ATP's Technology

AMERICAN THERMAL POWER

Electricity from Low Temperature Waste Heat

The Technology: How a Very Low Temperature Heat Engine works

The VLTHE combines technologies that have been proven for decades and centuries, in a new and uniquely valuable way. One example of combining proven technologies to create a new one was adding a steam engine to a ship. In the case of the VLTHE, we combine a heat engine, a heat pump, and a new turbine optimized for low temperatures and pressures. Here is a general overview of a new technology, centuries in the making.

Externally heated engines (“heat engines”) have been with us for centuries, and today are used in virtually every electric power plant, from coal to nuclear. All heat engines have a hot side, typically 500ºF/260ºF and higher, and a cold side. A working fluid, typically water, is heated by fuel, boiled to a superheated, pressurized vapor which is pumped to drive an expander (turbine, piston, etc.), which turns a generator. Work is extracted in the expander by lowering temperature and pressure, then the vapor is condensed back to liquid, typically using water for cooling. As much as 90% of the heat from the fuel is not used by the engine and requires cooling.

Heat pumps have been around for decades, commonly known as refrigerators or air conditioners. A heat pump also has a hot side and a cold side, but is rather the opposite of a heat engine. A heat pump transfers heat from one place to another, using a refrigerant as its working fluid. In air conditioning/refrigeration, cold refrigerant vapor captures heat from warmer air. A compressor raises the temperature and pressure of the vapor and sends the heat over to a condenser, where the heat is wasted (expelled to the environment) as the vapor is condensed back to liquid. Since the heat pump can take heat even from very cold air, waste heat of 90ºF/32ºC or more can supply plenty of btu’s for the heat pump to work with. Heat pumps use electricity but are very efficient, with 1 watt of electricity producing 5 or more watts of refrigeration.

One major aspect of our VLTHE technology (patents pending in the U.S. and worldwide) is combining a heat pump with a heat engine in a manner which mates the hot side of the heat pump to the cold side of the heat engine, and the cold side of the heat pump to the hot side of the heat engine. This not only allows intake of heat from very low temperature sources 90ºF/32ºC and up, it also recycles the waste heat from the heat engine itself, using both heat sources as fuel to run the heat engine.

So far, so good, but the heat supplied to the heat engine by the heat pump is not as hot as burning fuel. In fact, it is below 200ºF/93ºC. We overcome this in two ways. First, we use a refrigerant as the working fluid. Second, we use our unique patent-pending turbine.

Modern turbines evolved from the water wheels and paddle wheels of centuries past, and they all operate according to Newton’s 3rd Law of Motion (equal and opposite reaction). However, to optimize for performance at low temperatures and pressures, we return to the year 1685 and look also at Newton’s 2nd Law, concerning force, mass, acceleration, momentum, and so on. Our unique blade shape and the precise placement of our proprietary high-velocity injectors increase power three ways. By injecting the hot gas at very high velocity (Mach 0.7) we dramatically increase momentum. (Momentum= 1/2 of mass times velocity squared.) By almost reversing the incoming flow, we practically double the momentum again. With multiple blades and injectors, we multiply torque.

Sounds simple — once you think of it in the first place. But don't try this at home. For more information, contact us.