About DTS, Ltd.

My company, Denkmann Thermal Storage, Ltd. was incorporated in January of 1988 under the laws of the State of Illinois as a 'C' corporation (meaning little bitty company). I started out on my own in the Fall of 1986 as a sole proprietor but incorporated a little over a year later. At the time, thermal energy storage systems (TES) were hot ticket items - many were being installed in test markets across the U.S. TES was a big 'pull market' at the time, usually financed largely by electric utility rebates and EPRI. So here is where I planted my roots, assisting EPRI, owners, contractors and design engineers in design and startup. Here's where I found that it is far easier to make ice on a heat exchanger than it is to melt it and do so over numerous cycles.

My first commission came along in the Fall of 1986 but my full-time involvement didn't occur until January of the following year. The State of Illinois Center (now known as the Thompson Center, named after the former governor, Jim Thompson) houses over 3,000 state employees in a 1.2M ft2 glass box facility that looks like it just landed from the planet Zorgon (sorry, Helmut). The HVAC system centers itself around a large TES system with 8 - 100k pound ice-on-pipe thermal storage tanks located deep down inside the building on the third sub-basement level. The refrigeration system also doubles as a heat pump, having one of the highest heat pump COPs I've yet encountered.

The two major refrigerants used in those early days of TES were either R717 or R22. During the late '80's I participated in the design and installation of numerous TES systems, attempting to feed the ice-building heat exchangers with thermal expansion valves. "Opps - this doesn't work, let's try something else!" I gradually gravitated towards flooded heat exchangers and in 1997 was awarded letters of patent in this technology as 'second-named'; Harry Fisher was first named (deceased). The primary heat exchanger in this patent is rather novel in that it functions as an evaporator during ice building and as a condenser during the air-conditioning mode. However, this is exactly how an ammonia evaporator (with hot gas defrost) works, but with one difference. Here the ice is removed (defrosted) but the IceBear leaves the ice on the heat exchanger during melting while agitating water inside the melt cavity' which in turn agitates primary surface - this greatly enhances ?, a heat transfer coefficient.

My first experience with ammonia came in 1965 - a small hog chill room for a pork packager on the south side of St. Louis. Oh man - what a headache! The room itself was lined with galvanized sheet metal and man! - did that puppy ever sweat! And drip! Here's where I caught my first experience with BTR evaporators - absolutely guaranteed to make a tin-lined room full of little miss piggies hanging from rails sweat. If only I knew then what I know now - blow the air downward between the rows of hogs, not up!
Today I specialize in refrigeration consulting in all of its forms and sizes and using a wide variety of refrigerants, not just ammonia (although I feel that this is arguably the best and safest refrigerant in the world).

As many of you may already know, I have been affiliated with the University of Wisconsin (Madison) since 1986 as an instructor in several of the Ammonia Refrigeration Series courses for Engineering Professional Development. I also assist Prof. Doug Reindl in his endeavors at the Industrial Refrigeration Consortium (IRC), the Department of Engineering in addition to assisting my wide variety of clients.
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