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of cooling air could be ‘pressed’ through the finned tube bundle. Smaller bundle space means higher air velocity and whence a higher pressure drop for a given air flow. An increased number of layers (to bring the required cooling surface area within the limited plot area) also increases the pressure drop.
allowable motor power produce a higher airflow in combination with a higher static pressure head.
Te selection of this Whizz-Wheel fan in combination with the higher number of tube rows lead to the result that all of the suppliers strict requirements regarding space, absorbed motor power and noise level could be fulfilled. Tis placed the supplier in ‘pole position’ to win this job. Compared with the best (smallest) design of the coolers when fitted with conventional fans1
), the
final Whizz-Wheel based design requires 40 per cent less space. In spite of this smaller space, the consumed motor power of the coolers is 25 per cent below the maximum allowable level. With conventional fans1
(even with the larger
space) the permissible noise level was exceeded by 5dB(A). In the final Bronswerk design, the noise level is within the permissible limit. Although the coolers have more rows of finned tubes, the total height of the coolers is reduced by 0.6 metres. Even the weight of the coolers is 15,000kg less than with the conventional fans1
.
Te othe main benefits are not only for the smaller cooler but also for the overall project:
Fig. 2. A high-efficiency design (with Whizz-Wheel).
Te resulting pressure drop on the airside was far higher than is common in air-cooled cooler applications and higher pressure drop means higher driving power and a higher noise level. Te only feasible solution would be to employ a fan which delivered an optimal volume flow and static head within the constraint of maximum permissible power (in other words: highest efficiency). Also, the noise produced by that fan should stay below the maximum permissible noise level.
Te ultra-high
efficiency, ultra-low noise fan, the Whizz-Wheel, was considered. Tis fan is capable of achieving:
● A 50 per cent reduction of absorbed
motor power or ● For the maximum
Fig. 3. Compact Header design. For more information ✔ at
www.engineerlive.com/iog 1
‘ Conventional fan’ should be understood as the best available low noise, high efficiency axial flow fans before the Whizz- Wheel was available.
Johan van der Kamp and Hans van Essen are with Bronswerk Heat Transfer BV, Nijkerk, The Netherlands.
www.bronswerk.com
20
www.engineerlive.com
● Te ability to provide a suitable module on an existing platform without modifying the platform
structure; ● Maintaining the weight of the module below the maximum crane lift capacity to avoid the need for a
heavier crane; ● Fewer fans, so fewer E-power connection points and cables, and fewer components requiring
maintenance; ● No self-induced vibrations from the fans to the structure.
Te Whizz-Wheel design has led to several applications in which the space occupied by the coolers could be brought to allowable ultra compact dimensions. Together with the two other advantages of these fans, ie strongly reduced power consumption and strongly reduced noise generation, the result is that for many air-cooled coolers or condensers, specifications can be met that were unimaginable before the Whizz-Wheel. ●
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