Question:
Hi, I’ve been reading these newsgroups for a while and really enjoy the info. I’m trying to build a system that is made up of many types of generators, i.e. Wind, solar, hydro. I purchased a Bergey 10kw Excel that has the grid tie inverter and was thinking about using a Compaq UPS M2200 – UPS – 2200 VA – 220 volt inverter with it. I’m still in the planning stages of this project and need advice/comments on what can and can’t be done.solar pv panel size This will be an off grid project. Some of the ideas that I was thinking about were using the excess energy to heat up a large 10,000 gallon tank of water for winter heating/hot water and/or producing hydrogen for cooking. I know that this is vague but I just wanted to throw some info out to get some feedback. solar pv panel size
Response:
Hi, I purchased a Bergey 10kw Excel that has the grid tie inverter and was thinking about using a Compaq UPS M2200 – UPS – 2200 VA – 220 volt inverter with it. I’m still in the planning stages of this project and need advice/comments on what can and can’t be done. This will be an off grid project. solar pv panel size
Why did you get the grid-tie inverter if this is an off-grid project? I have a Bergey XL but have the battery charging model with dual Trace SW5548’s and a 48V/1640AH bank of Surrette 8CS25P flooded lead-acid batteries. If the wind doesn’t blow enough during the summer, I’d consider adding PV. I have no source for hydro unless someone comes up with a residential sized unit that can harness the tides.solar pv panel size
Response:
The grid tie was part of the wind generator that I purchased. It was a steal at the price I purchased it at. I suppose I could go to Bergey and exchange the grid tie for an off grid version since I’m in Oklahoma anyway. I do intend to include PV in this system as well. As for an inverter, the cost of the Trace and other are very high compared to the cost of the UPS inverter. The larger ones are true sine, I’m just concerned whether they will hold up over the long run.solar pv panel sizei, I purchased a Bergey 10kw Excel that has the grid tie inverter and was thinking about using a Compaq UPS M2200 – UPS – 2200 VA – 220 volt inverter with it. I’m still in the planning stages of this project and need advice/comments on what can and can’t be done. This will be an off grid project. Why did you get the grid-tie inverter if this is an off-grid project? I have a Bergey XL but have the battery charging model with dual Trace SW5548’s and a 48V/1640AH bank of Surrette 8CS25P flooded lead-acid batteries. If the wind doesn’t blow enough during the summer, I’d consider adding PV. I have no source for hydro unless someone comes up with a residential sized unit that can harness the tides solar pv panel size.
Response:
the cost of the trace system is well worth the price.I have installed quite a few system similar to yours and trace is for the most part bullet proof….don’t get to carried away with the size of your water tank your heating…you might not warm 10,000 gal but a degree or two…smaller the better..just two cents worth of experience..tom.. www.angelfire.com/wa2/solarshop
solar pv panel size The grid tie was part of the wind generator that I purchased. It was a steal at the price I purchased it at. I suppose I could go to Bergey and exchange the grid tie for an off grid version since I’m in Oklahoma anyway. I do intend to include PV in this system as well. As for an inverter, the cost of the Trace and other are very high compared to the cost of the UPS inverter. The larger ones are true sine, I’m just concerned whether they will hold up over the long run. Ral Hi, I purchased a Bergey 10kw Excel that has the grid tie inverter and was thinking about using a Compaq UPS M2200 – UPS – 2200 VA – 220 volt inverter with it. I’m still in the planning stages of this project and need advice/comments on what can and can’t be done. This will be an off grid project. Why did you get the grid-tie inverter if this is an off-grid project? I have a Bergey XL but have the battery charging model with dual Trace SW5548’s and a 48V/1640AH bank of Surrette 8CS25P flooded lead-acid batteries. If the wind doesn’t blow enough during the summer, I’d consider adding PV. I have no source for hydro unless someone comes up with a residential sized unit that can harness the tides.solar pv panel size
Response:
As for the water, I intended to use a solar/glycol panel to heat the water year round, the electric heater was to be used only as way to ensure excess energy would be diverted and used when needed. This would be a concrete tank with some type of rock installed to absorb the heat and retain it. I already have a pond planned for summer cooling, ie geothermal hydronics and thought this would be a good way to ensure winter heating. One of my real questions is: since the Bergey grid tie inverter requires power to be on the line to sync with, will a low VA/Watt inverter be enough to fool the inverter into believing that it is connected to the grid and/or is this a good idea? Ral – Hide quoted text — Show quoted text – the cost of the trace system is well worth the price.I have installed quite a few system similar to yours and trace is for the most part bullet proof….don’t get to carried away with the size of your water tank your heating…you might not warm 10,000 gal but a degree or two…smaller the better..just two cents worth of experience..tom.. www.angelfire.com/wa2/solarshop The grid tie was part of the wind generator that I purchased. It was a steal at the price I purchased it at. I suppose I could go to Bergey and exchange the grid tie for an off grid version since I’m in Oklahoma anyway. I do intend to include PV in this system as well. As for an inverter, the cost of the Trace and other are very high compared to the cost of the UPS inverter. The larger ones are true sine, I’m just concerned whether they will hold up over the long run. Ral Hi, I purchased a Bergey 10kw Excel that has the grid tie inverter and was thinking about using a Compaq UPS M2200 – UPS – 2200 VA – 220 volt inverter with it. I’m still in the planning stages of this project and need advice/comments on what can and can’t be done. This will be an off grid project. Why did you get the grid-tie inverter if this is an off-grid project? I have a Bergey XL but have the battery charging model with dual Trace SW5548’s and a 48V/1640AH bank of Surrette 8CS25P flooded lead-acid batteries. If the wind doesn’t blow enough during the summer, I’d consider adding PV. I have no source for hydro unless someone comes up with a residential sized unit that can harness the tides.solar pv panel size
Response:
…This would be a concrete tank with some type of rock installed to absorb the heat and retain it.
