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Keel cooler cast into lead
Does anyone have experience casting copper tubing into a lead keel?
To function as a keel cooler |
Keel cooler cast into lead
I am in the process of doing that now. Formed loops of 1/4" OD 70/30
copper/nickel alloy tubing running horizontally along either side of the keel bolts wired to sit about 1/4" inside the surface. Tubing is about 5' long. Theoretically it is a good bit more than needed but without definite data on the heat transfer through the lead and having only one chance I figured it was better to be a bit bigger rather than not big enough. Kept the diameter small and the runs as horizontal as possible to keep the velocity up and prevent oil from getting trapped at the bottom of the condenser. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Hess cutter 56" wrote in message oups.com... Does anyone have experience casting copper tubing into a lead keel? To function as a keel cooler |
Keel cooler cast into lead
Glenn,
Are you planning to us this as an evaporator? Matt Colie Glenn Ashmore wrote: I am in the process of doing that now. Formed loops of 1/4" OD 70/30 copper/nickel alloy tubing running horizontally along either side of the keel bolts wired to sit about 1/4" inside the surface. Tubing is about 5' long. Theoretically it is a good bit more than needed but without definite data on the heat transfer through the lead and having only one chance I figured it was better to be a bit bigger rather than not big enough. Kept the diameter small and the runs as horizontal as possible to keep the velocity up and prevent oil from getting trapped at the bottom of the condenser. |
Keel cooler cast into lead
"Matt Colie" wrote in message ... Glenn, Are you planning to us this as an evaporator? Matt Colie No. It will be the condenser. The evaporator goes in the refrigerator. The keel will be cold enough already. :-) -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
Keel cooler cast into lead
Glenn-
I recollect that you cast your ballast keel years ago, so will this be set in some kind of bog between the lead keel and the hull's (wood epoxy & glass) keel? Seems to me to be a very good idea to be putting such plumbing, if it can be made to work, in a place where it can be gotten to, if need be. I was beginning to worry a lot about pipes actually cast into a lead keel. Getting back to the original post- maybe if there were troughs cast (or machined) into the top of the lead casting, pipes for heat transfer could be set in them. A few thoughts from the barnyard engineer, Jim "Glenn Ashmore" wrote in message news:4p2Qf.492510$0l5.375670@dukeread06... "Matt Colie" wrote in message ... Glenn, Are you planning to us this as an evaporator? Matt Colie No. It will be the condenser. The evaporator goes in the refrigerator. The keel will be cold enough already. :-) -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
Keel cooler cast into lead
No. I cast the bulb years ago. Everything is ready to cast the fin except
my intestinal fortitude. :-) The fin is a lot more complicated and I have this recurring nightmare that I am going to get something slightly out of alignment and then have to sail through life slightly catawampus. But then I have been accused of that by the neighbors already. :-) -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Jim Conlin" wrote in message ... Glenn- I recollect that you cast your ballast keel years ago, so will this be set in some kind of bog between the lead keel and the hull's (wood epoxy & glass) keel? Seems to me to be a very good idea to be putting such plumbing, if it can be made to work, in a place where it can be gotten to, if need be. I was beginning to worry a lot about pipes actually cast into a lead keel. Getting back to the original post- maybe if there were troughs cast (or machined) into the top of the lead casting, pipes for heat transfer could be set in them. A few thoughts from the barnyard engineer, Jim "Glenn Ashmore" wrote in message news:4p2Qf.492510$0l5.375670@dukeread06... "Matt Colie" wrote in message ... Glenn, Are you planning to us this as an evaporator? Matt Colie No. It will be the condenser. The evaporator goes in the refrigerator. The keel will be cold enough already. :-) -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com |
Keel cooler cast into lead
Glenn Ashmore wrote:
No. I cast the bulb years ago. Everything is ready to cast the fin except my intestinal fortitude. :-) The fin is a lot more complicated and I have this recurring nightmare that I am going to get something slightly out of alignment and then have to sail through life slightly catawampus. But then I have been accused of that by the neighbors already. :-) Don't worry about it. You will do a far better job than most boatbuilder. Walk thru any boat yard and with bare ey, you'll be able to see the keels on many boats are off kilter. Even the great J-24 has to have it's keel faired to be symmetrical and remounted to be vertical, centered, and aligned, for the boat to not sail catty-wompus. Most people don't ever notice ....unless there's another boat of the same class sailing alongside, outpointing them. Fresh Breezes- Doug King |
Keel cooler cast into lead
I was planning to use pipe cast into the keel to cool the engine.!
