US 2011/0298333 A1 · DIRECT CONVERSION OF NANOSCALE THERMAL RADIATION TO ELECTRICAL ENERGY USING PYROELECTRIC MATERIALS

Abstract

The embodiment provided herein are directed to a pyroelectric (PE) energy converter which is capable of combining nanoscale thermal radiation and pyroelectric energy conversion for harvesting low grade waste heat. The converter advantageously makes use of the enhanced radiative heat transfer across a nanosize gap to achieve high operating frequencies or large temperature oscillations in a composite PE plate. The PE energy converter generally comprises a hot source, a cold source, and a PE plate, wherein the PE plate oscillates between the hot and cold source and the PE plate can be subjected to a power cycle in the displacement-electric field diagram. The hot and cold sources of the converter can be coated with SiO2 absorbing layer to further enhance the radiative heat fluxes. The converter comprising a PE plate made of 60/40 P(VDF-TrFE) operated between 273 K and 388 K experiences a maximum efficiency of 0.2% and a power density of 0.84 mW/cm2. The converter comprising a PE plate made of 0.9PMN-PT composite thin films achieve a higher efficiency and a larger power output namely 1.3% and 6.5 mW/cm2, respectively, for a temperature oscillation amplitude of 10 K around 343 K at 5 Hz.

Claims14

Dependent claims

A pyroelectric energy converter for direct conversion of nanoscale thermal radiation to electrical energy, comprising:

hot and cold plane sources, wherein the hot plane source is at temperature Th and the cold plane source is at temperature Tc, wherein Th is greater than Tc,
an oscillating pyroelectric plate comprising at least one pyroelectric material film sandwiched between first and second electrodes used to collect electric charges from the pyroelectric film and to apply an electric field, and
a plurality of actuators coupled to the pyroelectric plate enabling the pyroelectric plate to oscillate between the hot and cold plane sources, wherein the oscillating pyroelectric plate is movable between a first position in spaced relation with the cold plane source at a distance smaller than the radiation peak wavelength, λmax, given by Wien's displacement law (λmaxT=2898 mm K) wherein T is the temperature of the cold plane source, Tc, and a second position in spaced relation with the hot plane source at a distance smaller than the radiation peak wavelength, λmax, wherein T is the temperature of the hot plane source, Th.

A method of converting nanoscale thermal radiation to electrical energy, comprising the steps of:

applying an electric field to a pyroelectric plate between a hot plane source and a cold plane source, wherein the hot plane source is at temperature Th and the cold plane source is at temperature Tc, wherein Th is greater than Tc, and wherein the pyroelectric plate comprises at least one pyroelectric material film sandwiched between first and second electrodes used to collect electric charges from the pyroelectric film and to apply an electric field, wherein the pyroelectric plate is coupled to a plurality of actuators enabling the pyroelectric plate to oscillate between the hot and cold plane sources, and
moving the pyroelectric plate from a first position in spaced relation with the cold plane source at a distance smaller than the radiation peak wavelength, λmax, given by Wien's displacement law (λmaxT=2898 mm K) wherein T is the temperature of the cold plane source, Tc, to a second position in spaced relation with the hot plane source at a distance smaller than the radiation peak wavelength, λmax, wherein T is the temperature of the hot plane source, Th.

Dependencies are inferred from the claim text.

Direct conversion of nanoscale thermal radiation to electrical energy using pyroelectric materials

Life of this patent

Direct conversion of nanoscale thermal radiation to electrical energy using pyroelectric materials

Life of this patent

Abstract

Claims14