OA10450A - Solar thermal water heater - Google Patents

Description

4 010450

The present invention relates to a thermal solar water heater.

The known solar thermal water heaters have thermal sensors and storage balloons. These thermal sensors consist of black absorbers: copper tubes and aluminum sheets comprising two main collectors and a scale of tubes. The storage flasks consist of an outer black sheet cylinder, an insulating layer and an inner cylinder. However, experience shows that for these types of water heaters, in periods of low sunlight, especially during periods of great chills, their yield drops very quickly. To remedy this, an auxiliary resistor is provided in the installation: hence the intervention of an alternating current consumption. This intervention of the alternative electricity cancels the purely thermal aspect of the solar water heaters, also, in case the internal storage balloon is defective, it is practically impossible to repair it without damage to the external balloon since the assembly is welded and well closed to the installation.

The aim of the invention is the improvement of these solar water heaters in order to have a better thermal efficiency with a smaller sensor area without the need for a supplementary electrical resistance intervention. The storage balloon is also improved to allow the inner balloon to be easily removed and repaired in the event of a technical problem.

The water heater according to the invention comprises two main parts described in Figure N'1: that is to say thermal sensors (24) and a storage tank (25). Figure N'2 describes the different parts of a thermal sensor. It consists of a chest (16) aluminum that causes permanent stability in humid, saline or aggressive, because the aluminum resists corrosion, an insulator (14) which is a polyester foam that covers the inner part of the chest on a thickness of 4,5cm. The sensor also comprises an absorber (13) which is made of an aluminum sheet of variable dimensions and copper tubes. These tubes consist of two collectorsand a network of parallel tubes and a double glazing (12) which

Z 010450 i makes the system opaque to ultraviolet: the layers of air enclosed between these two glass plates (12) above the absorber act as insulator, reducing the radiation losses and in case of low sun, the ultraviolet 5 trapped by the double glazing (12) heat the sensor well. Lesverres are fixed by an aluminum profile (11) screwed. Rectangular shells (3) are attached to the tubes (2) and increase the heat transfer area (Figure N "1).

Fig. N'3 depicts the storage flask which comprises an outer black sheet cylinder (17) and an internal galvanized or stainless steel insert cylinder (17 '), a thermal insulation layer (10), a deflector (23) at the bottom of the inner tank to vent the jet of cold water arriving from the bottom of the flask: this involves a rise of the jet of cold water to the portion consisting of hot water. A depressurization system (19) or valve (Figure 4) was installed at the top of the flask to evacuate the excess steam in case of overpressure to avoid a possible explosion of the system. The system described in Figure N'4 consists of a calibrated spring (4), at the ends of which two disks are installed. In case of strong pressure on the disc (5) the spring (4) is compressed and the steam escapes through the hole (6), the disc (7) remains immobilized by the base (8) of the cylinder. The upper part of the outer cylinder is presented in a lid to allow, in the event of a need for maintenance, to pull out the inner tank. The assembly is very waterproof.

The operation of the solar water heater is shown in Figure N'1. The cold water enters the flask through the tube (9), then out the tube (21) to go into the sensors. As the water enters the various sensors, it heats up and thermosiphon into the flask through the tube (20) to exit through the tube (18) for use.

In the case of exchange 35, the thermal flux which enters the element in the element with the face situated at the thermal distance x at the level of the fins: at the thermal flux which leaves by conduction of the element by the face situated at the resistance (x + dx) the thermal flux that leaves by convection of the surface between x and (x + dx) 40 + 010450

We use here rectangular fins of width b of thickness e such that b >> ele perimeter P = 2. (b + e) = 2bla cross section of the fin A = b.e and 5 | h.P jl / 2with m = | ------ |

I k.A I 2.h | l / 2 10 the heat flux transmitted by the fin is: 1/2

Ts - Tf) * h: heat exchange coefficient between the surface of the fin and the tube 15 * A = constant: cross section of the fin * K: thermal conductivity of the material (aluminum): uniform * m: mass of the fins * Ts: temperature of the surface of the tubes * Tf '.temperature to infinity

With the fins, the total heat flux of the sensor is increased by 50% compared to a sensor without fins. 20

Claims (3)

010450 REVENDI CATION 1. Solar thermal water heater composed of the following elements to increase the heat transfer area and reduce radiation losses in case of low sunlight without the need for external electrical intervention: a) sensors consisting of an absorber with aluminum sheet which are fixed the copper tubes provided with rectangular fins whose role is to increase the heat transfer area; B) double glazing which makes the sensors opaque to ultraviolet. 2. Solar water heater equipped with a depressurizer (valve) installed at the top of the flask to evacuate excess steam in case of overpressure to avoid a possible explosion of the system. 3. Solar water heater with cover to remove the inner tank for maintenance purposes.