| Home |
| Search |
| Today's Posts |
|
|
|
#1
posted to rec.boats.cruising
|
|||
|
|||
|
On Sat, 08 Sep 2007 19:45:09 +0000, Larry wrote:
wrote in news:m4p4e354ggmshgch6l42g4gutlpd5g19u0@ 4ax.com: Explain that again in one syllable words for me :-) As I understand what you are saying you mean to remove the present water cooled exhaust manifold from the cooling system and replace it with a heat exchanger device to heat what? Water to make steam or oil to heat water to make steam? Or did I miss something there? To BOIL, not heat, seawater into steam...while still flushing the manifold with a tiny bit of seawater to carry the salt, biologicals and pollutants overboard at 212F. I want to turn the exhaust manifold into an evaporator, just like the big ships USED to have before RO. The water in the exhaust heat exchanger would have a controlled flow of seawater into it to A) maintain boiling temperature while B) flushing out the remnants overboard, self flushing evaporator, which isn't new. In general I agree but practically I'm not sure how much heat you can pump into the exhaust water jacket considering that we still want the engine to do its primary job of pushing the boat and exhaust back pressure effects horsepower output. Having said that I suspect that there would be some lower limit on the size of the engine below which the system is not going to produce enough BTU's of heat to evaporate a usable amount of water. If you are using a, say, 50 H.P. engine then a very small volume of water keeps the engine cool while if we are using a 2,000 HP engine then it requires a substantial amount of water to remove the heat. In short, the difference between a small fire and a big one. In addition, I want to replace the antifreeze in the water jacket with transmission fluid, or any free fluid that has a higher boiling point than water like transmission fluid, that must A) not boil, itself, other than at the head like the antifreeze does, now...and B) transfer higher than 300F heat to a secondary heat exchanger, another boiler heated by the coolant, not exhaust gasses, to boil even more seawater in a secondary self-flushing boiler. Both these steam outputs would go to one, or if necessary two, stainless steel condensors that look exactly like the pipe-in-a-pipe freon condensors on a marine air conditioner, which is very compact. This condensor would have a seawater jacket around the central stainless steel steam pipe it cools, dumping the heat of condensation into the hot water tank heat exchanger before dumping excess heat overboard. The condensor only need be pulled apart far enough so that gravity will drain the distilled water out of it at your worst angle of heel so it doesn't vapor lock...and be mounted above the engine far enough so only steam can reach it from the gas outlet of the various boilers below. Again, the theory is good but I'm not sure about how it works in practice. I say this because every design engineer understands that heat is energy and if it were practical internal combustion engines would be running at much higher temperatures then they do now. I suspect that higher temperature operation would be getting into the realm of exotic materials, difference in expansions of various engine parts, etc. I also suspect that lubrication would be a problem. Jet engine oil, for example operates at much higher temperatures then internal combustion engine oil but has far less lubricity (as a bunch of USAF folk learned to their despair when we converted the APU's from internal combustion power to turbine units). A power boat wasting millions of Btu/day would sink from fresh water flooding if this thing were left tanking it all. Being as the distilled water output from this contraption were HOT water, not cold as with RO, you might even be able to just tank it for that hot shower, directly. The water coming out of my steam condensor will burn you at 200F. To get a cold drink, you'd have to cool the engine distiller's water before drinking it....maybe with further seawater cooling, which is plentiful. There's so much great heat just going up the stacks and running out of the boat from the seawater indirect cooling systems on these monsters it's pitiful! Heat is POWER! All it needs is useful conversion. I've never figured out why a big power boat doesn't have a Stirling genset running off its waste exhaust heat, alone! God, it's certainly hot enough with enough Btus. The reason I ask is because many years ago I maintained a distillation plant that used exhaust heat to make steam. If I remember correctly the primary power was a Perkins 4-108 diesel and it didn't make enough exhaust heat to boil water at sea level atmospheric pressure. The distillation vessel was heated as hot as possible using the exhaust and then an engine driven vacuum pump dropped the pressure in the still to create steam at temperatures lower then 212F. It's not? That's most interesting. Maybe we should put the fluid coolant heat exchanger AFTER the exhaust heat exchanger and use the exhaust heat as a pre-heater if that's so. Anyone who forgot to open cooling water thruhull valve KNOWS how much heat and steam the water jacket can make! Hell, we're only using 30-35% of the energy in the fuel we're paying $3.50/gallon for, now. The rest of it goes overboard as waste heat. Pulling a vacuum on the boilers is also an excellent idea that's been used since the 1800s, or maybe even before to reduce the boiling point. I was trying to keep this as simple as possible and free running into current water tankage. I wonder why that system allowed all that water jacket heat that's so hard to get rid of to boil even more seawater? Whether this was done to increase thruput or because exhaust heat alone was not sufficient I do not recollect. In any event, given the cost of reverse osmosis systems using engine heat would seem rather