You are looking for some type of rock that has more heat capacity than water by volumesolar pv panel size
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I must admit that I’ve not done enough research on the water heating issue. I do already have the solar water panels, pump and exchange water tank. I read an article many years past (I’ll have to find it) that explained the dynamics of storing the heat in water and rock for use in home heating. Hence the thoughts of using rock and water. My real question concerns the inverters!solar pv panel size …This would be a concrete tank with some type of rock installed to absorb the heat and retain it. You are looking for some type of rock that has more heat capacity than water by volume? solar pv panel size
Response:
The grid tie was part of the wind generator that I purchased. It was a steal at the price I purchased it at. I suppose I could go to Bergey and exchange the grid tie for an off grid version since I’m in Oklahoma anyway.
It sure can’t hurt to talk to one of the people at the factory. I’d start with Steve Wilke. They’re selling a lot of units for California, so they may well have a need for the grid-tied version and be willing to make you a deal. I do intend to include PV in this system as well. As for an inverter, the cost of the Trace and other are very high compared to the cost of the UPS inverter. The larger ones are true sine, I’m just concerned whether they will hold up over the long run.
My understanding is that the Trace inverters are pretty reliable. (I have two, as I mentioned). Try www.altenergystore.com for good pricing. Their programmable relays could also be set up to control your excess power diversion. They can also be set up to automatically start a backup fossil fuel generator, if needed.solar pv panel size
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Water stores way more heat than rock per pound and I think per square foot up to about 100C, where water starts boiling. The advantage of rock is that it can be heated hotter (and of course it is solid, so the storage container cannot collapse if you forget and drive a tractor rig over the top of it). You can store heat energy at 500C or so in rock, in order to use it to drive a heat engine/heat pump. The hotter you store the heat, the smaller your storage volume has to be, but the faster the heat is lost through the insulation. A balance suggests that long term storage might best be done with water at near boiling and a heat engine/heat pump cycle except where it is very cold outside. I did the calculations to verify that a 10 foot diameter cylinder about 10 feet deep, with about a foot of a good quality insulation around the water tank, and a second outside tank to keep the insulation dry, could in principal store enough heat energy to supply a house for 3-4 months. Making this kind of thing work well and keeping the price reasonable needs some experience, but at least the physics seems to be OK. By the way, the reason to use 100C water, more than just to store more heat, is that having near a 75C temperature difference between the storage and the house permits you to run a heat motor (a sterling, or a low temperature steam engine of some sort), and this would let you have both electric power and the energy to run a heat pump and draw in 3-5 times the amount of heat that you have to draw from your storage. In effect this would increase the effectiveness of your stored heat as much as doubling or more the size of the storage. (The exact advantage depends on how long the storage stays hot enough to run the motor efficiently, and how cold it is outside. When it is more than about 30 degrees C colder outside than inside, the heat pump gain goes down rapidly and this becomes less valuable. For the Seattle area, where we keep our inside house at 63f and outside is typically around 45-50f during the time we need heat (which is really most of the fall, spring, and winter), it should work very well.) If you deliver heat to the tank from the top (or basically at the point where the water temperature is just barely colder than the incoming water), the tank will be striated with the hottest water at the top, and the bottom quite cold. This has the maximum heat energy for your system and you want to withdraw energy so as to keep it this way. So you run a heat engine from the hot top, to the cool house, then use it to run a heat pump and suck heat from the bottom of the tank or outside (which ever is hotter) into the house. If you have cloudy mild days, a plate style collector can heat the bottom of the tank,solar pv panel size and when it is clear, a collector with a modest focus gain could provide near boiling water for the top of the collector. If you have a high gain collector, say 500C, then you can drive a high temperature heat engine between the real hot oil or air, and the water near boiling at the top of the tank and then run a heat pump to suck low temperature heat from outside, or the bottom of the tank if you have a lot of low quality heat there and it is really cold outside, and pump that in to your hot water level. All you need to do the put heat in and keep the tank striated is to control the circulation so convection currents do not get to suck cold water into the flow and mix the levels. Around our place this year we are having a very bad water shortage. Suddenly making a large cistern like this makes sense, even if it is only to store the winter rain.
- Hide quoted text — Show quoted text – I must admit that I’ve not done enough research on the water heating issue. I do already have the solar water panels, pump and exchange water tank. I read an article many years past (I’ll have to find it) that explained the dynamics of storing the heat in water and rock for use in home heating. Hence the thoughts of using rock and water. My real question concerns the inverters! Ral …This would be a concrete tank with some type of rock installed to absorb the heat and retain it. You are looking for some type of rock that has more heat capacity than water by volume?solar pv panel size
Response:
Water stores way more heat than rock per pound and I think per square foot
Per cubic foot, nitwit. solar pv panel size
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Nick. I know that. Are you this rude with all your acquaintances, or is it just me?
solar pv panel size Water stores way more heat than rock per pound and I think per square foot Per cubic foot, nitwit. Nick
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Are you this rude with all your acquaintances, or is it just me?
