58results about "Collector thermal insulation" patented technology

The utility model provides a solar heat collection device, and belongs to the technical field of heat collection devices. A solar heat collection device comprises a frame body, a solar heat collection device and a solar heat collection device, the copper pipe is fixedly connected to the support, and the two ends of the copper pipe extend out of the frame body; the heat insulation cotton is fixed in the frame body, a containing groove matched with the copper pipe is formed in the heat insulation cotton, and the containing groove penetrates through the heat insulation cotton so that the two sides of the heat insulation cotton can make contact with the copper pipe; the two heat absorption plates are fixed to the two sides of the heat insulation cotton respectively and make contact with the copper pipe; and the two transparent cover plates are fixed on the frame body, and the two transparent cover plates are respectively distributed on the outer sides of the two heat absorbing plates.

The invention relates to a device (10) for converting solar energy into electrical energy and thermal energy, the device (10) comprising: a main body (12) having an upper side (14) which can be oriented towards the sun, an lower side (18) which can be oriented towards a building (16), and at least one lateral side (20) which is arranged between the upper side (14) and the lower side (18); a photovoltaic module (24) forming the upper side (14) for converting the solar energy into electrical energy; and a heat exchanger (28) having a fluid chamber (44) through which a thermal fluid (46) can flow, the fluid chamber (44) adjoining the photovoltaic module (24).

The utility model discloses a roof solar water heating system which comprises a flat-plate solar collector, an air source heat pump unit, a heat pump heating circulating water pump, a pipeline system and a heat preservation water tank. The flat-plate solar heat collectors are fixed on a roof foundation through a support, the flat-plate solar heat collectors are arranged in multiple rows and are connected in series through heat collector water pipes, and the two ends of each flat-plate solar heat collector are connected to the heat preservation water tank. The air source heat pump unit and the heat pump heating circulating water pump are connected to the heat preservation water tank through a circulating water pipe. The cold water supply pipe supplements cold water to the heat preservation water tank, the hot water supply pipe conveys hot water in the heat preservation water tank to all water consumption ports, and the hot water return pipe recovers unused hot water to the heat preservation water tank. The solar water heater can solve the problems that the water temperature of the solar water heater rises slowly and is unstable, residual hot water cannot be effectively utilized, and energy is wasted due to electric heating in cloudy and rainy days.

The application discloses a solar energy, air energy and phase change energy storage coupled heat pump unit which comprises a heat supply pipeline, a circulating heating mechanism and an integrated evaporator, a compressor, a condenser and an expansion valve which are sequentially installed on the heat supply pipeline; the integrated evaporator comprises an insulation shell, a heat absorption glass plate, a lower header tank, an upper header tank and an energy storage heat collecting pipe; the energy storage heat collecting pipe comprises a heat collecting sleeve pipe, an inner heat transfer pipe, a water inlet ring pipe, an upper sealing piston, a lower sealing piston and a limiting piece; air inlets are formed in opposite two side walls of the insulation shell; and the circulating heating mechanism comprises a circulating return pipe, a circulating water supply pipe, a heating water tank and a circulating pump. The heat energy is extracted from the solar energy, the air energy and the phase change energy storage, and is coupled with a water source heat energy unit to provide heating for buildings, so that the sustainable development of energy can be realized; when the water in the heat collecting sleeve pipe is completely frozen, the ice in the heat collecting sleeve pipe is discharged from the heat collecting sleeve pipe, so that the ice melting energy consumption can be reduced, and the subsequent rapid heating for the heat user is facilitated.

The application discloses an energy-saving and environment-friendly solar heat storage and supply device which can effectively improve heat storage capacity and solar energy utilization effect, and can effectively suppress the imbalance of solar heat production through the energy storage of a heat storage water tank. Meanwhile, the heat storage water tank comprises a water tank body in a cylindrical structure and a vacuum heat preservation cylinder, so that the heat preservation effect of the heat storage water tank can be effectively improved. When solar energy is slightly insufficient, the inner storage cavity stores hot water with a higher temperature, and the outer storage cavity stores hot water with a slightly lower temperature, so that the amount of heat dissipation of the outer storage cavity to the outside can be reduced. Meanwhile, the water in the outer storage cavity can be returned to solar energy for utilization when solar energy is seriously insufficient, so that the heat of output hot water is effectively ensured, heat storage effect and suppression capacity are improved, the control of the application is simple, energy loss can be effectively saved, and heat utilization effect and capacity are ensured.