{A Sabb 22hp}. The Keel cooler that came with the engine is 10' long 5/8 tubing My keel will be a long rectangle. Aprox. 10' x 15"x 15" .. Glenn do you plan to use some type of flux on the tubing , Before casting the lead ? And what type of wire do plan to use , To hold the tubing in place Thanks CW |
Keel cooler cast into lead
Glenn,
If it is a condensor, then the liquid refrigerant should carry the oil along and should not pool in the turns of the coil (notice please the "shoulds"). But I like th idea as you have it because: -You have separate turns so a damaged turn could be eliminated from the circuit. -You may decide to rework the refrigation to be reversable and so provide heat from the pond at little cost. Just be sure that you keep the keep above freezing in fresh water. If this idea appeals to you, you migth think of putting a little loop like a trap at the outlet end just before the lift so the oil has someplace to collect a form a big enough plug so it gets lifted out of the cooler. Sounds interesting - I'd love to hear how it works out. Matt Colie ex reefer guy (among the rest) Glenn Ashmore wrote: "Matt Colie" wrote in message ... Glenn, Are you planning to us this as an evaporator? Matt Colie No. It will be the condenser. The evaporator goes in the refrigerator. The keel will be cold enough already. :-) |
Keel cooler cast into lead
Glenn,
In the past I have done both bulbs and fins. The BIG thing is that the hydraulic pressure at the bottom of a fin mold is UN F.....g Believable!! (Fortunately - No one got hurt the day we learned all about that.) When we built a mold that could take about 15 (11+sf for heat) times the pressure water would exert, the next pour was still nervous but fortunately dull. Cooling takes WAY longer than I expected. Matt Colie Glenn Ashmore wrote: No. I cast the bulb years ago. Everything is ready to cast the fin except my intestinal fortitude. :-) The fin is a lot more complicated and I have this recurring nightmare that I am going to get something slightly out of alignment and then have to sail through life slightly catawampus. But then I have been accused of that by the neighbors already. :-) |
Keel cooler cast into lead
That is a WHOLE different creature. With refrigeration you are trying to
dump a few hundred BTUs an hour. With engine cooling you are dumping a few hundred BTUs a MINUTE. Lead is not the greatest heat conductor so you will need a lot more surface area than a bare tube condenser. It will be hard to bury that much and still keep the lead structurally sound. With my small diameter tube I am not to worried about the bond but I will sand blast the whole bolt frame/condenser assembly and paint the tubing with an acid flux formulated for tinning copper pots. I found that the copper/nickel wets out much better with it than regular acid solder flux. I wired the tubes in place with .032 316L stainless wire. Not ideal but I end up with a lot of 6' lengths every time I change from 316 to mild steel wire on my MIG welder so I figure to put it to some use. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Hess cutter 56" wrote in message oups.com... I was planning to use pipe cast into the keel to cool the engine.! {A Sabb 22hp}. The Keel cooler that came with the engine is 10' long 5/8 tubing My keel will be a long rectangle. Aprox. 10' x 15"x 15" . Glenn do you plan to use some type of flux on the tubing , Before casting the lead ? And what type of wire do plan to use , To hold the tubing in place Thanks CW |
Keel cooler cast into lead
The down side of casting a condenser in the keel is that it is an extremely