I don’t suffer fools gladly, Fred, and find most of your postings a waste of time. You often post nonsense, and seem to ignore practicalities, as in “some sort of Stirling engine.” We need more details. Consider the Carnot efficiency and magnitude of energy flows in the heat pump scheme you described…solar pv panel size
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Hi: I suggest going with a 24 volt system. There is a super wind generator that can be hooked up to the main battery bank and the excess going to heat water. 10,000 gallons of water is a LOT of water, you might consider something closer to “normal”. There are a lot of web sites that will give you a lot of good information about alternative energy and how to set it all up. My house was set up with the bare minimum. After I fried two wind generators that had built in regulators, I finally ordered one without the built in regulator (also called a brake), and simply run the wind generator through an isolater that charges two banks at the same time. If you want to sell your excess power, you want to set it up as a 24 volt system. And use a true sine wave inverter. Trace makes a good one. The only reason I even mention Trace is because they back their products. To the point of rebuilding a regulator (that was given to me) for free (I paid the shipping). Which says a lot for a company…. Cathy – Hide quoted text — Show quoted text – Hi, I’ve been reading these newsgroups for a while and really enjoy the info. I’m trying to build a system that is made up of many types of generators, i.e. Wind, solar, hydro. I purchased a Bergey 10kw Excel that has the grid tie inverter and was thinking about using a Compaq UPS M2200 – UPS – 2200 VA – 220 volt inverter with it. I’m still in the planning stages of this project and need advice/comments on what can and can’t be done. This will be an off grid project. Some of the ideas that I was thinking about were using the excess energy to heat up a large 10,000 gallon tank of water for winter heating/hot water and/or producing hydrogen for cooking. I know that this is vague but I just wanted to throw some info out to get some feedback.solar pv panel size
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Are you this rude with all your acquaintances, or is it just me? I don’t suffer fools gladly, Fred, and find most of your postings a waste of time.
Somewhere around adolescence more of us learn that no matter how much book learning we have, it’s not worth much if we’re nasty, condescending folks who use our learning to browbeat others. Unfortunately, Nick hasn’t learned that, and after one tantrum too many he has earned a spot in my killfile. There are plenty of folks who can do math and give informed answers; we don’t need the nasty ones. — Start-Up Education, P.O.Box 7072, Pueblo West, Colorado, 81007 USA Find out about Start-Up Education: solar pv panel size
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Are you this rude with all your acquaintances, or is it just me? I don’t suffer fools gladly, Fred, and find most of your postings a waste of time.
More specifically, I find most of Fred’s “solutions” frustrating. They remind me of that cartoon with the scientist and the blackboard covered with equations and a little box at the bottom that says “then a miracle happens”solar pv panel size Unfocused brainstorming. I’ve also noticed his fondness for nuclear power and the big business approach, aka Boeing. He claims to be a physicist, but often has trouble spelling that…solar pv panel size Somewhere around adolescence more of us learn that no matter how much book learning we have, it’s not worth much if we’re nasty, condescending folks who use our learning to browbeat others.
Some do, some don’t. They are often allowed to choose their behavior. Unfortunately, Nick hasn’t learned that, and after one tantrum too many he has earned a spot in my killfile…
How nice to have the last word. You may be showing some arrogance and condescension here too, and a desire to control the behavior of others. There are plenty of folks who can do math and give informed answers; we don’t need the nasty ones.
And a belief that everyone shares your beliefs. Speak for yourself, Ellen solar pv panel size
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Dear dear nick. I suffer fools gladly, since they are the only kind of people on this planet. There are a lot of folk working with sterling and steam engines. Were I to get specific it would literally take over the list. If you need more details, I suggest spending a bit of time with any of the hundred web sites for those interested. This idea has been developed to the point where basic design issues can now be developed a bit. The penultimate question is not if it is an idea of any possible merit, or a waste of time, but if it can be made to work practically. This involves choosing the right heat pump, Stirling or steam engine for the job. That a heat pump will provide a gain in effectiveness is proved by those who use em to improve their bottom line electric bill. Modifying one to do this job is as simple as choosing one that works with the house you are in and using an alternator to drive it’s AC motor. This is probably more efficient than a shaft and transmission drive, though not as good as a unit designed to run off a single shaft. I believe that we can take the process a step at a time without falling flat on our faces, and each step provides some items of value. The heat storage tank is a simple large scale thermal cistern. In fact, I thought it was your comment regarding this idea that convinced me it was worth thinking about. I had not imagined that a reasonable sized tank could store enough hot water to keep a house warm for months. The stirling/steam engine chosen needs a bit of work. I have a pretty good grip on the thermodynamics of the beast, but actually picking one off the line that can operate efficiently with a 50-70 C temperature difference is not so easy. The stirling can probably do it. The low temperature OTEC turbines designed to use the 30C temperature difference between the deep ocean and surface water show that it can be done, but not how best to do it for a household. Most of the moderate sized steam engines I have found operate with greater than 100C temperature differences, although there is no hard natural limit to lowering this using vacuum or a lower boiling temperature fluid. While some experimental stirling engines have been run on temperature differences as low as 2-3C, practical engines in the power level and temperature range we want do not seem to be readily available. I would say we have some modest design development to do. I had hoped that some one with some practical experience here might already know of a suitable engine for this application. It is pretty clear that the pistons need to be larger than for a higher temperature difference. The Carnot efficiency is set by the temperature difference Nick. This is why a heat pump works great only if the temperature difference is not too great. I am not sure what you mean by “energy flow”. The heat flow is as I described, from hot side, to motor to house. The mechanical energy from the motor drives the heat pump (with an alternator, electric motor taking the place of a shaft if convenient.). and then the heat flows from outside (or from a warm storage area) to the heat pump to the house. We give up a bit of efficiency converting the heat into energy by using the relatively warm house as the cold side for the heat engine, but we get to use 100% of the reject heat to do the job we need done. Power levels are on the order of those we are burning to provide heat for the house as it stands, if the heat is electric. For a typical house this ought to be on the order of 10KW of total heat input I think, so the motor needs to be about 5-10 HP.solar pv panel size (I am assuming gain from the heat pump here.) Nick. I am a physicist. Minor gaffs aside, I have a fair grasp of the thermodynamics we are dealing with. Practical experience I have almost none. In any case, if we are going to invent a better way to do it, we need to go beyond what is now practical to what can be made to be practical. So if you know of some practical reason that would make this concept impossible to bring to fruition, great, let’s hear it. Otherwise I need help figuring out how to make it practical. Perhaps one of our buds here likes to play with steam engines and is willing to try modifying one to run off this kind of low temperature difference heat?
