DIY heat engines for recovering waste heat.

[Dolph1983]

Hi, I'm running a project at the moment to build DIY heat engines and was hoping someone would have some ideas on sources of waste heat and applications for my machine?

Basically, a heat transfer fluid is supplied to the engine at about 80 degrees C, this fluid is heated by waste heat eg, solar heat or flue/exhaust gases. The engine works in a similar way to a steam engine (rankine cycle), however the water is replaced with refrigerant, so instead of generating steam it generates vapour at <100 degrees C.

The power cycle is called the 'Organic Rankine Cycle' and has been used for donkeys years in industry to recover and convert waste heat to electricity. I am trying to build a micro scale 1kWe unit for domestic use with biomass boilers and solar panels, but there are many other uses.

As a test bed i built a unit which can be piped into a gas boiler heating circuit to run it when the grid power goes down. So when power goes down the engine's battery supplies electricity to the gas boiler via a power inverter to get the boiler heated up. Then the boiler supplies some of its heat to the engine which generates enough electricity to sustain the boiler, recharge its battery and give a net output.

It's fairly easy to build and all the parts are available off the shelf, just needs some basic plumbing tools. I built it into an old washing machine housing!

Some photo's below show the test unit, it gives a shaft power of about 350 watts and a net electrical output of 190 watts. This one is just a baby, when it's fully grown it'll be giving a net output of 1kWe. The fully grown version will be housed in an old fridge freezer.





Stu.

 

[Dolph1983]

You could PM the website details to interested people. Me being one

Yes that sounds a good idea.

I'll give a bit more detail about the project and then people can PM me if they want to take a peek.

The project is called "BioGen" and the unit pictured at start of this thread is named "prepper". The BioGen project website is intended as a R&D think tank where members can input ideas if they wish. I then build the engine and provide the members with an update video every so often. At the end of the project, (provided we had enough paying members to bulk up the budget) we all get a copy of the technical manual which details exactly how to build the engine. I hold the rights to the machine but each member is licensed to build their own machine for personal use.

So far i have 15 paying members, the first guys joined about a year ago and payed £3.99. Once i had built a working prototype and released a video more people joined and payed £15 each. The project has cost me about £1200 so far, so the membership fees help to pay for new kit but it will never cover the costs entirely. I turn people away daily who want to join without contributing their fee simply because it is unfair on the members who have payed. There is plenty of potential in a device like BioGen, so its really about people supporting the project if they like it, then hopefully in the not so distant future we can all benefit. If enough girls and boys joined then there would be no reason why we could'nt fully develop a working product and get it tested for MCS. Then instead of paying Baxi £5000 to £7500 for a CHP unit you can build your own for a £1500, and fully service and maintain it yourself with low cost off the shelf parts.

I'm back at college at the moment studying a Mechanical Engineering HND (which is a direct result of this BioGen project) so even if i don't get many members i'll keep working on it while i'm studying. Here's a paper concerning micro ORC for those who want to know a bit more: http://www.labothap.ulg.ac.be/staff/squoilin/files/TFE_SQ010607.pdf

PM me if you think it might be for you

Stu

 

[Dannypipe]

i like it

Me too. Brilliant.

 

[Dolph1983]

IMO the problem with things like baxi Ecogen and others, is that they use a specially built sterling engine which costs a shed load of wonga to manufacture, they are not mass producing their ecogen so the price will stay high. If a machine which uses off the shelf parts can be designed and built it will be far cheaper than ecogen but hopefully still comparable in terms of efficiency and reliability.

Here is a link you guys and gals may have seen, if not, these guys have spent 10 years building a pellet fired CHP system which is a really good piece of engineering but there is a slight issue with price! it costs 22,000 euro's. They also must be suffering because they can't mass produce: Button Energy heating systems - bison-Powerblock

 

[markfxy]

the other problem with eco gen is you can only get it through BG

 

[ecowarm]

the other problem with eco gen is you can only get it through BG

Or calor for LPG

 

[zzzjim]

Lovely tech , but like car Air-con , heat + refrigerants + rotating parts

will it need re-charging once in a while ?

 

[Dolph1983]

Yeah pal, it would probably need a yearly maintenance interval, charge up then if needed, if it was seeing heavy use ie 24 hr's a day it may need more servicing. Which is fine when you can do it all yourself 😉 and the parts are cheap as chips.

 

[Rickster123]

Dolph I love it! I thought I had too much spare time! It looks genius!

 

[poorman]

Could you use a system like this for a large vehicle, a bus maybe as they produce a considerable amount of waste heat or has this been done?

 

[cssolar]

I think there is a great future for thermal electrical power generation.

Here in Spain a vacuum tube can boil its contents in under 3 hours, and hot water is quite easy to store, it would be great to be able to convert the heat energy to electrical energy.

I am pleased to see the baxi eco gen it is a brave move by them I am sure other company's will soon follow in their foot steps.

There is a company in the U.S. which is quite interesting they are developing a heat and electric system for domestic use combining solar and a sterling generator

it is worth a look -- cool energy inc.

Ps. good luck with your project dolph1983

Tony Spain