Patent Application
20140260003
The present invention relates to a wall structure, and more particularly to such a structure for a building.
As the general standard of living improves, there is increasing demand for industrial and residential buildings which can provide a more comfortable environment as well as being environmentally sustainable. One way to create such an environment is to have an effective heating, ventilation and air-conditioning (HVAC) system. Such a system forms an important part of the building by providing sustainable Indoor Air Quality (IAQ) and a comfortable environment for the occupants. Over the years, there have been many studies relating to HVAC systems. For example, an insulation model for a conventional HVAC system comprising two glass skins which form a cavity within which tempered fresh air can flow, is designed to create a comfortable and habitable environment by accommodating heat and mass transfer within the system. However, this kind of design may offer very small or ineffective energy savings, unless one or both IAQ or comfort of the building are compromised.
Accordingly, it is an object of the present invention to seek to overcome the above problems associated with the prior art.
According to a first aspect of the present invention, there is provided a wall structure for a building, comprising: a cavity for allowing air to flow through the structure between the building's interior and exterior, between the wall structure's inner and outer layers; and an electricity generating member for generating electricity using heat transfer and being located for transferring heat from the building's exterior to interior when exposed to relatively warm external conditions and from the building's interior to exterior when exposed to relatively cooler external conditions, and wherein the electricity generating member is located for promoting an energy transfer with air within the cavity.
In this way, the electricity generating member can generate electricity from an external heat source, such as the sun, when exposed to relatively warm external conditions (as compared to the interior of the building) and any energy which conducts through the layer can be used to warm the air within the cavity. As the air flows through the cavity, this in turn will help maintain a desired thermal level of, for example, a building to a level for the occupants. At least a portion of the energy will be converted to generate electricity by the electricity generating member. Further, in this way by controlling the air flow within the cavity the temperature of the electricity generating member can be regulated, which can be highly advantageous where such elements are highly temperature sensitive.
Conversely, when exposed to relatively cool external conditions (e.g. nighttime) where the interior of the building is warmer than the exterior, the electricity generating member can generate electricity using heat from the interior of the building. This thereby utilises a portion of the heat loss from the building (THOT,in -TCOLD,out) to generate electricity. At the same time, another portion of the heat loss may also used to heat ventilation air coming into the building via the cavity, thereby reducing the U value of the wall. In such a case, the wall construction works as a combined heat and power (CHP) source.
In this way, in hot climates, the electricity generating member can generate electricity from either external heat source such as the sun or heat absorbed via thermal mass thermal mass or Phase Change Material (PCM), and any energy which conducts through the layer can be used to warm the air within the cavity. Air extracted from the building will be allowed to flow through the cavity, this in turn will help to reject a high level of solar gains which severely influence the air conditioning, and a portion of the energy will be converted to generate electricity by the electricity generating member. Further, in this way, by controlling the air flow within the cavity the temperature of the electricity generating member can be regulated, which can be highly advantageous where such elements are highly temperature sensitive and reduce dramatically the need of air conditioning. The electricity generated could be used, for example, to power a local ventilating fan, data loggers, controls, sensors, LED lights, or stored for later use.
As will therefore be appreciated, the present invention therefore has dual/reversible operating modes as it can generate electricity in both hot and cold conditions, whilst using heat to warm the ventilation air in cold climates or, in warm climates, use air extracted from the building and flushed through the wall structure to reject the solar gains and the heat absorbed by external layers. In both cases, the delta T is used to generate electricity.
Conveniently, the electricity generating member is located such that energy conducted by the electricity generating member is transferable to the cavity.
Further, the electricity generating member is located such that energy carried by the cavity is conductible to the electricity generating member.
Further, the electricity generating member may be an organic thermoelectric material on the exterior surface.
Further, the invention could be coupled with cavities generated by dynamic insulation parieto or permeo or any type, or a combination of a conventional insulation and some dynamic exchange between outside and inside temperatures.
Preferably, circuitry and components are provided so that the electricity can be gathered and stored for example to be used when there is lack of heat energy to maintain the thermal level of the house by just heat conduction in cold climates or by heat rejection in hot climates.
Preferably, electronic circuit is provided to regulate the voltage and power from the electricity generating members.