- Hide quoted text — Show quoted text – Are you this rude with all your acquaintances, or is it just me? I don’t suffer fools gladly, Fred, and find most of your postings a waste of time. You often post nonsense, and seem to ignore practicalities, as in “some sort of Stirling engine.” We need more details. Consider the Carnot efficiency and magnitude of energy flows in the heat pump scheme you described..solar pv panel size
Response:
There are a lot of folk working with sterling and steam engines. Were I to get specific it would literally take over the list…
Go ahead Fred solar pv panel sizeLet’s see some brand names and numbers… If you need more details, I suggest spending a bit of time with any of the hundred web sites for those interested.
Any particular hundred?solar pv panel size …The penultimate question is not if it is an idea of any possible merit, or a waste of time, but if it can be made to work practically.
You might say that determines its merit. …That a heat pump will provide a gain in effectiveness is proved by those who use em to improve their bottom line electric bill. Modifying one to do this job is as simple as choosing one that works with the house you are in and using an alternator to drive it’s AC motor.
As simple as that. You’ve glossed over the heat-to-motion part again. …The stirling/steam engine chosen needs a bit of work.
Agreed. (Have you chosen one, then?) I have a pretty good grip on the thermodynamics of the beast, but actually picking one off the line that can operate efficiently with a 50-70 C temperature difference is not so easy. The stirling can probably do it.
Do what?solar pv panel size The low temperature OTEC turbines designed to use the 30C temperature difference between the deep ocean and surface water show that it can be done, but not how best to do it for a household.
Show what can be done? How much power do these turbines make, at what efficiency? How big are they, and what do they cost? They seem to have minimal relevance, if they don’t show how “it” can be done for a household. …practical engines in the power level and temperature range we want do not seem to be readily available. I would say we have some modest design development to do.
I’d say there’s lots to do, mainly in raising development money 
Some describe this as chickens and eggs. Good Stirling engines do not exist, so there’s no market for them, and nobody wants to develop one, since nobody wants to buy any. Some people say thermoacoustic engines are cheaper, with piezoelectric elements and almost the same (low) efficiency. They want to build them into oil furnaces to power the blowers (with a much higher temp heat source.) The Carnot efficiency is set by the temperature difference…
So you’d start with 60/(273+60), ie 18%, and go downhill from there, with a real engine. Say 5% overall heat-to-motion? I am not sure what you mean by “energy flow”…
As I understand your description, you suggest using a solar hot water heat source, with the house as a cold sink, for some mythical Stirling engine which turns an alternator shaft which provides electricity for a heat pump which helps heat the house… Would this also provide all the electricity the house needs in the winter? Or would that come from some mysterious but inexpensive photovoltaic house paint? …Power levels are on the order of those we are burning to provide heat for the house as it stands, if the heat is electric. For a typical house this ought to be on the order of 10KW of total heat input I think, so the motor needs to be about 5-10 HP. (I am assuming gain from the heat pump here.)
