Challenge/Solution Case Study: Correcting Overheating of Large Rectifier Unit for a Primary Aluminum Manufacturer

Nestor Rentas Challenge/Solution Case Studies


EFI Group was able to determine the root cause of overheating for two large rectifier units, develop a comprehensive solution, compile the required equipment specifications and obtain detailed quotes from several vendors for equipment that would allow the rectifiers to operate at maximum capacity.


The processing of aluminum requires a large amount of DC electrical current. In large rectifier units that generate large amounts of waste heat during the process, electricity is transformed from Alternating Current (AC) to Direct Current (DC). Two of the client’s rectifiers could not run at maximum ratings without overheating, reducing the amount of aluminum the plant could produce.


Since the rectifiers’ installation in 2003, the company had made several attempts to improve function with little success.

After reviewing the historical data and the available equipment documents, plus gathering empirical data from field measurements, EFI Group was able to calculate actual heat load at maximum rated current.

Calculations showed that the original and replacement heat exchangers were too small to remove enough heat and, under worst-case conditions, to run the rectifier at its full rated current. EFI Group then contacted several heat exchanger manufacturers to obtain detailed quotations on replacement units.


  • Heat transfer calculations detailing the actual heat load at the heat exchanger.
  • Cost estimate detailing multiple heat exchanger options.
  • Recommendations on which heat exchanger would best suit the application.
  • Preliminary general arrangement showing placement of the new heat exchangers.

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