FR2671861A1 - Atmospheric solar water heater - Google Patents

Abstract

This comprises a solar collector and a storage tank for a heat exchange fluid which is circulated through this collector. It also comprises a heat exchanger (5) which is located in the storage tank (3) and through which a secondary fluid (6) circulates. For collecting energy and for heat transfer.

Description

 The present invention relates to an atmospheric solar water heater comprising in particular an inertial storage device for hot water.

 A large number of systems for the production of hot water are already known, in which there is a mixture of primary and secondary fluids. In all these devices of the prior art, the withdrawal of hot water causes the mixing of a fluid at a temperature with another fluid which is at a lower temperature, and this, at equal volume; the temperature of the withdrawn fluid therefore varies at all times while the volume remains constant. In addition, the pressure varies as a function of variations in temperature, density and volume of the stored fluid. These variations cause mechanical stresses in all of the hydraulic circuits: for example in the pipes connecting the exchanger to the pressurized water absorber; the pipes for distributing hot water. This has in particular the obligation to install on these known devices safety and control accessories which are relatively complex and at the same time expensive.

 From experience, we know that in an energy storage tank located vertically, the temperature drop or a rise in unit of energy during a racking occurs between 75 and 80% of the capacity. In the case of a horizontal device, the drop in temperature of the drawn fluid manifests itself as soon as it is drawn off between 45 and 50% of the capacity.

 However, to integrate solar devices in architecture and the environment as well as possible, storage tanks and solar collectors are installed practically flat and parallel to the plane of the roof: this leads to an overload exceeding the limit load tolerated for constructions a not very old; other solar devices of the thermosyphon type, sometimes called low pressure, are also known, which must carry the charge of water contained in a reservoir of relative capacity and located in height in order to allow thermocirculation and racking in declination. The direct mixture of fluids at the base of the tank is located the replacement fluid which cold, flows directly into the sensor circuit. This results in thermal shock and significant mechanical stresses in the material constituting the reservoir. Hot water drawn at low pressure cannot be mixed due to the pressure differentials.

Such systems are also installed on top of a cover, which makes them, in most cases, not very accessible.

 The object of the present invention is in particular to provide a solar water heater which makes it possible to alleviate the drawbacks exposed above.

 Another object of the invention is to provide such a water heater which can easily be integrated into the architecture and / or the environment.

 These aims, as well as others which will appear subsequently, are achieved by an atmospheric solar water heater comprising a solar collector and a storage tank for a heat transfer fluid circulating in this collector, which water heater is, according to the present invention characterized in that it also comprises a heat exchanger arranged in the storage tank and in which a secondary fluid circulates.

 Advantageously, this heat exchanger is connected at one of its ends, called the inlet end, to a secondary fluid reservoir. At the inlet end of the exchanger is a device for homogenizing the temperature of the heat-transfer fluid: this device is, for example, a turbine driving in rotation a propeller and driven by the stream of secondary fluid.

 Preferably, the other end of the heat exchanger is connected to devices for using the secondary fluid. It can also include a secondary nozzle on the heat exchanger so as to withdraw a secondary fluid at a temperature determined according to particular uses.

 According to the present invention, the solar water heater also comprises means for collecting the secondary fluid after use and an energy recuperator.

 Preferably, this energy recuperator comprises a storage assembly in which is arranged a heat exchanger through which the collected fluids pass. This storage assembly comprises a heat transfer fluid in relation to the secondary fluid reservoir.

 The description which follows which is in no way limiting in nature must be read with reference to the attached single figure.

 An atmospheric solar water heater according to the present invention comprises a solar collector 1 preferably integrated in a roof, in which circulates a heat transfer fluid 2 or primary fluid and a storage tank 3.

 For example, a solar collector such as that described in document FR-A-2,591,322 can be used.

 The storage tank 3 has a cylindrical wall 4 made of thermostatic material, for example a high density concrete to which eutectic additives can be added. In this storage tank 3, a heat exchanger 5 is arranged: for example a coil in which a secondary fluid 6, such as sanitary water, circulates.

 This coil 5 is connected to one of its ends or inlet end, that is to say upstream, to a sanitary water tank 7 and downstream to domestic installations 8 using hot sanitary water. On this coil 5, it is possible to have nozzles 9 in order to draw off less hot sanitary water as required, such as for example for a shower installation 10: such water is then at the suitable temperature.

