5.3 Influence of tubeplate and tubenest geometry on thermal performance
It has been shown that the HEI and BEAMA documents give recommendations for the design of water-cooled surface type condensing plant, and describe the levels of performance which can be achieved. However, omissions on the separate treatment of tubeplate geometry and tubenest ventilation arrangements make it difficult to use this data when calculating new designs which have tubenests and venting systems differing from those for which the empirical dependence was obtained.
Two methods of design evaluation can be applied in the assessment of tubeplate geometries; there is the general subjective treatment, which involves evaluating the total pressure within the steam space and tubenest, and there is more recently the rigorous mathematical analysis using computer-aided numerical solutions which solve the heat and mass transfer equations for individual tubenests.
Each method is discussed in turn, the general principles of tubenest arrangement are outlined, and their practical application illustrated by reference to large condensers designed over the last 15 years.