Member Info for Phimx

Observer: Though I'm feeling a tinge of excitement that it might be as simple as you suggest

A few words on a piece of paper is all it takes to reconfigure the Chargers outputs

Observer: I interpret the news of the motor generator as a new product. They say embarking on new applications. Now if we just throw away the heat and produce 6.4 kWe from 20 kW input then we get electricity for 7p per kW a significant saving compared to the grid price at 12p. So you can charge your cars cheaper and if the prices is right feed it back into the grid. This could be a lower power device or a cheaper device because there is less thermal involvement

Observer: I'm not suggesting it was a lie, simply by aiming the device at the 15 kW market rather than 11.6 kW they thought it would have more appeal. They thought customers would want more heat than electric

Observer: some years later the marketing boys change the words, another way to write it up is "up to 15 kWt and 6.4kWe" but someone left in the simultaneous word which is a no no when using these figures because it leads people to think it's a perpetual energy machine. At Xmas after removal of the S word everything is fine.

Observer: regarding the motor generator ??? Surely that's what the charger is ?
Nonetheless from RNS 8 Jan 2015

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Sentec have assisted in the design of the control system including the user interface, diagnostics and management of the supply back into the Grid.
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The Grid tie in was sorted by Sentec 5 years ago - supposedly

Observer: the point I'm trying to get across is the early models did do 6.4 kW but were hobbled to give a greater thermal output I.e. 15 kW. The marketing boys then said you can have a product that gives 15kWt and 3.2 kWe. At the same time !

Remember it supposed to be a hot water boiler that uses the waste heat to give a bit of electric

Observer: your 14:31 I'll disagree on this one. It could be that the Disenco device produced 6.4 from a 20 kW input BUT for that you only get 11.6 thermal out. It may have been decided that wasn't enough for what they perceived the market to be, so they sacrificed some of the electric to give 15/3.2 using your heater element to burn 3.2 kWe. So now in the marketing you can now say up to 15 kWt and up to 6.4 kWe.

Remember the web site was redacted at Xmas time to remove the simultaneous word, that gave the impression you could have both larger outputs at the same time but was obviously incorrect for a 20 kW input limit.

Observer: I'll agree with you, I assumed that the 20 kW input was the some kind of standard supply that Inspirit were using. You may get more from your gas supply, haven't researched it. But for whatever reason Inspirit place a figure of 20 kW on the input, that could be because of the burner limitations. I take there figure as given but there is no reason to think more gas is available or the burner can use more.

Observer: The most water you get from your tap is when it's fully open and it also depends upon the the pressure the utility company provides. The same with gas and the blo**y internet download speed. With Inspirits tap fully open you get c 20 kW worth.

I thought my calculation was obvious. It is related to 6.4 and 3.2 kW. you can have 6.4 kW but only if the thermal is 11.6 kW. In the dark winter nights you can switch in your heater and that pumps up your heating to 15 kW but you lose out on your electric, it will drop to 3.2 kW. Assuming 20 kW in and 90% efficiency.

In input gas in will always depend upon local conditions in the same way as your water pressure depends upon how many taps are running in your house. So the figure stated, at least for a public gas connection will vary slightly. In a lab environment you could have great control over the input specification.

Not sure why you are pushing the efficiency angle. With the gas tap wide open then you get 18 kW (10% loss in the burner)applied to the Stirling engine and based upon its efficiency we get 6.4 kW (so Stirling Eff = 35% I must have messed up earlier!) So the thermal is what comes out of the Stirling 11.6 kW. Now obviously you could turn down the gas and get less of both outputs. BUT if you want more than 11.6 kW of heat then you switch in you heater, I suppose you could switch all 6,4 kW into the water to give you 18 kW. Standing back for a moment, you now have a simply water heater producing no electricity, not much of an improvement to the world. But if we limit the heat output to 15 kW we can also have 3.2 kW of electricity and gain something

Motor Generator - I thought all the conversion of the electrical output to the grid was sorted a long time ago .

