ES2260965A1 - Solar-powered heater for use in non-pressurized thermally-isolated drum, has heat exchanger with double-helix structure used to supply hot water into drum by heating cold water supplied from distribution system - Google Patents

Abstract

The heater includes solar sensors used in generating the heat for heating the water or liquid contained in a non-pressurized and thermally-isolated drum, and a steam accumulator linked to the atmosphere through a condenser to prevent evaporation loss. Cold water is supplied from a distribution system to a heat exchanger through a pipe. The heat exchanger has a double-helix structure for hourly circulation of water, and to eliminate hammering and stratify the water contained in the drum. The heat exchanger is used to discharge hot water in the drum.

Description

Atmospheric solar heater.

Object of the invention

The present specification refers to a application for an Invention Patent relating to a heater atmospheric solar, whose purpose is to generate from same heat production and accumulation for any application, such as domestic domestic hot water, industrial, heating or others.

The source of energy to produce heat is basically solar, and may also come from resistance electric, combustion, residual heat of other medium, pump heat or other applications.

The invention is composed of one or several solar collectors that heat the water contained inside of a thermally insulated and non-pressurized tank, that is, a open tank, atmospheric pressure, this heat being transferred to the cold water contained in the tank, coming from the public health distribution network, through a new heat exchanger located inside the accumulator, which It has the peculiarity of thermally stratifying the water contained therein.

The invention is capable of being used, both in small domestic facilities, as in medium or large facilities, applicable in hotel industries or any Another type of building.

Field of the Invention

This invention has its application within the industry dedicated to the manufacture of apparatus, devices or auxiliary elements for heating.

Background of the invention

In the last decades, they have been realized numerous systems for heating and water accumulation by solar energy medium, and all of them are characterized by the use of various models of solar collectors that have a black absorber that transforms solar radiation into heat, the which is transferred to a fluid, preferably water, which at its once, it circulates through a water accumulator, giving the heat to this accumulated water that is the one that will subsequently be consumed, being in other cases, this accumulated water that circulates through the solar collectors

In the latter case, problems may appear of obstruction by calcification of the interior of the panels solar, because this water is constantly renewed as it it consumes, extracting this hot water on the part upper and cold water being provided from the bottom, from of the distribution network.

These accumulators mentioned above, maintain a thermal stratification of water as it it consumes, since the cold water introduced by the bottom is maintained by its greater density in this area, although logically mix to a small extent with hot water due to turbulence caused by the cold water inlet flow.

In addition, the metal walls of the accumulator produce a heat flow from top to bottom, which reduces this thermal stratification

Except in some rare exception, which will be commented subsequently, the hot water tank is powered directly through the distribution network, and given that solar accumulators must have at least a volume of accumulation of several hundred liters and that the network pressure distribution is several bars, even reaching 7 or 8 bars, it is a net force on the upper walls and bottom of the accumulator of tens of tons.

The above asserted obligates tax on the construction of expensive and heavy accumulators, made of steel or other metal alloys, with a thickness that endows them with sufficient resistance to these efforts.

The use of these metallic accumulators, entails the problem of electrolytic corrosion on the walls of the accumulator, necessitating the use of a sacrificial anode, usually made of zinc or cadmium, immersed in the tank and that it is replenished periodically as it is consumed, due to the daily contribution of water from the public distribution network.

In view of the aforementioned, it is desirable, due to its low cost and zero maintenance, the use of zero-pressure accumulators that can be constructed with plastic materials of small thickness and low cost, as described herein.
moria

It should be stated additionally, that another problem of those found in conventional accumulators lies in the fact that when the drinking water is stored for days, bacterial colonies can proliferate under heat, with the consequent danger or risk to the user.

A solution to the aforementioned problem previously, be noted in the Invention Patent PCT / DK96 / 00539 in the name of Knudsen, in which the existence of a primary fluid circuit that circulates through the solar collectors, heating the water contained in an accumulator closed and partially pressurized, provided with a chamber of expansion in its upper part to absorb the dilations thermal of the same.

