Regenerative electrocaloric cooling device

Abstract

A regenerative electrocaloric (EC) device is provided. The regenerative EC device uses a special configuration to expand the temperature span T h -T c , thereby increasing the cooling power and improving the efficiency thereof. The EC regenerative cooling device includes two electrocaloric effect (ECE) elements/rings in direct thermal contact with each other. The two rings rotate in opposite directions and are divided into multiple sections with an electric field or electric fields applied to every other region/section and an electric field or electric fields removed from remaining sections.

We claim: 
     
         1 . A regenerative electrocaloric (EC) cooling device comprising:
 a first EC ring having N spaced apart first ring high electric field regions (HEFRs) and N spaced apart first ring low electric field regions (LEFRs);   a second EC ring having N spaced apart second ring HEFRs and N spaced apart second ring LEFRs, N being equal to or greater than 1;   said first EC ring rotating in an opposite direction to said second EC ring and in sliding contact therewith, said N first ring HEFRs, N first ring LEFRs, N second ring HEFRs and N second ring LEFRs fixed in space during rotation of said first EC ring and said second EC ring;   at least one hot end located between a first ring HEFR and a first ring LEFR;   at least one cold end located between a second ring HEFR and a second ring LEFR;   an electrical power supply in communication with said first and second EC rings and producing an electric field thereacross, said electric field across said first and second EC rings reducing an entropy and increasing a temperature thereof such that said first EC ring is at a higher temperature than said second EC ring and vice versa; and   a fixed ring in thermal contact with at least one of said first EC ring and said second EC ring, said fixed ring having N hot ends at a temperature of T h  and N cold ends at a temperature of T c , said fixed ring also having 2N spaced apart regions of heat exchange at said N hot ends and said N cold ends;   each of said heat exchange regions made from a high thermal conductivity material with a thermal conductivity >50 W/mK and separated from adjacent heat exchange regions by regions of a low thermal conductivity material with a thermal conductivity <0.3 W/mK;   said heat exchange regions at said N cold ends absorbing heat from an outside source of heat and said heat exchange regions at said N hot ends transferring heat to a heat sink such that heat is pumped from the outside heat source at T c  to the heat sink at T h .   
     
     
         2 . The regenerative device of  claim 1 , wherein each of said N first ring HEFRs is oppositely disposed from and in sliding contact with each of said N second ring LEFRs and each of said N first ring LEFRs is oppositely disposed from and in sliding contact with each of said N second ring HEFRs during said rotating of said first EC ring relative to said second EC ring. 
     
     
         3 . The regenerative device of  claim 2 , wherein heat passes from said N first ring HEFRs to said N second ring LEFRs and from said N second HEFRs to said N first ring HEFRs. 
     
     
         4 . The regenerative device of  claim 3 , wherein said first EC ring and said second EC ring rotate relative to a fixed ring, said fixed ring having N hot ends at a temperature of T h  and N cold ends at a temperature of T c , said fixed ring also having 2N spaced apart regions of heat exchange (at T h  and T c ), each of said heat exchange regions made from a high thermal conductivity material (thermal conductivity >50 W/mK) and separated from adjacent regions of heat exchange by regions of low thermal conductivity material (thermal conductivity <0.3 W/mK). The heat exchange regions at T c  absorb heat from an outside source of heat and the heat exchange regions at T h  transfer heat to a heat sink such that heat is pumped from an outside heat source at T c  to a heat sink at T h . 
     
     
         5 . The regenerative EC device of  claim 4 , wherein said first EC ring has a plurality of first ring EC segments and subsets of said plurality of first ring EC segments are located within each of said N first ring HEFRs and other subsets of said plurality of first ring EC segments are located within each of said N first ring LEFRs as said first EC ring rotates; and
 said second EC ring has a plurality of second ring segments and subsets of said plurality of second ring EC segments are located within each of said N second ring HEFRs and other subsets of said plurality of second ring EC segments are located within each of said N second ring LEFRs as said second EC ring rotates.   
     
     
         6 . The regenerative device of  claim 5 , wherein a ring segment of each of said subsets of said plurality of first ring EC segments travels from a first ring HEFR into the adjacent first ring LEFR, causing a lowering of temperature to T c  as a ring segment of each of said other subsets of said plurality of first ring segments travels from a first ring LEFR into the adjacent first ring HEFR, causing a rising in temperature to T h . 
     
     
         7 . The regenerative device of  claim 6 , further comprising a low thermal conductivity (thermal conductivity <0.3 W/mK) divider between adjacent first ring EC segments and between each adjacent second ring EC segments. 
     
     
         8 . The regenerative device of  claim 7 , further comprising a ring rotation source operable to rotate said first EC ring and said second EC ring opposite to each other, said ring rotation source also operable to rotate said first EC ring relative to said second EC ring at a constant angular speed or rotate said first EC ring relative to said second EC ring at a non-constant angular speed. 
     
     
         9 . The regenerative device of  claim 7 , wherein said ring rotation source has a first angular speed when said plurality of first ring segments are not aligned with said plurality of second ring segments and a second angular speed when said plurality of first ring segments are aligned with said plurality of second ring segments, said first angular speed greater than said second angular speed. 
     
     
         10 . The regenerative devices of  7 , wherein each of said plurality of first ring segments and each of said plurality of second ring segments is covered by a single electrode, said electrical power supply applying an electric field of magnitude |E H −E L | across each ring segment via said single electrode. 
     
     
         11 . The regenerative device of  7 , wherein each of said plurality of first ring segments and each of said plurality of second ring segments is covered by a M electrodes, said electrical power supply applying an electric field of magnitude |E H −E L | at increments of |E H −E L |/M across each ring segment via said M electrodes. 
     
     
         12 . The regenerative device of claims of  7 , further comprising a plurality of first EC ring-second EC ring-fixed ring units stacked together to form a large cooling device. 
     
     
         13 . The regenerative device of  claim 7 , further comprising a first small OD EC ring and a second small OD EC ring, said first and second small EC rings located and occupying an inner space within an inner diameter of said first and second EC rings. 
     
     
         14 . The regenerative device of  claim 7 , further comprising a plurality of first EC ring-second EC ring units stacked together to form a large cooling device and a plurality of first small OD EC ring and a second small OD EC ring units, said plurality of first and second small EC rings units located and occupying inner spaces within inner diameters of said plurality of first EC ring-second EC ring units.