The invention belongs to the technical field of solar water heaters, and particularly relates to a solar heat collector and a solar water heating system. The solar heat collector comprises a heat collector body and a sealing bag, the heat collector body comprises a shell and at least one connecting pipe, a heat collecting cavity is formed in the shell, the connecting pipe is communicated with the heat collecting cavity, an opening capable of being opened and closed and at least one avoiding hole are formed in the sealing bag, the heat collector body is inserted into the sealing bag through the opening, and the avoiding hole avoids the connecting pipe. After the connecting pipe extends out of the sealing bag through the avoiding hole, the avoiding hole is closed, and when the opening is closed, the vacuum degree in the sealing bag is smaller than or equal to the preset vacuum degree, so that the heat collector body is in a vacuum state, heat convection between the heat collector body and air is reduced, heat loss of the heat collector body is reduced, and the heat efficiency of the heat collector body is improved.

Solar heat absorption and heat preservation device Solar heat absorption and heat preservation device relates to the field of solar energy application. Mainly to solve the drawbacks and shortcomings of the existing heat absorption and heat preservation technology. In order to solve the problem. The present application provides several kinds of solar heat absorption and heat preservation device. 1, solar heat absorption plate: it mainly has metal water tank, sealing ring, light transmission glass. Put a circle of sealing ring in the metal water tank, put light transmission glass on the sealing ring. The gap between the light transmission glass and the water tank is filled with carbon dioxide or dry ice. Then seal. 2, solar heat preservation and heat absorption water tank: it mainly has heat absorption plate, metal water tank, heat-resistant insulation material, shell and the like. 3, solar steaming and baking device: it mainly has a cube, a cuboid, an irregular polyhedron. One or more faces are heat absorption plates, and the other faces are heat-resistant insulation materials.

This invention discloses a light-controlled molecular heterogeneous thermal storage device, belonging to the field of solar energy storage technology. The device includes a detachably connected first and second shell, both with mirrored inner surfaces. The first shell houses a light source assembly containing a xenon lamp and a first filter; the second shell has a magnetically attachable second filter on its top and multiple circular flow heat exchange channels running through its sides. A rotatable heat storage layer is fitted around each channel, and the interior is filled with a molecular light-switching material. A liquid metal thermally conductive layer is filled between the heat storage layer and the heat exchange channels. This invention achieves switching between natural light and auxiliary light modes through a detachable structure, adapting to different lighting conditions and enabling all-day operation; the rotating heat storage layer and mirrored inner wall ensure uniform illumination, and the liquid metal ensures efficient heat transfer, thereby significantly improving the energy storage and release efficiency of the molecular light-switching material and the system's controllability.

The invention belongs to the technical field of solar energy utilization, and relates to a lens condensation and heat collection device and a use method thereof. The shell is connected with the supporting frame through the rotating unit, the rotating part can drive the shell to rotate around the axis where the vacuum heat collecting pipe is located, the rotating unit is connected with the photo-thermal control system, the photo-thermal control system controls starting and stopping of the rotating unit, and the rotating unit drives the shell to rotate on the supporting frame. And the optical axis of the linear Fresnel lens is parallel to sunlight. The vacuum heat collection pipe is always located at the focus position of the linear Fresnel lens, efficient collection of light energy is facilitated, meanwhile, the linear Fresnel lens is beneficial to improving the light energy collection efficiency, the mirror surface area is obviously reduced compared with a reflection condensation heat collection mirror surface, the smooth surface of the lens faces outwards, dust accumulation is not prone to occurring, and cleaning is convenient. In addition, the linear Fresnel lens and the shell form a relatively closed space, so that the heat loss is reduced. The whole structure is simple, and later maintenance is facilitated.

The invention provides a full-natural, passive and zero-energy-consumption solar hot air space with a hemispherical shell push plate. And a thermal insulation closed space can be formed to heat, improve quality and pressurize air. The hemispherical shell push plate and the thrust vertical plate can close air inflow through thermal change force so as to control the pressure value range. And the system is low in cost. The device can be widely applied to civil, agricultural and industrial occasions where renewable energy sources such as solar energy are comprehensively utilized.

