WO2011031126A2

WO2011031126A2 - System for heating water using solar radiation

Info

Publication number: WO2011031126A2
Application number: PCT/MX2010/000084
Authority: WO
Inventors: Noel LEÓN ROVIRA; Edwin Mauricio HINCAPIÉ MONTOYA
Original assignee: Instituto Tecnológico y de Estudios Superiores de Monterrey
Priority date: 2009-09-08
Filing date: 2010-09-02
Publication date: 2011-03-17
Also published as: MX2009009568A; MX339698B; WO2011031126A3

Abstract

The present invention is a novel system that incorporates a solar collector system with direct radiation concentrated using Fresnel lenses. This system accumulates solar energy and uses that energy to heat domestic water. The system comprises a Fresnel lens, two tanks (one inside the other), a copper coil through which the domestic water circulates and which surrounds the inner tank, and thermal insulation for the outer tank. The Fresnel lens directly concentrates the sun's rays onto the exposed glass surface on the upper part of the outer tank. The inside of the main tank houses another smaller tank containing air and the lower part of the latter tank is black in colour, allowing the solar energy to be absorbed more efficiently and the heat generated to be transmitted to the water in the space between the inner and outer tanks. The main tank is thermally insulated with a layer of glass fibre, preventing the heat concentrated in the tank from escaping therefrom. The advantage over other systems is that the entire system is incorporated in one structure that includes the tank with the hot water.

Description

SOLAR RADIATION WATER HEATING SYSTEM

DESCRIPTION

FIELD OF THE INVENTION

Water storage and heating system.

OBJECT OF THE INVENTION

This invention relates generally to the collection and concentration of sunlight for the purpose of using solar energy. Specifically, the invention relates to the principles of heat transfer and optics in a water heating system that allows a house-room to be supplied with hot water.

BACKGROUND

The use of solar energy is constantly increasing, bringing technological developments with different objectives. This is because the energy of the sun's rays is in the form of electromagnetic radiation in lengths from infrared (long waves) to ultraviolet (short waves). And the solar energy received by the planet depends on the weather conditions, as well as the location and orientation of the surface. On average, about 1000 watts per square meter are received on a clear day, with the surface directly perpendicular to the sun's rays.

As an example of technological developments for the use of solar energy, we can mention solar collectors. These are devices that extract energy from the sun and convert it directly into usable or storable form.

There is a wide variety of hot water supply systems or solar collectors available in the market to produce water at the desired temperature. However, the investment and operational expenses are very high compared to other conventional systems because solar collectors are complex systems, this can be seen in patents US5653222, US4429545, US591759, US4269170 and US4,054,124. Normally, the solar collector includes a flat plate (panel) to receive the heat and a tubular conduit to transmit said heat to the water that circulates through the storage tank, these systems have elements of great size and high complexity in manufacturing due to the use of glass tubes in combination with other materials and fluids that hinder manufacturability, increase costs and require an expert to assemble such systems. Other patents such as US4586227, US4667653 and US6957014B2, US200500 71A1 refer to tanks that take advantage of solar energy for water heating, but differ in the arrangement of the parts of the system and the efficiency achieved by said systems. The invention presented as a collection and storage tank is significantly simpler than the aforementioned patents, which translates into a lower effective cost of the heating system

Due to the increase in energy prices and the continuous increase of the different types of devices that use solar energy to replace conventional energy, the development of a low-cost system with respect to the current ones represents a good opportunity to have a system for heat the water and reduce the high consumption of electricity and gas. The temperature reached by the system proposed here is for 50 ° C on average, enough for domestic use.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Exploded view of the main parts of the solar radiation water heating system.

Figure 2. Perspective view of the assembly of the main parts of the system where you can see the internal structure of the solar radiation water heating system. Figure 3. Longitudinal section of the main components of the solar radiation water heating system.

Figure 4. Perspective view of the coil.

Figure 5. Front perspective view Internal tank.

Figure 6. Front perspective view of internal tank base support.

