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Thread: Alternative Energy Projects

  1. #91
    Research suggests that the electricity consumption of a micro absorption chiller can be lower than I previously expected. The pumps I have selected are small 12 or 24 volt DC magnetic drive pumps that draw less than 43 watts electricity (20 watt model is also available). These small pumps will not support a chiller at a high cooling rate, but they should achieve a 1/2 to one ton rating. A typical rotating fan on high draws about 40 watts, but this assumes a very small ac motor... small DC motors are a lot more efficient. I believe I can get the total electricity consumption well under 200 watts for a chiller that is 12,000 btu/hour, and this includes a cooling fan for the absorbent cooler. A thermostatic fan may be the best solution as the fan can operate only when needed as when air temperatures rise during particularly hot days. This way the system does not require the fan load at night and additional battery discharge is avoided. This should take the electricity consumption down below 150 watts.

    Note that modern homes are often recommended for one ton of cooling for as much as 1200 s.f. A modest off grid home (imagine a 500-700 s.f. open cabin with excellent insulation and shading) can be cooled very well by the system I'm working on.

    ADDENDUM: I stopped this project (see post #100).
    Last edited by buenijo; 12-31-2013 at 09:43 AM.



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  3. #92
    Large biomass fueled Brayton Cycle engine. http://www.proepowersystems.com/Engine.htm

    This is exactly the approach I described in previous post (#53) with the only difference being that the air exhaust from this engine is sent directly to a biomass furnace to support combustion. In my system I was using that hot air to dry a desiccant. This animation makes the system clear. I've always understood since considering that approach that a good compressor, high temperature, and a good expander can result in an efficient system. I can't find any efficiency figures on this particular system, but the temperatures they cite suggest high efficiency.

    This particular configuration is good in my opinion. Sending the hot exhaust to the furnace will increase furnace temperatures all else equal, and most important it seems to me that a very simple furnace can be used here to generate the high temperature exhaust flue gases. A simple insulated fire box with a grate and rough cut firewood stacked inside could be used here. Finally, the heat from the system is available at the furnace exhaust for heating applications, and it's at a high temperature that could even be used to drive an absorption chiller.

    A low power and slow moving system might be worthwhile for a small off grid power plant fueled by biomass. Note that getting high efficiency with the modest pressures they are using hear (3.3 atmospheres) would require a large slow moving engine.

    ADDENDUM: I looked at the patent, and they are claiming a net efficiency of 36-40% assuming a 1500F compressed air temperature. The higher efficiency figure assumes a higher air pressure of 10 bar. The lower efficiency figure assumes 3 bar. This is what my estimates would have shown... but 1500F doesn't seem practical for a long lasting system using conventional components. Those temperatures will require some special provisions. Still, a small stationary system that can achieve only 20% net efficiency would be a game changer in remote off grid combined heat and power. Imagine such an engine that can maintain a constant low power for long periods at very slow speeds. You've got all that heat at the final exhaust (and some at the compressor cylinder) for space heating, water heating, water processing, fuel drying, even absorption cooling, or a refrigerant compressor could be driven off the engine at low output to provide a highly efficient vapor compression a/c system (no energy conversion losses in alternator, battery, inverter, compressor motor and a low constant cooling with large heat exchangers would be highly efficient... looking at a coefficient of performance of about 5 here). May also throw up some solar panels to augment electricity generation during the day and run the a/c system described in post #88 in tandem with the heat engine. If the engine is dedicated to electricity generation, then 1 hp will provide about 12 KWh of ac electricity per day.

    ADDENDUM: Note that in post #53 I noted that this configuration makes sense for use as a solar heat engine since the air heater can be placed on a solar concentrator with the bulk of the engine on the ground. It's instructive to consider this configuration as a rankine cycle (steam engine) without a phase change. In this case the mechanical work required of the compressor replaces the addition of latent heat and work of the feed pump in the rankine cycle.
    Last edited by buenijo; 09-02-2013 at 04:57 PM.

  4. #93
    Free Energy, kiddies. Oh yes. It do exist. For the time being it requires a jolt to get it started but...you know...work in progress.

