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  1. #14
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
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    1,781
    So I'm assuming since your only power is the running water, that it flows well year round? I'm also guessing it's pretty cold. Might look into a water cooled unit, and use a loop off the stream. The real advantage here is that it would be condensed with colder water (may have to have a tempering valve on it to recirc warm return back to the condenser to keep it from getting TOO low). The colder condenser would equate to a more efficient refrigerator, meaning less power draw. I do agree with the above statement about dual smaller units. The redundancy alone would be worth it, especially with multiple households depending on the storage. If you are calculating 6500-7000 BTU/hr, I'm thinking 2 5,000-6,000 ish units would work well, not have excessive starting surge individually, and pretty much keep up if one was down plenty long enough to get a tech out to repair.

  2. #15
    Join Date
    Jan 2013
    Posts
    19
    Quote Originally Posted by craig1 View Post
    Since you say it's for restocking small freezers, if you can keep the door openings to a minimum, you may be able to go to a static evaporator design that will significantly cut power usage. Think about a design like a chest freezer. No fans, no defrost, tiny compressor.


    The static evaporator could just be widely spaced copper tubing coiled in a box above the freezer, with an opening from the box to the freezer. The warm air in the freezer would naturally rise up to the coil and get cooled. You could have a door on the ceiling hole, so that when there is too much ice buildup, you close the door and then open another door on the evaporator box to the outdoors so that the natural heat melts the ice. It would need a pan to catch the water so it doesn't run down into the walk-in. So basically its a manual defrost you do once every month or so.

    The biggest problem with this is if you are loading it with unfrozen product it would have long pull down times.
    That is an interesting concept that I need to think about. Along these lines based on my infiltration load and a summertime RH in the 20% range do you think it would be practicable to bypass the automatic electric defrost circuits and go with a manual defrost. This way I could schedule the power draw from the turbine at times of low power usage and not run into a major loss of efficiency with frosted evaporator coils?

    As for the static evaporator design, yes most all of the products will enter at near room temperature. Would installing a blower across a table that the warm products are set on decrease the time to freeze? I know they wouldn't freeze as fast as with a stream of air directly from an evaporator.

  3. #16
    Join Date
    Jan 2013
    Posts
    19
    Quote Originally Posted by CraziFuzzy View Post
    So I'm assuming since your only power is the running water, that it flows well year round? I'm also guessing it's pretty cold. Might look into a water cooled unit, and use a loop off the stream. The real advantage here is that it would be condensed with colder water (may have to have a tempering valve on it to recirc warm return back to the condenser to keep it from getting TOO low). The colder condenser would equate to a more efficient refrigerator, meaning less power draw. I do agree with the above statement about dual smaller units. The redundancy alone would be worth it, especially with multiple households depending on the storage. If you are calculating 6500-7000 BTU/hr, I'm thinking 2 5,000-6,000 ish units would work well, not have excessive starting surge individually, and pretty much keep up if one was down plenty long enough to get a tech out to repair.
    Ok you touched on something with the water cooled systems I have been wondering about. I definitely have enough running water for a water cooled system. The tempering valve brought up a question I have on that. What is the temperature range for a water cooled system? My water runs from 34 degrees in the coldest winter to about 60 at the peak of summer.

  4. #17
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
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    1,781
    Quote Originally Posted by klamath View Post
    Ok you touched on something with the water cooled systems I have been wondering about. I definitely have enough running water for a water cooled system. The tempering valve brought up a question I have on that. What is the temperature range for a water cooled system? My water runs from 34 degrees in the coldest winter to about 60 at the peak of summer.
    It would vary by equipment, and you'd have to check each option out. A system CAN be designed to handle any range of water on the condenser, but it if isn't designed for it, going too cold would cause problems. Either way, since you are going to have a pump to pull stream water in, it isn't much more to put in a mixing valve, which would keep the water as cold as it is available, down to a set limit, which would then start mixing returning water back in.

    I'll be honest though, I've not worked on any water cooled refrigeration units. I know they are out there, but I'm not familiar with what qualities, sizes, and varieties are available. I'm just stating that if efficiency is that important (because of limited energy source), then it would be wise to at least consider the cold water that is available - assuming the water is often considerably colder than the air - if, however, the outside air is only 5-10 degrees warmer than the water, on average, then it doesn't make sense to bother with the water piping.