Care to explain this with some more details and numbers?solar pv panel size
Response:
The following link details the rock, water, phase change salts heat storage tradeoffs. solar pv panel size Dear dear nick. I suffer fools gladly, since they are the only kind of people on this planet. There are a lot of folk working with sterling and steam engines. Were I to get specific it would literally take over the list. If you need more details, I suggest spending a bit of time with any of the hundred web sites for those interested. This idea has been developed to the point where basic design issues can now be developed a bit. The penultimate question is not if it is an idea of any possible merit, or a waste of time, but if it can be made to work practically. This involves choosing the right heat pump, Stirling or steam engine for the job. That a heat pump will provide a gain in effectiveness is proved by those who use em to improve their bottom line electric bill. Modifying one to do this job is as simple as choosing one that works with the house you are in and using an alternator to drive it’s AC motor. This is probably more efficient than a shaft and transmission drive, though not as good as a unit designed to run off a single shaft. I believe that we can take the process a step at a time without falling flat on our faces, and each step provides some items of value. The heat storage tank is a simple large scale thermal cistern. In fact, I thought it was your comment regarding this idea that convinced me it was worth thinking about. I had not imagined that a reasonable sized tank could store enough hot water to keep a house warm for months. The stirling/steam engine chosen needs a bit of work. I have a pretty good grip on the thermodynamics of the beast, but actually picking one off the line that can operate efficiently with a 50-70 C temperature difference is not so easy. The stirling can probably do it. The low temperature OTEC turbines designed to use the 30C temperature difference between the deep ocean and surface water show that it can be done, but not how best to do it for a household. Most of the moderate sized steam engines I have found operate with greater than 100C temperature differences, although there is no hard natural limit to lowering this using vacuum or a lower boiling temperature fluid. While some experimental stirling engines have been run on temperature differences as low as 2-3C, practical engines in the power level and temperature range we want do not seem to be readily available. I would say we have some modest design development to do. I had hoped that some one with some practical experience here might already know of a suitable engine for this application. It is pretty clear that the pistons need to be larger than for a higher temperature difference. The Carnot efficiency is set by the temperature difference Nick. This is why a heat pump works great only if the temperature difference is not too great. I am not sure what you mean by “energy flow”. The heat flow is as I described, from hot side, to motor to house. The mechanical energy from the motor drives the heat pump (with an alternator, electric motor taking the place of a shaft if convenient.). and then the heat flows from outside (or from a warm storage area) to the heat pump to the house. We give up a bit of efficiency converting the heat into energy by using the relatively warm house as the cold side for the heat engine, but we get to use 100% of the reject heat to do the job we need done. Power levels are on the order of those we are burning to provide heat for the house as it stands, if the heat is electric. For a typical house this ought to be on the order of 10KW of total heat input I think, so the motor needs to be about 5-10 HP. (I am assuming gain from the heat pump here.) Nick. I am a physicist. Minor gaffs aside, I have a fair grasp of the thermodynamics we are dealing with. Practical experience I have almost none. In any case, if we are going to invent a better way to do it, we need to go beyond what is now practical to what can be made to be practical. So if you know of some practical reason that would make this concept impossible to bring to fruition, great, let’s hear it. Otherwise I need help figuring out how to make it practical. Perhaps one of our buds here likes to play with steam engines and is willing to try modifying one to run off this kind of low temperature difference heat? Are you this rude with all your acquaintances, or is it just me? I don’t suffer fools gladly, Fred, and find most of your postings a waste of time. You often post nonsense, and seem to ignore practicalities, as in “some sort of Stirling engine.” We need more details. Consider the Carnot efficiency and magnitude of energy flows in the heat pump scheme you described..solar pv panel size
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Comments interspersed
… I’ve also noticed his fondness for nuclear power and the big business approach, aka Boeing. He claims to be a physicist, but often has trouble spelling that.. solar pv panel size
I see you have not been inducted into our secrets. At risk of being blackballed, I will let you in. We have a test, administered usually in the 2nd year of college. If the student can understand thermodynamics, but has no trouble spelling, we try to get them to take up engineering. If they are so excited about the idea they just can’t slow down enough to spel rite, then we know, these are the ones we want. If you failed the test the first time, just remember to misspell a few words here and there, just as long as you do not confuse the Gibs Free Energy with perpetual motion. (It’s a physics joke.)
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- Hide quoted text — Show quoted text – Comments interspersed … I’ve also noticed his fondness for nuclear power and the big business approach, aka Boeing. He claims to be a physicist, but often has trouble spelling that…solar pv panel size I see you have not been inducted into our secrets. At risk of being blackballed, I will let you in. We have a test, administered usually in the 2nd year of college. If the student can understand thermodynamics, but has no trouble spelling, we try to get them to take up engineering. If they are so excited about the idea they just can’t slow down enough to spel rite, then we know, these are the ones we want. If you failed the test the first time, just remember to misspell a few words here and there, just as long as you do not confuse the Gibs Free Energy with perpetual motion. solar pv panel size
So that is why all the stuff you write in Word has so many red underlines in it…
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Go ahead Fred solar pv panel size Let’s see some brand names and numbers…
You need a 5-10 HP motor to run from 90-100C hot to about 25C cold. From my general parusal there are a few custom jobs, probably rather expensive, in the 2-3 HP range, most of them taylored for somewhat hotter input than this. Solstice for example shows a unit that is installed at the focus of a large solar mirror. Problem is, most of these places do not make these engines as a standard off the shelf item. I suspect there are just not enough folk to buy them at this time. I do not anticipate, at this time, that I would want to buy the unit if I could find a supplier. Too expensive. However, it is not that hard to build something like this, like I said, in principal. Shoot Stirling did it over 100 years ago, so it should be pretty easy for a good mechanic. If you were waiting for someone to step up and give you a brand name and number you are waiting till someone else does all the work for you. If you need more details, I suggest spending a bit of time with any of the hundred web sites for those interested. Any particular hundred?solar pv panel size
Just ask your web browser to go find Stirling Motors. Nevertheless, here are a few I checked on. There are about 30 others that I have visited, and a few hundred that my browser came up with that I have not visited.solar pv panel size In most of these cases we are dealing with a large professional lab reporting on a heavily funded NASA or some such level study. Great info, but not someone we can order a home unit from, or a model outfit with stuff way under a KW. As I said, we need some development in our particular area of need, and a standard product that can be manufactured in large enough quantities to obtain some benifit of scale. Doing it yourself seems quite reasonable, but not for everyone. Modifying one to do this job is as simple as choosing one that works with the house you are in and using an alternator to drive it’s AC motor. As simple as that. You’ve glossed over the heat-to-motion part again.
