It began well before 1994, but an event from that spring stands out as a turning point in my understanding of the need for energy awareness when designing or working on fluid power systems. I had been invited to assist in specifying a chiller for a hydraulic system at a facility in Claremont, N.H. There were five molding machines, each accompanied with a ten-ton chiller to cool the hydraulics. Business was good, and the company was purchasing a sixth machine but wanted to purchase the required chiller locally. The chiller company was unfamiliar with hydraulics and wanted me to listen in to be sure they were getting and giving sufficient information to properly specify the chiller. I was informed that the existing chillers were at maximum capacity and were inadequate in the hot summer months.
Each hydraulic system had a 40-hp (30-kW) and a 60-hp (45-kW) electric motor driving fixed displacement pumps. A ten-ton chiller is driven with a 10-hp (7.5-kW) motor, and a 5-hp (3.7-kW) motor was used to drive a pump, sending the chiller fluid through a coil in the reservoir. This brought the total power consumption to 115 hp (86.2 kW).
Chillers are rated in refrigeration tons. The term is based on the amount of cooling to be expected from a ton of ice. A one-ton chiller rejects 12,000 Btu’s per hour. Each hydraulic system was releasing 120,000 Btu’s per hour into the New Hampshire air. At first I thought there was something in the process that required this amount of cooling, but I soon realized that it was the hydraulic system itself that was generating the heat. Of the 115 hp (86.2 kW), 62 hp (46 kW) was used to either generate or remove heat. No one had associated the kilowatts entering through the electrical panel with the 600,000 Btu’s per hour that were being wasted. It was simply understood to be the cost of doing business when using fluid power.
Someone in our industry had designed this inefficient hydraulic system. The unwitting customer had bought from the lowest bidder without asking or being informed about the cost of ownership. I determined that I was going to do my best to design systems that were as efficient as I could make them and to help customers and fellow fluid power professionals expect the same.
My association with the International Fluid Power Society gave me a forum to express my ideas and concerns. I was given an opportunity to write a series of articles for the Fluid Power Journal, which I compiled under the title “Watts It All About.” Now, I am honored to have been asked to host a blog for the Journal using that title. Some of my articles can be found there, and I hope to have comments and ideas from readers as well.
By Dan Helgerson, CFPAI/AJPP, CFPS, CFPECS, CFPSD, CFPMT, CFPCC, CFPSOS LLC Fluid Power Journal Technical Editor
Come visit at http://fluidpowerjournal.com/watts-it-all-about/.