GB2450474A

GB2450474A - Glazing structure comprising liquid between two layers

Info

Publication number: GB2450474A
Application number: GB0710931A
Authority: GB
Inventors: Vincent John Hinksman; David Andrew Johnston
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-06-07
Filing date: 2007-06-07
Publication date: 2008-12-31
Also published as: GB0710931D0

Abstract

A glazing structure 1 comprises two layers of transparent solid material, and a liquid 2 in a space between the two layers. Circulation of the liquid and/or its absorbing and reflecting properties are utilised to control energy flow within and across the structure. The layers may be made of glass. Chemical compounds within the liquid may alter their optical properties in response to ambient conditions. Such chemical compounds may be photochromic and so responsive to light levels, or thermochromic and so responsive to temperature. Alternatively, a sensor and control system may measure ambient conditions and change the optical properties of the liquid. A filter or electrolytic cell may be provided to remove and return chemical compounds from the liquid. Alternatively, a pH indicator may be present in the liquid, and acidic or alkaline compounds may be added or removed from the liquid to modify its optical properties. The glazing structure may be used to maintain a comfortable temperature within an internal environment, or to provide privacy. The structure may be provided with a pump 6, and may be connected to a radiator 7 or a heat exchanger (8, Fig. 2) in a storage tank (9).

Description

I

DOUBLE GLAZING WiTH CIRCULATING LIQUID TO CONTROL RADIATiVE AND

HEAT TRANSFER BALANCE

This invention relates to a layered construction, consisting of two sheets of glass, with a liquid circulating in the intervening space. This liquid may alter its transmissive and/or reflective properties, to control the radiative transfer across it, and may extract the absorbed energy as heat, to be used elsewhere, or rejected to the external environment, or other heat sink.

When glazing is used for provision of solar (or other) lighting, for instance in buildings, the variation in light level can exceed the requirements for energy balance. For example, where windows or conservatories are used for passive solar heating, high levels of solar radiation can lead to excessive temperatures within the building, whereas low levels of lighting may be insufficient to compensate the heat losses from the building, leading to temperatures below the comfortable range.

In addition, occupants of buildings may prefer to have glazing, which provides a controllable degree of privacy.

To meet these requirements, the present invention proposes a layered structure, consisting of two layers of glass, with a liquid circulating in the intervening space. The liquid absorbs some of the radiant energy entering the system, being heated in the process. A clear liquid, e.g., water, may be circulated. Alternatively, a coloured material may be added to the liquid, to increase the fraction of light absorbed by the liquid. The absorptivity of this liquid can be changed, to control the fraction of incident light, which is absorbed, thus controlling the energy entering the internal environment.

The absorbed radiant energy heats the fluid, which can be used either to heat the rest of the building, via radiators, etc. or to heat water in a storage tank, for later use. Heat which is surplus to requirement can be returned to the external environment. In the latter case, materials added to the liquid can increase its reflectivity, rather than is absorption, thus rejecting the energy directly to the environment.

The variable transmission, provided by the circulating liquid, reduces the variations in the temperature of the internal environment, thus maintaining it within a comfortable range. The surplus energy, if any, can be extracted as heat, and diverted for other purposes.

A number of alternative mechanisms can be employed, which are described by referring to the accompanying drawings. These can be broadly categorised as passive and active. In passive systems, the circulating liquid, or a material within it, responds automatically to ambient conditions -generally temperature or light level. Active systems include sensors to monitor these ambient conditions. A control system then adjusts the transmittance of the liquid, to modify the ambient conditions.

A passive system is shown in Figure 1, and consists of a glass panel 1 with the circulating liquid 2, inlet manifolds 3 and outlet manifolds 4, circulation pipes 5 and pump 6, and radiators 7 (for space heating). Alternatively, as shown in Figure 2, a heat exchanger 8 may placed inside a hot water storage tank 9. A combination of these systems may be constructed, wherein some of the heated liquid passes through the radiators, and the remainder through the heat exchanger.

The active material in a passive system may be photochromic (sensitive to light), or thermochromic (sensitive to temperature). A photochromic material is selected, which is clear at low light levels, and becomes coloured at high light levels. A thermochromic material is selected, which is clear at low temperatures, and becomes coloured at high temperatures. In either case, the material used reduces the transmitted light level, when the internal temperature would tend to be high.

