FR2864608A1 - Solar water heater for e.g. individual sanitary facility, has reflectors with flanges, cylindro-parabolic collectors coupled to dwellings, and connection tubes having reduced surface contact with tank associated to cut-out points - Google Patents

Abstract

The heater has a set of reflectors (11) with flanges that reflect solar rays towards a collector. A set of cylindro-parabolic collectors (1) is coupled to dwellings. An articulation allows rotation of the collectors for their orientation towards the sun. Connection tubes (5) have reduced surface contact with an expansion tank associated to cut-out points (P1-P5). An electronic circuit regulates functioning of two heating units.

Description

The present invention relates to a set of devices for

  heat the sanitary water thanks to the sun.

  There are already solar water heaters whose operation is as follows: One or more glass floor planters of about 4m2 (for a family of 4) contain a matte black metal collector. They are exposed to the south-facing exterior, at a variable angle depending on the latitude. A calorie reserve of about 300 liters of water at 80 C contains a heat exchanger and a booster heater. A coolant w circulates between the collector and the heat exchanger using the 2 connecting tubes and a circulation pump or by thermosiphon. These solar water heaters are very expensive, they must be installed by solar specialists and can be depreciated financially only in the very long term.

  The devices according to the invention make it possible to remedy these drawbacks by considerably reducing the manufacturing cost, thus its damping is much faster. In addition it can be mounted by a handyman without particular knowledge in the field of solar.

  The parabolic solar water heater operates as follows: One or more Cylindro-parabolic sensors whose total opening area is also 4 M2 for 4 people, have a collector made of a black metal tube mat placed along the line of the parable and wrapped in a glass tube in which the empty can be done. A tracking device ensures the positioning of the sensor towards the sun, already known, it is constituted by a cache projecting its shadow to photocells. This device is enclosed in a glass envelope. The collector is connected by means of a double heat-insulated tube to a conventional 300-liter electric balloon via a device against freezing. The 2 connections of the solar collector circuit are on the pipes reaching the electric balloon; the go of the solar circuit on the cold arrival of the balloon and the return on the hot exit of the balloon. The water contained in the electric balloon circulates in the collector of the sensor in closed circuit using a circulation pump. The electrical resistance of the balloon only serves as a backup when the sun is failing.

  This system therefore has no specific reserve or heat exchanger.

  The only modification to be made to the electric balloon is the replacement of the mechanical thermostat by an electronic thermostat.

  The sensors used are preferably of the parabolic cylinder type, 2 types are retained: The 2-axis cylindro-parabolic sensors are the most efficient. They are oriented towards the sun on 2 axes (elevation and longitude).

  1-axis cylindro-parabolic sensors are less efficient. Only the plane defined by the font line and the axis of the parabola is oriented towards the sun. This causes angular losses and it is necessary to increase the surface of the sensors to obtain the same efficiency as with a 2-axis sensor. However, it is possible to limit these losses by making the inside of the reflector cheeks reflective, which must be perpendicular to the fire line, so that the light rays coming out towards the collector are reflected. Most of the sanitary circuits are equipped with An electric balloon, failing that, it is necessary to add one but that represents only a very reduced cost compared to a specific reserve with heat exchanger.

  The cylindro-parabolic sensors make it possible to obtain much higher temperatures. This has the effect of being able to recover calories that planar glass sensors can not recover at the beginning and end of the day and during the winter period when the sun is less strong but also a better control of the regulation and the possibility to connect the electrical resistance of the balloon (used as an adjunct) at the reduced rate (40% night savings in France).

  The cylindro-parabolic sensors are connected to the electric balloon with 2 connecting tubes (return and return) which are inserted into one another.

  The diameter of the outer tube is about one-third less than the sum of the two tubes (traditionally separated) for the same passage sections with less heat losses. Certainly there is a heat exchange between the two tubes but this is not lost energy. Since the water reaches a higher temperature at the collector, it comes out with about the same temperature difference as if the tubes were separated. With this process there is about 30% less heat losses.

  With the flat sensors there are problems of regulation because it is not possible (for example) to recover calories when the reserve is at 60 C and the flat sensor is at 50 C. The calories at low temperature can not not be recovered.

