Well, finally they got around to write a report on the manufacture of a refrigerator for an aquarium.
I’ll make a reservation right away that so far everything is in the form of an experiment, and you should not repeat the throwing headlong over.
Already found a few flaws, which so far there is no way to fix it. I’ll come home, I will change the design.
So what do we have ?! Here is what was taken (bought, found, stolen :-) for the manufacture of the so-called "prototype":
1. E-Bay bought 4 Peltier elements, 60 watts each (about $ 4 each).
2. 4 radiators were taken from computer processors. Coolers are installed on the radiators. In puffs, he grabbed two radiators without coolers from the table. I’ll come home, change it. The cooler is small in diameter, at 12 volts, therefore quite noisy. But they have one big plus: Coolers have a built-in intelligent control system. The speed of rotation is controlled by temperature. Although this does not make it possible to power them with low voltage. I can’t say how much these pieces of iron cost, because I just took them at work.
3. Cut the glass. When the master saw my size, he almost died. He said that he had such an order for the first time. There are 3x1 cm glass pieces of 20 pieces. At first it was suggested that I simply break the bottle and glue from these fragments :-) The price of the question is 100 r.
4. Well, all borochlo, such as sealant, tools, thermal grease, cogs, gadgets and other things should be in the household of any self-respecting self-respecting man.
In the beginning I thought I could do without radiators. But after conducting a couple of experiments with Peltier elements, I realized that without them in any way. The temperature difference between the "cold" and "hot" surfaces of the Pelt elements is about 50 degrees. According to the documentation, it’s generally 70. Therefore, in order for the outlet temperature to be 20 degrees, the outside will be heated to at least 70. Therefore, you can’t do without radiators.
I sketched here an approximate diagram of the entire device. The heat exchanger itself was made of ordinary 4ki silicate glass. Not the most suitable material, I did not find anything more suitable at that moment. There was no time. Most likely then I will make of stainless steel. I cook with argon. But for now, glass.
Glued the heat exchanger. There are partitions inside it to slow down the flow and increase the time of water passage through the heat exchanger. During the tests, I realized that it was an absolutely unnecessary undertaking. The flow rate can be adjusted by decreasing the outlet orifice or pump. I bought a bottom pump with a maximum flow rate of 100 l / h and the ability to adjust performance.
At the ends I glued a fitting from an insulin syringe. Also a big minus :-( The thickness of the sealant turned out to be too large and the nozzle does not hold tight. Even by negligence I almost pulled out one, I had to cover it with sealant.
To fix the radiators, make a chassis from an organizational set. Radiators are attached to it using racks for mounting boards and components in electronic equipment. The height of the struts is such that a heat exchanger with Peltier elements superimposed on it exactly enters the gap between the chassis and the radiator plane. Between the heat exchanger, Peltier elements and radiators a layer of thermal paste.
After drying the sealant, assembling and disconnecting the wires, I poured water into the basin and tested it. I don’t have a powerful power source here to power all the elements at once, so I worked on only one. Each element consumes about 5 amperes, at a voltage of 12 volts. Accordingly, you need a source holding a current of at least 20 amperes. I’ll be completely checking at home.
Test conditions: water temperature 30 degrees, air temperature 36, water flow through the heat exchanger about 60 liters per hour. One Peltier element is connected. Under these conditions, the temperature at the outlet of the heat exchanger was 28.5 degrees.
I think it’s not even bad for a "raw" sample. In principle, the main task of this device is not to cool, but not to give heat to the water in the aquarium, with increasing ambient temperature. I doubt that someone will pour boiling water into the aquarium, and then cool it
I would also like to note that the Pelt elements can act both as coolers and heaters. If you change the polarity of the connection, the "cold" side of the element begins to heat up. The “hot” side has a room temperature. By connecting the device through the controller, you can implement a different connection and use the device and cooler as a heater.
Do you need a refrigerator for your aquarium?
The first thing you can do in order not to spend money on an expensive water cooler is to try to start 1-2 fans in the upper part of the aquarium or sump (SAMP-a). Coolers can quite well reduce the temperature of the water (by 1-2 0 C). But they also have a serious minus, consisting in the fact that they consume excess electricity and increase the evaporation of water, quickly lowering its upper normal level. This can be quite unpleasant and expensive, especially if you add water to the aquarium from reverse osmosis. Aquarium refrigerators can use a lot of electricity, especially if they are designed for small aquariums, and you are trying to cool a huge amount of water.
If you keep a saltwater aquarium with fish and live stones only, then most likely you will not need to install powerful metal halide lamps or high power fluorescent lamps. Why waste electricity on animals that are virtually unresponsive to increased light brightness? In this case, you most likely will not need an aquarium cooler. As you already know, 1-2 fans will be enough for you to lower the temperature by 1-2 degrees.
You will definitely have to invest in an aquarium refrigerator if the water temperature in it often fluctuates or rises significantly, especially when keeping a reef aquarium or cold-water species of fish, shellfish and other animals. It is also recommended to buy a water cooler if you have a cooling fan, otherwise you will often have to add water to the aquarium instead of evaporated water, which is not economically viable.
Parameters of refrigerators for aquariums.
Water coolers are usually evaluated by their capacity and the volume of water in which they can hold the required temperature. Manufacturers usually recommend the volume of the aquarium for which a refrigerator can be used. If your aquarium is on the border of these parameters, it is better to buy a more powerful water cooler, otherwise you will spend a lot of electricity on the work of a weak refrigerator (it will constantly work). In addition, a weak cooler may not cope with the task assigned to it.
In our country most common and availableexternal refrigerators for aquariums. For their work, you will need to additionally buy a pump and tubes. With the help of a pump, through one pipe, water from the aquarium will enter the cooler, and through the second it will return to the aquarium. When using this refrigerator, it is recommended to have a spare pump and pipes, otherwise if something fails, you may have to wait until the morning, weekend or delivery from another city, before you can start the cooler again.
There are also domestic refrigerators. They have a so-called cooling coil, which is placed in a sump (SAMP). Its advantage is that you will not need to install additional pumps to pump water into the refrigerator and back into the aquarium.
Cooler purchase recommendations!
Refrigerators are quite expensive aquarium equipment. Before you buy any cooler, be sure to study its parameters and ask about their pros and cons in aquarium forums. To do this, simply enter the model of the refrigerator in the search engine and the word “overview”, “characteristics”, etc. You should not “send” only reviews in online stores selling refrigerators, as they can be “custom-made”, that is, specially written by sellers to increase sales. Be careful and pay attention to what you are reading, and only after a thorough study of the apparatus will you be sure that you have chosen the right cooler for your aquarium.
What to look for when buying a refrigerator for an aquarium?
- The price of the refrigerator
- Energy consumption
- Noise level (refrigerators can be quite noisy, especially large ones)
- Easy to maintain
- Will it be enough for normal cooling of your aquarium?
The main thing the aquarium refrigerator is designed for is to stably keep the water temperature at the same level. Stable water temperature in the aquarium is one of the components that contribute to good health of fish and corals.