp.767-774
• /
• 2008

This paper presented the heat transfer and pressure drop characteristics for micro plate heat exchanger with straight channel. The metal sheets for straight channel are manufactured by chemical etching and fabricated micro plate heat exchangers by using the vacuum brazing of bonding technology. The performance experiments are performed within the Reynolds numbers range of 15$\sim$250 under the same flow rate conditions for hot and cold sides. The inlet temperature of hot and cold water are conducted in the range of $30^{\circ}C{\sim}50^{\circ}C$ and $15^{\circ}C{\sim}25^{\circ}C$, respectively. Heat transfer rate and pressure drop are evaluated by the Reynolds numbers and mass flow rates as the inlet temperature variations of the hot and cold sides. Correlations of Nusselt number and friction factor are suggested for micro plate heat exchanger with straight channel using the results of performance experiment.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.6
• /
• pp.774-782
• /
• 2004

This article presents a numerical and experimental investigation for the single-phase forced laminar convective heat transfer through arrays of micro-channels in micro heat exchangers to be used for cooling power-intensive semiconductor packages, especially the stacked multi-chip modules. In the numerical analysis, a parametric study was carried out for the parameters affecting the efficiency of heat transfer in the flow of coolants through parallel rectangular micro-channels. In the experimental study, the cooling performance of the micro heat exchanger was tested on prototypes of stacked multi-chip modules with difference channel dimensions. The simulation results and the experiment data were acceptably accordant within a wide range of design variations, suggesting the numerical procedure as a useful method for designing the cooling mechanism in stacked multi-chip packages and similar electronic applications.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.32 no.12
• /
• pp.915-923
• /
• 2008

The performance experiments for a microchannel printed circuit heat exchanger (PCHE) of high-performance and high-efficiency on the two technologies of micro photo-etching and diffusion bonding were performed in this study. The microchannel PCHE were experimentally investigated for Reynolds number in ranges of 100 $\sim$ 700 under various flow conditions in the hot side and the cold side. The inlet temperatures of the hot side were conducted in range of $40^{\circ}C\;{\sim}\;50^{\circ}C$ while that of the cold-side were fixed at $20^{\circ}C$. In the flow pattern, the counter flow was provided 6.8% and 10 $\sim$ 15% higher average heat transfer rate and heat transfer performance than the parallel flow, respectively. The average heat transfer rate, heat transfer performance and pressure drop increases with increasing Reynolds number in all the experiment. The increasing of inlet temperature in the experiment range has not an effect on the heat transfer performance while the pressure drop decrease slightly with that of inlet temperature. The experimental correlations to the heat transfer coefficient and pressure drop factor as a function of the Reynolds number have been suggested for the microchannel PCHE.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.2
• /
• pp.87-93
• /
• 2015

Recently, the heat exchangers are requiring higher performance and reliability since they are being used under the operating condition of high temperature and pressure. To satisfy these requirements, we need special materials and bonding technology. This study presents a manufacturing technology for high temperature and high pressure micro channel heat exchanger using Inconel 617. The bonding performance for diffusion bonded heat exchanger was examined and analyzed. The analysis were conducted by measuring thermal and mechanical properties such as thermal diffusivity and tensile strength, and parametric studies about bonding temperature and pressing force were also carried out. The results provided insight for bonding evaluation and the bonding condition of $1200^{\circ}C$, and 50 tons was found to be suitable for this heat exchanger. From the results, we were able to establish the base technology for the manufacturing of Inconel 617 heat exchanger through the application of the diffusion bonding.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.3
• /
• pp.587-592
• /
• 2008

In order to investigate the performance of an internal heat exchanger for $CO_2$ refrigerant system, the experiment was performed. Four kinds of internal heat exchangers(IHX) were used. The effects on the IHX length, the number of tube, the operating condition and the type of IHX were investigated. With increasing of the IHX length, the capacity and efficiency increased. The pressure drop of the low-side was larger compared with that of the high-side. As the temperature of the gas cooler increased, the capacity and efficiency increased linearly. The operation condition of evaporator was suggested as two phase region rather than superheat region. The capacity and efficiency of the micro-channel was larger about 90% and 75% than those of the tube. But the pressure drop of the micro-channel was more larger, compared with that of the tube.