  A family of 4 consumes about 200 liters of water at 50 C per day. A 300 liter flask at 100 ° C. represents approximately 400 liters of water at 50 ° C. (leaving 300 liters of water at 50 ° C. in the flask). The median temperature to obtain 2 times 200 liters of water at 50 ° C. is about 70 ° C. Consequently 300 liters at 70 ° C. represent 200 liters at 50 ° C. and 300 liters at 30 ° C. (100 ° -70 ° C.) also represent liters at 50 C. Since a cylindro-parabolic sensor can deliver well over 100 C whatever the sun, it is interesting to determine 2 different temperature ranges for the 2 different heating modes: - From 0 at 70 C for heating with the auxiliary resistance.

  -From 0 to 100 C for heating with cylindroparabolic solar collectors. Most of the time this beach will be 70 C to 100 C.

  Although the theoretical hourly thermal efficiency of the cylindroparabolic sensors is about 20 to 30% less than the planar glazed sensors, all the advantages of the present invention are that the thermal efficiency actually recovered annually with 2-axis cylindro-parabolic sensors is equal to and even greater than that of even flat-panel glazed collectors.

  The accompanying drawings illustrate the invention: FIG. 1 represents the general diagram of operation.

  - Figure 2 shows an example of cylindrical parabolic sensor 2 axes in perspective.

  FIG. 3 represents an example of a cylindro-parabolic sensor 1 axis in section.

  FIG. 4 represents exemplary mounting of lines of cylindro-parabolic 1-axis sensors.

  - Figure 5 shows in 3 sections the traditional connecting tubes (5A) and (5B) and the improved connecting tubes (5C + 5D) or (5E).

  - Figure 6 shows the recovery of light rays for cylindro-parabolic sensors 1 axis in longitudinal section.

  - Figure 7 shows in 3 sections an example of a ball valve that can open and close the 5 cutoff points (PI) to (P5).

  FIG. 8 represents anti-twisting in cross-section. The marks (ST1) to (ST4) are thermal probes for the control of electronic circuits (CE1), (CE2) and (CE3).

  - (ST1) is a probe placed in the balloon, instead of the usual mechanical rod thermostat.

  - (ST2) is a probe placed in the collector (12) to measure the temperature of the water coming out of it.

  - (ST3) is an internal probe to the tracking device (13) which is heated by the greenhouse effect when the sun is shining.

  - (ST4) is a probe located outside but away from the sun.

  - (CE?) Is the electronic circuit enabling the orientation of the sensor by controlling the geared motors.

  - (CE2) is the electronic circuit providing protection against frost by operating a particular cycle.

  - (CE3) is the electronic circuit providing thermal regulation over 2 temperature ranges.

  According to FIG. 6, the 1-axis cylindro-parabolic sensors have light losses in the end of the reflectors (11). Given the angle of the sun with the furnace line (LF), the solar rays reflected by the ends of the reflectors (11) arrive outside the limits of the collector (12). If the cheeks (14) of the parabolic cylindrical parabolic reflectors (11) are perpendicular to the fire line (LF) and their inner face is reflective, the light rays are necessarily reflected within the limits of the collector (12). In addition, rays arriving directly on the reflective cheeks (14) are returned to the reflector (11) to end within the limits of the collector (12).

  According to FIG. 8, the 1-axis and 2-axis cylindro-parabolic reflectors have the drawback of twisting (in torsion). Effective anti-twisting is possible by making the collector (12) integral with the cheeks (14) of the reflectors (11). A tube, preferably round, even in glass, is particularly resistant to torsion. By ensuring the solidarity of the metal tube (18) or the glass tube (17) of the collector (12) with the cheeks (14) of the reflector (11) by any means, a rigid sensor is thus obtained.

  Although it takes more surface, parabolic 1 axis sensors have the great advantage of being able to integrate into homes. According to Figure 4, can be connected end to end on 1 or 2 mounting lines several cylindro-parabolic 1 axis sensors. This set can be mounted on a facade, a gable, a wall of any kind, a roof or a terrace facing south approximately. As an indication, a line of 8 meters of cylindro-parabolic sensors with a width of 60 centimeters represents 4.8 m? which is enough with a 300 liter balloon for a family of 4 people.

