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How feasible would it me to design a heat exchange system to cool houses in the tropics?Quote:
Originally Posted by watterinja
We have these systems for heating houses in the UK, but they can also be used to cool. The only problem is that the UK systems use a fairly specialist manifold system, which I think would be too complicated and too expensive for this part of the world. Simplify this and I think you could have a winner.
If it's ok with you, I'll set up a separate heat-pump thread & we can explore the ways the technology can be used.Quote:
Originally Posted by Marmite the Dog
A byproduct of a air-to-water heat-pump, is that while the water is being heated, the byproduct is cold air which can actually be used to cool a house. In Asia, this is a neat trick, that means you can both heat water for say hotels, homes, as well as providing some cooling load.
My mate and I were discussing this topic just last week.Quote:
Originally Posted by Marmite the Dog
All you need is a;
1. A water tower, a water tank or better still a swimming pool.
2. 2 second hand car radiators.
3. A large fan.
4. Some insulated pipe.
5. And a small electric water pump.
Don't want to give too much away but we are confident we can achieve an air temperature of 22 degrees celcius and that is cool enough for me! :)
^
Please tell me more
I got everything except #2 & #4
I'm listening :)
I will keep you posted Thety!
We envisage massive savings with regard to installation costs not to mention electrical energy savings.
Remove all electric wiring from you aircon's outdoor unit.Quote:
Originally Posted by Thetyim
Put the unit in your hot water tank. :)
Be interested to see what your calculated heat-load requirements are. You may find some surprises. Cooling air in a space requires a fair bit of heat-transfer. The air often feels cold on touching the skin, but is not enough to overcome the various room heat-losses & pull-down requirement. :)Quote:
Originally Posted by Loy Toy
Watch also things like humidity, post cooling & condensation inside the house. :)
Sounds like what I had in the US many years ago. Called it a swamp cooler.Quote:
Originally Posted by Loy Toy
https://teakdoor.com/images/imported/2009/04/466.jpg
^^ All of those dynamic reactions have to the considered mate and I am sure the prototype instalation will be modified and according to the results. Bit of fun really and between 2 common sense driven novices.:)
I will keep you posted also and I appreciate your advice! :)
^^ Pretty much as we see it but pumping the cool air through floor vents and possibly have cooling pipes in the wall cavities.
We will try various arrangements and piping configurations but firstly will spend our time determining what air temperature consistancy we can achieve and also considering condensation levels.
^^ When you're ready, please advise on your COP.
Have no advice. I know naught about the thermal characteristics and the like. I do know they are cheaper than air con on energy use but air con does a better job of cooling.Quote:
Originally Posted by Loy Toy
I have also used this type of device in the Arizona and California deserts... The key to optimum usability is a very low ambient humidity something not readily found here in the southern reaches. Might work in the hottest areas of dry Issan though.Quote:
Originally Posted by Norton
Spectacular results were achieved in Arizona even in midday 104 deg. F.
E. G.
That's why I asked for the COP of the system.Quote:
Originally Posted by Norton
It could turn out - horror - to be far worse than an aircon system. :)
As I remember, swamp coolers work well in dry climate 30% humidity range. I had one when I lived in the Mojave Desert and it did cool the house. In high humidity like Thailand I don't think they are very efficient.
I was thinking along the lines of a geo-thermal system, as I'm not a fan of Legionnaire's Disease. :)
.........:)Quote:
Originally Posted by El Gibbon
Holy crap. Drill a hole in the ground. A deep one here in Thailand. When you get steam coming out use it to drive a generator hooked up to an air con. All free and works good. That hole might be a tad expensive though.;)Quote:
Originally Posted by Marmite the Dog
A very, very valid point.Quote:
Originally Posted by Marmite the Dog
What are your thoughts on a geo-thermal system?
Umm, you don't need to hit a volcanic spring to get it to work, mate. :)Quote:
Originally Posted by Norton
If they could be made efficient, then I think they could be very viable.Quote:
Originally Posted by watterinja
Usually in the UK they dig trenches all over the place and lay the pipes in there. I saw one design where they used post footings for the house's construction, so they put the pipes in the steelwork, put that down the bore-hole and them poured the concrete posts as normal. This was done on a site that didn't have a large garden, but did have lots of posts.
