Stirlingengineforum.com

First, apologies, I've never posted in forums before, so keep in mind I'm a nubie...

I need some feedback as to the viability of a heat to power engine that I have built, and in particular what the expected efficiency might be. This is patent pending.

I've attached some diagrams that detail how it works. I'm curious if there is already something that was previously generated or if I've created an alternate to the Stirling engine. This engine takes advantage of the thermal properties of water (typically) but could use a number of liquids that had combinations of high thermal expansion and low compressibility. The idea is that the water would be in a fixed loop on the output side of the heat exchanger, with the only relief being to drive a hydraulic cylinder or motor. On the input side either hot or cold water is circulated and returned to the appropriate tank based on it's temperature. I believe drive can be attained for both the hot and cold cycles.

The one key item for me is that normally I can go to extremes to verify power in versus power out. In this case, I would have the hydraulic cylinder bore be very small. This would increase the travel based on the fluid expansion, and thus the amount of work performed. Assuming the cylinder rod does not bend and the seals can handle the pressure build up, I do not see an upper limit to the amount of power that can be generated. I would expect something to limit me to the power that went into the heat exchanger. I'm sure there is, just haven't resolved it yet.

I appreciate any feedback and certainly would welcome any questions.

I doubt I did an adequate job of explaining my system.

The Heat Exchanger is a model BL26-60D from WiseWater, got it from Amazon. It's a 60 plate heat exchanger and naturally it's the heart of the system. The water in its hydraulic side of the heat exchanger is 0.40 gallons and the converter is specified to transfer heat at ~600KBTU/HR. A shell and tube heat exchanger may work better yet. The pump is a garden variety hot water pump. The zone valves are there to cycle the hot and cold water thru the heat exchanger. The hot or cold water circulated on the primary side heats or cools the water up on the hydraulic side, causing expansion (pressure) or contraction (vacuum) on the hydraulic side. Either a hydraulic cylinder is used or a hydraulic motor is employed to convert to power. At the end of each hot or cold cycle, the "Cycle Pressure Equalizer" is activated to return the hydraulic fluid to zero pressure or vacuum to start the other half cycle.

My system is pretty much the exact opposite of a Stirling Engine. The Stirling approach depends on the compressibility of air and has to deal with poor thermal conduction. While my system works on the incompressibility of water, the excellent thermal conduction of water, and its expansion rate. Water's expansion rate actually increases with a rise in temperature:
water at 20 o C : 0.000207 (1/ o C)
water at 30 o C : 0.000303 (1/ o C)
water at 40 o C : 0.000385 (1/ o C)
water at 50 o C : 0.000457 (1/ o C)
water at 60 o C : 0.000522 (1/ o C)
water at 70 o C : 0.000582 (1/ o C)
water at 80 o C : 0.000640 (1/ o C)
water at 90 o C : 0.000695 (1/ o C)

So while my system works in my experiments from 25C to 75C (the PVC piping started melting at this point, switching to metal), running it at 260C (under pressure) yields 10 times more expansion. If you heat up 42 gallons of water, which is about 350 pounds, to 500C (under pressure), it has about the same energy as the Tesla model 3 battery, which weighs 1442 pounds. But it won't use any rare metals, won't catch fire, won't wear out, is easily recyclable, costs far less, and will recharge faster.

I believe the efficiency to be significantly better than the Stirling engine, but would appreciate an informed outside opinion. Please let me know if you have questions or suggestions. Again, this is patent pending.

You're only 100 yrs late...

https://en.wikipedia.org/wiki/Malone_engine

The efficiency of this kind of engine is going to depend not just on the relative heat of hot versus cold reservoirs, but also on how much energy is required to pump your working fluid around. This is fundamentally the same as for a Hot-Air engine, except that water has much more mass than air does.

You state that you expect this design to be more efficient than a Stirling - what is the basis for that?