  The articulations (15) allow the rotation of the cylindroparabolic sensors 1 axis for the orientation towards the sun as well as the kinematics of opening and closing. According to FIG. 3, this kinematics makes it possible to press the sensor against the surface on which the supports (16) are fixed. The exterior of the reflectors (11) is decorative (imitation stone for example) which allows the sensor to integrate well with the houses when it does not work, moreover the inside of the reflectors (11) is protected from bad weather and dirty little.

  According to FIG. 5, it is possible to limit the heat losses of the connecting tubes (5A) and (5B). To compare the processes it is necessary that the following basic parameters are equal: Equal insulation coefficients, - Equal crossing sections (Si = S2 = S3 = S4 = S5 = S6) - Equal lengths of tubes.

  - Temperatures of the equal liquids.

  Under these conditions, the heat losses are directly proportional to the surface of the tube or tubes in contact with the thermal insulation. Since the sections (S1) to (S6) are equal, it can be determined by calculation that the area of the tube (5C) or (5E) is about 30% smaller than the sum of the areas of the tubes (5A) + (5B ). There is therefore less heat loss despite the entropy generated by the temperature rise at the collector (12). The limitation of the thermal losses of the connecting tubes (5A + 5B) by the reduction of the lo surface in contact with the insulator is ensured by inserting the tube (5D) in the tube (5C) while preserving the equality of the sections ( S3) and (S4) or by partitioning the tube (5E) keeping the sections (S5) and (S6) equal.

  The electronic circuit (CE) ensures the positioning of the cylindro-parabolic sensors towards the sun. When the sun is shining, the temperature of the probe (ST3) is higher than that of the probe (ST4). Under these conditions, the sun tracking device (13) comes into action in order to align the sensor (1) towards the sun using the two geared motors.

  According to FIG. 1, the protection against freezing is ensured by an expansion vessel (3) associated with 5 hydraulic cut-off points (PI) to (P5) which are opened or closed in a particular cycle by the electronic circuit (CE2 ) to drive water from the solar circuit with the compressed air contained in the expansion vessel (3) without the aid of an external compressor. The 5 points of hydraulic cutoff (PI) to (P5) can be indifferently replaced by solenoid valves or by one to several motorized ball valves allowing 1 to 5 independent cut points. The cut-off point (P4) can be replaced by a valve or a non-return valve allowing the air to enter without coming out.

  When it has not frozen for some time, the air in the expansion vessel (3) dissolves in the water and the level rises. For the system to work properly, the expansion tank must have a volume equal to 2 or 3 times the capacity of the solar circuit and the air must be compressed just before flushing water from the solar circuit.

  Figure 7 shows an example of a motorized ball valve providing opening and closing of the cutoff points (P1) to (P5). The motorization of the valve is slow and allows the cycle without stopping the engine, except when the electrical circuit (CE2) waits for favorable conditions of recovery. The plug is pierced with two parallel holes in two different planes, perpendicular to the axis of rotation.

  When the probe (ST2) signals the risk of frost, the electronic circuit (CE2) starts the following cycle: - closing of (PI) and (P2) to isolate the solar circuit, - opening of (P3) to evacuate the pressure, opening (P4) to drain by gravity the expansion vessel.

  - closing of (P3) and (P4) when the expansion tank is empty - opening and closing of (P2) the time necessary to compress the air of the expansion tank (3) with the pressure of the water network - opening (P5) to expel the water from the solar circuit by means of the compressed air of the expansion vessel (3), - the electronic circuit (CE2) remains in standby. When the probe (ST3) is greater than (ST4), the cycle resumes, - closing of (P5) then opening of (P2) ensure the pressurization of the solar circuit.

  The cycle is thus completed and it can be re-engaged by the electronic circuit (CE2) if necessary.

  The essential feature of the thermal control is to be able to heat the water contained in the electric tank (2) in 2 different temperature ranges with 2 different heating means, 5 thanks to the electronic circuit (CE3).