Preferably, the electricity generating member has first and second surfaces, the electricity generating member being positioned within the structure such that the first surface is located for absorbing energy from the building's exterior and the second surface is located at or adjacent the cavity, so that when exposed to relatively warm external conditions the electricity generating member is located for generating electricity and conducting energy from its first to second surfaces for transference to air in the cavity.
Preferably, the electricity generating member comprises a thermoelectric layer. Thermoelectric materials can convert thermal energy directly into electricity, therefore the thermoelectric layer provides a simple method of heat conversion and reduces the extent to which heat energy is wasted during conversion. Further, the electricity generating member may be an organic thermoelectric material on the exterior surface.
Preferably, the wall structure further comprises an energy absorbing layer, wherein the energy absorbing layer is located at or adjacent the electricity generating member. The energy absorbing layer may function as a storage for the absorbed heat so that there will be a consistent supply of the heat energy to the electricity generating member, whether there is a surplus or shortfall of heat radiating from the heat source.
Preferably, the energy absorbing layer comprises an insulating material. The insulating material can be a thermal mass material or PCM which can store thermal energy for extended periods of time. Conventionally, such materials have been used to insulate buildings. Therefore it is preferable to use such a material with the electricity generating member, for example with the thermoelectric layer.
Preferably, the energy absorbing layer comprises a photovoltaic layer. The photovoltaic layer can absorb solar energy and convert it to electricity. This can assist to generate electricity more effectively. The excess energy which the photovoltaic layer is not able to convert can then be transferred to the thermoelectric layer and converted into electricity further. The excess energy can further be conducted to warm the air in the cavity for ventilation use in cold climates, or internal extracted air is used to cool down the photovoltaic or the photovoltaic and thermoelectric assembly in hot climates which thereby reduces solar gain, and hence heat conduction gain, as well as enhancing power generation.
Preferably, the first surface of the thermoelectric layer is provided at or adjacent the photovoltaic layer and the second surface of the thermoelectric layer is provided at or adjacent the cavity so that after a first energy conversion has occurred in the photovoltaic layer a second energy conversion can occur in the thermoelectric layer without minimising the loss of heat energy during the transfer. The thermoelectric layer uses the differential temperature between the photovoltaic layer and the cavity to generate the electricity. This ensures no or little energy is lost during the conversion/heating period in cold climates, whilst maximising heat rejection to the ambient in hot climates.
Preferably, the electricity generating member can comprise a photovoltaic layer or a photovoltaic layer coupled with thermoelectric layer. This can be cost effective and simplify the system.
Preferably, the photovoltaic layer is provided in the structure so that it is exposed to the exterior of the structure for absorbing solar energy.
Preferably, the electricity generating member is organic thermoelectric material so that it is exposed to the exterior of the structure for absorbing solar energy.
Preferably, the electricity generating member is organic thermoelectric material coupled with solid state thermoelectric material (thick or thin film) so that it is exposed to the exterior of the structure for absorbing solar energy.
Preferably, the wall structure further comprises an insulating layer for location at or adjacent the cavity on the opposite side of the cavity from which the electricity generating member is located, the insulating layer comprising an insulating material. This insulating layer helps the unnecessary loss of the heat energy.
Preferably, the electricity generating member is provided in a form of a planar element. In this way, the surface area for absorbing energy and transferring heat to warm the air in the cavity is maximised.
Preferably, the wall structure is provided as a panel. In this way the structure may be provided in modular form.
According to a further aspect of the present invention, there is provided a wall structure comprising:—inner and outer layers, an air channel allowing air to pass through the structure, and an electricity generating member, wherein the electricity generating member is positioned for generating electricity from an energy source external to the wall structure, the electricity generating member further being positioned adjacent the air channel, the air flow within the air channel being controlled to regulate heat energy transfer between the electricity generating member and air within the air channel. In this way, the temperature of the electricity generating member is controllable, which is highly advantageous where the efficiency of such members is substantially effected by temperature.
According to a further aspect of the present invention, there is provided a wall structure, comprising: a cavity for allowing air to flow through the structure and between inner and outer layers of the structure; and an electricity generating member for generating electricity using energy from an external source, wherein the electricity generating member is located for promoting an energy transfer with air within the cavity.
