Modular passive solar energy heating unit employing phase change heat storage material which is clearly transparent when in its high-stored-energy liquid state

For mounting in a wall or roof of a building containing an enclosed space for living or working within the building near such wall or roof and for being in a solar-radiation-receiving position, a passive solar energy heating window unit, comprising:

• a frame adapted to be mounted in such a wall or roof in such a position,
• at least one flat fluid-tight container mounted within said frame and having opposite parallel, flat, rigid, surface areas of clearly optically transparent material, the inner of said surface areas facing inwardly toward such an enclosed space when said frame is mounted in such wall or roof in such position, and the outer of said surface areas facing outwardly toward the exterior of the building when said frame is so mounted in such position,
• solar energy heat storage phase change material disposed in said container, said phase change material being polyethylene glycol characterized by a heat of fusion of about 33 to 37 ca./gm (4,170 to 4,670 Btu's per cubic ft.), a melting point of from about 13.degree. to 25.degree. C. (55.degree. to 77.degree. F.) and a specific gravity of approximately 1.125 to 20.degree. C.,
• said phase change material in said fluid-tight container being translucent milky white when in its low-stored-energy solid state and being clearly optically transparent to visible light when in its high-stored-energy liquid state for enabling a viewer to look through said fluid-tight container when said phase change material is liquid,
• at least one clearly optically transparent glazing in flat sheet form mounted in said frame, said transparent glazing being spaced from the outer surface area of said fluid-tight container and being arranged in said frame on the opposite side of said fluid-tight container from said enclosed space when said frame is so mounted in such position for permitting solar radiation to pass through said glazing sheet and to impinge upon said outer transparent surface area of said fluid-tight container when said frame is so mounted in such position,
• the outer side of said glazing sheet being disposed to face the incoming solar radiation, said inner side of said glazing sheet facing toward said outer transparent surface area of the fluid-tight container,
• gas being included between said inner side of the glazing sheet and said outer surface area of the container,
• said glazing sheet transmitting short wavelength solar and visible light rays while preventing longer wavelength heat rays from radiating through the glazing sheet,
• whereby when said phase change material is in its low-stored-energy solid state said fluid-tight container member presents a back-illuminated milky white appearance to a viewer in said enclosed space,
• whereby when said phase change material is in its high-stored-energy liquid state a viewer in said enclosed space can see through said fluid-tight container and through said glazing, and
• whereby said phase change material releases its heat of fusion as it changes back into a solid state for maintaining the enclosed space at a comfortable temperature.

A passive solar energy window heating unit for installation in a wall or roof of an enclosed space comprising:

• a peripheral frame adapted to be mounted in the wall or roof in a position for receiving solar radiation,
• at least one flat rigid fluid-tight container mounted within said frame and having two opposite parallel flat surface areas of clearly optically transparent rigid glazing material, the inner of said flat surface areas facing inwardly toward such an enclosed space when said frame is mounted in the wall or roof in such position, and the outer of said flat surface areas facing outwardly toward the exterior of the building when said frame is mounted in such position,
• solar energy heat storage phase change material filling container, said phase change material being polyethylene glycol characterized by a heat of fusion of about 33 to 37 ca./gm. (4,170 to 4,670 Btu's per cubic ft.), a melting point of from about 13.degree. C. to 25.degree. C. (55.degree. F. to 77.degree. F.) and a specific gravity of approximately 1.125 at 20.degree. C.,
• said phase change material in said fluid-tight container being translucent milky white when in its low-stored-energy solid state and being clearly optically transparent to visible light when in its high-stored-energy liquid state for enabling a viewer in the enclosed space to look outdoors through said fluid-tight container and through said two parallel flat transparent glazing surface areas when said phase change material is liquid,
• at least one clearly optically transparent glazing in flat sheet form mounted in said frame, said transparent glazing being spaced from and parallel to the outer flat surface area of said fluid-tight container and being arranged in said frame on the opposite side of said fluid-tight container from said enclosed space when said frame is mounted in such position for permitting solar radiation to pass through said glazing sheet and to impinge upon said outer transparent surface area of said fluid-tight container when said frame is mounted in such position,
• the outer side of said glazing sheet facing the incoming solar radiation, the inner side of said glazing sheet facing toward said outer flat transparent surface area of the fluid-tight container,
• said glazing sheet being transparent with respect to visible light rays while being opaque with respect to longer wavelength heat rays for transmitting visible light rays while preventing longer wavelength heat rays from radiating through the glazing sheet,
• said phase change material in its low-stored-energy solid stage in said fluid-tight container member presenting a back-illuminted milky white appearance to a viewer in said enclosed space and thereby provides a diffuse pleasant daylight illumination in said enclosed space,
• said phase change material in its high-stored-energy liquid state being clearly transparent for enabling a viewer in said enclosed space to see through said fluid-tight container and through said glazing sheet, and
• said phase change materal releasing its heat of fusion as it changes back into a solid state in said temperature range of 13.degree. C. to 25.degree. C. (55.degree. F. to 77.degree. F.) for maintaining the enclosed space at a comfortable temperature in said range.

A modular passive solar energy window heating unit adapted to absorb and store solar energy and subsequently to release the stored energy as thermal energy in an enclosed space such as living space or office space, said unit being adapted to be installed into existing window openings on a retrofit basis comprising:

• outer and inner clearly optically transparent flat glass glazing sheets,
• a frame encircling said two glass glazing sheets holding them in spaced parallel relationship and sealing the region between said two glazing sheets for forming a fluid-tight container of generally overall planar configuration,
• solar energy heat storage phase change material essentially filling said planar container, said phase change material being polyethylene glycol characterized by a heat of fusion of about 33 to 37 ca./gm. (4,170 to 4,670 Btu's per cubic ft.), a melting point of from about 13.degree. C. to 25.degree. C. (55.degree. F. to 77.degree. F.) and a specific gravity of approximately 1.125 at 20.degree. C.,
• said phase change material in said planar fluid-tight container being translucent milky white when in its low-stored-energy solid state for providing attractive illumination into the enclosed space from the window in which said retrofit unit is installed, and being clearly optically transparent to visible light when in its high-stored-energy liquid state for enabling a viewer in the enclosed space to look through said retrofit unit and out through the window, and
• said phase change material during phase change exhibits a change in volume of less than two percent during phase change for enabling the glass glazing sheets to accommodate such modest change in volume.