The active solar hot air collector is a hot air heat collecting device used for collecting solar heat energy to generate hot air and an active hot air supply device through a photovoltaic power generation direct-drive pipeline fan. Sunlight enters the heat collection box through the high-transmittance panel, the inner spiral heat collection black pipe rapidly converts light energy into heat energy, cold air in a space needing to be heated enters the heat collection box from the air inlet through the pipeline, and heat is rapidly taken away through the interior of the inner spiral heat collection black pipe. And the solar power generation panel (12v) generates power and directly drives the mute pipeline fan (12v) to quickly send hot air into a space needing to be heated through the air outlet through the fan work.

The invention relates to the technical field of green buildings, and provides a photovoltaic and photo-thermal integrated system and a preparation method and application thereof. The photovoltaic and photo-thermal integrated system provided by the invention is composed of photovoltaic glass for transmitting light to generate power, photo-thermal glass for selectively absorbing ultraviolet / infrared and converting the ultraviolet / infrared into heat energy, a fluid channel positioned between the photovoltaic glass and the photo-thermal glass, and transparent aerogel positioned on the indoor side of the photo-thermal glass. The photovoltaic glass allows part of visible light to penetrate into a room to provide natural lighting while generating power; ultraviolet and infrared parts in transmitted sunlight are efficiently absorbed by the photo-thermal glass and converted into heat energy, the heat energy is collected, conveyed and utilized by the intermediate fluid, the transparent aerogel is used for heat preservation and heat insulation, and meanwhile high visible light transmittance is guaranteed. Therefore, the photovoltaic and photo-thermal integrated system provided by the invention synchronously realizes three functions of photovoltaic power generation, photo-thermal conversion heat energy recovery and selective spectrum regulation and control, not only directly provides electric energy and heat energy for a building, but also remarkably reduces indoor refrigeration load and illumination energy consumption, so that the comprehensive energy consumption of the building is comprehensively reduced.

The utility model discloses a movable solar water heater which comprises a hot water barrel, a barrel cover is movably installed at the position, located at the upper end, in the hot water barrel, and three heat absorption frames are fixedly installed at the position, close to the upper end, in the hot water barrel. According to the movable solar water heater, the hot water barrel can be telescopically folded, so that the solar water heater is convenient to carry and store and is firmer and more durable, the hot water barrel and the barrel cover have the heat insulation and heat preservation effects, the barrel cover can be rotationally opened, and water in the hot water barrel can be directly taken; the water taking mode and the water filling mode are flexible enough, the hot water barrel and the heat absorption frame can absorb solar radiation energy, the water heating area of the solar water heater is larger, the side, absorbing the solar radiation energy, of the heat absorption frame can be adjusted and can be detached, and folding of the hot water barrel is not affected.

The utility model discloses a water storage tank of a solar water heater, which belongs to the technical field of solar water heater components and comprises a support frame, a water storage tank body is fixedly mounted on the outer surface of the support frame, a plurality of heat collecting pipes distributed at equal intervals are arranged on the outer surface of the water storage tank body, and an operation box is arranged in the water storage tank body. The self-cleaning assembly is located on the outer surface of the operation box and used for cleaning the joint of the water storage tank body and the heat collection pipe; through the design of the self-cleaning assembly, regular cleaning of the connecting position of the water storage tank body and the heat collecting pipe is achieved, a cleaning roller and a scraping plate can be driven to rotate only by starting an electric telescopic rod to push an operation box and then manually rotating a handle, and the cleaning roller and the scraping plate can be driven to rotate. Dirt and incrustation on the inner wall of the heat collecting pipe are effectively scraped, complexity and inconvenience of traditional manual cleaning are avoided, the cleaning efficiency is improved, and damage to equipment due to improper cleaning is reduced.

The invention belongs to the technical field of solar thermal power generation, and discloses a heat absorber heat preservation structure, a heat absorber tube panel structure and a tower type solar heat absorber. The tower type heat absorber heat preservation structure comprises a first heat preservation module and at least one heat preservation module fixing assembly, the first heat preservation module comprises a heat preservation space, the heat preservation space is configured to be a partial structure used for containing an object to be subjected to heat preservation or a whole structure used for containing the object to be subjected to heat preservation, and the first heat preservation module wraps the outer side of the object to be subjected to heat preservation; the heat preservation module fixing assembly is configured to be used for fixing the first heat preservation module to an object to be subjected to heat preservation, the heat preservation module fixing assembly comprises a penetrating component and at least one locking component, and the penetrating component comprises a built-in section and at least one extending section. According to the heat absorber heat preservation structure, the loss of heat in the object to be subjected to heat preservation can be reduced, the problems in the prior art can be effectively avoided, and the heat preservation module fixing assembly is arranged so that the first heat preservation module can be prevented from moving under the action of external force such as vibration.

