Abstract
This paper is an abridgement of a report† concerned with the results of two allied investigations carried out on a natural-draught cooling tower for the purpose of studying the causes of variations in the results obtained when testing cooling towers. Such tests are usually infrequent and the results obtained do not reflect the possible variations which can occur owing to changes in atmospheric conditions. The first purpose of the investigations was to obtain accurate air temperatures at different levels in a vertical plane covering positions from 4 ft above ground level to a height corresponding to the top of the tower, to check the validity of the specified requirement that the wet- and dry-bulb temperatures should be taken at 4 ft above ground level.
The second purpose was to endeavour to measure the temperature of the outlet air above the packing inside the tower by means of special long resistance elements, from which a reliable heat balance could be obtained, thus affording more precise data with which to analyse the tower performance. With these ends in view, a considerable number of tests were carried out, using recording apparatus, and the results obtained are considered to have a relative accuracy of a high order.
This paper gives the results obtained, and a theoretical assessment of information derived from these results, including the effects of inversions, of changes in barometric pressure, and of variations in wind velocity. This investigation has also afforded an opportunity to make a critical appraisement of the Chilton coefficient C.
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