Figure 7. Front view of the complete system with the lens to concentrate the sun's rays and the base of the outer tank.

Figure 8. Perspective view lens and lens holder. DETAILED DESCRIPTION OF THE INVENTION

This invention relates generally to the collection and concentration of sunlight for use in heating water for domestic use. Specifically, the invention relates to the principles of heat transfer and optics. The system reaches the concentration of sunlight through a Fresnel lens and a glass surface located on top of the cylindrical container. The cylindrical container is the element that conserves heat, said container has on its exterior a material with a suitable thermal resistance that prevents convection from inside to outside. Inside this tank, there is another tank, also in a cylindrical shape whose function is to transmit solar radiation to the bottom of it, which is painted black, and which absorbs heat to the fluid by absorbency. Around the tank, there is a coil where water passes to be heated.

The thermal energy storage more advantageously comprises what can be termed a minimum entropy of the system, with the thermal energy in the body of water heated by the heat exchanged with the outside of the fluid storage tank, The temperature will depend on the intensity of the solar radiation available to the collecting tank.

The solar radiation water heating system, reason for this invention, is shown in an exploded view in Figure 1, and consists of:

A cylindrical container tank (3) which is surrounded by an insulating layer (2) and supported on a metal structure (10) (see figure 7), said container has at its upper end an internal edge parallel to its base which allows hold a cylinder (5) by its outer edge. The cylinder (5) is slightly conical, made of steel sheet, has its lower end covered and whose inner surface is black to more efficiently absorb the solar radiation concentrated by a lens (11), the cylinder is supported by a metal base (1) (see figure 6) and in its open counterpart 2 translucent circular caps (9a and 9b) of equal diameter are located, concentric with the axis of the cylinder and parallel to the base thereof. The translucent circular covers are fastened by means of a lid (8) and are separated proportionally to the thickness of the lid while maintaining a gap between them. Both the cover (8) the outer edge of the cylinder (5) and the inner edge of the cylindrical container tank (3) coincide in their external diameters and are held together by means of nut (6) and thyme (7). Surrounding the cylinder (5) along its entire length is a coil (4) (see figure 2 and 3) which has at its ends 2 connections (4a) and (4b) (see figure 4) which in turn coincide with the inlet and outlet holes of the cylindrical container tank (3).

A solar radiation concentrating device (11) preferably a Fresnel lens is located in the upper part of the cylindrical container tank and in turn is held by a metal support with at least 3 equidistant bars (see figure 8) that provide stability to the device concentrator (see figure 7). It should be noted that the distance between the device and the concentrator device varies according to the efficiency of the concentrator device. For a lens of average efficiency the distance between the lens, preferably Fresnel type and the upper part of the cylindrical tank is approximately 50 cm; but nevertheless The lens clamping design can be made so that this distance is adjustable according to the solar radiation conditions during the annual periods.

The solar radiation water heating system captures the solar radiation through the lens (11) and concentrates this radiation through the translucent circular caps (9); The radiation is brought to the bottom of the cylinder (5) causing the heating of the cylinder, which transmits it by conduction to the liquid (which has a specific heat equal to or greater than the specific heat of the water) contained within the cylindrical container (3) and that consequently it will increase its temperature by at least 60 ° C, which by conduction will transmit the heat to the water that circulates through the coil that at its outlet (4b) will be at the optimum temperature for domestic use of at least 45 ° C; For an outlet temperature of 50 ° C, a 1.5-meter cylindrical tank, a preferably Fresnel lens of approximately 0.8 meters in diameter and a 1.5-meter-long coil are required to form 5 turns with a diameter of 30 cm. With this data as a preferred example, approximately 200 liters of water with a temperature of 50 ° C can be produced.