The utility model relates to the technical field of heating assemblies, and discloses a novel photovoltaic photo-thermal heating assembly which comprises a base, the upper portion of the base is fixedly connected with a supporting frame, the upper portion of the supporting frame is fixedly connected with a photovoltaic panel, the outer side of the photovoltaic panel is fixedly connected with a U-shaped pipe, and the right side of the U-shaped pipe is fixedly connected with a water storage tank. A heat insulation layer is fixedly connected to the inner side of the water storage tank, a heat preservation layer is fixedly connected to the inner side of the heat insulation layer, a first water pump is fixedly connected to the front side of the upper portion of the base, a first water pumping pipe is fixedly connected to the input end of the first water pump, and a first water conveying pipe is fixedly connected to the output end of the first water pump. A heat exchange assembly is arranged on the outer side of the storage battery and used for exchanging heat with the storage battery. According to the utility model, through the cooperation of the U-shaped pipe, the storage battery, the heat exchange pipe, the water pump I, the water storage tank and other structures, the photovoltaic photo-thermal heating assembly can fully utilize heat energy, and the utilization rate of energy is improved.

The utility model relates to the technical field of soil heat storage, in particular to a soil heat storage type solar heat supply comprehensive system which comprises a conical frame and a butt joint bottom plate, a heat preservation inner container is arranged on the inner wall of the conical frame, heat storage grooves are formed in the conical frame and the heat preservation inner container, a heat storage water tank is fixedly connected to the bottom end of the butt joint bottom plate, and the heat storage water tank is fixedly connected with the butt joint bottom plate. The two sides of the heat storage water tank are fixedly connected with liquid conveying side frames. Through the arrangement of the conical frame, the butt joint bottom plate, the heat preservation inner container, the heat storage tank, the heat storage water tank, the water storage tank, the heat conduction plate and the heat conduction strip, the equipment can conduct more efficient and even soil heat storage type solar heat supply comprehensive operation. A worker firstly paves soil used for heat storage in a heat storage groove of a conical frame, then the conical frame is integrally installed in a heat storage water tank through a butt joint bottom plate at the bottom, and at the moment, temperature control solar hot water in the heat storage water tank can pass through a heat conduction plate at the bottom of the butt joint bottom plate.

The application discloses a kind of solar-driven biomass continuous pyrolysis system and method based on thermochemical heat storage, system includes: solar heat collecting unit, for collecting solar radiation energy;Biomass pyrolysis reaction unit is equipped with biomass feed inlet and product discharge port;Thermochemical heat storage unit is equipped with CO2 import and CO2 export, internally filled with thermochemical heat storage material with MgO / MgCO3 as active component;Thermochemical heat storage unit is respectively with solar heat collecting unit and biomass pyrolysis reaction unit by heat exchange medium circulation pipeline heat exchange;CO2 circulation subsystem;Control system, with solar heat collecting unit, biomass pyrolysis reaction unit, thermochemical heat storage unit and CO2 circulation subsystem electric connection, according to preset parameter automatic adjustment operating mode and heat exchange medium flow.This scheme will unstable solar energy into chemical energy storage, and release in the form of heat energy, for biomass pyrolysis provides continuous, controllable heat source.

The utility model provides a tower type solar thermal power generation heat absorber. The tower type solar thermal power generation heat absorber comprises a tube panel, an upper header, a lower header and a plurality of fins, the tube panel comprises a plurality of heat absorption tubes which are arranged side by side and form the tube panel in a surrounding mode, and the tube panel is a polygonal cylinder or a cylinder. The upper header is fixedly connected with one end of the tube panel, is communicated with all the heat absorption tubes and is communicated with at least one upper inlet and outlet pipeline; the lower header is fixedly connected with the other end of the tube panel, is communicated with all the heat absorption tubes and is communicated with at least one lower inlet and outlet pipeline; the plurality of fins are arranged between every two adjacent heat absorption pipes and are fixedly connected with the two adjacent heat absorption pipes; along the axis of the tube panel, each heat absorption tube is of a spiral structure surrounding the axis, each heat absorption tube at least surrounds the tube panel by one circle, and the technical problem that the heat absorber is prone to tube explosion due to the fact that the heat absorber is affected by weather, clouds, control and the like can be solved.

