Thermosyphon Solar Systems
These equipments have a natural circulation based on convection currents formed in the fluid at different temperatures.
If we heat a water tank at the bottom when the bottom water warms, it becomes less dense and rises to the surface where it cools. Then returns to the bottom of the container and thus a natural circulation flow is generated.
This is the operating principle of a thermosiphon team, which will be essential that:
- The solar collector (heat sources) is always located below the level of the accumulator.
- The primary circuit is as short as possible and with a continuous slope facilitila natural circulation.
Operation of the thermosyphon system
When it reaches sufficient solar radiation, that is, with greater than 200 W / m2 values, increases fluidacumulat temperature sensors and circulates through the primary circuit until the accumulator. Then gives this heat, without mixing with drinking water inside.
Operation in the primary circuit is thermosiphon. The difference in the mouths of the usual sensor (T2-T1) temperature is usually 5 to 15 ° C, depending on the level of insolation.
As it heated, the water is stratified storage tank temperature, that is, the upper part is occupied by hot water and at the bottom is the coldest water. In vertical storage, this differential serde temperatures can reach 15 ° C. In horizontal storage, this spread down to only 4-5 ° C.
Basic elements of a thermosyphon system
Such facilities have a very simple configuration with few elements.
Solar collectors: in these systems, water circulation through the sensor is not forced and therefore desirable that the pressure drop is minimal, namely, that the tubes forming the grill sensor, are the maximum diameter possible.
In terms of the number of sensors connected, it is not recommended to connect more than 10 m2 of collectors, because the loss of catchment circuit load will be too high and considerably reduce the performance of the system.
Battery: The battery used in computers operating in indirect thermosyphon circuit usually double envelope type, because they are those with a larger exchange surface with minimal pressure drop in the circuit.
The arrangement of the storage tank facilitate the natural circulation. In this case, the best configuration would be to use vertical storage to take advantage of temperature stratification, but the constraints of aesthetic integration make the most teams incorporate horizontal accumulators.
Another feature to consider is that the water intakes of the primary circuit components, are similar to a pipe union in order to avoid losses burden reductions diameter.
It is also important that the cold water inlet is located at the bottom of the tank in order to prevent this area cool hot water entry of new water occurs.
Security elements of a solar thermosyphon system
To protect the primary circuit overpressure is mandatory to install a safety valve (VS) that has no element isolating or cutting hydraulically isolate installation.
This is the only necessary element of safety in plants operating at ambient pressure. In pressurized installations or sobrepressionades it is essential to add an expansion (VE) and a manometer.
For the specific characteristics of these facilities, it is not viable to install protection elements active low temperatures (frost) or against high temperature (overheating).
Last review: September 22, 2015