Furukawa Electric has recently developed and released
"PowerKicker", a vertical cooling device using heat-pipe
based on natural convection to be used for thyristors in
railways' substations. The device features high efficiency,
non-powered operation based on natural convection and
small footprint along with the use of water that is a working
fluid of global-environment friendliness.
Concurrently with the development of power electronics
in late years, semiconductor power devices such as gate
turn-off (GTO) thyristors, thyristors and diodes are used in
railways' substations for power conversion of high output.
These devices require some cooling means to remove the
heat generated at the conversion.
Conventionally, boiling cooling device using CFCs or
CFC substitutes as cooling medium were generally used
in this industrial field together with heat-pipe cooling
devices of horizontal type. However, there has been a
growing requirement for a new cooling method in view of
equipment's footprint reduction as well as global environment
preservation to cope with the global warming problem
caused by ozone depletion. To make a heat-pipe
cooling system maintenance-free, it was normal practice
to employ a horizontal-cooling scheme based on natural
convection. Such a horizontal-cooling scheme, however,
often caused problems of installation space because the
heat-radiating fins had to be very long because of their
poor heat radiating efficiency.
In an effort to solve this problem, Furukawa Electric has
developed the PowerKicker that enables footprint reduction
regardless of being a natural convection type, and put
it into practical application. See Photo 1.
1. STRUCTURE AND FEATURES OF POWERKICKER
Conventional boiling cooling system as shown in Figure 1
creates problems about global environment preservation
such as ozone depletion and global warming because its
structure is such that heat-generating components are
directly immersed in an electrical-insulating cooling medium
such as CFCs or CFC substitutes consuming a large
amount of such a cooling medium.
On the other hand, horizontal cooling device using heatpipe
based on natural convection as shown in Photo 2
can, since it uses heat-pipes as a heat-radiating component
toward the fins, not only provide high thermal conductivity
due to the use of heat-pipes but also take global
environments into consideration due to the use of deionized
water as a working fluid. The heat-pipe is known for
its high thermal conductivity

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