Stirling + Heatpump = Free Energy?

[arnoldlaine]

Further to my other comments the secret to the heat pump Stirling engine theory is the reuse of the waste heat from the Stirling engine.

For instance a Stirling engine might only produce 20 percent motive force but the heat losses can easily be recycled via the heat pump.

Stirling engines need a temperature difference to work.

Heat Pumps using change of pressure and change of matter state do not require a positive temperature difference and in fact can pump heat from a colder mass to a warmer mass thus producing a significant increase in temperature difference.

Heat pumps are looking for sources of heat this is why it is so easy to recycle virtually all the lost heat back through the heat pump.
Heat pumps can have COPs of over 6.
It is the heat pump that is key to the system working and producing free energy from the environment. The Stirling engine that is used can be relatively inefficient because the heat pump can reuse the waste heat.

Practical free energy should be possible but remember that no more energy goes into the system than comes out. Thus no laws of physics are broken.

Even with a simple thing like opening a window we use very little power but the energy flow through the window can be many thousands of times more than the effort used to open the window.

In the summer months in the Temperate regions of the Earth virtually all our heating is free from the sun and in the winter we still only pay for about 2 percent of the heating costs. The other 283 degrees are free. Think about it. Absolute zero is minus 273 degrees C. That is where we would be without the free heat from the sun!

[gregory.hickling]

This is obviously an intriguing idea. It should work as long we don't loose sight of what is actualy being achieved.

Think of the process as a bit like an electrical transformer or hydraulic ram pump. An electrical transformer converts from 'many electrons at low voltage' to 'few electrons at high voltage'. A hydraulic ram pump converts from 'large amount of water with low pressure energy' to 'small amount of water with high pressure energy'. In both cases there is an energy balance so no laws of physics are contravened.

Here we are fundamentaly talking about a thermal transformer. The heat pump is the core of this, it can push heat from a low temperature to a high temperature, it just requires a motive force. In this case the Stirling engine is envisaged to provide this. Now, if we look at it very simply we are considering 'large amount of heat at low temperature' to 'small amount of heat at high temperature'. From this model it becomes abvious that:

1. just as a certain number of electrons must 'drop out the bottom' of the electrical transformer and a certain amount of water must 'drop out the bottom' of the hydraulic ram then in this case a certain amount of heat (at low temperature) is going to have to 'drop out the bottom';

2. efficiency is important in all stages if this is going to work.

Point one indicates that there must be some real energy balance where this system is going to work so we just have to keep at it until we have worked out the details. Point two indicates that talk of 'the Stirling motor can be inefficient because the energy is free' is at least missguided if not simply wrong. Put simply, as motor efficiency falls then ever greater amounts of heat must 'fall out the bottom' for every Joule we push to higher temperatures. Eventually we will be leaking all the energy available out of the motor and there will be nothing left to drive the pump.

Using analogy (and working from gut feel) the afficiency of the heat pump will be most important for the temperature to which we can push the compressed heat. As efficiency falls in the pump then it will become increasing difficult to achieve a usefull temperature increase. Sooner or later the heat just gets moved with no temperature increase at all. However, this last point is a bit windy especially as we can probably not seperate the efficiencies and products of the two machines this cleanly.

Furthermore, statements like 'Low efficiency is o.k. because the energy is free AND WE CAN USE THE WASTE HEAT TO HEAT WATER OR SPACE.' also miss the basic point. We wanted to get some kind of mechanical work out of the system even if only for internal use. If you are just interested in the heating effect then drive the heat pump with an externaly powered electric motor and get all the high temperature heat you could ever need. The point was to avoid the external inputs and make the system self-sufficient at the very least.

So in concluson, I would suggest that as long as we start with sufficiently large hot and cold heat sinks with a useful deltaT and have sufficiently good mechanical efficiency in the mechanical parts we could certainly get both high temperature heat and excess mechanical work out of the system.

GlobalTrucker

P.S. (Working from memory) I once heard of a system that did just this. The Festival Hall in London was built with a Stirling motor/heatpump heating system. The heat sinks were ambient air and river water (it is located next to the Thames river). It did work, at least as a scientific show piece, but was later replaced by 'cheap' fossil fuel heating. The reasons for this may have been to do with maintenance costs. If you dig around in the internet you might find some references to it, I am just too busy at the moment.

[stan.hornbaker]

QUOTE:So in concluson, I would suggest that as long as we start with sufficiently large hot and cold heat sinks with a useful deltaT and have sufficiently good mechanical efficiency in the mechanical parts we could certainly get both high temperature heat and excess mechanical work out of the system.END-QUOTE

A Stirling engine used as a heat pump or cryo-cooler works best at temperatures below atmospheric and requires mechanical work input to drive it. There is NO excess mechanical work output from such a system.

As always there if no free lunch. Capiche?