permanent installation. No way to fix it once it is done so I added one extra loop. If one of the working loops springs a leak I can just switch over to the spare. I have had them pressurized with nitrogen to 250pis for 3 months now so hopefully they will not leak once they are inside the lead. The loops are a continuous downward slope so the oil will pool right at the return end. Probably could have made it a bit more efficient with a larger OD tube to slow the refrigerant down, get more surface area and less pressure drop but I read so much about oil getting trapped in the condenser and starving the compressors that I got scared. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Matt Colie" wrote in message ... Glenn, If it is a condensor, then the liquid refrigerant should carry the oil along and should not pool in the turns of the coil (notice please the "shoulds"). But I like th idea as you have it because: -You have separate turns so a damaged turn could be eliminated from the circuit. -You may decide to rework the refrigation to be reversable and so provide heat from the pond at little cost. Just be sure that you keep the keep above freezing in fresh water. If this idea appeals to you, you migth think of putting a little loop like a trap at the outlet end just before the lift so the oil has someplace to collect a form a big enough plug so it gets lifted out of the cooler. Sounds interesting - I'd love to hear how it works out. Matt Colie ex reefer guy (among the rest) Glenn Ashmore wrote: "Matt Colie" wrote in message ... Glenn, Are you planning to us this as an evaporator? Matt Colie No. It will be the condenser. The evaporator goes in the refrigerator. The keel will be cold enough already. :-) |
Keel cooler cast into lead
On Fri, 10 Mar 2006 13:23:26 -0500, "Glenn Ashmore"
wrote: The loops are a continuous downward slope so the oil will pool right at the return end. Probably could have made it a bit more efficient with a larger OD tube to slow the refrigerant down, get more surface area and less pressure drop but I read so much about oil getting trapped in the condenser and starving the compressors that I got scared. Glenn, did you give any thought to circulating water through the keel, and then using that to cool the condenser? That would allow you to use a combination air and water cooled condensing unit, and if anything went wrong with the keel loop (and I'm concerned that it will), at least you have the air cooling as a backup. |
Keel cooler cast into lead
The idea was to avoid the circulating pump. If the whole thing craps out I
can always add a couple of conventional tube-in tube condensers and pull seawater off the sea chest. I plan to keep the vacuum pump, extra refrigerant and HVAC tools on board. Should be good for a few free beers from fixing systems on other boats if I ever get down island. :-) -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Wayne.B" wrote in message ... On Fri, 10 Mar 2006 13:23:26 -0500, "Glenn Ashmore" wrote: The loops are a continuous downward slope so the oil will pool right at the return end. Probably could have made it a bit more efficient with a larger OD tube to slow the refrigerant down, get more surface area and less pressure drop but I read so much about oil getting trapped in the condenser and starving the compressors that I got scared. Glenn, did you give any thought to circulating water through the keel, and then using that to cool the condenser? That would allow you to use a combination air and water cooled condensing unit, and if anything went wrong with the keel loop (and I'm concerned that it will), at least you have the air cooling as a backup. |
Keel cooler cast into lead
Thanks Glenn That makes sense ! CW
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Keel cooler cast into lead
Glenn, Your in the keel cooler will work fine, it should also work on
the hard if that side of the keel is not in direct sunlight all day. Don't forget that these compressors without fan cooling depend only on super-cooled refrigerant as the main source of compressor heat removal, so if the compressors are located in a tight area supplemental cooling is required especially in tropical climates. Frigoboat has now added a small heat sink to compressors connected to their keel cooler compressors but I don't think it is large enough to do any good in the tropics. Dick |
Keel cooler cast into lead
Thanks Richard. I feel a lot more comfortable knowing you pass on the idea.