 On the water inlet pipe 11, which is therefore disposed between the sanitary water tank 7 and the coil 5, is located a device for homogenizing the temperature of the heat transfer fluid 2 contained in the storage tank 3.

This homogenization device is for example constituted by a turbine 12 driving in rotation a propeller 13 which is immersed in the heat transfer fluid 2 contained in the storage tank 3. This creates a convective current in this fluid thus making it possible to homogenize the temperature of this fluid at any point in the storage volume.

 As has already been said, an atmospheric solar water heater according to the present invention also comprises a device for collecting used sanitary water 14 and an energy recovery device 15. The latter comprises a coil 16 in which circulates the waste water which is immersed in a heat transfer liquid 17. This makes it possible to heat the water contained in the tank 7. The waste water from the energy recovery device 15 has thus lost most of its calories: this drop in temperature inevitably leads to sedimentation of the products in suspension in the hot hot water. The water discharged at the end of the decantation device is therefore partly purified.

 The storage tank 3, which could also be called a cavity accumulator, is produced by molding. In fact, a mold is used for the conformation of the tank: this mold has two parallel walls, the first external can be formed by the wall of the hollowed out space for implanting the storage tank, and the second internal, in the form of a bucket, which will be recovered during demolding. Between the two walls, concrete of known formula is poured in order to obtain a thermostatic storage tank.

 The energy recovery device can be produced in the same way as the storage tank 3.

 The present invention as described relates to a solar water heater in particular for sanitary water. But the same device could also be used to cool an air conditioning fluid: it suffices to replace the solar collector with a cold source.

 The purpose of the example embodiment below is to better enable those skilled in the art to understand the advantages of the present invention; it has no limiting character.

EXAMPLE
The temperature of 11 sanitary water or secondary fluid re 6 at the inlet of the heat exchanger 5 is approximately 2 ° C. and that of the heat-transfer fluid 2 in the storage tank 3 is 60 ° C. The flow of water 6 in the heat exchanger 5 is approximately 1.2 m3 / hour.

 In this example, the developed surface of the copper coil 5 is 1.5 m2 and has a thickness of one millimeter.

The density of the wall of the storage tank 3 is 0.5 in concrete having a density of 1.2 t / m3.

 Under these conditions the temperature of the sanitary water 6 at the outlet of the coil 5 and of 58.5in for the first eighty liters. The yield is therefore 98.5X.

 In order to improve the circulation of the fluid 2 and the coolant 17, a servo motor, 18 and 19, respectively, can be deposited at very low pressure; the fluid is sucked in and circulates in a loop by delivery, it is an open circuit at atmospheric pressure.

 Such a device can also be used for heating runways both for cars and for planes.

Claims (9)

 1. Atmospheric solar water heater comprising a solar collector and a storage tank for a heat transfer fluid circulating in this collector, characterized in that it also comprises a heat exchanger (5) disposed in the storage tank (3) and in which a secondary fluid (6) circulates.  2. Solar water heater according to claim 1, characterized in that the heat exchanger (5) is connected at one of its ends, or inlet end, to a reservoir (7) of the secondary fluid (6) .  3. Water heater according to claim 2, characterized in that at the inlet end of the heat exchanger (5) is located a device for homogenizing the temperature of the heat transfer fluid (2).  4. Water heater according to claim 3, characterized in that the device for homogenizing the temperature consists of a turbine (12) rotating a propeller (13).  5. Solar water heater according to any one of claims 2 to 4, characterized in that at its other end, the heat exchanger (5) is connected to devices (8) for using the secondary fluid ( 6).  6. Solar water heater according to any one of claims 1 to 5, characterized in that it comprises at least one secondary connection (9) on the heat exchanger (5).  7. Solar water heater according to any one of claims 1 to 6, characterized in that it comprises means (14) for collecting the secondary fluid (6) after use and an energy recuperator (15).  8. Solar water heater according to claim 7, characterized in that the energy recuperator (15) comprises a storage assembly in which is disposed a heat exchanger (16) through which the collected fluids.  9. Solar water heater according to claim 8, characterized in that the storage assembly comprises a heat transfer liquid (17) in connection with the reservoir (9) of secondary fluid (6).