attractive. And any RO uses more power which equals more fuel expense we can no longer afford. It's a shame to let so much heat just blow out the stacks and be poured overboard as hot seawater when there are so many uses for it....like distillation, heat engines driving gensets, etc. ----------------------------------------------------------------------- I love things like this. When I was using my little 1KW Honda EU1000i genset to power the service van, I noted that its tiny exhaust was exiting separately from its air cooling exhaust. So, I welded a pipe nipple to the engine exhaust so I could pipe it where I wanted it. The exhaust gas and cooling air exhaust come out on the same end through some plastic louvers. The truck is cold in winter with only a small engine heater for the driver. The back was always cold to work in. So, I moved the tiny genset from its mount outside the rear door to inside the back of the "cabin" and used some flexible natural gas pipe, stainless steel with external ribs that would act as a radiator, made into a big loop behind a cabinet where there was a void open to the cabin air. The exhaust heated the tubing, the tubing heated the air, what came out was really HOT air wafting up from behind the cabinet. The cooled exhaust gasses went through a hole in the deck to be vented to atmosphere below the truck's floor. Exhaust gas is heavier than air, so it vents away from the cabin and this also drains the water vapor that condenses in my heat exchanger...it runs a full stream, suitable to fill my PortaPottie! The exhaust gas is about 75F coming out...a good exchange of heat. Because the genset is INSIDE the cabin, all of the waste heat coming out of its air cooled engine is POURING out onto the deck of the cabin. I'm recovering around 98% of all waste heat. When it's 30F outside the poorly-insulated truck box, I can make it 80F inside in an hour!.....and have up to 1KW of electrical power, 120VAC 60 Hz to power the shop. The noise was awful...so I built a foam cabinet out of 4" thick foam packing crate foam I got for free. The cabin air intake to cool the engine goes through a little foam muffler on the intake end. The exhaust gas heat exchanger and cooling air outlet goes through yet another foam muffler I built onto the other end...making it amazingly more quiet. Voila!...Gasoline heater and genset! You wouldn't want to live with it...but it sure is nice trying to work on a cold day in January where it's WARM as Toast!...(c; After all, old cars had exhaust gas heat exchangers heating the cars back in the early part of the 20th Century....not hot water heaters which came later. 1 gallon of gas provides electrical power and cabin heat for all day....(c; Larry Bruce in Bangkok (brucepaigeATgmailDOTcom) |
|
#2
posted to rec.boats.cruising
|
|||
|
|||
|
wrote in news
7f6e352nobhftlvbnrfrja65nvtgv8e5b@4ax.com: if it were practical internal combustion engines would be running at much higher temperatures then they do now. I suspect that higher temperature operation would be getting into the realm of exotic materials, difference in expansions of various engine parts, etc. I also suspect that lubrication would be a problem. Remember the ceramic diesel invented that had no cooling system and no lube oil? http://www.patentstorm.us/patents/4846051-claims.html Lubrication was by GAS, not liquid. It was too efficient, of course, so it had to be BURIED. Ever wonder why boats don't have air cycle refridgeration and air conditioning? http://www.patentstorm.us/patents/4846051-claims.html -75F is plenty cool to cool off the cabin, right? 1967, Chrysler sedan in Mohave Desert with 6 engineers inside enjoying a ROVAC rotart compressor/expander air conditioning system running on AIR, not freon. Temp with 6 passengers in a Plymouth? 57F....cool plenty! Oops...too environmentally friendly. You can't charge $8 for 12oz of AIR at WalMart like R134a. Can it! Quick! Larry -- Search youtube for "Depleted Uranium" The ultimate dirty bomb...... |
|
#3
posted to rec.boats.cruising
|
|||
|
|||
|
On Sun, 09 Sep 2007 02:19:17 +0000, Larry wrote:
wrote in news 7f6e352nobhftlvbnrfrja65nvtgv8e5b@4ax.com: if it were practical internal combustion engines would be running at much higher temperatures then they do now. I suspect that higher temperature operation would be getting into the realm of exotic materials, difference in expansions of various engine parts, etc. I also suspect that lubrication would be a problem. Remember the ceramic diesel invented that had no cooling system and no lube oil? http://www.patentstorm.us/patents/4846051-claims.html Lubrication was by GAS, not liquid. It was too efficient, of course, so it had to be BURIED. Ever wonder why boats don't have air cycle refridgeration and air conditioning? http://www.patentstorm.us/patents/4846051-claims.html -75F is plenty cool to cool off the cabin, right? 1967, Chrysler sedan in Mohave Desert with 6 engineers inside enjoying a ROVAC rotart compressor/expander air conditioning system running on AIR, not freon. Temp with 6 passengers in a Plymouth? 57F....cool plenty! Oops...too environmentally friendly. You can't charge $8 for 12oz of AIR at WalMart like R134a. Can it! Quick! Larry Gas or air lubrication is hardly news. My Machinery's Handbook of 1950-something had tables of clearance for air lubed bearings. As I remember it the ceramic engine never got out of the laboratory stages but I do remember some pretty high efficiency numbers claimed for it. A charge of freon for the pickup is about $4.00 here :-) I Bruce in Bangkok (brucepaigeATgmailDOTcom) |
|
#4
posted to rec.boats.cruising
|
|||
|
|||
|
|
| Reply |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| NAUTIC SHOP CLEARANCE | Boat Building | |||
| NAUTIC SHOP CLEARANCE | Electronics | |||
| E Machine Shop | ASA | |||
| Treasure from the Thrift Store (long) | Cruising | |||