In Thailand, the post holes are not usually that deep, so a change would have to be made there, as you'd probably need over 2 metres in depth depending upon the efficiency and number of posts, as well as the size of the area that needs to be cooled.
There are a few companies in Thailand providing ventilation cooling system for factory halls, mostly they can achieve 5 degree Celsius below room/hall temperature...
A big vent thing ranges from 6 to 20 k thb for some industrial use...
Higher humidity in air, less efficiency ! Those kind of things are called desert coolers as well, as picture shown few thread up, in India, it works well in Dehli but not good in Bombay due to humidity !
Should find some links by digging my fair visit files...
The heat exchange with a deep hole is another story, used a lot in Switzerland, to cool or to warm up, mainly factories, prolly to expensive investment for a house as per today...
There is a fair regarding this topic in october :
Event Name : The 7th - Bangkok Refrigeration, Heating, Ventilation, and Air-Conditioning 2009
(Bangkok RHVAC 2009) https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Date : 7 - 11 October 2009
Trade days : 7 - 9 October 2009 (10.00 – 18.00 hrs.)
Public days : 10 - 11 October 2009 (10.00 - 18.00 hrs.) https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Venue : IMPACT ARENA, EXHIBITION AND CONVENTION CENTER MUANG THONG THANI
99 Popular Road, Banmai Subdistrict, Pakkred District, Nonthaburi 11120 Thailand https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Organizer : Department of Export Promotion, Ministry of Commerce, Royal Thai Government Office of
Trade Fair Activities
22/77 Rachadapisek Road, Chatuchak, Bangkok 10900 Thailand
Tel : (66) 2 513 1909 to 15 ext. 299, 272 and 293
Fax : (66) 2 513 1565, 2 512 2234
Website : Fair Information : Bangkok Refrigeration, Heating, Ventilation and Air-Conditioning 2009 , www.thaitradefair.com
E-mail : rhvac[at]depthai.go.th https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Co-Organized by : >> Air Conditioning and Refrigeration Industry Club, The Federation of Thai Industries https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Supporters by : >> Thai Refrigeration Association >> Air Conditioning Engineering Association of Thailand >> Thai Industrial Standards Institute, Ministry of Industry >> Department of Industrial Promotion, Ministry of Industry >> Electricity Generating Authority of Thailand >> ASHRAE Thailand Chapter https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif List of Exhibits : >> Air- Conditioning >> Refrigeration >> Heating >> Ventilation >> Part, Material and Service >> Tools & Equipment >> Others https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Number of exhibitors : Approximately 180 companies/ 525 booths from both domestics and overseas https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Visitor profile : Trade days : Buyers, importers, manufacturers, traders, distributors, wholesalers,
retailers,department stores, etc.
Public days : Trade visitors, local consumers and foreign tourists are expected. https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif FIGURE DATA 2007 2009 (Expected) 1. Number of exhibitors 172 companies / 516 booths 180 companies / 525 booths 2. Participating countries Thailand, Malaysia, Singapore, India, Taiwan, USA, Italy, China Thailand, South East Asia, Middle East, India, Europe, USA 3. Exhibition area 9,500 Sq.m. 10,000 Sq.m. 4. Number of visitors
https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Trade days https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif Public days
6,200 8,836
7,500 12,000 5. Major visiting countries Malaysia, India, Singapore, China, Vietnam, Korea, Philippin, Iran and Indonesia ASIAN, South is Asia, Middle East, China, South America, Latin America and Europe
The problem with wanting to cool is that the cooling in a conventional aircon system is on the evaporator end (inside). The condenser (outside) end essentially passes the (room heat)+(compressor heat)=(condenser heat) into the surrounding air. In other words, moving low-grade thermal energy - room air - to high-grade thermal energy & dumps it.Quote:
Originally Posted by Marmite the Dog
Now, in this scenario, you would need to dump the condenser heat into the geo-thermal system at rather a large temperature - probably at entry, at anything around 60-100'C (depending on compressor load), dropping off to a saturation temp of anything between say 40-65'C.
Chances are that this heat could present some problems in the ground loop - not sure - haven't though it through carefully. It's doable - but, has to be designed properly. May be expensive.
For an air-to-water heat pump, we use this condenser load to raise the temperature of water to anywhere as high as 65'C (HFC's), or even 80'C (CO2).
https://teakdoor.com/images/smilies1/You_Rock_Emoticon.gif
A heat-pump on test in my lab, in Laos. The AWHP is the white box on the top of the stand.