  The electronic circuit (CE3) thanks to the probe (ST1) activates the auxiliary resistance below 65 C, stops it at 70 C and it switches on the circulation pump (4) if the probe (ST2) is higher 20 C (adjustable) to the probe (ST1).

  All the mentioned temperature values are intended to give orders of magnitude and that variations of these values are possible without departing from the scope of the present invention. For example, the storage temperature of the water in the flask may be 120 C instead of 100 C, which shifts the other temperatures.

  For safety reasons, the safety valve or group (6) is retained and a thermostatic valve (7) is added to the outlet of the electric balloon to prevent burns.

  The devices according to the invention are particularly intended for the production of domestic hot water.

Claims (6)

  1 - Set of devices for cylindroparabolic solar water heater characterized in that it comprises - less loss of light at the end of reflectors (11) cylindroparaboliques 1 axis by making the inside of the cheeks (14) reflecting reflectors (11) so to return the sun's rays to the collector (12).   - An anti-twist for reflectors (11) cylindro-parabolic 1 axis which is lo assured by making the collector (12) integral with the cheeks (14) of the reflector (11).   - several 1-axis cylindro-parabolic sensors connected together and integrated into dwellings.   an articulation (15) ensuring the rotation of the cylindro-15 parabolic 1 axis sensors.   - less heat loss of the connecting tubes (5) by reducing the surface of the tubes (5A) + (5B) in contact with the thermal insulation, a protection against freezing composed of an expansion tank (3) ) associated with 5 hydraulic cut-off points (PI) to (P5) which are opened or closed in a cycle by the electronic circuit (CE2) to drive water from the solar circuit with the compressed air contained in the expansion tank (3).   a thermal regulation ensuring the operation of the two heating means in two different temperature ranges by means of the electronic circuit (CE3).   2 Device according to claim 1 characterized in that the cheeks (14) of the reflectors (11) cylindro-parabolic 1 axis are perpendicular to the fire line and their inner face is reflective.   3 - Device according to claim 1 characterized in that the antivrillage cylindro-parabolic sensors (1) is provided by making the metal tube (18) or the glass tube (17) of the manifold (12) integral with the cheeks ( 14) reflectors (11) by any means.   4 Device according to claim 1 characterized in that several 1-axis cylindro-parabolic sensors are connected end to end on 1 or 2 assembly lines and that the integration of the assembly lines to homes can be done on a facade, a pinion, any wall, roof or terrace facing south approximately.   - Device according to claim 1 or claim 4 characterized in that the kinematics of opening and closing and the orientation towards the sun cylindrical parabolic 1 axis sensors are provided through the joints (15) of the cheeks (14) with the supports (16).   6 - Device according to claim 1 characterized in that the reduction of the surfaces of the tubes (5A) + (5B) in contact with the thermal insulator is provided by insertion of the tube (5D) into the tube (5C) retaining the equal sections (S3) and (S4) or by the partitioning of the tube (5E) keeping the sections (S5) and (S6) equal.   7 - Device according to claim 1 characterized in that the 5 points of hydraulic cutoff (PI) to (P5) can be interchangeably replaced by solenoid valves or by one to several motorized ball valves allowing 1 to 5 independent cut points and that the cut-off point (P4) can be replaced by a valve or non-return valve allowing the air to enter without coming out.   8 - Device according to claim 1 or claim 7 characterized in that the opening and closing cycle of the cutoff points (PI) to (P5) controlled by the electronic circuit (CE2) successively causes: the closure of (PI ) and (P2), the opening of (P3) then of (P4), the closing of (P3) and (P4), the opening and closing of (PI) or (P2), the opening of (P3) P5), then wait and when the electronic circuit (CE2) allows, the closing of (P5) and the opening of (P2).   9 - Device according to claim 1 characterized in that the electronic circuit (CE3) through the probe (ST1) engages the auxiliary resistance (21) below 65 C, stops at 70 C and that activates the circulation pump (4) if the sensor (ST2) is 20 C io (adjustable) higher than the sensor (ST1).