• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.42-53
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• 2004

An experimental study on the refrigerant-side pressure drop of slit fin-tube heat exchanger has been carried out. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the pressure drop on design conditions of condenser in micro-fin tube for R22 and its alternatives, R407C (R32/125/134a, 23/25/52 wt.％) and R410A (R32/125, 50/50 wt.％). Experiments were carried out under the conditions of inlet refrigerant temperature of 6$0^{\circ}C$ and mass fluxes varying from 150 to 250 kg/$m^2$s for R22, R407C and R410A. The inlet air conditions are dry bulb temperature of 35$^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.43 m/s. Experiments show that pressure drop for R410A and R407C were 17.8∼20.2％ and 5∼6.8％ lower than those of R22 respectively for the degree of subcooling of 5$^{\circ}C$. For the mass fluxes of 200∼250 kg/$m^2$s, the deviation between the experimental and predicted values for the pressure drop was less than $\pm$20％ for R22, R407C and R410A.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.106-111
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• 2001

The performance characteristics of heat pump system using the new refrigerant subcooling system were investigated. The new heat pump system has the ice storage tank to accumulate the latent heat of the refrigerant during the night-time. The heat is released to subcool the saturated refrigerant liquid at the outlet of a condenser in the daytime. The experimental apparatus is a well-instrumented heat pump which consisted of a refrigerant loop and a coolant loop. The test sections(condenser and evaporator) were made of tube-in-tube heat exchanger with the horizontal copper tube of 12.7[mm] outer diameter and 9.5[mm] inner diameter. The evaporating temperatures ranged from $-5[^{\circ}C]$ to $0[^{\circ}C]$ and the subcooling degrees of the refrigerant varied from $15[^{\circ}C]$ to $25[^{\circ}C]$. The test of the ice storage was carried out at evaporating temperature of $-10[^{\circ}C]$ and the ice storage mode is an ice-on-coil type. The main results were summarized as follows ; The refrigerant mass flow rate and compressor shaft power of the heat pump system were independent of the subcooling degrees. The cooling capacity o the heat pump system increases as the evaporating temperature and subcooling degree increases. The cooling capacity of the heat pump system is about 25 to 30% higher than that of normal heat pump system. The COP of the heat pump system which subcooled the refrigerant liquid at the outlet of the condenser is about 28% higher than that of the normal heat pump system.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3196-3206
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• 2021

For the Korean design of the PCCS (passive containment cooling system) in an innovative PWR, the overall thermal resistance around a condenser tube is dominated by the heat transfer coefficient of steam condensation on the exterior surface. It has been reported, however, that the calculated heat transfer coefficients by thermal-hydraulic system codes were much lower than measured data in separate effect tests. In this study, a new empirical model of steam condensation in the presence of a noncondensable gas was implemented into the MARS-KS 1.4 code to replace the conventional Colburn-Hougen model. The selected correlation had been developed from condensation test data obtained at the JERICHO (JNU Experimental Rig for Investigation of Condensation Heat transfer On tube) facility, and considered the effect of the Grashof number for naturally circulating gas mixture and the curvature of the condenser tube. The modified MARS-KS code was applied to simulate the transient response of the containment equipped with the PCCS to the large-break loss-of-coolant accident. The heat removal performances of the PCCS and corresponding evolution of the containment pressure were compared to those calculated via the original model. Various thermal-hydraulic parameters associated with the natural circulation operation through the heat transport circuit were also investigated.

• Journal of Energy Engineering
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• v.16 no.3
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• pp.149-154
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• 2007

An experimental study on the air-side pressure drop of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side pressure drop in the literature is not based on a consistent approach. This paper focuses on method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry and wet surface pressure drop estimation in fin-tube heat exchanger. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the air-side pressure drop on design conditions of condenser and evaporator. Results are pre-sented as plots of friction f-factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of $150{\sim}250\;kg/m^2s$ with air flows at velocity ranges from 0.38 m/s to 1.6 m/s.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.523-524
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• 2008

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.323-327
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• 2008

본 연구는 판형 핀-관 열교환기의 열전달 특성을 상용 CFD 코드인 SC/Tetra를 사용하여 해석한 내용에 관한 것이다. 해석조건은 입구속도 0.63 m/s, 튜브온도 $44.5^{\circ}C$이다. 해석 열교환기는 총6가지로 검토하였으며 각각의 온도분포와 유동패턴을 해석하고 판형 핀-관 열교환기의 열전달 특성을 비교 검토하였다.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.4
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• pp.184-195
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• 2005

This paper describes the recent work on advanced technology concepts applied to air cooled heat exchangers for residential air-conditioning. The concepts include vortex generators for the air-side, micro-fin or flat tubes for the refrigerant-side. Advances in understanding of heat transfer mechanisms, predictive models are discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.3
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• pp.220-229
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• 2003

An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150~250 kg/$m^2$s with air flows at velocity ranges from 0.6 m/s to 1.6 m/s.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1748-1755
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• 2001

The shell and tube heat exchangers were introduced to apply to a big capacity condenser and a high pressure feed water heater for power plant in the beginning of 1990s. Design and manufacturing technology fur shell and tube heat exchangers have been developed until now. But it is very difficult to calculate the expected performance characteristics of the shell and tube heat exchanger, because there are many design parameters to be considered according to internal structure and the shell side heat transfer mechanism complicately related to the design parameters. Design parameters to be considered in the design stage of shell and tube heat exchanger are shell and tube side fluids, flow rate, inlet and outlet temperature, physical properties, type of heat exchanger, outer diameter, thickness, length of tube, tube arrangement, tube pitch, permissive pressure loss on both sides, type of baffle plate, baffle cutting ratio. The propose of study is an analysis TEMA(Tubular Exchanger Manufacturers Association) E shell and tube heat exchanger performance with changing a number of baffles(3, 5, 7, 9, 11) and tubes(16, 20) and determined optimal baffle spacing.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.5
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• pp.952-961
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• 1989

The purpose of this study is to investigate the behavior of operational and design factors on the performance characteristics of a horizontal fin-tube heat exchanger under phase change conditions for refrigerant. The flow and heat transfer in the heat exchanger are simulated numerically taking into account the variations of heat transfer coefficients, thermodynamic and flow properties of refrigerant, and the axial heat conduction in the tube wall. As the results of this study, it was found that the annular flow model was more reasonable physically than the homogeneous one for the two phase flow of refrigerant and axial heat conduction of tube wall did not have a great influence on the analysis. The effects of refrigerant pressure, mass flow rate of air, diameter of tube and the number of fins per unit length of tube were also discussed.