Low Level Heat Powers Low Cost Hydraulic Engine

Deluge, Inc. has developed a thermal hydraulic engine that is now ready for commercialization. The company has just successfully completed long term field testing of the technology, and has obtained patents on the design in nearly 40 industrialized countries world wide.

The Natural Energy Engine^™, requires no combustion, operates virtually silently, and generates no emissions. Developed over the past 10 years, it operates by utilizing low level heat energy, 180°F (82°C) is suitable for many applications, from solar, geothermal, or any other heat source, including waste heat from existing processes.

The main components of the engine system are quite simple – a piston/cylinder and a heat transfer system. The cylinder contains a piston and a working fluid, and depending on the application may have a module to reposition the piston after each stroke. The heat transfer system comprises heat exchangers, a system to circulate the heat transfer fluid (typically water), and a simple circulation controller. 

The key difference between a traditional combustion engine and the NE Engine is that the NE Engine relies on the transfer of heat to, and its subsequent removal from, a working fluid within the cylinder. As the working fluid is heated it expands, providing the pressure to drive the piston, and is subsequently cooled to complete the cycle.

“It is a thermal hydraulic engine,” says Brian Hageman, the inventor of the Natural Energy Engine. “It uses the same principles of expansion and contraction from heat as a thermometer, and uses the expansion to create powerful hydraulic pressure in a manner similar to an automobile’s brakes.”

The Company projects that engine configurations can easily be priced at 60-85% of power systems that produce equivalent output.

The NE Engine creates mechanical energy in a three step process:

Step 1:  Heated water is collected – for many applications 180°F is suitable.

Step 2: The hot water enters a heat exchanger where the heat is transferred to a working fluid. The working fluid, typically liquefied CO2, has a very high coefficient of expansion, meaning that it expands and contracts significantly, based on its temperature, while remaining in a liquid state. As the working fluid is heated, it expands, pushing a piston in the engine’s cylinder.

Step 3: Cooling water – generally in the range of 100° lower than the input water, with varying differentials depending on the application – then enters the heat exchanger causing the working fluid to contract, readying the piston for another stroke. 

Proof of the engine’s operating principles was first demonstrated at the U.S. Department of Energy’s Rocky Mountain Oil Testing Center in Wyoming, where a prototype engine successfully pumped crude oil from underground formations using geothermal energy as the sole source of heat for operation.

In early 2006, Deluge embarked upon extensive field testing, conducting a multi-engine long term test under varying conditions in Kansas fields, and completed well over 100,000 hours of continuous operation over more than a year.  The results exceeded even Deluge’s expectations in terms of reliability, costs, and performance.

Comments

[Tim]

What's the difference between this technology and a Sterling engine?

[Vit]

Sounds like Stirling where working fluid is actually a fluid. Apparently the design is different from Stirling.

[Volker]

From what I read that is not a Stirling system. In a Stirling motor you have two pistons and move the internal gas from cold to warm cylinder (and vice versa).

From the descriptions here you only have a single, sealed cylinder. Instead of moving the internal gas around (as in a Sirling) they switch between heating/cooling water. As this means re-cooling/heating the cylinder I guess the efficiency is worse than that of a Stirling, plus there is more stress to the material (due to the heating/cooling cycles) leading to earlier fatigue in the cylinder material.

[Peter Hunt]

I sure would like to see the details in terms of output efficiency., start up cycles, the elements that determine it's effectiveness such as working fluid. Is there any phase change? How many lbs per HP?

Don't get me wrong, I like bottoming cycles but this seems to massive to be pratical for any thing but a low HP steady state installation.

Can you explain the Erricson cycle?

[Peter Hunt]

I sure would like to see the details in terms of output efficiency., start up cycles, the elements that determine it's effectiveness such as working fluid. Is there any phase change? How many lbs per HP?

Don't get me wrong, I like bottoming cycles but this seems to massive to be pratical for any thing but a low HP steady state installation.

Can you explain the Erricson cycle?

[Reality Czech]

Efficiency and power will both be poor.  This is essentially a Newcomen engine with the cylinder and boiler combined.  The cylinder will have to be heated for each power stroke and cooled for each condensing stroke, making the operation very slow and losing efficiency due to the extra heat transferred without doing useful work.

[Stephen Boulet]

What if the piston/cylinder were made out of some material with a low thermal mass, like ceramic? It seems like the pressure would need to be high to have CO2 liquid at these temps.

Stephen

[Stephen Boulet]

What if the piston/cylinder were made out of some material with a low thermal mass, like ceramic? It seems like the pressure would need to be high to have CO2 liquid at these temps.

Stephen

[Reality Czech]

Reducing the losses due to the bad design does not eliminate them.

The inefficiencies of engine designs like this have been known for centuries (literally).  The only way someone can claim this as an improvement, and get people to believe it, is a pervasive ignorance of basic thermodynamics.