We were talking about the problem in sections. The heat pump section of this puzzle can be dealt with quite independently. The little motor that makes it go can be driven by a more or less standard generator, or replaced entirely if you can reach it and connected by drive shaft to the motor we are laboring over. There is no technical issue here that requires more than hacksaw level modifications at most. Actually producing clean 60Hz AC for it may be a good idea because we could use it for the rest of the house anyway. But the details are just details. There is no hidden physics here to catch you up and even my rather limited mechanical abilities should not be strained too much. …The stirling/steam engine chosen needs a bit of work. Agreed. (Have you chosen one, then?)
No. Not at all. I have about 4 basic ideas with only the vaguest idea of which would work best. I can run a standard steam engine, pulling a vacuum on the cold side. This will permit the hot side to boil down to a temperature as low as freezing. The only problem is the gas density, and thus the available work, becomes smaller the colder the hot side gets, and of course vacuums tend to leak and would have to be sucked down regularly. This means large pistons, and vacuum tight connections. I can use a low boiling material. An alcohol would work OK, or even butane. I can circulate the hot/cold water right up to the engine, so the pressurized butane would only be a gallon or so, and relativly easy to keep tight, but still, who wants hot butane in the house. Amonia, perhaps, but almost as dangerous. There may be some nice secondary vessles that would make this kind of engine safe enough. As an alternative to a couple square foot of piston, a turbine might be usefull. I like the Tesla turbine, for it’s simplicity, but I still haven’t found anyone with much practical experience working with the conditions we want to work with. I debate the stirling engine. A good high efficiency engine but it is right at the edge of my skill limits to build. And I need to make a pretty big one for this task. I have been trying to come up with a variation that would be easier to build, but would still work well. I will let you know if I can get it to work. Do what?
Operate at a temp dif of 50C and produce 5 HP at least, in a package that I can build without borrowing an NC milling machine and a thousand bucks worth of custom milled stainless. The low temperature OTEC turbines designed to use the 30C temperature difference between the deep ocean and surface water show that it can be done, but not how best to do it for a household. Show what can be done? How much power do these turbines make, at what efficiency? How big are they, and what do they cost? They seem to have minimal relevance, if they don’t show how “it” can be done for a household.
Let’s put it this way. They are experamental, so cost is mostly irrelevant. The cost includes someone like me cogitating on how to design the thing, and someone like you telling us it can’t be done, on top of the cost of actually making this one of a kind. They do show that the thermodynamics works as expected, and that a large unit (I think the demo was only a few hundred KW, small for a city, but a bit large for a home) can be made efficient enough to make practical power from only a 30C delta. The relavance is that it may be possible to scale the plant down and make a system that will work. What is not at all clear is whether after the scaling down the system will cost less than half a million or not. If they did not work, there would be no reason to try. Since they did, it makes a good deal of sense to try. After all, we have almost twice the temperature delta and a lot of really bright back yard machinests. We just need to get em started in the right direction. Now, what way was that again? … The Carnot efficiency is set by the temperature difference… So you’d start with 60/(273+60), ie 18%, and go downhill from there, with a real engine. Say 5% overall heat-to-motion?
OK. Let me draw this more clearly. The heat engine, without losses, puts all the input heat into either output heat or energy. Due to the very high efficiency of a generator/motor, we will ignore for the moment the relatively small losses in moving from mechanical to electrical and back. The heat pump is exactly the same but reversed. The ratio of input heat to output energy and vice verse, is a larger number when the temperature difference is lower. That is, if the temperature difference is small, you get little energy out, but you do not have to put much energy in either. The outside will be assumed to be around 5-10C, the house around 25C, and the source about 90C. I get about 21% for the hot stage heat to energy. The cold stage however only takes about 7% to pump the same heat into the house. The overall gain then is a factor of 3.8. For every BTU we suck from the 90C tank, we suck 2.8 from the outside. This advantage goes up rapidly if the outside temp is warmer than 5C, but also goes down fast if it is much colder . Friction losses and leakage blows hell out of this estimate, so we have to make pretty good motors and pumps or we just won’t get the performance. However, it should be possible to get a 80-90% thermodynamic efficiency (that is the % of the peak carnot efficiency of the “perfect” heat engine) with a motor as large as 5-10 HP, at least I think that is reasonable. A nice compact little turbine? Well, that is the point. Not enough work in this area. But the thermodynamics and some close data points suggest that we may be able to develop this system with a bit of work. BTW, there is a lot of energy in this tank. We could certainly use it to generate a lot of electric power without impacting it’s operation as heat source for the house much. The home heating demand is really large compared to a couple of lights here and there. Well, my vision for this system is a complete thermal and electrical management and storage system, to provide home heating, hot water, and refrigeration, with a minimum of waste. I think that is a good idea,solar hot water heaters pennsylvsnia but it is going to take some development for sure.