The accumulated hot water is not consumed, but circulating driven by an electric pump, by the primary of an external heat exchanger, by whose secondary circuit circulates by its own pressure, the drinking water, which is Instantly heated for use or use.

The Invention Patent requested as PCT / DK96 / 00539 on behalf of Knudsen, although it solves the problem of Bacterial infections, does not solve the pressure problem in the heat accumulator, since this is a closed tank at pressure above atmospheric pressure, with the chamber of expansion cited above.

The Patent of Invention in the name of Knudsen, no solves the problem of pressure in the heat accumulator, since that this is configured as a closed pressure vessel, higher than atmospheric pressure, with the expansion chamber cited, and also breaks the thermal stratification of water accumulated, because when circulating through the external exchanger, it goes away progressively standardizing the water temperature of the entire accumulator, resulting after a certain consumption, an invention constitutive of an accumulator full of warm water, unlike of conventional models, where you have hot water in the upper part, and cold water in the lower part.

This invention described below, determines the use of an open accumulator, that is, communicated with the atmosphere, unlike the covered battery in the Knudsen Invention Patent.

Description of the invention

More specifically, the solar heater Atmospheric object of the invention is constituted from a simple, open deposit, which traditionally presents two problems, that is, the fact that being under pressure atmospheric, boils at 100 degrees Celsius, and with a temperature easily attainable in a solar installation with low consumption and high heat stroke, losing water in the form of steam that is evacuated to the atmosphere, and secondly, having no pressure, the accumulated water does not circulate to the places of consumption, must be driven by some mechanical device or assistant.

Specifically, the problems cited previously they are solved from an accumulator that presents an exit hole that at the top that communicates with the part of the atmosphere, through a metal tube, conductor of heat, so that, when approaching or performing a stage of proximity, the accumulated water temperature at 100 degrees Celsius, the vapors rise through the tube, being cooled by contact with the walls of the same, which in turn give heat to the external air by driving through its wall.

Similarly, water vapor, initially at 100 degrees Celsius, reduce its temperature by condensing in the form of liquid water that slides down and returns to the equipment through its own weight

If the accumulator temperature were lower at boiling temperature, heat losses from this ducts are negligible, since there is no vapor pressure, only there would be a small heat leak by conduction, through the air contained inside this metal tube.

Logically, the solution lies in not consuming the hot water accumulated, since this water or any other replacement fluid that suits, or with any additive that improve the performance and thermal accumulation capacity of water, will be used exclusively as a means of accumulation of heat, which will be transferred to drinking water by means of a heat exchanger inside the accumulator, in the form of double propeller with right and left rotation, or single propeller with alternating right and left rotations, in order to cushion the water hammer that occurs when performing the opening or closing of the taps at the points of consumption.

The cold water of the distribution network is going to enter through the lower end of the exchanger and after run it upwards, it will exit at the top heated for consumption or to power a heating network or Any other use.

The heat exchanger proposed in the The present invention also solves the problem of thermal stratification of the accumulated water and improves the stratification of conventional devices, because at begin the circulation of cold water through the lower turns, cools the accumulated water in the lower zone in the first instance, verified as the lowest temperature of the accumulator, continuing by the central turns of the propeller and reducing the temperature from the middle zone, so that it reaches the upper zone of the accumulator already preheated, reaching at this point the temperature maximum, and the water or other fluid contained in the accumulator, circulates by natural convection and laminar form, without turbulence or mixing, as it cools, until it reaches the thermal level that corresponds to it in this natural stratification induced by the helical exchanger mentioned above.

In short, the atmospheric solar heater is composed of one or several solar collectors that, placed in a sun place on the building and oriented conveniently, they heat the water or other fluid that circulates through inside, driven by an electric pump, controlled by a differential thermostat that drives the circulation if the temperature in the collectors it is significantly higher than the temperature in the lowest point of the accumulator, or the installation is arranged without thermostat, nor of the circulation pump, in which case, the  accumulator must be located at sufficient height and proximity of the collectors to be convection circulation natural fluid when the fluid is heated in the manifolds and distribute its density, ascending spontaneously towards the accumulator, physical mechanism called thermosiphon.