I am worried about compressor cooling too. I have two BD50s mounted on an aluminum skid at the bottom of a locker. That is a mighty enclosed space. The control units have those dinky little fans that come with the compressors but I believe I am going to add a duct fan to draw air up from floor level, blow it over the compressors and exhaust it under the galley cabinets. Keep my toes warm while I am cooking. :-). -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com wrote in message oups.com... Glenn, Your in the keel cooler will work fine, it should also work on the hard if that side of the keel is not in direct sunlight all day. Don't forget that these compressors without fan cooling depend only on super-cooled refrigerant as the main source of compressor heat removal, so if the compressors are located in a tight area supplemental cooling is required especially in tropical climates. Frigoboat has now added a small heat sink to compressors connected to their keel cooler compressors but I don't think it is large enough to do any good in the tropics. Dick |
Keel cooler cast into lead
BD Module selection
Danfoss offers a series of special electronic modules for their 12 volt BD35 BD50 compressor to address differant installation and operating problems. There are two different modules to hopefully address the radio noise problem, A soft start module for the BD50, An AC/DC model to eliminate the battery charger when connected to shore power and Danfoss's automatic speed control model. Unfortunately they don't sell one model that has all of these functions. For more information on this see the current post on my forum at http://www.kollmann-marine.com Glenn, I would recommend the automatic speed control module described by Danfoss as Adaptive Energy Optimization module (AEO). Here are some additional recommendations: · These units are so quite I would add a green 12 volt LED to the module's unused fan terminals small + and F. · All these modules have a chip inside for troubleshooting if a 12 volt low amp LED is connected to module terminals small + and D. A red LED is recommended here as the only time it will be on is when there is a problem. · If you need to add a supplemental cooling fan I would control it with a inexpensive temperature Snap Disc Control switch available from WW Granger. I have used there model 2E246, fan turns on at 120 degrees and off at 110 degrees the objective is to keep the compressors below 130 degrees F if possable, cost $7. |
Keel cooler cast into lead
Richard, I would definitely prefer the AEO module but have not found anyone
selling them. R-Parts got a few in and immediately sold out. I even considered programming my own microcontroller to adjust a digital pot in the thermostat line to control the speed but decided it would take a lot more R&D than I wanted to invest. If I find a couple in the future I will swap out the originals. I figure a couple of spare power modules might rescue somebody down island one day. :-) I do plan to add the indicator LEDs. Saw that in the instruction sheet and wonder why everyone doesn't do it. Thanks for the idea about the thermal switch. That will definitely go in the system. The exhaust fan will be buried behind the galley cabinets so it won't make much noise but no reason to use amps when they are not needed. Think I will stick one on top of each compressor and wire them in parallel so that if either needs more air the fan comes on. Heard so many stories about RFI from these power modules that I am going to great lengths to suppress it. Lined the compressor compartment with copper bug screen, adding chokes to the power lines and running all the signal lines in shielded twisted pair. Hopefully that will help. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com wrote in message ups.com... BD Module selection Danfoss offers a series of special electronic modules for their 12 volt BD35 BD50 compressor to address differant installation and operating problems. There are two different modules to hopefully address the radio noise problem, A soft start module for the BD50, An AC/DC model to eliminate the battery charger when connected to shore power and Danfoss's automatic speed control model. Unfortunately they don't sell one model that has all of these functions. For more information on this see the current post on my forum at http://www.kollmann-marine.com Glenn, I would recommend the automatic speed control module described by Danfoss as Adaptive Energy Optimization module (AEO). Here are some additional recommendations: · These units are so quite I would add a green 12 volt LED to the module's unused fan terminals small + and F. · All these modules have a chip inside for troubleshooting if a 12 volt low amp LED is connected to module terminals small + and D. A red LED is recommended here as the only time it will be on is when there is a problem. · If you need to add a supplemental cooling fan I would control it with a inexpensive temperature Snap Disc Control switch available from WW Granger. I have used there model 2E246, fan turns on at 120 degrees and off at 110 degrees the objective is to keep the compressors below 130 degrees F if possable, cost $7. |
Keel cooler cast into lead
I was present during 105 degree ambient tests of the AEO in freezers
and was impressed with its performance but if you can not find them, the next best thing is a Frigoboat SSC. I have one on my test bench and it performs much like the AEO even adjusts for day night economy. The SSC also has the LED built in including six differant speed LEDs. There are a series of tests on the SSC in my 12/24 volt book. The BD50 will require a soft start feature if operated at max RPM in a warm climate, both of these controllers have soft start features. Dick |
Keel cooler cast into lead
The SSC is a good option. Calder did a comparison of the control algorithms
