Harnessing test emissions

Janine Love- July 23, 2012

What do you do if you are a major diesel engine manufacturer that 2.5 million gallons of fuel each year and wants to cut its energy costs and CO2 emissions? The problem is you have to test your engines, and this particular manufacturer runs millions of miles of tests monitoring durability and performance with dynamometers, and it dumps huge amounts of heat into the air through cooling towers on the factory roof.

I know this setup is a bit off the beaten path for Test&Measurement World, but it does deal with harnessing heat, and that’s a big concern for many of our readers as well. And besides that, I just thought this was a really cool story. So here goes…

To test the diesel engines, the company’s engineers use test stands in a huge testing facility next to the manufacturing plant. The test stand includes a diesel engine and a dynamometer (which applies a load to the engine that simulates towing a 40ft, fully loaded trailer weighing about 20tons): see Figure (image courtesy of UCR CE-CERT). The test beds are cooled with a system that circulates water through the hot machinery, then pumps it up to the cooling towers, then reuses the water to cool the machinery again. The heat is released into the air above the plant.



In a pilot project, the company worked with AEM, Inc. to replace the eddy-current dynamometer on two of the test stands with an induction motor and a four-quadrant Sinamics S150 variable frequency AC drive (VFD) from Siemens. According to Siemens, the VFD has an active front end, meaning that it has the capability to recover the energy previously wasted as heat and return it to the company’s own power grid.

The result?  The company captured the wasted heat energy and returned it to the factory grid, saving about $150,000 a year in utility costs. Now, the new approach is installed in eight stands, and, once deployed across all 30 test stands, this solution could save $2.2 million and reduce CO2 emissions by 15 metric tons each.

Now this story sure does appeal to my green, tree-hugging nature. How about you? Any good energy-saving test stories out there?