    Last edited by Natural Citizen; 08-31-2013 at 11:42 AM.

  5. #94

  6. #95
    Good personal account of using a forklift battery in an off grid solar system (see comments by SCharles):

    http://www.wind-sun.com/ForumVB/show...m-ideas-please

  7. #96
    Check out interviews of Steven Harris at www.battery1234.com. I've long believed that the most practical backup system for a grid failure is a battery system. Steven makes a thorough discussion of various ways to go about this. A good battery kept on a float charge with grid power can be ready for use (with an inverter) whenever a grid failure occurs. A small generator can be kept on hand for battery charging should the power be lost for an extended period. If natural gas is available, then this is best fuel source. However, many small gas engines can be tri-fueled (gasoline, propane, or natural gas). This is a very practical configuration.
    Last edited by buenijo; 10-03-2013 at 01:59 AM.



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  9. #97
    Quote Originally Posted by buenijo View Post
    Check out interviews of Steven Harris at battery1234.com. I've long believed that the most practical backup system for a grid failure is a battery system. Steven makes a thorough discussion of various ways to go about this. A good battery kept on a float charge with grid power can be ready for use (with an inverter) whenever a grid failure occurs. A small generator can be kept on hand for battery charging should the power be long for an extended period. If natural gas is available, then this is best fuel source. However, many small gas engines can be tri-fueled (gasoline, propane, or natural gas). This is a very practical configuration.
    i agree with this, especially if you buy an inverter that can take PV input as well as a generator input. that way you can buy panels and add to your generating capacity as time goes on.

    to me, the idea situation would be to have a large enough battery backup for the necessary loads (freezers/fridges, furnace, etc) and plan to shut down all circuits not needed/used during an outage.then a normal 5k (ish) generator, converted to propane, with 100lb bottle of propane stored.
    should give you enough stored energy to keep the batteries charged and food cold/house warm for a while.
    if you can back feed the grid and use that money to add to your system, even better.

  10. #98
    Quote Originally Posted by Kelly. View Post
    i agree with this, especially if you buy an inverter that can take PV input as well as a generator input. that way you can buy panels and add to your generating capacity as time goes on.

    to me, the idea situation would be to have a large enough battery backup for the necessary loads (freezers/fridges, furnace, etc) and plan to shut down all circuits not needed/used during an outage.then a normal 5k (ish) generator, converted to propane, with 100lb bottle of propane stored.
    should give you enough stored energy to keep the batteries charged and food cold/house warm for a while.
    if you can back feed the grid and use that money to add to your system, even better.
    Mr. Harris discusses what he considers to be the ideal configuration, and I agree with him. His advice is to keep the generator loaded down whenever it is used to charge the battery. This can be done by powering the battery charger along with all systems in the home with AC directly from the generator. When the generator is shut down, then the loads in the home can be switched to the inverter powered by the battery. Ideally, get as much work done while the generator is running to minimize battery discharge after the generator is shut down. Also, generators operate most efficiently when loaded down.

    Interestingly, he can't say enough good things about the small Honda and Yamaha inverter generators. I had mentioned the Honda EU2000i last year on these forums after I witnessed one in action and got a spectacular review from the owner. The reviews on Amazon are also outstanding. These are pricey, but efficient, very quiet, and highly reliable. They also have tri-fuel retrofits available. Natural gas is the best fuel. Mr. Harris points out that the natural gas system is extremely reliable. Generally, during a loss of grid power the natural gas supply is not affected. There is an exception he points out in earthquake country (i.e. California generally) where natural gas is shut down in the event of an earthquake in case natural gas supply lines are compromised. I see nothing better than these small generators for this purpose (backup power generation during grid failures of limited duration). Now, for an off grid situation, I would do something different. The main differences in an off grid system is having to use a much larger battery and the use of solar panels.