for the Danfoss AEO, Frigbot SSC and the Isotherm ASU in the October 2004 Professional Boatbuilder. Of the three the SSC seemed to have the most sophisticated program. Works similar to the AEO by monitoring run times and adjusting speed but the SSC has an "ideal" profile that it tries to fit to over time. The Isotherm unit really just watches the system voltage and turns the compressor to high speed when it sees the system is being charged. Not necessarily the best for temperature control but saves the most battery amps. I have an idea for a program that was sort of a blend of all three and could do a lot more but decided that I didn't want to risk a frige full of spoiled food because of a programming error. :-) An interesting side note: I have met several folks who have been cruising for a long time that complain that their compressors run to long and want to speed them up when in actuality they are most efficient when they run 59 minutes out of every hour. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com wrote in message oups.com... I was present during 105 degree ambient tests of the AEO in freezers and was impressed with its performance but if you can not find them, the next best thing is a Frigoboat SSC. I have one on my test bench and it performs much like the AEO even adjusts for day night economy. The SSC also has the LED built in including six differant speed LEDs. There are a series of tests on the SSC in my 12/24 volt book. The BD50 will require a soft start feature if operated at max RPM in a warm climate, both of these controllers have soft start features. Dick |
Keel cooler cast into lead
Oops! Acid flux depends on being washed off after soldering. Might this be
a problem? Roger http://home.insightbb.com/~derbyrm "Glenn Ashmore" wrote in message news:mUiQf.497330$0l5.326643@dukeread06... snip With my small diameter tube I am not to worried about the bond but I will sand blast the whole bolt frame/condenser assembly and paint the tubing with an acid flux formulated for tinning copper pots. I found that the copper/nickel wets out much better with it than regular acid solder flux. |
Keel cooler cast into lead
Not really. Because there is so much mass the lead will take over 3 hours
to start solidifying. The flux should float to the surface and be washed and ground away in the post casting operations. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "derbyrm" wrote in message news:V9HQf.854379$xm3.37448@attbi_s21... Oops! Acid flux depends on being washed off after soldering. Might this be a problem? Roger http://home.insightbb.com/~derbyrm "Glenn Ashmore" wrote in message news:mUiQf.497330$0l5.326643@dukeread06... snip With my small diameter tube I am not to worried about the bond but I will sand blast the whole bolt frame/condenser assembly and paint the tubing with an acid flux formulated for tinning copper pots. I found that the copper/nickel wets out much better with it than regular acid solder flux. |
Keel cooler cast into lead
The Isotherm ASU system is a progressive speed adjustment based on
evaporator temperature feedback and efficiency adjustments has nothing to do with voltage. The Automatic Speed Up function is an extra bonus to the automatic temperature speed control. Advancing compressor speed when a charging current is available will store additional surplus energy in the system's holding plate. I do not see how anyone could believe that the SSC is better than the ASU from the tests that I have run. I recommended Danfoss's AEO first as it is a Completely new module. My second choice was Frigoboat's SSC over Isotherm's ASU for two reasons, Isotherm will not sell their unit separate you must buy a complete system and the ASU has limited control when the tropical heat load exceeds its automatic adjustment range. |
Keel cooler cast into lead
Interesting. Calder's article said nothing about the ASU monitoring
anything but system voltage. My thought was that the ideal control would monitor box temperature, evaporator temperature and cycle time. That way it could sense when the box had been loaded with warm items and react faster to frequent opening. Strictly time based algorithms take several cycles to adjust to changing conditions. Reading the latest Isotherm literature it looks like the ASU comes pretty close but it seems oriented towards holding plates. Apparently the ASU replaces the whole power unit where the SSC just varies the thermostat circuit resistance. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com wrote in message ups.com... The Isotherm ASU system is a progressive speed adjustment based on evaporator temperature feedback and efficiency adjustments has nothing to do with voltage. The Automatic Speed Up function is an extra bonus to the automatic temperature speed control. Advancing compressor speed when a charging current is available will store additional surplus energy in the system's holding plate. I do not see how anyone could believe that the SSC is better than the ASU from the tests that I have run. I recommended Danfoss's AEO first as it is a Completely new module. My second choice was Frigoboat's SSC over Isotherm's ASU for two reasons, Isotherm will not sell their unit separate you must buy a complete system and the ASU has limited control when the tropical heat load exceeds its automatic adjustment range. |
Keel cooler cast into lead
The reason we want to control compressor speed is to use the lowest amount of daily onboard power and maintain the box temperature we want at all times. We by a compressor that can produce the results we want and generally more capacity output most of the time. Cutting down on capacity by lowering compressor speed improves SCOP (System Coefficient Of Performance). Whenever the box temperature can be maintained at the compressors slower speeds and still have it cycle off the end result will be fewer daily amp-hrs consumed. What all three of these speed controllers do is compensate for day night and seasonal temperature changes. They all will change speed but slowly when warm product is added to the box. The SSC and ASU both can be set to manual to speed up the cooling process. I believe only the SSC will provide actual compressor speeds at the panel. All of these units change the milliamp flow in the thermostat circuit to control compressor speed. |
Keel cooler cast into lead
Richard, You got me thinking (which can often be dangerous).