  5. #18
    Join Date
    Jan 2013
    Posts
    19
    I guess I need to do an evaluation of the average year around water temperature compared to the average air temperature. Off the top of my head I would say that that in the summertime the water is 20 degrees colder and in the winter they run about the same. It would be interesting to know for the same air/water temperature what condenser design transfers heat better?
    Quote Originally Posted by CraziFuzzy View Post
    It would vary by equipment, and you'd have to check each option out. A system CAN be designed to handle any range of water on the condenser, but it if isn't designed for it, going too cold would cause problems. Either way, since you are going to have a pump to pull stream water in, it isn't much more to put in a mixing valve, which would keep the water as cold as it is available, down to a set limit, which would then start mixing returning water back in.

    I'll be honest though, I've not worked on any water cooled refrigeration units. I know they are out there, but I'm not familiar with what qualities, sizes, and varieties are available. I'm just stating that if efficiency is that important (because of limited energy source), then it would be wise to at least consider the cold water that is available - assuming the water is often considerably colder than the air - if, however, the outside air is only 5-10 degrees warmer than the water, on average, then it doesn't make sense to bother with the water piping.

  6. #19
    Join Date
    Sep 2002
    Posts
    12,480
    Off grid electric defrost - Please! You are talking to the wrong people out there. <g>

    If this were me, and it has been, I would set up a separate water-wheel and drive the compressor mechanically. Your losses are too great going from mechanical energy, to electric, maybe inverting, transforming, and then back to mechanical work again at the compressor. A large low speed piston compressor is your best bet in my opinion. I would want to include a gas or diesel drive back-up drive if you can manage it. All water cooled of course - as the water is flowing you can use a static condenser and save the condenser fan HP too. Use reverse cycle defrost - it's just a standard 4-port HP valve piped in. Almost no electrical use. In fact; I think I would use a small solar panel, with a small deep-cycle battery, and run this whole system with zero electrical costs. All you would need to power electrically would be a small timer and a small solenoid valve coil. Maybe 15-20 watts total power required.

    The super insulation is a good idea but also having eutectic plates in the box instead of a standard evaporator coil would be the way to go. You can also then well over-chill at night while the heat gains are less - and save the evaporator fan HP while you do it.

    PHM
    ------





    Quote Originally Posted by klamath View Post
    I have been reading this site for a number of years but still I am uncertain if I am in the right subforum.. Hopefully I don't get myself banned right off the bat.

    Little back ground.
    I am not a HVAC/ freezer tech and don't plan on doing the refrigeration equipment myself except for the freezer box. The local tech's seem a little scared of the job so if I can narrow down what I need done I can get them to do the job of sell me the right equipment.

    Location; Mountains of Northern Ca.

    Access; 60 miles of two lane highway, 3 miles of tar and gravel road, 6 miles of unimproved dirt road, 2 miles of steep ATV trail from the nearest reasonable town.

    Power source; 6KW dry hot season, 14kw wet/cold season microhydro turbine. Voltage 120/240 single phase but soon to be converted to 3Ph.

    Freezer box; Imperial 8'x8'x10',galvanized steel, 3.5", urethane, inside of its own 10.5'x10.5'x9' building with lap siding walls, in the shade. The interior of the box will be reduced in length by adding 6.25" of of Urethane board to the end walls and covered and sealed with galvanized steel sheets. The floor will be galvanized steel sheets covering 5 Inches of urethane board on concrete. The remaining two walls and ceiling will be covered on the exterior with 7.5" of urethane board and 1.5" of perlite board.

    Usage of Freezer;serving 4 possibly 5 households as a bulk storage freezer that resupplies household freezers. Product loading in harvest season and hunting season about 150# of meat, fruits and vegetables a week, all other times loading will be less. The door is 38"x84" and will be opened, on average once a day for 30 seconds.

