Water, wind and sun are the most accessible and inexhaustible sources of energy that nature gives to humans. It is no coincidence that in recent years they have again received the closest attention from both science and industry, as well as enthusiasts of technical creativity and amateur designers. We have already talked about some of the “home” devices they create using wind and sun in our publications in the KDM and Small Mechanization sections. Today we introduce you to a solar heating installation designed by the Bulgarian engineer Stanislav Stanilov.
Today it is difficult to live without hot water supply. Whether you need to wash dishes or a car, take a shower or wash the floor – in all these cases you need warm water. It’s good for those whose home is centrally supplied with it; But what about the owners of individual houses and dachas? You can, of course, build a “boiler room” furnace, but it will require a lot of fuel. Meanwhile, not only in summer, but even in the cold seasons of spring and autumn, you can provide your home with hot water without spending even the smallest amounts of fuel. To do this, it is enough to make a water heater powered by… the sun.
1 – float valve of the front chamber, 2 – drainage pipe of the storage tank, 3 – pipeline for supplying cold water to the front chamber, 4 – heat-insulating box of the storage tank, 5 – cold water input pipe, 6 – cold water supply pipe to the mixers; 7 — pipe for supplying hot water to the mixers, 8 — pipe for supplying hot water to the storage tank, 9 — solar collectors, 10 — drain valve, 11 — valve for filling the system, 12 — “hot” pipe of the solar collector, 13 — storage pipe for recharge , 14 — anterior chamber, 15 — anterior chamber drainage pipe.
The solar boiler room is not too complicated: the design includes a solar collector, which in this case consists of two identical blocks (if necessary, the number of blocks can be increased), a hot water storage tank and a front chamber.
Several well-known principles were used in the design of the solar water heater. So, for example, for the heater itself – the “greenhouse effect”, that is, the property of the sun’s rays to pass freely through a transparent medium into a closed space and turn into thermal energy, which is no longer able to overcome the transparent “roof” of the installation. And in the hydraulic system, the thermosiphon effect is used, that is, the property of a liquid to rise upward when heated, displacing colder water and forcing it to move to the place of heating. It should also be noted that during the development, the effect of accumulation and conservation of thermal energy was also taken into account: in the installation, “captured” solar energy, converted into thermal energy, is accumulated and stored for a long time.
Of course, the fundamental principle in the design was “do it yourself”: all the components of the water heater must be available for manufacturing on your own and from such semi-finished products or raw materials, materials that can be purchased on the open market or picked up from scrap metal.
So, a little about the design of a solar water heater and the principle of its operation.
The collector is a tubular radiator enclosed in a box, one of the sides of which is glazed. The radiator is welded from steel pipes, and 1 or 3/4 inch water pipes are used for inlet and outlet, and for the grille it is better to use thin-walled pipes of a smaller diameter – for example, a pipe Ø 16X1.5 mm. In total, one grid requires 15 such pipes with a length of about 1600 mm.
The collector box is wooden, assembled from boards 25…30 mm thick and 120 mm wide. The bottom of the box is made of plywood or hardboard, it is reinforced with slats with a section of 30X50 mm. The box is carefully insulated; This can be done using packaging or construction foam: it is laid on the bottom, a sheet of tinplate or galvanized roofing iron is fixed on top of it, and a radiator is placed on top. The radiator is secured in the box with steel strip clamps.
The radiator pipes and the metal sheet at the bottom of the box are painted with matte black paint. It is advisable to seal the cover glass so that heat loss due to convection is minimal. It is advisable to paint the outside of the box with silver in order to reduce losses due to heat radiation.
All connections – both welded and threaded – must be strictly sealed. The pipe connection is standard, using couplings, tees and angles, sealed with hemp and paint.
A tank with a capacity of 200-300 liters can serve as a coolant storage tank . In principle, any suitable barrel is suitable for this purpose. If it is impossible to select a container of the required capacity, use two or three, connecting them using pipes into a single system. It is also advisable to thermally insulate the storage device. The ideal option would be to place the container (or containers) in a plank or plywood box with the inter-wall space filled with any heat insulator – construction foam, slag wool, dry sawdust or even chopped straw or hay. For the same purpose, it is advisable to paint the barrel (or barrels) itself inside and out with silver. It should also be used to paint the outside of the box.
The forward chamber is designed to create a constant, not too high pressure in the hydraulic system – 800…1000 mm of water column. If we draw an analogy with a car’s cooling system, we can say that the front chamber plays the role of an expansion tank here. It can be made from any suitable vessel with a capacity of 30-40 liters, for example, a large can or even an aluminum pan of the same capacity. The fore-chamber is equipped with a feeding device that allows it to operate in automatic mode. Its basis is a float valve, which is used in everyday life for waste tanks: it can be purchased at plumbing stores.