The utility model belongs to solar heating technology field, specifically disclose a box body light -concentrating type solar medium temperature heat collector, the utility model discloses a sealed box body of one side glass cover, the bottom and the side surface of box body are equipped with heat preservation layer, be equipped with upper flow collecting pipe and lower flow collecting pipe in the box body, be equipped with at least two fin heat absorption unit between heat preservation layer and glass cover, the both ends of fin heat absorption unit are connected with the upper flow collecting pipe and lower flow collecting pipe of the intercommunication box body respectively, fin heat absorption unit includes fin adsorption pipe and reflector, and fin adsorption pipe sets up at the light -concentration of reflector surface. The utility model discloses the synergistic effect of metal light -concentrating structure and straight -through type flow channel design, can realize the stable output of medium temperature, improve the pressure intensity of system output, improved the reliability of medium temperature pressure bearing. The utility model can be widely applied to the light -heat conversion field of solar energy.

The application discloses a temperature control automatic water feeding method using a phase change material, which is implemented in a solar water heater provided with a phase change material layer for heat storage and release, and is characterized in that, during the heating process of the device under the solar radiation, the expansion effect generated by the phase change of the phase change material from solid to liquid drives the execution member to act, the water feeding section size of the water feeding channel of the water sandwich layer is controlled, and the water feeding section of the water feeding channel of the water sandwich layer is correspondingly increased along with the gradual expansion of the phase change material. The application can utilize the expansion characteristics generated in the phase change process of the phase change material, can better control the water feeding of the water sandwich layer of the solar water heater, and can improve the heating efficiency of the hot water.

The utility model provides an integrated solar heat collector which comprises multiple groups of outdoor heat collection and heat preservation cylinders, exhaust pipes are connected in series among the multiple groups of outdoor heat collection and heat preservation cylinders in an inserted mode, multiple groups of heat exchange pipes are arranged at the bottoms of the exhaust pipes, and the heat exchange pipes of the multiple groups of outdoor heat collection and heat preservation cylinders are connected. Compared with the prior art, the indoor energy-saving heat preservation barrel is additionally arranged, the number of outdoor heat collection systems can be reduced, double loops are adopted for heating heat exchange, heat exchange is more sufficient, the temperature of an outdoor system is balanced, and the indoor energy-saving heat preservation barrel is additionally arranged. The heat exchange efficiency is higher, the time for waiting for hot water during water taking can be shortened due to the fact that the indoor water taking opening is close to the water taking point, the problem of domestic water in summer is solved, and the purpose is achieved through the manual three-way valve, the short circuit pipe and switching of the main control circuit and the auxiliary control circuit in summer.

The invention provides a solar vacuum heat collector matrix with a suspended cable net rack structure, which comprises upright posts, net rack cross rods, steel strands, a heat collection net, a heat collection tube seat and a hanging basket, the upright posts on two sides are symmetrically and vertically mounted on the ground, the net rack cross rods on two sides are respectively and fixedly connected to the tops of the upright posts on two sides, and the steel strands are arranged on the net rack cross rods. The side face of the stand column is fixedly connected with an inclined pull line used for enhancing the stability of the stand column, the heat collection net is hung on the steel strand, the heat collection pipe base is hung on the steel strand in an abutting mode, a heat conduction pipe is fixedly connected into the heat collection pipe base, the hanging basket is assembled on the steel strand, and a pulley mechanism and a motor driving mechanism are arranged in the hanging basket. A longitude and latitude grid structure constructed by the steel strands and the stand columns can be directly erected above large-span facilities such as a vegetable greenhouse and a biogas digester without depending on a building roof or a traditional support, and can be seamlessly connected with heat utilization equipment for biogas production, greenhouse planting and the like.

