Electrohydrodynamic acceleration of charging process in a latent heat thermal energy storage module

Abstract

A latent heat thermal energy storage (LHTES) unit can include a shell, a tube, a phase change material (PCM), a first electrode, and a second electrode. The shell may be an outer housing, and the tube may extend through an interior of the shell. The PCM may be located between the shell and the tube. The first electrode may be located on the shell, and the second electrode may be located on the tube. The first electrode and the second electrode may be arranged to apply an electric potential from the tube to the shell and across the PCM, and the second electrode may be arranged to inject unipolar charge into the PCM to induce electrohydrodynamic (EHD) flow within the PCM.

What is claimed is: 
     
         1 . A latent heat thermal energy storage (LHTES) unit comprising:
 a shell that is an outer housing of the LHTES unit;   a tube extending through an interior of the shell;   a phase change material (PCM) located between the shell and the tube;   a first electrode located on the shell; and   a second electrode located on the tube, wherein the first electrode and the second electrode are arranged to apply an electric potential from the tube to the shell and across the PCM, and wherein the second electrode is arranged to inject unipolar charge into the PCM to induce electrohydrodynamic (EHD) flow within the PCM.   
     
     
         2 . The LHTES unit of  claim 1 , wherein a first melting rate of the PCM exposed to the EHD flow is higher than a second melting rate of the PCM not exposed to the EHD flow, and wherein a first time to charge the LHTES unit is lower than a second time to charge a different LHTES unit that does not include the EHD flow. 
     
     
         3 . The LHTES unit of  claim 1 , wherein the second electrode is an emitter for unipolar charge injection, and wherein the first electrode is a collector electrode for unipolar charge injection. 
     
     
         4 . The LHTES unit of  claim 1 , wherein the second electrode is configured to inject the unipolar charge into the PCM to cause approximately uniform melting of the PCM regardless of an orientation of the shell. 
     
     
         5 . The LHTES unit of  claim 4 , wherein the shell is oriented vertically such that the tube extends parallel with respect to a direction of gravity. 
     
     
         6 . The LHTES unit of  claim 4 , wherein the shell is oriented horizontally such that the tube extends perpendicularly with respect to a direction of gravity. 
     
     
         7 . The LHTES unit of  claim 1 , wherein the PCM is an organic PCM that includes paraffin wax. 
     
     
         8 . The LHTES unit of  claim 1 , wherein the second electrode is configured to adjust a charge injection into the PCM based on an intensity of the EHD flow and a performance of the LHTES unit. 
     
     
         9 . The LHTES unit of  claim 1 , wherein the EHD flow in the PCM is configured to generate a uniform cylindrical velocity field between the shell and the tube.  2   
     
     
         10 . A method for inducing melting in a latent heat thermal energy storage (LHTES) unit, the method comprising:
 applying an electric field between a first electrode of the LHTES unit and a second electrode of the LHTES unit, wherein the LHTES unit includes a phase change material (PCM);   inducing electrohydrodynamic (EHD) flow in the LHTES unit with a unipolar charge injection; and   inducing, by the EHD flow, a phase change in the PCM.   
     
     
         11 . The method of  claim 10 , wherein a first melting rate of the PCM exposed to the EHD flow is higher than a second melting rate of the PCM not exposed to the EHD flow, and wherein a first time to charge the LHTES unit is lower than a second time to charge a different LHTES unit that does not include the EHD flow. 
     
     
         12 . The method of  claim 10 , wherein the first electrode is coupled with a shell of the LHTES unit, wherein the second electrode is coupled with a tube of the LHTES unit, wherein the second electrode injects the unipolar charge into the PCM to cause approximately uniform melting of the PCM regardless of an orientation of the shell. 
     
     
         13 . The method of  claim 10 , further comprising adjusting charge injection into the PCM using the second electrode and based on an intensity of the EHD flow and a performance of the LHTES unit. 
     
     
         14 . The method of  claim 10 , further comprising generating a uniform cylindrical velocity field between a shell of the LHTES unit and a tube of the LHTES unit. 
     
     
         15 . The method of  claim 10 , wherein inducing the EHD flow and/or inducing the phase change are performed while the LHTES unit is vertically oriented. 
     
     
         16 . The method of  claim 10 , wherein inducing the EHD flow and/or inducing the phase change are performed while the LHTES unit is horizontally oriented. 
     
     
         17 . A method for controlling a melting rate of phase change material (PCM) in a latent heat thermal energy storage (LHTES) unit, the method comprising:
 receiving input parameters comprising properties about the PCM, a target melting rate, and an orientation of the LHTES unit;   determining an electric field and charge injection regime to induce EHD flow for achieving the target melting rate based on the properties about the PCM and the orientation; and   outputting control signals to a power supply to apply the determined electric field between a first electrode of the LHTES unit and a second electrode of the LHTES unit, wherein applying the electric field results in unipolar charge injection and EHD flow for melting the PCM.   
     
     
         18 . The method of  claim 17 , wherein:
 the orientation of the LHTES unit is vertical such that a tube of the LHTES unit is parallel with a direction of gravity; or   the orientation of the LHTES unit is horizontal such that a tube of the LHTES unit is perpendicular to a direction of gravity.   
     
     
         19 . The method of  claim 17 , wherein the first electrode is coupled with a shell of the LHTES unit, wherein the second electrode is coupled with a tube of the LHTES unit, wherein the second electrode injects the unipolar charge into the PCM to cause approximately uniform melting of the PCM regardless of an orientation of the shell. 
     
     
         20 . The method of  claim 17 , further comprising adjusting charge injection into the PCM using the second electrode and based on an intensity of the EHD flow and a performance of the LHTES unit.