SpinOffs

   

We Are All Being Robbed!  Some Thoughts on Energy Heat Recovery

by Francis A. Di Bella, P.E. on Sep 27, 2017 10:12:54 PM

There are not many people who would argue that if you only received 30% of a commodity that you need to purchase every day to enable you to have your share of “…life, liberty and the pursuit of happiness”, then you should have some recourse to get the rest of your order or some money back. However, each day, everyone in the United States and throughout the world purchases energy. The availability of a ready source of affordable energy is one of the criteria for a country’s industrial economy and the prosperity of its citizens. Every engineer learns very quickly that not all the energy you pay for can be transformed into useful form. The engine in the transport vehicle that brings you to work is likely to have an efficiency as low as 25%. The hot water for the lavatories in your office building has been heated with a much more respectable efficiency of 80-90%, at least according to the First Law of Thermodynamics.  However, if your office building is heating water to only 105-110°F, using a fossil fuel-fired furnace, then the Second Law of Thermodynamics can be used to determine the second law efficiency to be only 15%. In contemporary engineering thermodynamics terms, you’ve increased the entropy of the universe. In contemporary layman’s terms, you’ve been robbed!

The CN300: Converting Low Temperature Heat to Electric Power

by Concepts NREC on Sep 1, 2016 1:23:00 PM

Concepts NREC introduces licensing for its new compact, high-speed, hermetically sealed turbogenerator. Nominally rated for 300 kWe, the CN300 is designed for converting low temperature heat to electric power using an Organic Rankine Cycle (ORC) process.

 

Historical Perspective
Increasing concerns for protecting the environment and the escalating cost of energy itself have raised interest in energy conservation to an all-time high. This interest extends to waste heat recovery systems. These systems produce electric power by converting thermal energy to electrical energy. And, when site conditions involve temperatures too low for conventional heat recovery systems, ORC processes become the best solution. These are typically defined as any heat source at temperatures below 800oF. In fact, according to one U.S. Department of Energy report, there could be as much as 1.5 to 2.0 quadrillion BTU/year of heat with temperatures below 500oF available from exhaust gas streams in the industrial sector alone. Naturally occurring heat sources may be just as plentiful.

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