Compared to conventional solar collectors, the system described here has the advantage of being low cost due to its simplicity in manufacturing, ease of assembly and low maintenance. These characteristics will allow both governmental entities (such as ISSSTE or INFONAVIT) and construction companies to invest in this system and implement it in the various existing housing programs, of social interest or those with ecological and sustainable projects through the implementation of systems that use energy alternatives. The cylindrical container (3) stores a liquid preferably water that increases its temperature since it is coated on the outside of an insulating layer (2) made of mineral wool, ceramic fiber or preferably fiberglass, which prevents the heat acquired by The water inside the container tank reaches thermal equilibrium with the outside. The cylindrical container (3) is made of stainless steel sheet to prevent corrosion, and has a water inlet pipe at the bottom of its wall, as well as an outlet pipe from at the top of its wall, where said pipes coincide with the entrance and exit of the coil (4).

The inlet pipe allows the supply of cold water to the tank and the outlet pipe allows the channeling of hot water to the hot water supply network of the house-room.

Preferred embodiment example. The solar radiation water heating system, described above, in its preferred embodiment example consists of:

A stainless steel cylindrical container, coated on the outside of an insulating fiberglass layer that prevents the heat acquired by the water inside the cylindrical container from escaping outside.

The cylindrical container is made of stainless steel foil to prevent corrosion, and has a water inlet pipe at the bottom of its wall, as well as an outlet pipe at the top of its wall, both copper pipes to conduct better the heat.

The inlet pipe allows the supply of cold water to the tank and the outlet pipe allows the channeling of hot water to the hot water supply network of the house-room. Inside the cylindrical container there are several elements that intervene significantly in the process of heating water for domestic use: the first one is a copper coil that is in direct contact with a cylinder that receives radiation, also of steel stainless.

The cylinder is slightly conical, made of steel sheet with the black interior, to more efficiently absorb the solar radiation concentrated by a lens, preferably Fresnel type. In turn, this solar radiation concentrated in the cylinder is transmitted by conduction as heat, it made a liquid, preferably water, that surrounds it. Said liquid has a specific heat equal to or greater than the specific heat of the water. The third one, a top cover, is made of steel, which concentrically has a pair of circular glasses of equal diameter located aligned one below the other, to allow the entry of solar radiation concentrated by the lens.

Claims

Having sufficiently described my invention, I consider it as a novelty and therefore claim as my exclusive property, the content of the following clauses: 1. A solar radiation water heating system characterized in that it comprises:

• A hollow cylindrical container tank with a closed base, manufactured of a corrosion-resistant material with low thermal conductivity, surrounded by an insulating layer and supported on a metal structure at whose upper end the inner edge is parallel to its base, which allows to hold a cylinder by its outer edge;

• The aforementioned cylinder is characterized by having its lower end covered and whose inner surface is black; this is also supported by a metal base and in its open counterpart two translucent circular covers of equal diameter are located, concentric with the axis of the cylinder and parallel to the base thereof, the translucent circular covers are held by means of a lid and are they are separated proportionally to the thickness of the lid and between the circular covers it is exerted empty,

• A coil that surrounds the cylinder in its length and has two connections at its ends that coincide with the inlet and outlet holes of the cylindrical container tank,

• Located at the top of the cylindrical container tank is a solar radiation concentrator device that is held by a metal support with at least 3 equidistant bars that provide stability to the concentrator device.

2. The solar radiation water heating system according to claim 1 characterized in that the distance between the device and the lens varies according to the efficiency of the lens; for an average efficiency lens the distance between the preferably Fresnel type lens and the top of the cylindrical tank is approximately 50 cm; However, the lens clamping design can be made so that this distance is adjustable according to the solar radiation conditions during the annual periods.

The solar radiation water heating system according to claim 1 characterized in that the solar radiation concentrating device is preferably a Fresnel lens.

The solar radiation water heating system according to claim 1, characterized in that the water outlet temperature depends on the length of the coil, the flow of the working water, and the internal temperature of the second tank and the water that it go around For an outlet temperature of 50 ° C, a 1.5-meter cylindrical tank, a preferably Fresnel lens of approximately 0.8 meters in diameter and a 1.5-meter-long coil are required to form 5 turns with a diameter of 30 cm. With this data as a preferred example, approximately 200 liters of water can be produced at a temperature of 50 ° C.