^ The energy consumption of an air-to-water heat-pump is around 14-20% of what a direct resistive element heater will consume (measured in the lab).
At the same time, the cold air can be used to cool the house.
By-the-way, the AWHP shown above will, serve the daily needs of a 20-room hotel, or guest-house.
The hot rocks project worked in Cornwall
However the cost of drilling an fuel you amy as well use iced champagne for cooling
The Arizona system is also unsuitable here.
Passive design, roof extraction and alignment etc are more cost effective ,I also swear by Hebel block .
The subtle use of screens light shelf and plants can all assist.
I designed my own home here usung 20cm thickness like a Thai temple.
The Uni of Queensland and Oz in general has a lot of good info and experience.PM if you wish advice on anew design or retro fit.
What's the point? No one can understand your retarded ramblings.Quote:
Originally Posted by Felix Sphinx
The trick with passive cooling of a home would be to have as much natural draft flowing through the home as possible, to begin with. Good thermal insulation & heat-barriers would be essential. These cost in terms of initial capital outlay, but are free thereafter (except for maintenance).
Once you've exhausted all the 'natural tricks', then it's time to begin modifying the environment artificially - these costs are ongoing. The trick here is to keep them as small as possible by using cunning designs.
That doesn't seem to be how it's usually done. I'm nick this from Wiki, as it's explained better than I can do it.Quote:
Originally Posted by watterinja
Geothermal heat pump - Wikipedia, the free encyclopediaQuote:
Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat. Heat pumps can capture heat from a cool area and transfer it to a warm area, against the natural direction of flow, or they can enhance the natural flow of heat from a warm area to a cool one. The core of the heat pump is a loop of refrigerant pumped through a vapor-compression refrigeration cycle that moves heat. Heat pumps are always more efficient than pure electric heating, even when extracting heat from air.
But unlike an air-source heat pump, which extracts or exhausts heat to or from the outside air, a ground-source heat pump exchanges heat with the ground. This is much more efficient because underground temperatures are relatively stable through the year. Seasonal variations drop off with depth and disappear below 10 m due to thermal inertia.[2] Like a cave, the shallow ground temperature is warmer than the air above during the winter and cooler than the air in the summer. A ground-source heat pump extracts that ground heat in the winter (heating) and exhausts heat back into the ground in the summer (cooling).
It's basically a load of plastic piping, a manifold and a vapour compression fridge.
^ It's a fair bit more than that... :rofl:
Try using plastic piping on a hvac system. :)
Water is a much better condensing medium than air so you could have a cool water supply to use for your condenser cooling you could gain quite a bit over 100*F air for the job.
I used a sea water heat exchanger for my condenser on my last cruising boat when I built my holding plate reefer system and had a deep freeze and a fridge box on one compressor and could maintain -20 in the freezer box with 1/2 hour per day engine time, and that charged all batterys with a 150 amp alternator as well as made 3 gallons of fresh water and well.
BG... that was in moving water. No problem there - an infinite heat-sink.
For pumping heat down into a ground-loop, for an hvac condenser, is going to have to dissipate the heat into either local ground-water, or the soil. Has any work been done on this in Thailand? Would be interesting.
The cost of the ground-loop would also be a bit, I'd imagine.
All perfectly doable, but not yet sure on how to determine the condenser design closely, under Thai conditions. (A ground-loop evaporator, in Europe is a given). Would probably need some info from ground drillings, or house foundations. How deep would this coil need to go - for instance?
If you had a large tank or pool, that could be pumped round to act as a cooling agent
as long as you don't mind swimming in warm water
I think the key to a cooling system that has been suggested is the relative humidity. Will work well in a climate with a low humidity, but as one climbs up the humidity ladder, this type of cooling system doesn't work as well.
Personally, I have not tried this in Thailand but it might work. I do know that in the summer; midwest regions of the states found this idea not the best.
All the systems I have seen in the UK use plastic piping. The copper pipe system, though more efficient isn't so widely used due to its expense.Quote:
Originally Posted by watterinja
I suppose I should've quoted this from Wiki instead.