[RML]

I'll bet they are using a Malone cycle. The expansion ratio of a liquid is fairly good near the critical point so you can get a good density change with relatively low dT.

Efficiency of the Malone can be very good as well (reported similar to Stirling in Malones' original work) but much depends on the regenerator and overall engine design.

Also, as a guy that worked on many Stirling engines, I can tell you that the cyclic stress from pressure is much easier to deal with than the low cycle fatigue of heating up a Stirling engine (800 C) for each start.
High pressure sealing of a piston for the Malone is the big challange though...

[donb]

There must be hundreds of ways to make inefficient engines. This looks like yet another.

RML mentions cyclic stress from pressure (which all reciprocating engines have). But to make this one work, there is cyclic thermal stress as well.

The design relies on a single heat exchanger. This means it will see cyclic thermal stress. Also, if there is only one heat exchanger, either it must be thoroughly drained each half-cycle, or the hot and cold fluids will mix. Any mixing will cause further loss of efficiency, and may be undesirable for other reasons (e.g., hot brine contaminating and cold fresh water).

Good observation by RML about using fluids around their critical point - for CO2 it is 88°F.

The original posting links to a web site with further information. Some extravagant claims are made, such as no valves for the engine (thus simple and less friction). While there may not be valves for the working fluid, there certainly are valves for the hot and cold fluids running through the heat exchanger. So complexity and friction are back in.

Perhaps a better engine would have two cylinders - a small one pumping CO2 liquid and a large one pumping CO2 gas, with a hot heat exchanger in the CO2 flow from the small to large cylinder, and a cold heat exchanger in the flow back (plus appropriate valves for the working fluid). No excess thermal cycling, no mixing of hot and cold fluids.

There is nothing wrong with low efficiency designs that tap into waste energy if they can be done cheaply. But it looks to me that a better design could extract more shaft power from less waste heat using less material.

Engineering is the art and science of doing for $1 what any damn fool can do for $3.

[Stephen Heyer]

I think all the discussion about efficiency is pointless. From what I read, I gather the whole point of this engine is that it works off low grade waste heat, essentially free energy (you don't have to pay for it).

All that matters is that it do whatever it is supposed to - say pump oil, with, in effect, free energy.

[donb]

Stephen - read my last two paragraphs.

[casey]

Why is DOE sinking money in this if it is nothing new?

[casey]

I am familiar with a facility that produces 75,000 ACFM of flue gas at 430 deg F. What is the best way to convert it to electricity with the greatest efficiency without spending > $1 million? What efficiency should we be shooting for? Lets make money!!

[RML]

Hey Casey,
A lot depends on your ability to reject heat and the flue gas composition but a few things to consider:
If you want really cheap, you could use a steam engine- compound expansion if you want to get fancy.
A better system may be an organic rankin. You won't want to loose the working fluid with this so probably best to use a motor technology that's easy to seal with a rotary shaft seal. It's probably cheapest and easiest to use a vane motor but you could also use a screw expander or if you really want to get tricky, use a turbine.

[Reality Czech]

Casey, what temperature do you need to get proper draft in your stack and avoid condensation of corrosive liquids?  Lofting of the plume to keep the neighbors happy?

[Casey C]

The temperature of the steam coming out of the wet scrubber is 120 deg F. The plant manger says we can't cool the flue gas below the dew point or we will get sulfuric acid. I don't know what the dew point is.

[Manu Sharma]

The engine developed by Deluge appears to be a Minto wheel which too produces mechanical energy through heat transfer.

[Manu Sharma]

Correction:
Just read the original article... looks like there's no wheel in this case, though the conversion is the same as in a Minto wheel.

[davea0511]

This is very different than anything done before. Fluid expansion only - no phase change. Very interesting. If there are inefficiencies they are related to the design, not the technology. We should look at this the same way we look at the first internal combustion engine - the first of it's kind. Whatever deficiencies exist I'm sure will be engineered away with time, and given it's uniqueness it's sure to find a niche that Stirling and other thermal engines do work as well in (otherwise why not just use a stirling)?

[Ice Czar]

Patent Number 5899067
and a pimp for http://www.pat2pdf.org/ which I just adore ;)

[sreenivasan]

can you please explain what is erricso cycle with T-S diagram

[Matt]

I bet any $$$ that this engine is vaporware or ahem. liquid ware.

I bet it will never see the light of day.

[Al]

Then check them out in the "light of day" in Hawaii...2 of them

[Cyril R.]

Organic Rankine is not economical for such low delta Ts. It is a huge challenge to make any system economical for such small temperature difference. Do these guys have it?

Carnot is not the way to go for low temperature heat. If infrared nano antenna's pan out, a plate heat exchanger style generator might be devised with reasonable efficiency. Since emissivity rises to the fourth power of the absolute temperature difference, high grade heat is still desireable even then.

[energychina]

if the engine is the same as you said, it's great!