The invention relates to the technical field of concentrating solar thermal power generation, and discloses a transient temperature rise suppression device and method for a tower type concentrating solar exposed tubular heat absorber. The transient temperature rise suppression device comprises a heat absorption tube, and the outer surface of the heat absorption tube is divided into a light receiving side and a backlight side; the temperature rise buffer assembly, the heat transfer coupling assembly, the heat insulation layer and the folding and unfolding structure are installed on the backlight side of the heat absorption pipe. The temperature rise buffer assembly comprises a packaging shell, a phase change heat storage medium packaged in the packaging shell and a heat conduction enhancing structure making contact with the phase change heat storage medium, and the heat transfer coupling assembly is arranged between the outer wall of the heat absorption pipe and the temperature rise buffer assembly. The temperature rise buffer assembly is arranged on the backlight side of the heat absorption pipe, the low-heat-resistance heat conduction channel is built in combination with the heat transfer coupling assembly, the phase change latent heat of the phase change heat storage medium is used for absorbing redundant heat generated when irradiation suddenly increases, peak clipping of the wall temperature of the heat absorption pipe and limiting of the temperature rise rate are achieved, and the damage risk of thermal stress impact to the heat absorption pipe and the connecting position is effectively reduced.

A cladding panel that collects and / or emits thermal energy, which includes: a first panel; a second panel with an extrados adhered to an intrados of the first panel, forming a leaktight seal, with a low-relief channel, the channel being attached to the intrados of the first panel to form a conduit; an inlet connector for heat-conducting fluid, connected to a first end of the channel; and an outlet connector for heat-conducting fluid, connected to a second end of the channel, wherein the first panel is made of calibrated laminated ceramic with a flat, smooth intrados and a flat, smooth extrados and has a uniform thickness of 3-6 mm, and the second panel is made of waterproof heat-insulating plastic that is stable up to 120° C.

The utility model discloses a water tank structure of a solar water heater, which comprises a water tank main body, a water inlet, a water outlet and an exhaust port are arranged on the water tank main body, a fixed pipe body and a movable pipe body are arranged at the water inlet, a fixed ring is arranged in the fixed pipe body, a filter screen is arranged on the fixed ring, and a plurality of heat collecting pipes are arranged below the water tank main body. The water tank body comprises a shell, a heat preservation layer and an inner container, end covers are arranged on the two sides of the shell, a waterproof ring and sealant are arranged between the end covers and the shell, a protective sleeve is arranged between the heat collection pipe and the water tank body, a fixed pipe and a movable pipe are arranged on the exhaust port, and an adjusting device is arranged on one side of the movable pipe. The connection sealing performance between the end cover and the shell is improved, water leakage is prevented, the movable pipe is arranged in the fixed pipe, the exhaust radius at the exhaust port is convenient to adjust, the exhaust effect is guaranteed, and the water tank body is protected.

The invention discloses a cross-seasonal storage and extraction collaborative U-shaped well system for an oil gas central processing station, and belongs to the technical field of geothermal exploitation and application. Comprising a one-two mode geothermal well, a solar heat collection field, a sand remover, a U-shaped heat exchanger, a first buffer tank, a second buffer tank, an evaporator, a compressor, an expansion valve, a condenser, a first circulating water pump, a second circulating water pump, a third circulating water pump, an intelligent central controller and a multi-depth soil temperature sensor array. And a meteorological data interface module and a plurality of intelligent electric control valves. Through ingenious system configuration and valve control logic, efficient cooperation of solar energy and geothermal energy on the cross-seasonal time scale is achieved, the solar energy and waste heat generated by core facilities of an oil and gas central processing station are utilized for supplementing consumption of the geothermal energy, soil heat unbalance is relieved, and the utilization rate of the geothermal energy is increased. And the intermittency of solar energy is compensated by utilizing the stability of geothermal energy, so that the purposes of saving energy, reducing emission and prolonging the service life of the system are finally achieved.

A cladding panel for collecting and / or emitting thermal energy comprising: a first panel (10); a second panel (20) having a front face (21) attached to the back face (12) of the first panel (10) to form a tight seal, said second panel (20) further having a low profile channel (40) attached to the back face of the first panel (10) to form a conduit; an inlet connector (41) for connecting a heat transfer fluid to a first end of said low profile channel (40); and an outlet connector (42) for connecting a heat transfer fluid to a second end of said low profile channel (40), wherein said first panel (10) is made of a laminar calibrated ceramic having a flat and smooth back face and a flat and smooth front face and having a uniform thickness of 3-6 mm, said second panel (20) is made of a waterproof and thermally insulating plastic stable at temperatures up to 120°C.