Quote:
Closed loop
Most ground-source heat pump system have two loops on the ground side: the primary refrigerant loop is contained in the appliance cabinet where it exchanges heat with a secondary water loop that is buried underground. In a closed loop system, the secondary loop is typically made of High-density polyethylene pipe and contains a mixture of water and anti-freeze (propylene glycol, denatured alcohol or methanol). After leaving the internal heat exchanger, the water flows through the secondary loop outside the building to exchange heat with the ground before returning. The secondary loop is placed below the frost line where the temperature is more stable, or preferably submerged in a body of water if available. Systems in wet ground or in water are generally more efficient than dryer ground loops since it is less work to move heat in and out of water than solids in sand or soil.
As compared to direct exchange systems, closed loop systems need an additional heat exchanger between the refrigerant loop and the water loop, as well as an extra water pump. Some manufacturers have a separate ground loop fluid pump pack, while some integrate the pumping and valving within the heat pump. Expansion tanks and pressure relief valves may be installed on the heated fluid side. The lower efficiency of closed loop systems requires longer and larger pipe to be placed in the ground, increasing excavation costs. ASHRAE defines the term ground-coupled heat pump to encompass closed loop and direct exchange systems, while excluding open loops.
Closed loop tubing can be installed horizontally as a loop field in trenches or vertically as a series of long U-shapes in wells(see below). The size of the loop field depends on the soil type and moisture content, the average ground temperature and the heat loss and or gain characteristics of the building being conditioned. A rough approximation of the initial soil temperature is the average daily temperature for the region.
Vertical
A vertical closed loop field is composed of pipes that run vertically in the ground. A hole is bored in the ground, typically, 75 to 500 plus feet deep. Pipe pairs in the hole are joined with a U-shaped cross connector at the bottom of the hole. The borehole is commonly filled with a bentonite grout surrounding the pipe to provide a good thermal connection to the surrounding soil or rock to maximize the heat transfer. Grout also protects the ground water from contamination, and prevents artesian wells from flooding the property. Vertical loop fields are typically used when there is a limited area of land available. Bore holes are spaced 5–6 m apart and the depth depends on ground and building characteristics. For illustration, a detached house needing 10kW (3 ton) of heating capacity might need 3 boreholes 80 to 110 m (270 to 350 feet) deep.[5] (A ton of heat is 12,000 British thermal units per hour (BTU/h) or 3.5 kilowatts.) During the cooling season, the local temperature rise in the bore field is influenced most by the moisture travel in the soil. Reliable heat transfer models have been developed through sample bore holes as well as other tests.
I understand that, but some units that are put on boats use the conventional fan cooled radiator type condensers.Quote:
Originally Posted by watterinja
and I do not think that ground loop will go as well here as it does in a more temperate climate where you have at least night time cooling as there is not much below mid seventys here and mostly clay soils and in our area there is no real water as I drilled a well to 59 meters and came up dry.
I really do not think you would get below 65*F here and that would take a fair size ground loop unless you also incorporated a conv. fan cooled condensor too.
We went down 1.5 meters with our foundation pillars when we built and it was very warm at that depth.
But swamp coolers did work quite well when I worked at Nevada Test Site and with ours running if you got in front of it you damn sure developed goose bumps in a hurry, and Air con there was not good as it was to dry and you would develope a cough.
^^ MM - fair-enough, they're running a secondary loop in plastic.
Instead of dumping the condenser heat into the ground, why don't you simply heat water for your home? This is precisely what the AWHP is designed to do.
-----
^BG - good points.
Interesting comment about the humidity being too low - developing a dry cough.Quote:
But swamp coolers did work quite well when I worked at Nevada Test Site and with ours running if you got in front of it you damn sure developed goose bumps in a hurry, and Air con there was not good as it was to dry and you would develope a cough.
That happens quite often in my home state as it is dry and when it gets below freezing then there is no moisture in the air at all and either you have a water kettle on the heater stove if wood or gas or use commercial humidifiers that use expensive distilled water or do not last to long with heavy mineral water.Quote:
Originally Posted by watterinja
My gram used to have a few playing marbles in the pot and they would collect the lime and solids and get as big as golf balls and she would throw them out and put in some more of my marbles.
Well, you're the designer. Get on and design it. :PQuote:
Originally Posted by watterinja
It's already designed... How many kW do you require?
About 60.Quote:
Originally Posted by watterinja