• Fibers and Polymers
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• v.5 no.1
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• pp.19-24
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• 2004

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at $200^{\circ}C$. The time dependence of the properties was not linear.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2260-2262
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• 2004

After steam turbines in power plant drives generator and maintains it at rated speed using high temperature and high pressure steam energy, they regulate the output of generator when synchronized in parallel with the power system. By the way, as the steam flow into turbine can not be reduced fast even though the electrical load is lost, the turbine gets into dangerous situation due to the increase of its speed. At this time, the duty of the turbine governor is "how to limit the speed within its overspeed trip setpoint and escape from danger." For the purpose of it, there are various ways known. Some overspeed protection methods for steam turbines now being operating in korea are introduced in this paper.

• 열병합발전
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• s.36
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• pp.16-21
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• 2003

For many years, T/G Supplier has constructed a number of thermal power plants and researched to improve the performance and the reliability of steam turbine, which are achieved by advances in design and materials technology. In recent, interest is renewed in advance steam condition as means of improving economy of thermal power plant and reducing environmental pollution. Improvements in the maximum power have been driven by the development of advanced rotor and bucket material and longer last stage bucket. Improvements in efficiency have been brought through advance in mechanical efficiency and thermodynamic efficiency. This paper describes a number of new steam path design features introduced to the steam turbine product. And also this paper describes new design technologies' development, new technologies' trend and technologies' development for ultra-super critical steam turbine.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.312-317
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• 2000

High efficient steam turbine stage has been developed with the help of the 3-dimensional design tool. In this stage design, the compound leaned stacking method has been adopted to reduce the secondary flow loss of a turbine passage and to increase the performance efficiency for the turbine nozzles. And the turbine buckets have been designed with the quasi-3-dimensional turbomachinery blade design method. To verify the stage design, therefore, the 3-dimensional numerical simulation of a steam turbine stage was conducted. In this design, CFX-TASCflow was employed to predict the turbulent flow of a steam turbine stage. The analysis was performed in parallel calculation using the HP N4000 8 CPUs machine. The result showed CFX-TASCflow could be used as the 3-dimensional flow analysis tool of steam turbine design.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.513-514
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• 2006

A CFD analysis for a thermal mixing experiment during steam jet discharge was performed to develop the analysis methodology for the thermal mixing between steam and subcooled water and to find the optimized numerical method. In the CFD analysis, the steam condensation phenomena by a direct contact was modelled by the so-called condensation region model. The comparison of the CFD results with the test data showed a good agreement as a whole, but a small temperature difference was locally found at some locations. However, the commercial CFD code of CFX4.4 together with the condensation region model can simulate the thermal mixing behaviour reasonably well when a sufficient number of mesh distribution and a proper numerical method are adopted

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.877-885
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• 2008

Steam injection heater is the most widely used method for fresh water generator throughout industry. This method is often chosen because of its simplicity. The steam bubbles condense and give up their heat to the surrounding liquid. Experimental study on steam injection heater has been performed in order to find the effect of major parameter. And conservation equation and Bernoulli obstruction theory are used for numerical simulation model of vapor flow-rate. Qualitative comparisons between simulations and measurements show a good agreement and the simulation models are thereby verified.

• Journal of Mechanical Science and Technology
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• v.17 no.1
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• pp.114-121
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• 2003

Water droplet erosion is one of major concerns in the design of modern large fossil steam turbines because it causes serious operational problems such as performance degradation and reduction of service life. A new erosion model has been developed in the present study for the prediction of water droplet erosion of rotor blades operated in wet steam conditions. The major four erosion parameter : impact velocity, impacting droplet flow rate, droplet size and hardness of target are involved in the model so that it can also be used for engineering purpose at the design stage of rotor blades. Comparison of the predicted erosion rate with the measured data obtained from the practical steam turbine operated for more than 90,000 hours shows good agreement.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.610-616
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• 2003

Recently, the common concern of nuclear power industry in the development of technology mitigating and preventing the aging of steam generator tubes prevails, because the trends of steam generator flaws at Uljin unit #1,2 and KSNP(Korea Standard Nuclear Power Plant) impose a burden on the operation of nuclear power plant. While the regulatory agency is demanding the establishment of the advanced general performance maintenance system, the steam generator management program adapting advanced technology is being developed which may comply with EPRI PWR SG Guidelines based on NEI 97-06 ‘ General Guidelines including all the maintenance aspects consist of the tube integrity assessment criteria, repair limit, allowable leakage level, water chemistry will be composed in order to obtain the approval of regulatory agency and be applied to Nuclear power plant early 2005. This presentation is to introduce maintenance state including SG tube degradation and main contents of advanced SG management program being developed, and futhermore update present and future plan, and estimate the alternation after the completion.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.407-410
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• 2002

A series of steam explosion experiments using real core materials of $ZrO_2$ and corium(a mixture of $ZrO_{2}\;and\;UO_{2}$) has been performed to evaluate the risk of steam explosion load in nuclear power plants. Surprisingly, spontaneous steam explosions are observed far both materials, which have been thought to be inexplosive so far. The dynamic pressure and morphology of the debris clearly indicate the evidence of an explosion. The experimental results also indicate that $ZrO_2$ is more explosive than corium.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.4
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• pp.88-101
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• 1992

Properties of water and steam are very important for the steam ejector CAD program as a subroutine and design of the Shell & Tube type steam condenser. Present formular programs are based on the Skeleton Table of ASME, and are able to calculate the thermodynamoc properties of water and steam throughout the whole of the region that extend in pressure from 0 to 1000 bar and temperature from 0.01 to 80$0^{\circ}C$. When comparing calculated values for specific volume, enthalpy and entropy with the Skeleton Table 1967 and IAPS Skeleton Table 1984, values fell well within tolerances specified except near the extremes of the range of interest at the critical point and triple point, where deviations were slightly larger.