News
FALLING FILM RIG READY
TO SERVE INDUSTRY
By Benjamin Brits
As one of only a handful of tube heat transfer testing rigs in the world , South Africa ’ s University of Pretoria is home to this one . The rig , named “ Big Bertha ”, was the six-year result of the work put in during the PhD degree of Dr Bradley Bock – now a senior lecturer at the university in the department of mechanical engineering .
The rig was acquired from a Swiss university after the professor who commissioned it retired - so the find was quite fortunate for the South African team at the time .
“ As part of my PhD it took about four years to get the rig set up again , to understand the equipment , recalibrate everything after it was in storage for so long , and repair the minor damage sustained while transporting it over from Europe . We had to replace a couple of thermocouples and electronic modules that were broken in the shipping process . Having some background
The falling film test rig “ Big Bertha ” at the University of Pretoria .
information on the rig from the original creator , we understand it took about 10 years to build it from scratch and as you will see [ from the attached photos ], there ' s a lot going on with it . The rig is fairly unique in the sense that I am aware of only a few universities in the world that have testing facilities like this ,” says Bock .
" The study of falling film evaporators will allow for their improvement ."
All image credits © RACA Journal | Benjamin Brits
Dr Bradley Bock sets up the test rig ’ s high-speed camera .
So , what is this test rig exactly ? It ’ s aim is to study and measure the relationship of the heat exchange process taking place in a refrigerant falling film evaporator ( which , in simple terms , involves dripping refrigerant over tubes with water flowing inside ) rather than the more common traditional flooded evaporators used in the refrigerant industry . The study of falling film evaporators will allow for their improvement through optimising their various configurations in heating and cooling applications , and also significantly lower the refrigerant charge needed compared to flooded evaporators . The rig contains a bank of finned or enhanced tubes . The major advantage of this equipment , and its big ‘ selling point ’, is its large tube bank ( 30 tube capacity in total ) that can accommodate different
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