    Mr. Harris also discusses what I consider to be a good idea for some settings. An inverter can be powered from the battery of one's car and used for essential functions during a loss of power (like cooling the fridge/freezer). A deep cycle battery might even be charged from the car during a loss of power, and this battery can be used to power modest loads while the car is not running. Yeah, this is not an efficient set up, but it's practical for a loss of power of short duration. He also discusses and provides a video on how to install a battery bank in a vehicle that is charged by the alternator, and can be used with an inverter during a loss of grid power or for powering equipment in remote settings. This is a great system for disaster preparedness... or camping. There are lots of other cool ideas like charging all manner of small electronic appliances directly from a small 12 volt deep cycle battery.

    On back feeding the grid, a solar array can be used in a grid-tie configuration, but reconfigured for off-grid during a loss of power. There are even systems that do this automatically. This approach allows the solar array to reduce the electric bill while also providing electricity during loss of power. Personally, I don't like this idea unless grid power happens to be very expensive.
    Last edited by buenijo; 10-02-2013 at 06:40 PM.

  11. #99
    I'm not sure if this post is appropriate for this thread, but perhaps. There appears to be some momentum behind a new automobile that could be available next year. Check it out here: www.eliomotors.com.

    Personally, I love the idea.
    Last edited by buenijo; 10-03-2013 at 02:08 AM.

  12. #100
    Well, I had been reporting on the progress of a micro absorption chiller project of mine. I hate to disappoint anyone who might have had some interest in this, but I have decided to stop the project. The main reason is that I don't see such a system competing effectively with highly efficient split ductless a/c and heat pump systems that can be powered from photovoltaics. The fact that PV hardware continues to fall in price and increase in quality also led me to this decision. I've also come to appreciate the costs involved with this project. Basically, I can't justify the costs required to design a functional unit only to scrap it for a system powered by PV. Finally, considering the amount of biomass that must be gathered and processed for use in the chiller pretty much wrapped things up for me. It seems I am now fully behind photovoltaics for off grid power generation. If one desires total energy independence (no fossil fuels), then a wood gas engine system can be used for backup power generation (bulk battery charging) when solar insolation is insufficient for any reason (like during inclement weather). A wood gas engine system can also be used to power an automobile if desired, and the gasifier can be used for heating applications as well (like water heating and space heating). However, note also that most split ductless a/c systems also operate in heat pump mode, so a large PV array could contribute to space heating during cold weather to eliminate a small amount of fuel that would otherwise be consumed.

    In summary, if one desires total energy independence while maintaining a modern household, then go with photovoltaics and wood gasification.
    Last edited by buenijo; 12-31-2013 at 11:15 AM.

  13. #101
    Man recently installs 12.5 KW grid tie solar system at $1.72/watt before subsidies. He saved money by doing the install himself. It doesn't look difficult at all.

    http://ecorenovator.org/forum/solar-...lar-array.html

    Off grid systems are going to be higher because of the battery. My research shows I could get the hardware for a 6 KW off grid system for about $13,000 (panels, 3 midnite classic MPPT controllers, racking, wiring, 24 volt 804 amp hour forklift battery, 3 KW pure sine inverter).

  14. #102
    UKIP energy spokesman Roger Helmer interviewed on atomic energy (video): http://www.youtube.com/watch?v=S1hlLjxYsKk&feature=youtu.be

  15. #103
    Quote Originally Posted by r123 View Post
    UKIP energy spokesman Roger Helmer interviewed on atomic energy (video): http://www.youtube.com/watch?v=S1hlLjxYsKk&feature=youtu.be
    It seems Roger Helmer is a proponent of Nuclear power plants. There is good reason for this in my opinion. The safety record of nuclear power is exemplary. The main problem I have with nuclear power is the extreme government interventions. It's impossible to know the real costs involved under these conditions. Yeah, this pretty much applies to all energy technologies, but my impression is that things are even more contorted in nuclear power. I expect controls (and costs) to rise further due to Fukushima.

    Personally, for central power, I prefer coal and natural gas. Note that I don't buy the "climate change"/"global warming" line one bit. I'm all for coal as long as the emissions are clean (I do NOT consider CO2 as a "pollutant" to be scrubbed, I consider it as plant food). Let's crank out combined cycle power plants fueled by natural gas (50%+ efficiency in converting btu's to electricity delivered to the home), and large coal-fired supercritical steam plants (40%+ efficiency in converting btu's to electricity delivered to the home, and with fuel costs lower than natural gas!).