According to a further aspect of the present invention, there is provided a wall structure for a building, comprising: inner and outer layers; an airflow channel between the inner and outer layers for allowing air to flow between the interior and exterior of the building; and an electricity generating layer for generating electricity using a temperature differential and being located in thermal conductive communication with the airflow channel, wherein the electricity generating layer is operable in two modes: a first mode where electricity is generated by the temperature differential between a relatively warmer outer layer and a relatively cooler inner layer under a first ambient condition, and a second mode where electricity is generated by the temperature differential between a relatively warmer inner layer and a relatively cooler outer layer under a second ambient condition.
When the wall structure is configured for hot climates it promotes airflow through the airflow channel from the interior of the building to its exterior under a first ambient condition such that the airflow acts to cool the electricity generating layer for rejecting solar gains. Preferably, the wall structure is configured for hot climates by providing the airflow channel between a inlet in the inner layer and an outlet in the outer layer, with the inlet being located at a lower position than the outlet.
When the wall structure is configured for cold climates it promotes airflow through the airflow channel from the exterior of the building to its interior such that the airflow entering the building is warmed. Preferably, the wall structure is configured for cold climates by providing the airflow channel between an inlet in the outer layer and an outlet in the inner layer, with the inlet being located at either a higher or lower position than the outlet.
According to a further aspect of the present invention, there is provided a wall structure for a building, comprising: an energy adsorbing layer for adsorbing heat from the building's exterior when exposed to relatively warm external conditions and from the building's interior when exposed to relatively cooler external conditions; and an electricity generating member for generating electricity using heat transfer and being located for adsorbing heat from the energy adsorbing layer.
Preferably, the wall structure further comprises an exterior energy adsorbing layer exposed to the exterior of the structure for generating electricity by absorbing solar energy.
Preferably, the energy adsorbing layer or the exterior energy adsorbing layer is a thermoelectric layer.
Preferably, the exterior energy adsorbing layer is an organic thermoelectric layer.
According to further embodiments of the present invention there may be provided a wall structure for overcoming thermal bridge issues with a non insulated wall structure comprising thermal bridges or a solid wall. In this way, the electricity generating member is positioned for generating electricity from heat conduction or loss from the wall structure and hence converts a portion of the heat loss or gain to electricity. Examples of thermal bridges, but not limited in construction, may be a Timber Frame, a precast concrete Panel, a concrete block, etc.
Illustrative embodiments of the present invention will now be described with reference to the accompanying drawings, in which:
Operation of the first embodiment of the present invention will now be described.
Heat from the sun radiates the exposed surface of the external layer 4 and the heat is absorbed into the energy absorbing layer 30 adjacent to the external layer 4. In some embodiments, layer 4 could be provided as an organic thermoelectric layer which itself could be used to generate electricity, thereby enhancing the power generation at a first stage. The energy absorbing layer 30 conducts at least some of the heat energy to the thermoelectric layer 20 whilst additionally storing at least some of the remainder of the heat energy. Once the heat energy is conducted, the first surface of the thermoelectric layer 20 adjacent to the energy absorbing layer 40 is hotter than the second surface of the thermoelectric layer adjacent to the cavity 10. As a result of this temperature differential, the thermoelectric layer generates electricity which is supplied to an electrical circuit (not shown). The electrical circuit may, for example, then be used to directly power a fan, electrical devices, feed power into the grid, or supply power to a battery storage for later use.
At the same time, the heat energy received on the first surface of the thermoelectric layer 20 is also conducted through the structure to warm the air in the cavity 10. The air flows into the cavity 10 from the interior is then warmed up and released to the exterior of the building to maintain a desired thermal level within the building.
In
In this embodiment, the thermoelectric layer 20 utilises macroscopic film technology to provide a plurality of micro generators operating across the layer. Relatively small differences in temperature between an exposed first surface and a second surface adjacent to the cavity can be used to convert thermal energy directly into electricity, which is output to the electrical circuit.
In this connection, such a thin or thick film thermoelectric layer 20 can deliver power generation densities in excess of those achieved from conventional thick film devices, and are therefore preferred. For example, output power levels of >100 mW at ΔT=70K and >300 mW at ΔT=120K were achieved with modules that measured 3.5 mm×3.5 mm in size, corresponding to output power densities of ˜1-3 W/cm2.