Reading further on the ASU Isotherm spends a lot of time talking about monitoring system voltage and increasing compressor speed when there is extra power available i.e. battery charging. This is great for holding plates but of no particular value in evaporator systems. The one thing I see that the ASU has over the AEO or the SSC is that it looks at evaporator temperature as well as run time to optimize compressor speed. The key to maximum efficiency in an evaporator system is to keep the compressor running as long as possible as slow as possible. In process control systems the easiest systems to control are the ones that are stable or change slowly. A top opening refrigerator qualifies as long as you don't add a lot of warm items or accidentally leave the hatch open. The AEO works fine in this situation but will require an hour to adjust to a major variation like adding a lot of warm items and then it has to start readjust back to normal over several cycles after the box recovers. The AEO algorithm also reaches equilibrium at 32 minutes run time. It seems to me that with a well insulated box that stayed under the on point for longer than 6 or 7 minutes the speed would not get as slow as it could. The SSC has a target of 50 minutes run time in an hour which might give a better overall COPE. I would like to see a system with 3 set points; off, on and exception and maybe an adjustable duty cycle. As long as the box stays below the exception point the control would adjust compressor speed to maintain a 90 to 95% duty cycle. If the box warmed above the exception point the compressor would run at high speed until the box recovered but that cycle would not be used to calculate the normal run speeds. That way the control could react quickly to new loads and return to normal operation as soon as the box recovered. The duty cycle could also be adjusted downward when the boat was on shore power or charging and power was not at a premium. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com wrote in message ups.com... The reason we want to control compressor speed is to use the lowest amount of daily onboard power and maintain the box temperature we want at all times. We by a compressor that can produce the results we want and generally more capacity output most of the time. Cutting down on capacity by lowering compressor speed improves SCOP (System Coefficient Of Performance). Whenever the box temperature can be maintained at the compressors slower speeds and still have it cycle off the end result will be fewer daily amp-hrs consumed. What all three of these speed controllers do is compensate for day night and seasonal temperature changes. They all will change speed but slowly when warm product is added to the box. The SSC and ASU both can be set to manual to speed up the cooling process. I believe only the SSC will provide actual compressor speeds at the panel. All of these units change the milliamp flow in the thermostat circuit to control compressor speed. |
Keel cooler cast into lead
Glenn, You want a climate control for a jet aircraft that has
anticipators to make a correction in advance of the actual temperature change. Heat transfer in a box is slow because static air is the conductor from the heat source to the evaporator, where heat it is drawn away by a small compressor. Frigoboat's SSC will give you every thing you need but you my need to switch to manual and advance speed before adding a large volume of warm product. I have included a number of gadgets in my 12 volt book that can shorten the reaction time by, increasing airflow across evaporator, starting compressor or speeding it up when a charging voltage above 13.2 is present. You don't need a holding plate in a refrigerator to store surplus energy, product in the box and the box itself can store one Btu per degree per pound, of material. In a freezer when the product is already frozen additional energy stored is only ½ a Btu per degree per pound or 144 Btu per pound added when when the phase change from a liquid to a solid occures. .... |
Keel cooler cast into lead
I have probably spent to much time working with PID and fuzzy logic
controllers. :-) There is so many sophisticated off the shelf industrial process controllers these days I can see the day when we will see a marine refrigeration controller that will do a lot more than we can think of. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com wrote in message ups.com... Glenn, You want a climate control for a jet aircraft that has anticipators to make a correction in advance of the actual temperature change. Heat transfer in a box is slow because static air is the conductor from the heat source to the evaporator, where heat it is drawn away by a small compressor. Frigoboat's SSC will give you every thing you need but you my need to switch to manual and advance speed before adding a large volume of warm product. I have included a number of gadgets in my 12 volt book that can shorten the reaction time by, increasing airflow across evaporator, starting compressor or speeding it up when a charging voltage above 13.2 is present. You don't need a holding plate in a refrigerator to store surplus energy, product in the box and the box itself can store one Btu per degree per pound, of material. In a freezer when the product is already frozen additional energy stored is only ½ a Btu per degree per pound or 144 Btu per pound added when when the phase change from a liquid to a solid occures. .... |
