Cooling tower performance, calculations

An important thermodynamic parameter in cooling tower calculations is the ratio of the thermal capacity of the water stream to that of the sir stream. This parameter is referred to as, the tower capacity factor. It is shown that when air or water efficiency, are plotted against the capacity factor test points for a given tower are found to lie on a single smooth curve. The correlation is obtained, irrespective of whether the equipment is used as a water cooler or air cooler, and irrespective of the temperature levels, temperature ranges and barometric pressures. The paper also shows that when a specified amount of heat has to be rejected into a specified air stream, optimum performance giving the lowest average water temperature is obtained when the water flow rate is chosen so that its thermal capacity is equal to the potential thermal capacity of the air stream. 13 refs, cited. 

The design of large natural draft cooling towers and analysis of their performance are complicated by the effects of variations in ambient air humidity. Often the effluent air from the tower is assumed to be at 100% relative humidity, to simplify calculations for design parameters. This study avoids the simplification, and proposes a procedure for determining the major design parameters for a natural draft tower. The theoretical and empirical relationships applicable to heat balance, heat transfer and transport, and tower draft and air resistance are given. 13 refs, cited. 

The calculations performed for SCOR show that all transients could be adequately managed in a passive way (in the vessel, in the RRP loop, and in the heat sink) with only 4 out of 16 RRP loops, whatever the heat sink pool or air-cooling tower. This represents a redundancy of 16 times 25%. The RRP operation is compatible with an active or passive mode whatever the primary pressure or temperature. Since the in-vessel heat exchangers of the RRP loop are located very close to the core, and thanks to the flow bypass of the venturi, the RRPs are operational in a two-phase flow mode in case of a small primary water inventory. Long term cooling may be ensured in a totally passive mode thanks to the RRP with air-cooling tower. 

Calculate the performance AT. This is the difference between the water leaving the tower and the wet bulb temperature. You can judge the performance of the cooling tower as follows ... 

This demonstrates how the countercurrent design may become prohibitive if performance above a certain level is required. Furthermore, in most instances the water within the tower will be cooled, and Heiuy s law constant will be lower. This would result in less efficient gas transfer near the bottom of the tower. This effect can be evaluated on the computer program, but not in hand calculations. This example simply delineates the maximum and minimum possible tower heights, and shows the necessity for consideration of the effect of cooling. 

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