The fluid that circulates through the collectors may be the content in the accumulator, which is under pressure atmospheric, or it may be another liquid that, in a closed circuit, yields heat, by means of an internal or external exchanger, to fluid contained in the accumulator, which will normally be water or a aqueous solution of salts of latent heat of dissolution, by example, Glauber salt, Sodium Thiosulfate Pentahydrate or others, in order to increase the thermal accumulation capacity of the deposit.

To prevent freezing of the fluid, in the adjacent collectors or pipes during the night stages, it choose to activate the circulation pump, when the temperature in the collectors are approaching a point close to freezing, until the temperature in them rises several degrees, and if the thermosiphon circulation system, a fluid or aqueous solution that has a higher freezing temperature to the attainable in the winters of the geographical area in which The installation is located.

The accumulator that you will preferably have, with non-limiting character, cylindrical shape and vertical position, is thermally insulated on its outer face, having a hole with filling cap, indicating the optimum fluid level content, this level being close to the upper face of the accumulator.

The vapors chamber that remains in the area superior, communicates with the atmosphere through a metal tube which, provided with cooling fins, ascends with a length enough that when the temperature of the fluid is approach the boil and the vapors rise up the tube communication with the atmosphere, they give heat to the air circulating through the walls of the tube and its fins refrigerators, condensing the vapors in the inner wall and forming drops that return to the tank by their own weight, consequently the problem of the leakage of vapors in the deposits open to the atmosphere.

The exit to the solar collectors, from fluid contained in the accumulator, will be made from the most under the accumulator, because this is the coldest zone of the same, and the return to the accumulator of the fluid already heated as it passes through the collectors, will be made in the upper area of the latter, through a tube that widens internally to avoid turbulence in the pouring of the incoming liquid, avoiding mixing it with the fluid contained in that area of the accumulator and enabling rise, if its temperature is higher than that corresponding to that level, or that descends, if this were lower, remaining in the same level as the entrance hole, if the same match.

In this way, the solar heating process of the fluid, instead of breaking the thermal stratification, cooperates with the natural formation of it.

Once described the primary circuit and of heat collection and accumulation, the circuit is described secondary or heat transfer to drinking water, or in its case, to the heating fluid, by a new exchanger inside the accumulator.

The cold water coming from the network of distribution, enters the network pressure through a tube of copper or other heat conducting material, from the bottom of the heat accumulator without mixing with the fluid contained in the same, and this tube forks into two helical branches ascending soldiers with each other back and forth, circling half  of the flow to the right and the other half to the left, thereby that before a variation of flow or abrupt closing of a tap, it is the water hammer was canceled, since when they were welded together turn right and turn left, the angular momentum total of the surrounding water is null, being compensated the blow of each expires with its coaxial counterpart, whose blow is inverse to the previous, and finally these two branches join in the area top of the accumulator, to a duct that exits the accumulator with the water heated to be distributed and consumed, or in case of use for heating, to be distributed to radiators, floor radiant or other means of heat transfer to the building.

The double helix exchanger described previously, it can be replaced by a single propeller, but with a change of direction in each lap run by water, alternating right turns with turns to left, so that the water hammer is compensated by flexion of each turn with respect to the previous and subsequent.

Normally, it will be water or other fluid contained in the heat accumulator, which circulates through the solar collectors, but as mentioned above, you can opt for using an independent circuit for heat collection on the plates, and transfer to the accumulator by an exchanger inside.

This will consist of a tube of the same material of the water exchanger or similar, welded to it with downward circulation, and being both exchangers soldiers, you can increase your efficiency, but at the same time, you  increases the surface of contact with the water of the accumulator, since that their surface are shared in the two processes of heat transfer, that is, collection and consumption.

The heat exchanger circuit consumption, that is, secondary circuit, both in its version of double helix, like single helix with alternate turns, it turns out be an optimal heat exchanger integrated in the accumulator, because the cold water of the network is preheated with warm water in the lower area of the accumulator vessel, and as it rises, receives heat from the water strata at mild temperature superior, so that when you reach the upper turns, yes what receives a small amount of heat, keeping almost invariably the temperature of the fluid contained in the high zone of the accumulator.