    As far as photovoltaics goes, this is a great tool in the hands of the individual for opening up options to reside in remote regions where utility lines either are not available, or would be too expensive to establish. In other words, it is ideal for off grid/remote homes. However, it is also a useful tool for combating a monopolistic energy utility that likes to raise rates willy nilly, or one that provides poor and/or intermittent service. The prices for photovoltaic hardware continues to fall, and we are approaching the point in a few years when the cost of electricity generated by distributed photovoltaic systems reaches grid parity for many regions in the U.S. Already, it is cost competitive to traditional electricity sources in many international markets.
    Last edited by buenijo; 10-07-2013 at 04:19 PM.

  16. #104
    Quote Originally Posted by buenijo View Post

    I'm all for coal as long as the emissions are clean (I do NOT consider CO2 as a "pollutant" to be scrubbed, I consider it as plant food).
    Right. Except all of the trees are being chopped down. One example off of the top of my head would be agribusiness giants like Monsanto (for one) chopping down the rainforests for Monoculture GMO Crops and Biofuels and whatnot.



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  18. #105
    Quote Originally Posted by Natural Citizen View Post
    Right. Except all of the trees are being chopped down. One example off of the top of my head would be agribusiness giants like Monsanto (for one) chopping down the rainforests for Monoculture GMO Crops and Biofuels and whatnot.

    Yeah, that sucks. There are other sources of biomass that will take up CO2, but the concentration of CO2 will certainly go up either way. I'm not convinced this is so bad. After all, the Earth supported it in the past. I know, but we're changing it too fast! Can we be sure that this will be detrimental? If so, then by what standard? Call me skeptical, but I haven't seen any worthwhile evidence that our increasing CO2 levels is harmful on net balance. I have seen a lot of hype and bull$#@! shoveling (a la Al Gore).
    Last edited by buenijo; 10-06-2013 at 12:00 PM.

  19. #106
    Tokyo's Daily Radiation Readings Underscore the Fallacy of the Fukushima Radiation Hysteria: http://educate-yourself.org/cn/tokyo...r03dec12.shtml Are wind farms saving or killing us? A provocative investigation claims thousands of people are falling sick because they live near them The symptoms they claim to have suffered may vary – including dizziness; increased blood pressure and depression – but the theme remains the same. Read more: http://www.dailymail.co.uk/home/mosl...#ixzz2XRwvjbYc Marijuana: Hemp Made Cars Running on Hemp, Supressed Oppertunities . I’ll guess the oil and steel industry didn’t want this world to be green. Nor to be a bit more peaceful either. With that much hemp around needed to fuel all our engines and to replace many of the metals and plastics, the temptation of that first marijuana sigaret would be too close around the corner for the masses. The powers that be like the people more to consume stupifying and aggressifying alcohol products so they’ll stay in their matrix: http://www.youtube.com/watch?v=DKEubbn_2oA
    In Praise of Tokyo Electric Power Company TEPCO: http://educate-yourself.org/zsl/toky...r03oct13.shtml

  20. #107
    The Myth of Nuclear ‘Waste’ by Marjorie Mazel Hecht. There’s no such thing as nuclear waste! This nasty term was invented just to stop the development of civilian nuclear power.The spent fuel from nuclear power plants is actually a precious resource: About 96% of it can be recycled into new nuclear fuel. No other fuel source can make this claim—wood, coal, oil, or gas. Once these fuels are burned, all that’s left is some ash or airborne pollutant by-products, which nuclear energy does not produce.Thus, nuclear is a truly renewable resource. Furthermore, unlike wind, solar, and other so-called alternative energy sources, a nuclear fission reactor (the fast reactor or breeder reactor) can actually create more fuel than it uses up: http://larouchepac.com/node/14724