Furthermore, the insulting layer 40 utilises a thermal mass material or PCM which is capable of storing thermal energy for extended period of time. This type of material is capable of absorbing heat energy, for example, during the daytime, to thereby reduce the cooling load on the structure and then release the heat during the night thereby reducing the heat load. Examples of such materials may include water, rock, earth, brick, concrete, fibrous cement, caliche and ceramic tile.
As mentioned above,
During the heating cycle, the heat from the sun (H) radiates the exposed surface of photovoltaic layer or organic thermoelectric layer 50. The photovoltaic layer or organic thermoelectric layer 50 absorbs the radiation and converts the thermal energy into electricity. During absorption, the temperature of the photovoltaic layer or organic thermoelectric layer 50 will rise. Therefore, this heat energy is conducted to the first surface of thermoelectric layer 20 located adjacent to the photovoltaic layer or organic thermoelectric layer 50, causing a temperature differential between its first and second surfaces, resulting in electricity generation. By having two layers which are capable of generating electricity, the structure seeks to take optimal advantage of the available energy and minimise any waste of energy. The thermoelectric layer 20 further conducts the heat to thereby warm the air in the cavity 10, the cavity 10 being located adjacent the second surface of the thermoelectric layer 20. This air will be circulated or released to maintain a desired constant thermal level and thus high standard of IAQ in the building.
During the cooling cycle, internal air is extracted through the structure to reject the heat absorbed by the layers and, during this, the air is cooled down the photovoltaic and/or thermoelectric assembly, which accordingly enhances the electricity generating performance of the photovoltaic and/or thermoelectric assembly.
The photovoltaic layer or organic thermoelectric layer 50 operates in the same way as described above. However, in this embodiment, the photovoltaic layer 50 acts as both an energy absorbing layer and an electricity generating member thereby taking full advantage of the photovoltaic material's properties. Therefore, the photovoltaic layer or organic thermoelectric layer 50 absorbs the energy radiated from the sun (H), generates electricity and warms the air in the cavity 10. This results in an environmentally sustainable system, without compromising the IAQ and thermal level by utilising available energy to obtain an optimum result.
In this connection, the efficiency of photovoltaic modules is very sensitive to temperature. For example a temperature rise of 10K leads to a loss of 5% in conversion efficiency. As such, by controlling the air flow within the air cavity, the temperature of the photovoltaic module can be controlled, i.e. relatively cool air in the cavity provided from the outside, or from within a building (in hot climates) can be used to reduce the temperature of the photovoltaic modules and therefore maintain and stabilise its efficiency. In the case of the organic thermoelectric layer, the building will benefit from the heat absorbed as an electrical source.
The internal layer 10 is for direction towards the interior of a building and may be formed of plaster board, plaster, block, or any other suitable construction material. The construction layer 30 may be formed of concrete block or timber frame or any other suitable construction material 30.
In this embodiment the thermoelectric layer 20 converts both heat escaping from the fabric (thermal bridge) into electricity and heat gained by the fabric (thermal bridge) into electricity.
As shown in
As shown in
In this embodiment, the external layer 40 is an organic thermoelectric layer which absorbs the radiation and coverts a portion of this energy into electricity. However, in other embodiments, the outer organic thermoelectric layer 40 may be replaced by an external construction/cladding layer 40, which would absorb radiation but not generate electricity itself. Such an embodiment would therefore not be as effective at optimising energy recovery.
As will be appreciated from the above examples, the present invention allows surplus energy to be stored during warm conditions for certain period of time and then utilised later to generate electricity during cooler conditions. This allows for electricity to be generated over much longer periods of time, improving the overall efficiency of the energy generating apparatus.
It will be understood that the embodiments illustrated above shows applications of the invention only for the purposes of illustration and not drawn to scale. In practice the invention may be applied to many different configurations, the detailed embodiments being straightforward for those skilled in the art to implement.
For example, although in the embodiments illustrates a structure as part of a building's wall, it could be incorporated into other structures such as a building's roof or as part of the flooring. In such cases, the apparatus may be provided in the form of a panel and/or be used in a modular construction.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1117626.0 | Oct 2011 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB2012/052543 | 10/12/2012 | WO | 00 | 4/9/2014 |