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There are a lot of folk working with sterling and steam engines. Were I to get specific it would literally take over the list. If you need more details, I suggest spending a bit of time with any of the hundred web sites for those interested. This idea has been developed to the point where basic design issues can now be developed a bit. The penultimate question is not if it is an idea of any possible merit, or a waste of time, but if it can be made to work practically. This involves choosing the right heat pump, Stirling or steam engine for the job. solar hot water heaters pennsylvsnia
Pardon my ignorance here, but is there any information/merit to a Nitinol (“Memory Metal”) engine? I’ve seen rudimentary example designs, but don’t recall seeing anything ‘developed’. Dorsai
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There are a lot of folk working with sterling and steam engines. Were I to get specific it would literally take over the list. If you need more details, I suggest spending a bit of time with any of the hundred web sites for those interested.
solar hot water heaters pennsylvsnia The heat storage tank is a simple large scale thermal cistern. In fact, I thought it was your comment regarding this idea that convinced me it was worth thinking about. I had not imagined that a reasonable sized tank could store enough hot water to keep a house warm for months. The stirling/steam engine chosen needs a bit of work. I have a pretty good grip on the thermodynamics of the beast, but actually picking one off the line that can operate efficiently with a 50-70 C temperature difference is not so easy. The stirling can probably do it. . Most of the moderate sized steam engines I have found operate with greater than 100C temperature differences, although there is no hard natural limit to lowering this using vacuum or a lower boiling temperature fluid. While some experimental stirling engines have been run on temperature differences as low as 2-3C, practical engines in the power level and temperature range we want do not seem to be readily available. I would say we have some modest design development to do. Snip In any case, if we are going to invent a better way to do it, we need to go beyond what is now practical to what can be made to be practical.
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Somewhere around adolescence more of us learn that no matter how much book learning we have, it’s not worth much if we’re nasty, condescending folks who use our learning to browbeat others.
And some of us, after learning that one lesson, continue to learn. We learn it really doesn’t matter how anyone phrases their speech, but it is important that the facts be correct and either well understood or explicity stated. This is extremely helpful when interacting with people who have different values and perspectives than one’s self. And finally, something that most people seem to learn eventually, is that coddling fools and whiners wastes time and energy and does nobody any good. Why should they be allowed to misguide anyone else? They need to be straightened out, and it makes no sense to mince words. Call a spade a spade and be done with it. If people are grown up enough to deal with real life and the hard knocks that brings, what’s a few words? Like it or lump it. Oh, and Nick… Keep on keeping an eye on my math, please! sdb — Evidently some sorry coward was offended by one of my posts. The wuss was too scared to speak out in public. Poor baby… *** More guns means less crime. ISBN:0-226-49363-6 *** Watch out for munged e-mail address. User should be sdbUse1 and host is at bigfoot.com Do NOT send me unsolicited commercial e-mail (UCE)!
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I’m not sure how much energy it would take to heat 10,000 gallons to near boiling, but I’m fairly sure it would take alot more energy than solar can provide. The sun don’t shine 24/7. My two bits Dragonfly – solar hot water heaters pennsylvsnia Go ahead Fred Let’s see some brand names and numbers… You need a 5-10 HP motor to run from 90-100C hot to about 25C cold. From my general parusal there are a few custom jobs, probably rather expensive, in the 2-3 HP range, most of them taylored for somewhat hotter input than this. Solstice for example shows a unit that is installed at the focus of a large solar mirror. Problem is, most of these places do not make these engines as a standard off the shelf item. I suspect there are just not enough folk to buy them at this time. I do not anticipate, at this time, that I would want to buy the unit if I could find a supplier. Too expensive. However, it is not that hard to build something like this, like I said, in principal. Shoot Stirling did it over 100 years ago, so it should be pretty easy for a good mechanic. If you were waiting for someone to step up and give you a brand name and number you are waiting till someone else does all the work for you. If you need more details, I suggest spending a bit of time with any of the hundred web sites for those interested. Any particular hundred? Just ask your web browser to go find Stirling Motors. Nevertheless, here are a few I checked on. There are about 30 others that I have visited, and a few hundred that my browser came up with that I have not visited. www.stirlingengine.com hsolar hot water heaters pennsylvsniasolar hot water heaters pennsylvsnia. Great info, but not someone we can order a home unit from, or a model outfit with stuff way under a KW. As I said, we need some development in our particular area of need, and a standard product that can be manufactured in large enough quantities to obtain some benifit of scale. Doing it yourself seems quite reasonable, but not for everyone. Modifying one to do this job is as simple as choosing one that works with the house you are in and using an alternator to drive it’s AC motor. As simple as that. You’ve glossed over the heat-to-motion part again. We were talking about the problem in sections. The heat pump section of this puzzle can be dealt with quite independently. The little motor that makes it go can be driven by a more or less standard generator, or replaced entirely if you can reach it and connected by drive shaft to the motor we are laboring over. There is no technical issue here that requires more than hacksaw level modifications at most. Actually producing clean 60Hz AC for it may be a good idea because we could use it for the rest of the house anyway. But the details are just details. There is no hidden physics here to catch you up and even my rather limited mechanical abilities should not be strained too much. …The stirling/steam engine chosen needs a bit of work. Agreed. (Have you chosen one, then?) No. Not at all. I have about 4 basic ideas with only the vaguest idea of which would work best. I can run