    We hear a lot about “green jobs” in the renewables industry. The reality is rather
    different. A recent report called “Worth The Candle?” by Verso Economics
    demonstrates that for every job created in the renewable sector, four jobs are
    destroyed elsewhere in the economy. How? By driving up energy costs, reducing
    competitiveness and deterring investment. A Spanish study entitled “Effects on employment of public aid to renewable energy sources” by Professor Gabriel Calzada Alvarez at King Juan Carlos University questions whether “green jobs” are worth the public investment. According to this document renewables have received €28.7 billion in subsidies. This is nearly €600,000 for each of the 50,200 jobs created. Meanwhile renewables businesses are collapsing. In the US, President Obama touted solar-PV company Solyndra as a text-book example of renewables and green jobs: it soon went belly-up. A study by The Washington Post shows that of the approximately $19 billion loaned so far, a total of just 3,545 jobs have been created.That comes to over $5 million per job.
    In China, solar PV manufacturers are facing a crisis as demand fails to match projections and prices slip below costs. Renewables are not about “green jobs”.
    They’re about green unemployment. In the UK, the world’s largest wind turbine manufacturer, a Danish company called Vestas, has scrapped plans to build an offshore wind factory in Kent. The 70 hectare site would have housed a facility designed to build the Danish company’s 7MW V164 offshore wind turbines but a lack of confirmed orders led to the project being cancelled. This decision is the second time that Vestas has opted out of the UK market; in 2009 it closed down a plant making onshore turbines on the Isle of Wight. Contrary to the claims of the green lobby, the renewable industry is unsustainable. It needs massive ongoing public subsidy. Such levels of subsidy are unaffordable,especially in current economic times. These subsidies are also profoundly regressive. They take money from poor consumers, including pensioners, and give it to rich landowners and corporations.

  21. #108
    Quote Originally Posted by r123 View Post
    In Praise of Tokyo Electric Power Company TEPCO: http://educate-yourself.org/zsl/toky...r03oct13.shtml
    Do you endorse this? What evidence is available?

  22. #109
    The best source of information that I've yet discovered for learning about modern photovoltaic systems (off grid OR grid tied) is the discussion forums at www.windsun.com. I highly recommend this resource for anyone interested in learning about these systems, especially those who are doing serious research before purchasing a system.

    I actually stumbled onto the forum while researching the split ductless a/c systems I mentioned earlier in the forum. There are a few people active on the forum who have been using these systems to cool their home (off grid homes powered by a/c) with amazing results. You can check out that particular thread here: http://www.wind-sun.com/ForumVB/show...split+ductless . This thread and others have me totally convinced that a modest and modern home (superior insulation, etc.) can be cooled very effectively with a good vapor compression a/c unit powered by photovoltaics.
    Last edited by buenijo; 10-12-2013 at 05:09 PM.
    "There are no solutions. There are only trade-offs." Thomas Sowell

  23. #110
    See this thread on induction cookers: http://www.wind-sun.com/ForumVB/show...n-cooker/page1
    "There are no solutions. There are only trade-offs." Thomas Sowell

  24. #111
    I'm discussing the intermittent ammonia absorption refrigeration system. I've posted on this before. Here are a couple of relevant examples:

    http://knowledgeableideas.blogspot.c...-icemaker.html

    http://crosleyautoclub.com/IcyBall/crosley_icyball.html

    I'm presenting these systems again as I believe a system similar to an icy ball would be very useful in the off grid setting (really, it's suitable more for an extreme setting). Also, it's something that can be devised without breaking the bank. However, the unit must see outstanding insulation to reduce the size of the system. If anyone is interested in this prospect for food refrigeration, then I recommend that you first look into extreme insulation. Thick polyurethane is a good prospect. Another prospect I've considered should interest the reader. I understand that some cryogenic storage tanks use crushed perlite under vacuum as insulation. The basic idea here is to have a vessel within a vessel, fill the annular space between the two vessels with dry crushed perlite, then seal the space and draw a vacuum. This might prove difficult to do... so, I think a worthwhile project might be to vacuum seal the perlite in modules (like durable plastic bags - maybe even vacuum equipment designed for food storage) that can be used as insulation.

    It takes some imagination to consider possibilities. What I'm considering is a small super insulated vessel with an integrated micro intermittent ammonia absorption system. A furnace similar to a wood gas camp stove the size of a large soup can burns less than a half pound of dry sticks to recharge the unit daily. A few cubic feet of storage capacity would make for a very useful unit that would be easily transported.

