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  • #61
    Originally posted by Sunking View Post
    Tony what you are going to have to grasp is the Law of Thermal Dynamics. Heat is measured in BTU's, and BTU's can be converted into mechanical energy minus losses, and mechanical energy can be converted to electrical energy minus losses. Once you understand that and how many BTU's you have to generate you will understand the challenge. A steam powered turbine is the most efficient way to generate electricity with heat energy. The heat source can be anything like I said, just choose your poison. But to use a sterling engine requires a place to transfer all the heat very quickly and it has to be massive.
    The most practical use of the Sterling engine these days is in homework problems for a thermodynamics class, since they illustrate the principles and are easier to calculate about (the math is a lot simpler and more idealized) than an internal combustion engine.

    For some really exotic environments like a space traveling instrument pack in a near solar orbit, able to radiate heat into space at close to absolute zero, with a heat source that is constant, a working fluid like hydrogen, and no gravity to add additional forces to the moving parts, they might have a use. Their big advantage for that environment would be that they are not affected by radiation like semiconductors are.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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    • #62
      Originally posted by Mike90250 View Post
      you want an ammonia absorption refrigerator !
      http://en.wikipedia.org/wiki/Absorption_refrigerator

      Solar heat starts the cycle, and night time finishes it. Huge capacity, and equally huge risk if improperly engineered.
      There has also been some experiments with using off-peak power from the grid to make ice to cool an office building during on-peak hours. Since I have not heard anything recently, I suspect they have not met expectations.
      The phase change between ice and water is a very inexpensive way to store the cooling power and does not use any hazardous chemicals outside the refrigeration unit itself.

      (Actually, too much water is toxic when ingested, and prolonged immersion in water can cause asphyxiation.)
      SunnyBoy 3000 US, 18 BP Solar 175B panels.

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      • #63
        Originally posted by walter69 View Post
        has anyone tried to use solar energy to refrigerate a sufficient amount of liquid, then when is cold - recirculate it and with use of a heat exchanger blow the cold air instead of an AC. That would eliminate a need to generate energy when it is less needed [during daylight] and store it for the peak hours [5PM to 9PM] in a large number of batteries?
        There have been "solar" air conditioners around for years that use thermal energy from the sun to change the state of the refrigerant that gives off the latent heat that is then used in the conventional air conditioning cycle.

        As far as storing unneeded electricity in batteries, that is a completely different discussion.

        -Mark

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        • #64
          Ice Energy Storage is Real

          Originally posted by inetdog View Post
          There has also been some experiments with using off-peak power from the grid to make ice to cool an office building during on-peak hours.
          And there is an entire company betting on the technology which makes "tons" of sense. Unfortunately, Off-Peak pricing schedules from the utilities and "smart dynamic pricing" are what's needed for this technology to succeed, and the utility companies have not implemented them.

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          • #65
            Originally posted by Art VanDelay View Post
            And there is an entire company betting on the technology which makes "tons" of sense. Unfortunately, Off-Peak pricing schedules from the utilities and "smart dynamic pricing" are what's needed for this technology to succeed, and the utility companies have not implemented them.
            Here's a press release for a company that offers something similar, http://eon.businesswire.com/news/eon...Trane/AHR-Expo. There is a reason this system was installed at a school. Schools, and public buildings in general, are easy suckers for some of these systems since the taxpayer is footing the bill. Ice is a cheap way to store thermal energy and consuming electricity at $0.05/kW is better than $0.12/kW, but how long is the break even? 10 years? more? You are still using a heat pump (refrigerator) to generate the ice in the first place, so you are just moving the electricity consumption to a different part of the day, but you're still consuming the energy. This new equipment isn't free and there are better ways to spend money.

            -Mark

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            • #66
              Originally posted by GreatBallofFire View Post
              Ice is a cheap way to store thermal energy and consuming electricity at $0.05/kW is better than $0.12/kW
              I bet you it is not. It appears you are assuming the conversion processes of using electricity to make ice from water, and then later at some point covert the ice back to electricity is 100% efficient. I would bet you anything it is less than 50% efficient. So that $0.05/Kwh is now costing more than 12 cents, and you are wasting energy in the process. In other words you burned 2 or more units energy to get 1 unit or less out of it. That is why hydrogen and ethanol are a waste of resources.
              MSEE, PE

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              • #67
                Originally posted by Sunking View Post
                I bet you it is not. It appears you are assuming the conversion processes of using electricity to make ice from water, and then later at some point covert the ice back to electricity is 100% efficient. I would bet you anything it is less than 50% efficient. So that $0.05/Kwh is now costing more than 12 cents, and you are wasting energy in the process. In other words you burned 2 or more units energy to get 1 unit or less out of it. That is why hydrogen and ethanol are a waste of resources.
                Sunk, you and I actually agree, I just did a poor job of explaining myself. Of course the process is not 100% efficient and as I said in the very next sentence, you're still consuming electricity to generate the ice in the first place. We are on the same page, you just picked one sentence out of an entire paragraph and ignored the rest of what was actually written there.