An active system is shown in Figure 3, and includes the components present in a passive system, and also a light sensor 10 and/or temperature sensor 11, a control unit 12 to respond appropriately to the ambient conditions, and a transducer 13, which alters the optical properties of the liquid, by any one of a range of mechanisms. As for a passive system, the heated liquid 2 may be passed through radiators (not shown), or through a heat exchanger 8 in a hot water storage tank 9.

A number of mechanisms can be used within the transducer to alter the composition, and hence transmittance, of the liquid. Some of these are listed below.

1. A filter 14, shown in Figure 4, can be placed in a diverter pipe 15, placed in parallel with the normal flow pipe 16. When the light level or temperature is low, as measured by the sensor, the control unit diverts the liquid into the diverter pipe 15. The filter 14 removes some or all of the coloured material from the solution, thus increasing the transmittance.

This increases the quantity of light passing through the panel, thus increasing the temperature of the internal environment. When the sensor 10 or 11 and transducer 13 indicate that the light level needs to be reduced, the liquid is made to flow, in the reverse direction, through the filter 14. This removes previously absorbed material and returns it to the liquid, thus decreasing its transmittance.

2. An electrolytic cell, with one or both electrodes made of a transition metal, adds this metal to the solution, or removes it from the solution -depending on the polarity of the applied voltage. This alters the transmittance of the solution, and hence controls the light passing through the panel to the internal environment.

3. The liquid can include a pH indicator -a chemical which changes colour significantly at a well defined pH. An injection/extraction system is then used to add or remove acidic or alkaline material to/from the material, in order to shift the pH of the solution above or below the transition level.

In addition to acting as a controllable passive solar heating system, the glass panel can also provide adjustable transparency, and thus provide a controllable degree of privacy for occupants of the building. As this function will be determined be user preference, rather than ambient conditions, it is only suitable for the active control systems, as defined above, rather than passive ones. This additional function can be added to the previous one of temperature control, by adding a manual override to the temperature and/or light-dependent control unit. Whereas a glass panel for temperature control only may incorporate a liquid which remains partially transparent, under all operating conditions, one design to provide privacy would include a liquid with a controllable opacity (and optionally controllable reflectivity).

Claims

I. A multi-layered structure, consisting of two layers of glass, or other transmissive solid material, with a liquid circulating within the space between these two layers, wherein the circulation of the liquid and/or its absorbing and reflective properties are utilised to control the energy flow within and across the structure.
2. A multi-layered structure, as claimed in Claim 1, wherein the level of light passing through the glass panel, to an internal environment, is controlled to maintain a comfortable temperature within that environment.
3. A multi-layered structure, as claimed in Claim I and Claim 2, wherein chemical compounds within the liquid alter their optical properties, in response to a change in ambient conditions.
4. A multi-layered structure, as claimed in Claim 1, Claim 2 and Claim 3, wherein the chemical compound is a photochromic material, which changes its optical properties at a light level determined by appropriate selection of the material.
5. A multi-layered structure, as claimed in Claim 1, Claim 2 and Claim 3, wherein the chemical compound is a thermochromic material, which changes its optical properties at a temperature determined by appropriate selection of the material.
6. A multi-layered structure, as claimed in Claim I and Claim 2, wherein a sensor measures the relevant ambient condition, and acts, via a control system and a transducer, to change the optical properties of the liquid.
7. A multi-layered structure, as claimed in Claim 1, Claim 2 and Claim 6, wherein a filter is placed in the circulation system, which removes chemical compounds from the liquid, or by suitable alteration in the flow direction, returns these chemical compounds to the liquid, in order to modify its optical properties.
8. A multi-layered structure, as claimed in Claim 1, Claim 2 and Claim 6, wherein an electrolytic cell is placed in the circulation system, which removes chemical compounds from the liquid, or by alteration in the electric polarity, returns these chemical compounds to the liquid, in order to modify its optical properties.
9. A multi-layered structure, as claimed in Claim 1, Claim 2 and Claim 6, wherein a pH indicator is present in the liquid, and acidic or alkaline compounds are added or removed to or from the liquid, in order to modify its optical properties.
10. A multi-layered structure, as claimed in Claim 1, wherein the opacity and/or reflectivity of the circulating liquid is altered to provide a controllable degree of transparency, in order to provide privacy.