SHF, Yet another trait we share, "preachin' to the choir".
After the design considerations for hydronic heat, there is still the cooling, dehumidification, ventilation/air changes, filtration dimension to the problem. Usually little or none of the equipment involved in the hydronic heat distribution is useful in the above air handling involved tasks as the air handler requirement is not a part of the equation with hydronics. That is why I am considering chilled water distribution to zone controlled fan coil units for cooling.
I have contacted a manufacturer of baseboard heating fan coil units designed to mount in the kickspace under cabinets and heat with circulated hot water. For a small one-time engineering charge for CAD documentation and extra cost of brazing in some condensate drain fittings and extra powder coat for water resistance (condensate) they will build units for me in low volume (onesies twosies or so where or so could be as many as 10 or more) This will allow me to use the same pumps and some of the same plumbing for cooling as for heating. Still I will nead a whole house ventilation system with a balanced heat recovery system for air changes and filtration.
I expect that my dehumidification requirements will exceed my cooling requirements so I will need to engineer in extra dehumidification so I don't waste a lot of expensive KWH chilling the house while trying to dehumidify. The house ends up cooler (at great expense) than you need just trying to dehumidify sufficiently. At RH levels at or below 50%, lots of little creatures don't reproduce very well if at all and many die in a fairly short time. Even if they live for a week or two (without reproducing) they will be history before long. Moderately low RH (40-50%), besides promoting better health, feels comfortably cool whilethe air temp is several degrees warmer than wold be required with higher RH levels.
Since most practical dehumidification mechanisations have been compressor/refrigerant systems there is often not that great a savings over just runing the AC. Well, there are now much more efficient mechanical dehumidifiers and a clever no-extra-electricity method. I am attracted to the no-extra-electricity method. This employs a special heat exchanger, actually two finned heat exchanger assemblies connected by heat pipes. "Brief" digression follows.
Tech note: Heat pipes are typically thin walled copper tubes lined inside with a material having good capilary action, wetted with a liquid solution, often proprietary, that vaporizes well at the operating temperature to be employed. I think ammonia in water was used at one time. This device "pipes" heat from one end to the other of the tube quite efficiently, much much more efficiently and quickly that just a copper tube or a copper rod. In brief,it functions thus: As heat energy is adsorbed at one end, the liquid in the inner lining at that end is vaporized. Molecules of vapor propogate toward the otherend, taking the absorbed heat of vaporization with them, at just under the speed of sound, around 700 mph. As these molecules arrive at the other end and contact its cool environment, they condense back to liquid giving up their heat of vaporization (heating that end of the tube). the liquid is transported back towards the original end where it started out by capilary action as that end is drier (liguid is being evaporated there, drying it) and away from the condensing end that is gaining liquid and its capilary material is being saturated as liquid condenses.
This action repeats continuously as long as heat is added to the one end and removed from the other. There isn't anything to wear out (molecules usually don't wear out due to repetitive evaporation and condensation or rain would have worn out all the water a long time ago.)
OK, an interesting parlor trick or AMAZING science fact but how does it dehumidify with no additional expenditure of electricity? 1. Bend the heat pipes into a U shape. 2. Put fins on both ends to increase surface area in contact with air. 3. put an air conditioner's evaporator (the finned coil that gets cold) in the middle of the U.
Air flows past the first side of the U into contact with the evaporator and is chilled (this is what air conditioners do). This cold air continues past the second side of the U. When this chilled air cools the second side of the U that initiates condensation of the material inside the heat pipe. The warmer air coming into the system past the first side of the U gives up heat to the vaporizing material inside the tube. This pre-chills the air coming into the evaporator which chills that air again (making for an accumulated delta T greater than if the heat pipe wasn't employed). The doubly chilled air sheds much of its water since dehumidification is a function of the delta T, bigger temp drop is more water condensed out. As the doubly chilled air passes over the second side of the U it is warmed up to about what it would have been if only the standard air conditioning was used, i.e. no heat pipes. There is no net gain or loss of heat energy but temporarily at the right moment the moist incoming air is chilled much lower than it would have been without the heat pipes, thus effecting greater dehumidification than with just the standard air conditioning approach.
As no additional electrical energy is used (ok there is a tiny bit more aerodynamic drag blowing air through the extra fins) yoiu get a bunch better dehumidification and the only cost is a one-time purchase of equipment that doesn't have conventional moving parts and doesn't wear out.
If you are really into the physics of this you know that I glossed over the topic of latent heat. Except for the heat generated by running the refer unit and the circulating fan there is no heat created or destroyed, no magic, just clever thermodynamic manipulation to derive a benefit. If you consider the total heat energy of the incoming air stream and account for the heat in the condensate being thrown away (or used to top off the pool since it is distilled water) and the SEER of the refer etc it all balances out. I think there is a great future for applications of heat pipes. I first saw them demonstrated at the Long Beach Convention Center in about 1972 at an electronic engineering conference/exposition. This technology was used in the F-111 swing wing fighter bomber to get heat out of internal electronic packages. There are small heat pipe systems currently being sold as coolers for high speed Pentium processors.
Patrick (Again, if you joined the Tractorbynet forum as no-credit or pass-fail, this is not on the quiz.)
P.S. If there are any serious/practical cooling and dehumidification schemes/suggestions that are compatible with hydronic heating equipment, please put me out of my misery and give me a clue.
.jpg)
