Optical methods for phase change materials
AssigneeVito NV
InventorRobbe Salenbien
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Abstract
A device for measuring the state of a phase change material inside a vessel, the device includes at least one optical fiber arranged inside the vessel, the optical fiber including a cladding around a core, a light source emitting light coupled into a first end of the at least one optical fiber at a wavelength λ, optical measuring devices for measuring the amount of light at the output at a second end of the at least one optical fiber. The at least one optical fiber also includes a plurality of sections with the cladding removed so that at these sections the core is in direct contact with the phase change material inside the vessel and where the refractive index at the wavelength λ of the core is higher than that of the phase change material in a first phase and lower in a second phase.
Claims20
A heat storage vessel having a device for measuring a state of a phase change material inside the heat storage vessel, the phase change material having a step-wise change of refractive index at change of phase, the vessel comprising:
- at least one optical fiber arranged inside the heat storage vessel, said at least one optical fiber having a cladding around a core,
- a light source emitting light coupled into a first end of the at least one optical fiber at a wavelength λ,
- optical measuring means for measuring the amount of light at the output at a second end of the at least one optical fiber,
- wherein the at least one optical fiber comprises one or a plurality of sections with the cladding removed so that at these sections the core is in direct contact with the phase change material inside the vessel and wherein the refractive index at the wavelength of the core is higher than that of the phase change material in a first phase and lower than that of the phase change material in a second phase, the refractive index of the core lying within the step-wise change of refractive index at the phase change,
- wherein the plurality of sections having a removed or no cladding of the at least one optical fiber are distributed throughout the heat storage vessel such that the ratio of phase change materials in different phases can be determined by measuring the light intensity at the output of the at least one optical fiber.
A method for calibrating a measurement system for optical measurements on a phase change material in a vessel, the phase change material having a step-wise change of refractive index at change of phase, the vessel having at least one optical fiber arranged inside the vessel, said at least one optical fiber comprising a cladding around a core, the at least one optical fiber having a plurality of sections with the cladding removed so that at these sections the core is in direct contact with the phase change material inside the vessel and wherein the refractive index of the core is higher than that of the phase change material when the phase change material is in a first phase and lower than that of the phase change material when the phase change material is in a second phase, the refractive index of the core lying within the step-wise change of refractive index of the phase change material at the phase change, and wherein the plurality of sections having a removed or no cladding of the at least one optical fiber are distributed throughout the heat storage vessel such that the ratio of phase change materials in different phases can be determined by measuring the light intensity at the output of the at least one optical fiber, the method comprising the steps of:
- coupling a light source to an input of the at least one optical fiber,
- measuring a maximal intensity of light emitted at an output of the fiber when the phase change material is all in the first phase state,
- measuring a minimum intensity at the output of the fiber when the phase change material in the vessel is all in a second phase state, and
- storing the minimum and maximum intensity values.
A method for calibrating the state of a PCM material in a vessel comprising at least one optical fiber having a cladding around a core and the at least one optical fiber comprising one or a plurality of sections with the cladding removed wherein the sections having a removed or no cladding are distributed throughout the heat storage vessel such that the ratio of phase change materials in different phases can be determined by measuring the light intensity at the output of the at least one optical fiber, the method comprising the steps of:
- measuring a maximal intensity at the output of an optical fiber by providing a light beam of coherent light at a first wavelength and intensity I at the entrance of the optical fiber, wherein said first wavelength is chosen such that the refraction index of a core of the optical fiber is always higher than the refraction index of a cladding of the optical fiber or the PCM material,
- measuring a minimum intensity at the output of the optical fiber by providing a light beam of coherent light at a second wavelength λ and same intensity I at the entrance of the optical fiber, the second wavelength being chosen such that the refraction index of the phase change material is always larger than the refraction index of the core,
- storing the minimum and maximum intensity values as a function of the intensity I.
Dependencies are inferred from the claim text.