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Spring doesn't stay long, and then it’s back to the sticky hot summer days. As summer heat becomes unbearable, air conditioners in every house become active and yet again the electric bills start soaring, disgustingly adding salt to the wound. And if your country happens to be within the tropical boundaries, this further makes the situation hostile.
Conventional air conditioners are efficient- there's no doubt about that- but they come with huge costs in the form of electric consumption and the associated utility bills. More electric usage from such units would mean that more hydro-electric and nuclear power plants will have to be installed in the future, resulting in the destruction and occupation of precious land and other natural resources in the process.
However, interestingly of late, scientists have started looking for many different renewable methods for replacing the above rather costly counterparts. Air conditioning is no exception and is at the core of their research.
Water as we know is the basis of life on this planet and moreover has unconditionally provided us with simple solutions to most of the energy related problems. Whether it’s a hydroelectric power station or a cheaply operated evaporative air conditioning unit, water forms the main and ubiquitous element everywhere - a magical fluid that’s available FREE of cost and plentifully on this planet.
Before moving into the proposed design of our homemade air conditioner, let’s study a few of the following conventional AC designs and their drawbacks:
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Air Conditioners Incorporating Freon
An electrical compressor compresses cool Freon in liquid form and in the process Freon heats up and turns into gas.
The gaseous Freon is then forced through a set of coils placed externally behind the AC cabinet where it dissipates its heat into the outer atmosphere. The cooled Freon gas is then forced back through another set of coils where it is allowed to expand.
In the process it evaporates and cools down to freezing temperatures before it reaches back to the compressor to repeat the cycle. This cooling effect is radiated inside the room through a fan to produce the required effect inside a room.
Drawbacks: In case CFC or Freon leaks out can escape into the uppermost layer of our atmosphere where through a chemical reaction can help depleting and rupturing the precious ozone gas envelope - making our planet and us exposed to the lethal UV rays from the sun.
Running the compressor of the above room air conditioners involves high electricity consumptions and bills.
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Air Conditioners that Use Ammonia and Water
Here ammonia acts as the chiller component whereas water acts as the absorbent.
From an ammonia water mixture, ammonia is forced out by heating the mixture in a gas-fired burner.
The separated ammonia is then passed through an outdoor coil and condensed.
The above condensed or the liquid ammonia is forced through another set of low pressure coils where it expands and evaporates to generate the required cooling after which it’s finally reabsorbed in water to repeat the cycle.
Drawbacks: Although ammonia is a highly degradable chemical agent and also does not affect the ozone layer in any way, it is definitely harmful to us in case it leaks out into our rooms. Therefore ACs using ammonia need to be positioned such that any leaking gas is kept well away from the room where it’s installed, quite a complicated and critical affair.
The running cost is also high, equal to the Freon ACs.
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Air Conditioner Based on Evaporation Principle
The important property of water of absorbing the ambient temperature while evaporating has been exploited to cool houses since the early ages. Even today the coolers based on evaporative technology use the above feature of water extensively.
The figure alongside shows the internal mechanism of a standard air cooler, also called a swamp cooler, based on the evaporative principle.
As we can see the entire process takes place inside a rather large box type enclosure.
The side walls of the enclosure have slotted ventilations for the surrounding warm air to get in.
A layer of thick spongy pad is placed immediately after the side ventilations inside the box.
A small electric water pump is used to transfer water from the bottom reservoir over these pads from the top so that they are properly soaked. The excess water drips down back into the reservoir.
A motor/pulley mechanism is used to rotate the propeller of a large fan at the front of the box. When it starts moving, the surrounding air is sucked inside the box through the side ventilations.
The air is dragged in through the water soaked pads where due to evaporation the sucked air loses its temperature and becomes cool.
The cooled air is ultimately forced out by the fan outside into the room, for the desired cooling.
The above principle may be enforced or implemented through different ways and may also be enhanced through new innovations.
For example, water sprinklers are used over the roofs of many houses where the water droplets evaporate helping the house to lower their internal temperature. The principle has been thoroughly studied and improved by NREL and they have succeeded in building a super efficient air conditioner entirely based on evaporative technology.
Although quite cheaper than an ammonia air conditioner, a swamp cooler may be accompanied with certain drawbacks. Here, the evaporated water molecules are distributed into the premise, unnecessarily increasing the relative humidity of the room. This can become a big nuisance especially for the coastal countries where the RH remains already on the higher side for most months. Also the efficiency of these units drastically fall as the surrounding humidity increases.
In our present design of homemade air conditioner, we rather take a different approach and use cold water to produce the required cooling effect, but not in a evaporative manner. This is a bit costly than the swamp coolers, but surely way ahead as far as the efficiency is concerned.
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Building the Homemade Air Conditioning System
The idea of our homemade air conditioner with cool water is very simple. Get a few bottles of freezing cold water, empty them in a tank, and use it to cool the room by circulating it through a simple coil/fan mechanism set up.
Let’s learn the procedure through the following steps:
The set-up is shown alongside, as we can see, it utilizes very ordinary low cost items such as a plastic/thermacole (EPS) basket, copper tube or coils, a table fan, and a few bottles of cold water.
An over head tank made up of plastic and lined up with thermacole, which is probably one of the best bad conductors of heat (coldness being also a temperature) is used as the main storing compartment for the passive energy in the form of the cold water.
A conduit copper pipe is attached to the base of this tank which further forms into a large spirally wound coil having a diameter equal to the procured table fan for the purpose. The end of this copper spiral ultimately terminates into another tank for retrieving the melted or the exhausted ice water.
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How to Run the Homemade Air Conditioner
The over head tank is specifically made of plastic, ABS to be precise. This box is further placed inside a thermacole container such that the ABS box snugly slides inside it.
The tank is first filled with freezing cold water; you can simply get it from in your home refrigerator itself.
The thick thermacole lining around the container helps keep the near-freezing temperature of the water intact and allow its exhaution very slowly so that the low temperature of the dripping water through the copper coils is sustained for a longer period time.
As soon as the cold water fills-up the whole “copper spiral," copper being extremely good conductor of heat instantly starts radiating the coolness through its outer walls into the atmosphere around it. However this makes only the air immediately around the coils colder and will not help to serve the purpose we are up to.
We need to “shoot" or rather spread the low temperature created around the coils over the entire enclosed area or the room where it has been installed.
This is simply done using a table fan. Make sure that the diameter of the fan exactly matches to that of the copper spiral or vice versa for maximum efficiency.
You will find that by keeping the fan very close to the copper spiral and switching it ON amazingly initiates the generation of fresh cold breeze all over the place.
A control cock fitted at the end of the copper piping is used to control the flow of the seeping water into the collector tank. This is directly proportional to the rate of cooling the room: the faster the water escapes from the tap, the greater the radiation of the cooling effect.
The design has a striking advantage over the age old ordinary evaporative type of coolers where the cold air is also accompanied with moisture undesirably raising the RH of the premise to uncomfortable levels. Here copper being non porous allows only the freezing temperature to circulate, restricting the water content from shedding into the surrounding.
The following data will confirm the high efficiency of the above homemade air conditioner using cool water, compared to a conventional air conditioning system.
- Set- up cost not more than 20% of the commercially available units.
- Electric comsumption less than 50% compared to the conventional ACs.
- The main cooling agent being cold water is available very cheaply or is derived from the home refrigerator itself costing less than a dollar per month.
- Each filling of the tank with cold water lasts for more than 15 hours of air cooling.