Keel cooler cast into lead
On Sun, 12 Mar 2006 11:45:50 -0500, "Glenn Ashmore"
wrote: I have probably spent to much time working with PID and fuzzy logic controllers. :-) There is so many sophisticated off the shelf industrial process controllers these days I can see the day when we will see a marine refrigeration controller that will do a lot more than we can think of. Glenn, following along in this discussion, it sounds like you picked an evaporater unit instead of a holding plate system. If so, I'm curious why you did that. Perhaps my situation is different because I have a large generator available, but I really like the idea of only needing to run the compressors for a few hours per day. |
Keel cooler cast into lead
I tossed the holding plate/evaporator question around for several years
before settling on evaporators. Holding plates do have an advantage in that they only have to be frozen down once or twice a day but that can also be a disadvantage because it ties you to the boat. Evaporators are more or less self maintaining so with a large enough battery bank and some alternate energy sources we will be able to venture ashore for longer periods and fly home for a week or so to visit the grandchildren without having to worry about the refrigerator. Evaporators also tend to hold a more constant box temperature and you are not limited to the single temperature that a holding plate is designed for. I also like ice in my drinks and remote undeveloped anchorages (if you can find one anymore) and evaporators do a better job of making ice. When I started looking evaporators were the cheaper alternative and holding plates were the energy champs. That is not totally true anymore. The little Danfoss compressors and controls have gotten a lot more efficient over the past 5 or 6 years and with a couple of solar panels, bigger banks, and the charging system they require a well designed evaporator system can actually cost more. I have attempted to set my systems up so that in normal use I can charge batteries and make water for about 90 minutes every other day. Time will tell how well it works out but evaporators just turned out to be the better option for the way we plan to use the boat. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Wayne.B" wrote in message ... On Sun, 12 Mar 2006 11:45:50 -0500, "Glenn Ashmore" wrote: I have probably spent to much time working with PID and fuzzy logic controllers. :-) There is so many sophisticated off the shelf industrial process controllers these days I can see the day when we will see a marine refrigeration controller that will do a lot more than we can think of. Glenn, following along in this discussion, it sounds like you picked an evaporater unit instead of a holding plate system. If so, I'm curious why you did that. Perhaps my situation is different because I have a large generator available, but I really like the idea of only needing to run the compressors for a few hours per day. |
Keel cooler cast into lead
Years ago I was shown a system that supposedly optimized efficiency by
monitoring the line from the condenser to the compressor and keeping the refrigerant's phase change as close to the compressor as possible without trying to pump liquid. We were working with fixed speed compressors (on/off) so it wasn't practical for our use. Have you seen that scheme? Roger http://home.insightbb.com/~derbyrm wrote in message ups.com... The reason we want to control compressor speed is to use the lowest amount of daily onboard power and maintain the box temperature we want at all times. We by a compressor that can produce the results we want and generally more capacity output most of the time. Cutting down on capacity by lowering compressor speed improves SCOP (System Coefficient Of Performance). Whenever the box temperature can be maintained at the compressors slower speeds and still have it cycle off the end result will be fewer daily amp-hrs consumed. What all three of these speed controllers do is compensate for day night and seasonal temperature changes. They all will change speed but slowly when warm product is added to the box. The SSC and ASU both can be set to manual to speed up the cooling process. I believe only the SSC will provide actual compressor speeds at the panel. All of these units change the milliamp flow in the thermostat circuit to control compressor speed. |
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