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Metal matrix composites (MMCs) are still scarcely described due to various combinations of used materials and a wide array of technologies. Applying the Failure Mode and Effect Analysis (FMEA) method to describe the quality of metal composite castings may contribute to eliminating specific (characteristic only to these materials) defects. This part of the analysis determines the criticality numbers, meaning the frequency of a given failure, detectability level and significance of a given failure to the group of specific composite casting failures. It contributes to establishing the priority number (P), which is a measure used to assess risk, a notion essential in discussing quality in a composite casting.

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Abstract:The diameter and configuration of tubes are important design parameters of power condensers. If a proper tube diameter is applied during the design of a power unit, a high energy efficiency of the condenser itself can be achieved and the performance of the whole power generation unit can be improved. If a tube assembly is to be replaced, one should verify whether the chosen condenser tube diameter is correct. Using a diameter that is too large increases the heat transfer area, leading to over-dimensioning and higher costs of building the condenser. On the other hand, if the diameter is too small, water flows faster through the tubes, which results in larger flow resistance and larger pumping power of the cooling-water pump. Both simple and complex methods can be applied to determine the condenser tube diameter. The paper proposes a method of technical and economic optimisation taking into account the performance of a condenser, the low-pressure (LP) part of a turbine, and a cooling-water pump as well as the profit from electric power generation and costs of building the condenser and pumping cooling water. The results obtained by this method were compared with those provided by the following simpler methods: minimization of the entropy generation rate per unit length of a condenser tube (considering entropy generation due to heat transfer and resistance of cooling-water flow), minimization of the total entropy generation rate (considering entropy generation for the system comprising the LP part of the turbine, the condenser, and the cooling-water pump), and maximization of the power unit's output. The proposed methods were used to verify diameters of tubes in power condensers in a200-MW and a 500-MW power units.

The steam condenser is one of the most important element in whole power plant installation. Their proper design and operation makes a significant contribution to the efficiency of electricity production. The purpose of this article is to propose a two-dimensional mathematical model that allows modeling condenser work. In the model, the tube bundle is treated as a porous bed. The analysis has been subjected to a two passes power condenser with a capacity of 50 MW. The mathematical analysis was compared with the results of experimental studies. The average error between the model and the experiment for difference of cooling water temperatures was 5.15% and 11.60% for the first and second pass respectively. This allows to conclude that the proposed model is good enough to optimize future work of the condenser.