• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.642-647
• /
• 2008

The boiler structure is determined by combustion characteristics and construction costs in the combustion chamber of a large commercial boiler. The heat transfer in boiler is composed of the radiation and the convection. The convective heat transfer has happened to back-pass heating surface. The combustion gas sequentially passes through the reheater tube, 1st economizer tube, and 2nd economizer tube. In case of being lowered in boiler height, we have to install additional tube bundle in back-pass heating surface for increasing the heat transfer of boiler, which causes the noise and vibration from combustion gas. When the combustion gas passes through the back-pass tube bundle in specified load of commercial boiler, this paper analyzes the acoustic characteristics between vortex-shedding frequency and natural frequency in tube bundle cavity. The case study reduce the resonance by changing natural frequency characteristics of tube-bundle cavity using a way to install ant-noise baffle in the direction of combustion gas flow.

• Plant Journal
• /
• v.17 no.1
• /
• pp.38-49
• /
• 2021

In order to increase power plant efficiency, the steam temperature was increased to 610 ℃ which deteriorates the durability of the boiler tube and as the use of low-calorie coal increases the post combustion and delayed combustion phenomenon, the overheating of the final reheater and the tube rupture are becoming frequent. In order to prevent overheating of the final reheater, desuperheater water injection was increased, leading to a decrease in boiler efficiency. In this study install a baffle plate at the back of some overheated tube groups, thereby reduce the temperature of the tube by reducing the amount of combustion gas, and the reduced combustion gas moves to an adjacent place to increase the temperature of other tubes. As a result of the study, the temperature deviation between tubes decreased 1.5. And the heat-reducing injection amount was reduced to 6,929 kg/h and the maximum tube temperature was reduced to 623.4℃ which is 6.6℃ more below than the control standard of 630℃.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.61-66
• /
• 2003

Fouling is very serious problem in heat exchanger because it rapidly deteriorates the performance of heat exchanger. Cross-flow heat exchanger with vortex generators is developed, which enhance heat transfer and reduce fouling. In the present heat exchanger, shell and baffle are removed from the conventional shell-and-tube heat exchanger. The naphthalene sublimation technique is employed to measure the local heat transfer coefficients. The experiments are performed for single circular tube, staggered array tube bank and in-line array tube bank with and without vortex generators. Local and average Nusselt numbers of single tube and tube bank with vortex generator are investigated and compared to those of without vortex generator.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.1
• /
• pp.50-59
• /
• 2000

An experimental study has been carried out in order to investigate the heat storage characteristics for a latent heat storage tank with horizontal shell and tube type. The heat exchanger consisted of horizontal cylindrical capsules with a staggered tube bank layout. Based on the obtained data, the effects of flow rate and inlet fluid temperature on the melting time and heat storage rates were examined. It is found that the melting time decreased with increase of the flow rate and the inlet temperature. Results also show that at the initial stage of heat transfer the heat storage rate represents the maximum value and rapidly decreases.

• Journal of computational fluids engineering
• /
• v.12 no.3
• /
• pp.13-19
• /
• 2007

A numerical simulation on the heat transfer and flow field was carried out to improve the performance of the shell and tube heat exchanger. The steady incompressible 3-D Navier-Stokes solution is obtained with the actual operational condition and geometry of the heat exchanger. Based on this study, it is noted that the present geometry of the heat exchanger causes poor heat transfer since the air inside shell does not flow through the tube bundle, but around it. The enhancement of the heat transfer can be achieved by the variation of the design factor like the sealing strip located on the top/bottom and middle of the baffle, but it causes the increasement of the pressure drop. In this paper, the effects of the location and size of the sealing strips and flow rate through the heat exchanger on the heat transfer and pressure drop are studied.

• 한국전산유체공학회:학술대회논문집
• /
• 2007.04a
• /
• pp.149-152
• /
• 2007

The numerical simulations on the heat transfer and flow field were carried out for the improvement of the performance of the shell and tube heat exchanger. The steady incompressible 3-D Navier-Stokes solution is obtained with the actual operational condition and geometry of the heat exchanger. The present geometry of the heat exchanger causes poor heat transfer since the air inside shell dose not flow through the tube bundle, but around it. The enhancement of the heat transfer can be achieved by the variation of the design factor like the sealing strip located on the top/bottom and middle of the baffle.

• Journal of KSNVE
• /
• v.11 no.2
• /
• pp.285-291
• /
• 2001

The impingement of a weak shock wane discharged from the open end of a shock tube upon a flat plate was investigated using shock tube experiments and numerical simulations. Harten-Yee Total Variation Diminishing method was used to solve axisymmetric, unsteady, compressible flow governing equations. Experiments were carried out to validate the present computations. The effects of the flat plate and baffle plate sizes on the impinging flow field over the flat plate were investigated. Shock Mach number was varied in the range from 1.05 to 1.20. The distance between the plate and shock tube was changed to investigate the effect on the peak pressure. From both the results of experiments and computations we obtained a good empirical equation to predict the peak pressure on the flat plate.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.562-567
• /
• 2000

The Impingement of a weak shock wave discharged from the open end of a shock tube upon a flat plate was investigated using shock tube experiments and numerical simulations. Harten-Yee Total Variation Diminishing method was used to solve axisymmetric, unsteady, compressible flow governing equations. Experiments were carried out to validate the present computations. The effects of the flat plate and baffle plate sizes on the impinging flow field over the flat plate were investigated. Shock Mach number was vaned in the range from 1.05 to 1.20. The distance between the plate and shock tube was changed to investigate the effect on the peak pressure. From both the results of experiments and computations we obtained a good empirical equation to predict the peak pressure on the flat plate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.361-364
• /
• 2009

The cooling system optimization for injection molds was studied with a response surface method in the previous research. It took so much time to find an optimum solution for a large product due to an extensive amount of calculation time for the CAE analysis. In order to use the optimization technique in the actual design process, the calculation time should be much reduced. In this study, we tried to reduce the number of design variables with the concept of the close relationship between the depth and the distance of cooling channels. The optimum ratio of the distance to the depth of cooling channels for a 2-dimensional problem was 2.0 so that the optimum ratio was again sought out for 4 industrial products. The major cooling effect of the injection molds for large products rely on baffle tubes. The optimum ratio of the distance to the depth for baffle tubes was 2.0 for the large products. The result enables us to reduce the number of the design variables by half in the cooling system optimization problem.

• Journal of computational fluids engineering
• /
• v.19 no.3
• /
• pp.20-23
• /
• 2014

The flow pattern inside the inlet chamber of the tube side is one of the key parameters influencing on the performances of the shell-and-tube type of heat exchangers(STHE). In order to improve the flow distribution, the baffle shaped as the porous plate is installed in the inlet chambers. In the present study, numerical simulation has been performed to investigate the flow features of the tube side of the STHE in sense of the hydraulic performances. The flow fields have been analysed by the three-dimensional Navier-Stokes solvers with the proper turbulent models. Computational domain is ranged in the whole of the tube side of the STHE. The numerical results showed that the presence of the baffles improves the redistribution of the flow injecting to the tube bundels. The good agreements of the numerical results with the experimental results of PIV measurements have been shown for the validation of the numerical methods adopted in the present papers.