    NOTE: Anhydrous ammonia (i.e. pure ammonia) is a controlled substance. However, it can be acquired in the form of industrial cleaning products up to 29% ammonia in water. This concentration is almost sufficient to be used directly in this application (assuming water used as the absorbent as in the icy ball). It would be easy to adjust the concentration since the ammonia is separated during heating (just drain some water out from the absorber after heating until the proportion is right). It's also possible to distill the ammonia out by connecting a vessel of the ammonia/water to a condenser placed in a freezer, evacuating air, then gently heating the vessel to slowly evaporate the ammonia (a long steel tube in the freezer connected to the condensing vessel can catch some water vapor by freezing on the tube). The problem with this set up is that the system is under some positive pressure (but not very high, so it should be reasonable to do this). This problem can be solved by using calcium chloride to absorb the ammonia vapor from the solution. I'll discuss this here: the boiling point of the ammonia/water solution is lower than water. If one connects a calcium chloride vessel to a vessel containing the ammonia/water solution, then pulls vacuum briefly to evacuate air (to speed the absorption process), then ammonia vapor will evaporate quickly from the solution causing it to boil. Some water will leave with the ammonia vapor, and it's desirable to minimize this. This can be done by (1) putting the ammonia/water vessel in an ice bath, (2) placing the calcium chloride vessel in a freezer, and (3) connecting a long steel tube to the calcium chloride vessel (tube is also in freezer). (1) keeps the ammonia water solution cold to inhibit water evaporation, and also prevents the solution from freezing by adding heat during the absorption process. (2) removes the heat of absorption allowing the calcium chloride to increase absorption rate, and lowering the temperature allows the calcium chloride to hold more ammonia. (3) will keep water out of the calcium chloride by freezing the water vapor on the cold tubing wall as described before. I like the idea of using calcium chloride in an "icy ball" set up (modified) as it provides pure ammonia to the evaporator. Also, since it is a solid, then it may do better at absorption without providing check valves as is required with water (although, the calcium chloride will liquify after absorbing sufficient ammonia - better results will probably be had with a check valve, but if it works well enough without, then it seems best to do without the check valves). DANGER: Do not cap the calcium chloride vessel after it absorbs ammonia at low temperature as pressure will build as temperature increases (use a cork or provide a means of relief). As long as the vessel is kept in a freezer, then the ammonia will not vent.

    Continuous Operation: Considering the icy ball gives me hope for a continuous ammonia absorption system for air conditioning. Consider that absorption is achieved in the unit with a single small tube extending down into the absorbent solution, with no active cooling to the absorbent, and with the evaporator maintained at low temperatures. A system that provides a large evaporator maintained at a higher temperature, providing excellent cooling of the absorber, and bubbling the ammonia vapor into the solution with a perforated plate similar to a shower head might just work exceptionally well. The main problem I saw with the absorber in my lithium bromide/water system was the extremely low pressures made the flow of water vapor easily disrupted - and the only solutions I considered proved too expensive to be practical. Having much higher pressures and lower evaporator temperatures makes many things possible (and potentially a lot less expensive). Consider that a rise in evaporator temperature from 19F to 20F increases the pressure of ammonia by roughly 1 psi, whereas a rise in evaporator temperature from 39F to 40F increases the pressure of water vapor by only 1/200 psi. So, you see the problem. For mere mortals with very limited funds, ammonia is way to go.

    A configuration I consider is to fuel a system by a small wood gasifier where the hot fuel gases are sent to a combustion chamber to heat the system. The evaporator could be used to freeze water while the condenser heats water. The system can operate at a high rate during the day (perhaps 2 tons) when a PV array is producing thereby powering the pumps and fans required of the system without discharge on a battery system. When shut down, then the cold store provides chilled water for a fan coil unit, and the heated water is available for use as required - the operation of the fan coil unit is done while the absorption unit is shut down (small mag pump for chilled water plus fan consumes only about 50 watts dc for the small unit I'm considering - about 1/2 ton). The system can also be configured to heat and distribute hot water to the fan coil unit for space heating, and it can be configured in heat pump mode to provide heat in excess to that provided by the furnace (done by tapping the heat from the absorber).