1 — solar collector, 2 — “hot” pipe of the solar collector, 3 — intake pipe for hot water exiting the storage tank, 4 — front chamber drain pipe, 5 — storage tank drain pipe, 6 — front chamber float valve, 7 — front chamber, 8 — pipe supply of cold water to the anterior chamber, 9 — storage tank replenishment pipeline, 10 — water supply inlet, 11 – cold water supply to the mixers, 12 – hot water supply to the mixers, 13 – “cold” pipe of the solar collector.
The assembly of a solar water heating device begins with placing the storage device in the attic of the house in a heat-insulating box and anterior chamber. The mass of a storage tank filled with water is significant, so you should make sure that the ceiling in the selected location is strong enough to support the weight of the massive tank.
The fore-chamber is placed close to the storage tank so that the water level in it exceeds the water level in the storage tank by 0.8-1 m.
Solar collectors are located on the south side of the house at an angle of 35 to 45° to the horizon. It is best to place them so that these panels become the natural roof of a house or small veranda.
In order to connect all the elements of a solar water heater into a single system, you will need pipes of two sizes: “inch” and “half-inch”. With the help of the latter, the high-pressure part of the system is mounted – from the water supply inlet to the anterior chamber, as well as the output of heated water from the storage tank: “inch” ones are used for the low-pressure part of the heater.
It should be noted that the performance of the system largely depends on its tightness and the absence of air pockets, therefore the installation of pipelines should be treated with particular care. It is also advisable to paint all pipes with silver and carefully insulate them – for example, using foam rubber and polyethylene tape, with which strips of foam rubber are bandaged to the pipe. Having completed this operation, it is better to cover the bandaged pipe with silver.
The system is filled with water through drain valves at the bottom of the radiators – in this case there will be a guarantee against the appearance of air pockets in the system. The filling process ends when water flows from the drainage pipe of the anterior chamber.
Now we connect the anterior chamber to the water supply inlet and open the flow valve; in this case, the water level in the front chamber will begin to decrease until the float valve operates. By bending the float holder, you can achieve the optimal water level in the fore-chamber.
1 – protective glass, 2 – frame (steel corner), 3 – bottom (hardboard 5 mm thick), 4, 7 – walls of the collector box (board with a cross-section of 120X25 mm), 5 – steel plate (strip with a cross-section of 2.5×20 mm ), 6 — corner overlay, 8 — bottom reinforcement (wooden block with cross-section 30X50 mm), 9 – coupling, 10 – radiator tube, 11 – radiator intake pipe, 12 – radiator mounting clamp, 13 – heat reflector (galvanized roofing iron or tinplate), 14 – heat insulator (foam, glass or slag wool).
After filling the system with water, the radiators will immediately begin to heat it up – this happens even in cloudy weather. Warm water will rise up, filling the storage tank and displacing cold water, which will enter the radiator. The process occurs continuously until the temperature of the water entering the radiator is equal to the temperature of the water coming from the radiator. When water is consumed from the storage tank, its level in the front chamber will decrease; then the float valve will operate and add water to the anterior chamber. Cold water from the front chamber will flow into the lower part of the storage tank, so there is practically no mixing of the water. Warm water is drawn from the very top of the storage tank.
It should be remembered that at night, when the temperature outside is lower than the temperature of the heated water, the solar water heater will begin to heat the street using a radiator – the thermosiphon effect also works in this case, pumping heat in the opposite direction. Therefore, the hydraulic system must have a valve that prevents the reverse circulation of water from the radiators to the storage tank, which makes sense to shut off in the evening and at night.
Water supply to the sink or shower can be done using standard mixers. This measure is by no means superfluous: in sunny weather the water temperature can reach 80°, and it is difficult to use such water. In addition, faucets will significantly save hot water.
If the performance of a solar water heater does not suit you, it can be significantly increased by introducing additional sections of solar collectors into the thermal circuit – the block design of the installation allows this to be done.
Based on materials from the magazine “Direct yourself” (Bulgaria)
Recommend to read
OUTDOOR SHOWER
When the device of the summer garden shower, individual developers do not always find a technically correct solution to this is not such a difficult task. We will tell you about the most...
THE “PATCHWORK” OF SUBMARINES
By the beginning of the First world war, all naval power was quite easy to divide the main with a significant naval power with diverse and numerous ships of all classes, and secondary,...