a standard steam engine, pulling a vacuum on the cold side. This will permit the hot side to boil down to a temperature as low as freezing. The only problem is the gas density, and thus the available work, becomes smaller the colder the hot side gets, and of course vacuums tend to leak and would have to be sucked down regularly. This means large pistons, and vacuum tight connections. I can use a low boiling material. An alcohol would work OK, or even butane. I can circulate the hot/cold water right up to the engine, so the pressurized butane would only be a gallon or so, and relativly easy to keep tight, but still, who wants hot butane in the house. Amonia, perhaps, but almost as dangerous. There may be some nice secondary vessles that would make this kind of engine safe enough. As an alternative to a couple square foot of piston, a turbine might be usefull. I like the Tesla turbine, for it’s simplicity, but I still haven’t found anyone with much practical experience working with the conditions we want to work with. I debate the stirling engine. A good high efficiency engine but it is right at the edge of my skill limits to build. And I need to make a pretty big one for this task. I have been trying to come up with a variation that would be easier to build, but would still work well. I will let you know if I can get it to work. Do what? Operate at a temp dif of 50C and produce 5 HP at least, in a package that I can build without borrowing an NC milling machine and a thousand bucks worth of custom milled stainless. The low temperature OTEC turbines designed to use the 30C temperature difference between the deep ocean and surface water show that it can be done, but not how best to do it for a household. Show what can be done? How much power do these turbines make, at what efficiency? How big are they, and what do they cost? They seem to have minimal relevance, if they don’t show how “it” can be done for a household. Let’s put it this way. They are experamental, so cost is mostly irrelevant. The cost includes someone like me cogitating on how to design the thing, and someone like you telling us it can’t be done, on top of the cost of actually making this one of a kind. They do show that the thermodynamics works as expected, and that a large unit (I think the demo was only a few hundred KW, small for a city, but a bit large for a home) can be made efficient enough to make practical power from only a 30C delta. The relavance is that it may be possible to scale the plant down and make a system that will work. What is not at all clear is whether after the scaling down the system will cost less than half a million or not. If they did not work, there would be no reason to try. Since they did, it makes a good deal of sense to try. After all, we have almost twice the temperature delta and a lot of really bright back yard machinests. We just need to get em started in the right direction. Now, what way was that again? … The Carnot efficiency is set by the temperature difference… So you’d start with 60/(273+60), ie 18%, and go downhill from there, with a real engine. Say 5% overall heat-to-motion? OK. Let me draw this more clearly. The heat engine, without losses, puts all the input heat into either output heat or energy. Due to the very high efficiency of a generator/motor, we will ignore for the moment the relatively small losses in moving from mechanical to electrical and back. The heat pump is exactly the same but reversed. The ratio of input heat to output energy and vice verse, is a larger number when the temperature difference is lower. That is, if the temperature difference is small, you get little energy out, but you do not have to put much energy in either. The outside will be assumed to be around 5-10C, the house around 25C, and the source about 90C. I get about 21% for the hot stage heat to energy. The cold stage however only takes about 7% to pump the same heat into the house. The overall gain then is a factor of 3.8. For every BTU we suck from the 90C tank, we suck 2.8 from the outside. This advantage goes up rapidly if the outside temp is warmer than 5C, but also goes down fast if it is much colder . Friction losses and leakage blows hell out of this estimate, so we have to make pretty good motors and pumps or we just won’t get the performance. However, it should be possible to get a 80-90% thermodynamic efficiency (that is the % of the peak carnot efficiency of the “perfect” heat engine) with a motor as large as 5-10 HP, at least I think that is reasonable. A nice compact little turbine? Well, that is the point. Not enough work in this area. But the thermodynamics and some close data points suggest that we may be able to develop this system with a bit of work. BTW, there is a lot of energy in this tank. We could certainly use it to generate a lot of electric power without impacting it’s operation as heat source for the house much. The home heating demand is really large compared to a couple of lights here and there. Well, my vision for this system is a complete thermal and electrical management and storage system, to provide home heating, hot water, and refrigeration, with a minimum of waste. I think that is a good idea, but it is going to take some development for sure.
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This involves choosing the right heat pump, solar hot water heaters pennsylvsnia Stirling or steam engine for the job.
I am most interested in deciding which Stirling engine will produce electrical or at least mechanical power from heat. Failing that I want to use a steam engine for the same purpose. Sensible Steam in Missouri has some nice small units but too small for me. I am looking for a way to produce up to 50 KW in one project and 100 KW in several others using biomass as fuel. Cornelius A. Van Milligen Kentucky Enrichment Inc
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vercharge the battery as long as the sun goes down each night. vermont solar laminate pv panel
A 104 F Florida tub used 1.5 hours per day lost 20K Btu/day (180 kWh/mo) over average 73 F days in 1995, but some tubs live in 30 F air… A better cover and fewer bubbles would help. With these parameters, it seems like conventional pool and spa heaters don’t really do the job. They might keep the tub warm all day, rather than reaching a high temperature for a short period of time. I’d still need to fire up the gas heater to get to operating temperature.
I heard about a plant, in Africa somewhere… where about 400 mirrors was computercontrolled. All the mirrors sent the sunlight against a small piece of glasspipe. The water was offcourse flowing, in the glasspipe. This raised the temperature in the highlighted area to more than 100 degrees celcius, and also completely cleaned the water, in the same provess. In this way a small solar powerplant could work… but only on sunny days.