Observer: I was thinking electrical, that is where the value lies but also hot water storage. The economies depend on being able to use the output. I don't know what the grid pays if you were to feed it to them.

I do not have storage in my house and I'm mister average - I'm sure. Hans up everyone with hot water storage.

The Inspirit Charger has a place in the world but not on the scale John Gunn suggests - in my opinion. I thus question its viability and think it will go the journey of others

observer: With the perfect operating regime 24 hours per day and using all of your 11.6 kW of heat
then 6.4 x 12 p = 76.8p/hour or £6 ,728 not too shabby. Payback in £11,500/6728 = 1.71 years !

Observer: If if if an application can be found that has a constant thermal load of about 11.6 kW for 24 hours a day then there are some good advantages to be had, great savings producing 6.4 kW of free electricity. Even then I think to maximise its potential it has to be married with a storage syste. Inspirit's talk of millions of boiler replacements won't fit with the chargers preferred operating regime. Undoubtedly there will be many close things that will still provide gains but not on the scale suggested by Inspirit

Observer: Also, the efficiency of their Stirling engine hasn't changed one jot since Disenco built around 2008. The Stirling efficiency being around 16-17 % - fairly mundane. Nothing really changed, just a bit shuffling around of the figures. I think, since buying the Disenco device they have been out of their depth, in every department - engineering, money, ambition etc. etc.

Observer: So you'll have redo your calculations, you'll end up losing some of your electric profits. Maximum benefit is obtained when 6.4 kWe is output.

Observer: I think your estimates are flawed. You cannot keep increasing the input gas. Inspirits input max figure of 20 kW will be for a maximum flow rate and unless you pressurize the system that's all you'll get. Now we've already agreed that modulation occurs, so for 15 kWt and 6.4 kWe something has to give. Assuming it's thermal and 90% Eff therefore the outputs will be 11.6 kWt and 6.4 kWe. If you want to use your idea of a heating element to cater for the thermal overloads then you'll have 15 kWt and 3.2 kWe .......... Eureka !!!!! a doubling of output can occur.

Calculating the economics are going to be difficult as I've said before. From other studies which use a cycle approach, and I'm prepared to back down on this, the economies never match the manufacturers figures

Observer: Why do you use the term 'we've' and not 'they' Is that a clue as to your invest interest here ?

Observer: Eureka moment indeed - well done, eminently sensible idea. I know, for me, I become one tracked thinking about something. It's normally only when I stop thinking about the problem at hand and then come back to it from a different direction that I make any progress. It's particularly apparent when doing a crossword.

Work out the economics and savings when you are switching in and out of the grid ??

Observer: The line about insufficient electric for a power shower was intended to be slightly flippant.

Observer: I was pondering the nursing home application and I got to thinking about the hot water aspect. The Stirling is slow to up its game for load changes so how will this affect it use. As you've stated a secondary boiler kicks in and supplies the hot tap water. It is a point I haven't considered, it would seem that for most applications a secondary boiler will be needed. A small boarding house might be a potential commercial customer but again I see problems with only 15 kW available then once a couple of guests start to run a bath and the kitchen is using water it could be problematic. We have become accustomed to instant gratification.

After all this thing has been designed to fit under a kitchen worktop

Observer: You guessed correctly. There was a discussion about some sort of controller which led me to discover about boiler rooms. So your lead boiler is running most of the time and its the Inspirit Charger supplying a miserly 15 kW. I'm guessing some kind of quiescent load. and then another boiler kicks in when the load changes. I'm having trouble trying to think of a suitable premises where the heat load would change this way. Medium sized office block, doctors surgeries ?
Even the nursing homes that were to be used as test beds don't quite figure in my head. I would have thought the load there would be fairly constant and also a bit too high for a 15 kW version; 10-15 beds say and communal areas . Small hotels would be along the same lines. I don't find it obvious where the customers are but I'm prepared to be educated.