                -Mark

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                • #68
                  Originally posted by GreatBallofFire View Post
                  you just picked one sentence out of an entire paragraph and ignored the rest of what was actually written there.
                  I did not ignore the rest of what you said. Effectively what followed was you stated:
                  so you are just moving the electricity consumption to a different part of the day
                  Which is true and an effective strategy of moving demand to off-peak hours. It is what you left out I expanded on.
                  MSEE, PE

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                  • #69
                    Originally posted by Sunking View Post
                    I bet you it is not. It appears you are assuming the conversion processes of using electricity to make ice from water, and then later at some point covert the ice back to electricity is 100% efficient.
                    The context of this was in cooling a building. Once you have the ice, you are not converting it to produce electricity, you are using it to cool air or heat-exchange fluid to cool the building. The bigger inefficiency is on the input side where you use electricity to make the ice, but that is not a lot more inefficient that using the electricity to cool the building directly. Heat pump thermodynamics does tell us that cooling something to 32F is less energy efficient than cooling it to 45F. But what would the output temperature of the heat exchanger have to be anyway to efficiently cool the building air?

                    It is absolutely correct that the price differential between on-peak and off-peak electric rates has to be big enough to allow for the energy losses on both input and output, pay for the initial cost of the equipment in a reasonable time, and pay any increased maintenance cost it might add. Most gee-whiz calculations leave out at least one of those.
                    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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                    • #70
                      At least one company is trying thr sterling engine/solar to generate power.

                      http://thepowerdish.com/media/pdf/002.pdf

                      Don't know the cost of this system, but I'd bet it is high. Might even make wind gennys look cheap.

                      WWW

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                      • #71
                        The solar dish is a knockoff of the Sandia design sold to Sterling Energy Systems (SES) (that went Bankrupt last year). The technoogy was expensive and building a sterling engine that would last was never really proved. They did know how to make good PR videos and PBS did a show on Solar that gave them a good PR bump.

                        STM Power sold several so called commerical Sterling generators for two projects. One set were installed but eventually scrapped as unreliable and the other set were delviered but never installed. The company went bankrupt.

                        The Carnot cycle is not negotiable

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                        • #72
                          research "Whispergen" - this was going to be a world-changing technology based on combining a normal C.H. boiler with a stirling engine to create a hugely energy-efficient system...UK trials were happening ...
                          I put my name on the list... but they've gone awfully quiet.
                          Last edited by Naptown; 09-27-2012, 06:03 PM. Reason: removed link
                          AlexisSalazar

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                          • #73
                            Originally posted by AlexisSalazar View Post
                            research "Whispergen" - this was going to be a world-changing technology based on combining a normal C.H. boiler with a stirling engine to create a hugely energy-efficient system...UK trials were happening ...
                            I put my name on the list... but they've gone awfully quiet.
                            It has ''gone awfully quiet'' because it was all BS. The entire line of thought is dead until someone steps in and makes major improvements in the technology.
                            [SIGPIC][/SIGPIC]

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                            • #74
                              Hi To all investors I have some fantastic new great ideas on how to build the worlds greatest stirling engine. It will be powerful enough to run a generator at least big enough to power a major city.

                              Just PM your credit credit card details And you will become one of the first tier investors and be in on the huge profits we will be generating.

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                              • #75
                                Originally posted by Sunny Solar View Post
                                Hi To all investors I have some fantastic new great ideas on how to build the worlds greatest stirling engine. It will be powerful enough to run a generator at least big enough to power a major city.

                                Just PM your credit credit card details And you will become one of the first tier investors and be in on the huge profits we will be generating.
                                Done - if you have trouble reading the details it is because I used the super encrypto keyboard - just copy and paste and should work.
                                [SIGPIC][/SIGPIC]

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