    For water freezing you don't want to just put the evaporator into water directly as ice formation will occur on the tube and lower heat transfer (and lower evaporator temperature, pressure, and affect the performance of the system). A better solution is to cool a water/glycol solution contained in an insulated vessel. Containers of water can be added to the system. The allows the evaporator to be heated by a liquid for good heat transfer, and the heat is derived from the multiple water containers surrounded by the cold solution. The water in the containers will freeze, and they will keep the solution cool. The water/glycol solution can be used directly as chilled water by pumping it to the fan coil unit with the small mag pump. A great benefit of this set up is ease in controlling the cooling rate of the system. A fan on the fan coil unit (and one might use more than one fan coil unit - imagine one for central cooling a cabin, and another for spot cooling while sleeping) can use a thermostat or the speed of the fan can be controlled to adjust the cooling demand. A store of chilled water makes this far more practical than trying to control the output of the absorption system. This way the absorption system operates at a fixed rate for simplicity. Note that the continuous system is inherently safer than an icy ball since the heat is applied to a compact steel tubing coil, the vessels are smaller, pressure is limited with a relief valve on the solution pump discharge, and the high pressure vapor side is connected to a large condenser. The only pressure vessels in the system (that is not small diameter tubing) is the absorber vessel and separator vessel that may be thick steel piping. The absorber is at a modest pressure (well under 100 psig), but the separator may approach 400 psig - and the separator is the smaller vessel, so I see the system as inherently safe with a rational design.

    NOTE: The continuous system requires an ammonia/water solution pump, and a high output system will require active cooling with a cooling water pump and with heat exchanger and fan (outside fan coil unit). Therefore, the system is operated during the day to allow a PV array to provide the required dc electricity which would be roughly 1/5 that of a conventional a/c unit of equal cooling capacity. In principle, the same could be done with a conventional a/c unit operated as an opportunity load on a PV array. However, one big problem here is the cold storage. The performance of a vapor compression system depends on the temperature difference between the evaporator and condensor. Well, the evaporator temperature must be very low to freeze water, and the condenser temperature will be higher when operated during a summer day (and a great deal higher if one tries to use it for water heating to a sufficiently high temperature to be useful). So, the vapor compression system will require significantly more than 4 times the electricity consumed by the absorption system (assuming the same kind of set up). Of course, one can simply power a/c as an opportunity load on a large PV array. However, this prospect is more interesting and versatile.

    NOTE: I suggest a HyPro piston pump with stainless steel internals and teflon seals for the ammonia solution pump. It's also possible to build a plunger pump fairly simply using a small threaded pipe section with two check valves on the end - a length of smooth steel shaft is used as the plunger - the plunger reciprocates in the pipe to draw in and discharge fluid through the check valves - just have to seal the plunger - this can be done by providing a washer on the pipe end with same outside diameter as the pipe and with an inner hole just large enough for the plunger, cut a hole in the pipe end cap just large enough for the plunger, then pack the space between the washer and end cap with teflon compression packing, then tighten the end cap to seal. Note that teflon works very well with ammonia, so teflon tape on all threaded points is also good practice. A prospect for a pump motor is a 24 volt dc gear motor used for electric scooter applications (cheap and reasonably efficient).

    ZERO ELECTRICITY: I just considered a way to drive a plunger pump for the ammonia/water solution using the differential pressure between the regenerator and condenser. The pump is hermetically sealed, self-starting, and cycles at a rate directly proportional to the rate the system is heated. This configuration has advantages over traditional 100% heat powered ammonia absorption refrigeration systems that operate at a constant pressure. The pump makes it possible to force the fluid through compact heat exchangers that can reduce thermal losses and regenerate heat back into the system. By contrast, the traditional systems rely on thermosiphon which cannot tolerate restrictions to flow. This new system can be more compact and more efficient.
    Last edited by buenijo; 04-05-2014 at 09:51 AM.
    "There are no solutions. There are only trade-offs." Thomas Sowell

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