Before I begin I would like to add that most of my experience has been through trial and error and any faulty assumptions in my reasoning are the result of trying to reason my own involvement out of these said errors so please be critical of the information I am presenting but keep it within reason.
Recently, I've been working on some water conservation projects in Hilton Head, SC. This particular project was not developed by myself but was the brainchild of a local industrial engineer turned operations guru whose name shall not be named to protect him (but I bet he'll love to see that I mentioned him in this blog).
This gentleman noticed that an open-looped water-cooled ice maker was discharging large amounts of water down the drain and might be better utilized as a source of water for irrigation. His idea was simple: Collect the discharge water in a rain barrel and connect it to a solar-powered pump to produce a self-contained irrigation system.
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| The water collection system beside the ice machine with booster pump and 12V power supply with inverter (Note: the pump will soon be placed on the floor.) |
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| The single solar panel that is not permanently affixed to the roof and will be counter weighted with concrete blocks (like a satellite dish). |
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| The pump below the power supply which is below the charge controller. |
For those of us that have no interest in the beautiful thermodynamic cycle of refrigeration then I will provide you with a simple explanation and illustration of how efficient and yet wasteful open-looped water-cooled refrigeration units can be below.
Most air conditioners and refrigeration units work by the principle that expanding gases cool and compressing gases warm by cycling refrigerant (such as R410A or in the old days, Ammonia) through a condensor and an evaporator. The evaporator is responsible for pulling heat out of what is intended to be cooled (i.e. water or air) by using the heat in what is intended to be cooled to change the refrigerant from a liquid to a gas (this is known as a phase change or latent heat exchange). This vaporized refrigerant is then cycled to a condensor where this vapor is condensed back down to it's liquid phase which results in a heat release. This is best observed by noticing that the food in your refrigerator remains cold while the excess heat is released out of the top, back, or bottom.
For most refrigeration cycles (i.e. our refrigerators and air conditioners) this excess heat is transferred between the hot condensor and the ambient temperature but water is a much more efficient means of collecting, storing, and transferring heat (this partially explains why hydronic (or water) heating systems have been so popular over the years). Therefore, if you want to make large amounts of ice in a hurry a water cooled refrigeration unit is ideal but the downside is that with an open-looped water cooled refrigeration unit that excess water is lost down the drain. (Note: There are closed-loop water cooled ice makers that send this warmed water to a storage tank, like your hot water heater, to preheat water.)
For our project we used a 350 gallon Graf Top Tank, Leader EBS 3/4 HP Booster Pump, a collection of PVC pipe and fittings, and we powered the irrigation pump with 127 Watt, 7.3 Amp BP Solar panel (that was just laying around the shop) that stored the power in a Xantrec XPower Powerpack 1500 (which was also just laying around the shop and the pack itself has a modified sine wave inverter for converting DC power to AC). We also had a few other items including a charge controller for the battery pack and miscellaneous tools for plumbing, drilling holes, etc...
We learned a lot from our first endeavor and I've listed those below:
1) The more parts you have the more you have to lose.
2) The water collection tank that you choose was never intended for your purpose so you will have to modify it.
3) A hole saw kit is an ideal investment for drilling holes into your water collection tank
4) The use of an exterior marine grade sealant is an excellent fail safe for when you do not tighten your fittings properly and your tank is already put together.
5) Never ever connect the leads from your charge controller to the wrong side of the battery (I burned out our first charge controller this way.).
6) A check valve (used to prevent backflow in a well water system) is ideal to prevent the static pressure caused by the height of the water from turning your pump and causing a slow drain on your system and this should be placed on the outgoing water portion of the pump.
7) Never damage the threads on the housing of your pump as it is made in Italy and it is impossible to get a new one or a replacement part.
8) And lastly, your pump should be placed as close to or below the outlet on your water collection tank as instructed in the manual of the booster pump.
Besides the steep learning curve, and after some help connecting it to the unused irrigation system, we now have an irrigation system that is solar powered and provides, according to my calculations and the limitations of the storage capacity of the single 12V battery, approximately 200 gallons of irrigation for something that would have just gone down the drain (10 min. of power at 20 gallons per minute).
This is only the beginning and we are just starting other projects which include the collection of condensation produced from two HVAC systems to provide water for another 50 gallon water collection system, scraping together a solar hot water heating system, starting a compost project, growing an herb garden, purchasing an electric vehicle that is made in the USA, and more importantly...having fun.
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