    Here are my big dilemmas.
    Power draw.
    Compressor starting amps (The generator driven by the pelton water turbine is a 18KW single phase or 30KW 3 phase Marathon. The 6KW figure comes because of lack of water to drive the turbine in the summer/fall. The whole 6kw will not always be available for the freezer because of other uses)
    The 2KW figure I keep seeing for an electric evaporator defrost is scary. A hot gas defrost sounds better but the amount of time a tech would need to install it in my situation could very well be out of my price range.
    I am not keen on the idea of paying a tech to install equipment that won't even start on the power.
    The brief conversation I had with a tech, he read off a figure of 12,000 btu/h for an 8x8x8 low temp freezer but I hadn't given him the whole picture yet. Do I need 12,000btu/h?
    I have been looking at self contained side or top mount refrigeration units but whether they would fit though the extra insulated walls and still function correctly is a big question?
    Any ideas or thoughts that would help me approach the local techs with enough knowledge as to not waste their time and my money would be appreciated.
    Is this even possible?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  7. #20
    Join Date
    Jan 2013
    Posts
    19
    Quote Originally Posted by Poodle Head Mikey View Post
    Off grid electric defrost - Please! You are talking to the wrong people out there. <g>

    If this were me, and it has been, I would set up a separate water-wheel and drive the compressor mechanically. Your losses are too great going from mechanical energy, to electric, maybe inverting, transforming, and then back to mechanical work again at the compressor. A large low speed piston compressor is your best bet in my opinion. I would want to include a gas or diesel drive back-up drive if you can manage it. All water cooled of course - as the water is flowing you can use a static condenser and save the condenser fan HP too. Use reverse cycle defrost - it's just a standard 4-port HP valve piped in. Almost no electrical use. In fact; I think I would use a small solar panel, with a small deep-cycle battery, and run this whole system with zero electrical costs. All you would need to power electrically would be a small timer and a small solenoid valve coil. Maybe 15-20 watts total power required.

    The super insulation is a good idea but also having eutectic plates in the box instead of a standard evaporator coil would be the way to go. You can also then well over-chill at night while the heat gains are less - and save the evaporator fan HP while you do it.

    PHM
    ------
    Thanks for jumping in. Actually you are totally right on the direct water turbine drive compressor but there is no inverter/battery/transformer loses as I have a direct AC system. In fact I have plumbed the raceway drain into the construction. As I build all my turbines I will design the power torque curves specifically for the compressor. However Before I get that done I want an electrical system to start with and then it will become the backup when the turbine system is on line.
    You have me researching eutectic now.

  8. #21
    Join Date
    Sep 2002
    Posts
    12,480
    How does the turbine couple with the alternator?

    PHM
    ------



    Quote Originally Posted by klamath View Post
    Thanks for jumping in. Actually you are totally right on the direct water turbine drive compressor but there is no inverter/battery/transformer loses as I have a direct AC system. In fact I have plumbed the raceway drain into the construction. As I build all my turbines I will design the power torque curves specifically for the compressor. However Before I get that done I want an electrical system to start with and then it will become the backup when the turbine system is on line.
    You have me researching eutectic now.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  9. #22
    Join Date
    Sep 2002
    Posts
    12,480
    Without batteries h where do you redirect any surplus generating capacity?

    PHM
    --------




    Quote Originally Posted by klamath View Post
    Thanks for jumping in. Actually you are totally right on the direct water turbine drive compressor but there is no inverter/battery/transformer loses as I have a direct AC system. In fact I have plumbed the raceway drain into the construction. As I build all my turbines I will design the power torque curves specifically for the compressor. However Before I get that done I want an electrical system to start with and then it will become the backup when the turbine system is on line.
    You have me researching eutectic now.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  10. #23
    Join Date
    Jan 2013
    Posts
    19
    Quote Originally Posted by Poodle Head Mikey View Post
    How does the turbine couple with the alternator?

    PHM
    ------
    Direct drive through a flex coupling.

  11. #24
    Join Date
    Jan 2013
    Posts
    19
    Electric load controller. At the present the excess heat goes into a hot water tank and purged back into the tail race.
    Quote Originally Posted by Poodle Head Mikey View Post
    Without batteries h where do you redirect any surplus generating capacity?

    PHM
    --------

  12. #25
    Join Date
    Oct 2005
    Location
    B.C. Canada
    Posts
    858
    Good point phm.
    I would love to see some pics of your turbine / generator setup

  13. #26
    Join Date
    Jan 2013
    Posts
    19
    Here' a photo of my hydro plant while it was under construction. I couldn't get the photo to implant so had to go with a link. http://s783.photobucket.com/user/kla...tml?sort=3&o=7

    http://s783.photobucket.com/user/kla...tml?sort=3&o=6

    http://s783.photobucket.com/user/kla...ml?sort=3&o=19

    There are two separate types of turbines driving the generator, a pelton and turgo. They both operate on different head pressure and water volume. The pink one is the pelton while it was a wax model before is was cast in silicon bronze.

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