This mode or way of transferring heat carries implicit minimal growth of the entropy of the invention, as water or other fluid contained in the accumulator reduces slightly its temperature in the area of contact with the exchanger, descending by natural convection and in laminar circulation, up to the level corresponding to its nominal temperature, without mixing with intermediate levels by those who have traveled, given the absence of turbulence.

Finally, it should be noted that the accumulator it can be provided with immersion resistance in its axis power plant to heat the water contained in the same when due to weather conditions, or due to an excess of consumption, the accumulated water has cooled, and this resistance is puts into operation by means of a thermostat, whose probe Thermal is placed in the middle zone of the accumulator.

The heat accumulator described above and Its heat exchange means, can be used in hot water production and distribution facilities sanitary or heating, in which heat is not captured by solar energy, if not that is generated by combustion, resistors electric, heat pumps or by any other means, because all the advantages described in this invention remain regardless of the origin of the heat.

Description of the drawings

To complement the description that is being performing and in order to help a better understanding of the characteristics of the invention, is accompanied herein descriptive, as an integral part of it, a sheet of plans in which with an illustrative and non-limiting nature, represented the following:

Figure number 1.- Corresponds to a view of the object of the invention, relative to a solar heater atmospheric.

Preferred Embodiment of the Invention

In view of figure number 1, you can observe how the atmospheric solar heater (1) presents a accumulator (2), cross section and an exchanger double helix (3), indicating that the circulation through thermosiphon is achieved from the fact that the water contained in the accumulator (2), circulates through the outlet orifice (6), until it enters the solar collector (1) through its entrance lower (4), being heated inside by the effect of the incident solar radiation, and driven by the thermosiphonic effect until leaving through the top fitting (5) and through an insulated tube  thermally, it is introduced into the accumulator (2), by means of the widening (7), whose purpose is to prevent all turbulence so that the flow of hot water moves to the area thermal corresponding to its nominal temperature.

The primary circuit, or heat collection, it can also be by forced circulation, in which case, it will be necessary place a pump between its lower inlet (4) and the orifice of output (6) operated by a differential thermostat.

Water, or other liquid contained in the Open accumulator (2), once heated, will be stratified thermally, being in the hottest area, a chamber of vapors (13) that communicates with the atmosphere through the hole (18) to through the heat sink duct (14), which in case of boiling of the accumulated water, cools the rising vapors, condensing them and returning in liquid form to the accumulator through the hole (19).

The optimum level of water contained in the tank is maintained by means of the filler cap (16) or by a buoy that replace the water lost by evaporation in long periods of time, and this accumulated and heated water is not consumed, but gives its heat to the secondary water circuit for sanitary use of heating, through the exchanger (3) than by its geometry cancels the water hammer that would occur in a propeller simple when cutting the flow sharply.

The cold water coming from the network of distribution, enters with its corresponding pressure through the duct (8) inside the accumulator and without mixing with the water contained, forks by branches (10) and (11) of the two mutually welded propellers, traveling a helical path  ascending, clockwise to the branch (10) and in the direction counterclockwise the branch (11), gradually warming as that ascends, being expelled for consumption by the duct (9) and stratifying the accumulator as described previously.

Claims (2)

1. Atmospheric solar heater characterized by incorporating in its interior, a secondary exchanger (3), which transfers the accumulated heat to the circulating water to be consumed or for heating, having a double helix exchanger welded, with ascending circulation clockwise ( 10) and counterclockwise (11) formed by two branches to eliminate the water hammer and thermally stratify the liquid contained, having a vapor chamber (13) that communicates with the atmosphere, through a metal tube (14) constituting a heat sink to condense the boiling vapors, having a hole (19) to return to the accumulator in liquid form and provided with an exchanger. 2. Atmospheric solar heater, according to the first claim, characterized in that the propeller of the exchanger is provided with ascending turns that change, in each turn, its direction of rotation alternately to right and left.