A thermal storage system and temperature controlled container comprising the same

Abstract

Passive thermal storage systems and methods comprising at least one thermal storage module for storing thermal energy in a predetermined temperature range, are disclosed. The thermal storage module comprises an FT unit and a Heat Storage (HS) unit at least partially filled with a first Phase Change Material (PCM). The HS unit comprises a container. The thermal storage module may be in the form of a stacked structure comprising the FT unit having a first wall with a first heat exchange surface and the HS unit having a second wall with a second heat exchange surface, the first and second heat exchange surfaces being in thermal contact with each other. The thermal storage system may be used to maintain the temperature of the payload of a temperature controlled container at a predetermined value or within a predetermined range.

1 . A passive thermal storage system for storing thermal energy in a predetermined temperature range, the thermal storage system comprising at least one thermal storage module comprising:
 a fluid transporting (FT) unit comprising:
 a passageway configured for circulating a heat transfer fluid therethrough; and 
 an inlet port for the inflow of the heat transfer fluid to the passageway and the outlet port for the outflow of the heat transfer fluid from the passageway, 
 wherein the inlet port and an outlet port of the FT unit are releasably connectable to a heat transfer fluid system, the heat transfer fluid system being configured for circulating the heat transfer fluid through the FT unit of the thermal storage system via the inlet and outlet ports; and 
 a first Heat Storage (HS) unit at least partially filled with a first Phase Change Material (PCM), wherein the first HS unit comprises a container at least partially filled with the first PCM material; 
 wherein the thermal storage module is in the form of a stacked structure comprising the FT unit having a first wall with a first heat exchange surface, and the first HS unit having a second wall with a second heat exchange surface, the first and second heat exchange surfaces being in thermal contact with each other such that thermal energy can be transferred between the heat transfer fluid in the FT unit and the first PCM in the first HS unit so that the first PCM of the first HS unit can at least partially change phase in the predetermined temperature range. 
   
     
     
         2 . The thermal storage system according to  claim 1 , wherein the heat transfer fluid is a pumpable single phase fluid. 
     
     
         3 . The thermal storage system according to  claim 1 , wherein the heat transfer fluid is a pumpable multi phase fluid. 
     
     
         4 . A passive thermal storage system for storing thermal energy in a predetermined temperature range, the thermal storage system comprising a thermal storage module comprising:
 a fluid transporting (FT) unit ( 10 ) comprising:
 a passageway configured for circulating a heat transfer fluid therethrough; and 
 an inlet port for the inflow of the heat transfer fluid to the passageway and an outlet port for the outflow of the heat transfer fluid from the passageway; 
 wherein the inlet port and the outlet port of the FT unit are releasably connectable to a heat transfer fluid system, the heat transfer fluid system being configured for circulating the heat transfer fluid through the FT unit of the thermal storage system via the inlet and outlet ports; and 
 a Heat Storage (HS) unit at least partially filled with a first Phase Change Material (PCM); 
 wherein the first PCM of the HS unit is configured for being in thermal contact with the heat transfer fluid of the FT unit such that thermal energy can be transferred between the heat transfer fluid in the FT unit and the first PCM in the HS unit so that the first PCM of the HS unit can at least partially change phase in the predetermined temperature range; 
 wherein the heat transfer fluid is a pumpable multi phase fluid comprising a substance which changes phase while circulated through the FT unit. 
   
     
     
         5 . The passive thermal storage system according to  claim 3 , wherein the multi phase heat transfer fluid is a two-phase fluid configured for changing between a solid phase and a liquid phase. 
     
     
         6 . The thermal storage system according to  claim 5 , wherein the multi phase heat transfer fluid is in the form of an ice slurry. 
     
     
         7 . The thermal storage system according to  claim 3 , wherein the multi phase heat transfer fluid is a second PCM. 
     
     
         8 . The thermal storage system according to  claim 7 , wherein the second PCM has a phase changing temperature range different from the predetermined temperature range. 
     
     
         9 . The thermal storage system according to  claim 1 , wherein the heat transfer fluid remains within the FT unit upon disconnecting the thermal storage system from the heat transfer fluid system. 
     
     
         10 . The thermal storage system, according to  claim 4 , wherein the thermal storage module is in the form of a stacked structure comprising the FT unit having a first wall with a first heat exchange surface and the HS unit having a second wall with a second heat exchange surface, the first and second heat exchange surfaces being in thermal contact with each other. 
     
     
         11 . The thermal storage system according to  claim 1 , wherein the first and second walls are substantially the same. 
     
     
         12 . The thermal storage system according to  claim 1 , wherein the stacked structure comprises a second HS unit, the first HS unit being in thermal contact with the first wall of the FT unit, the second HS unit being in thermal contact with a second wall of the FT unit. 
     
     
         13 . The thermal storage system according to  claim 12 , wherein the stacked structure comprises a plurality of alternating layers of the first HS unit and the FT unit being in thermal contact with each other. 
     
     
         14 . The thermal storage system according to  claim 1 , wherein the first HS unit is a closed volume container. 
     
     
         15 . The thermal storage system according to  claim 1 , wherein the first HS unit comprises a plurality of heat conducting elements configured for being in thermal contact with the first PCM material. 
     
     
         16 . The thermal storage system according to  claim 15 , wherein each of the plurality of heat conducting elements are in the form of a porous structure having a predetermined porosity and are at least partially submerged in the first PCM. 
     
     
         17 . The thermal storage system according to  claim 16 , wherein the porous structure is an open cell porous structure. 
     
     
         18 . The thermal storage system according to  claim 16 , wherein a volumetric porosity of the porous structure is between 75% and 98%. 
     
     
         19 . The thermal storage system according to  claim 16 , wherein the porous structure is a metal foam. 
     
     
         20 . The thermal storage system according to  claim 19 , wherein the metal foam has a surface-to-volume ratio (SVR) between 300 m 2 /m 3  and 1500 m 2 /m 3 . 
     
     
         21 . The thermal storage system according to  claim 19 , wherein the metal foam has an average cell diameter of less than 10 mm. 
     
     
         22 . The thermal storage system according to  claim 1 , wherein at least one of the first HS unit and the FT unit has a substantially beam like shape with a height being significantly smaller than a width and a length. 
     
     
         23 . The thermal storage system according to  claim 22 , wherein at least one of the first HS unit and the FT units have a height between 1 mm and 40 mm. 
     
     
         24 . The thermal storage system according to  claim 4 , wherein the FT unit comprises an extruded profile comprising the passageway for the heat transferring fluid. 
     
     
         25 . The thermal storage system according to  claim 4 , wherein the thermal storage module comprises an extruded profile comprising the passageway for the heat transferring fluid. 
     
     
         26 . The thermal storage system according to  claim 4 , wherein the thermal storage system comprises a second FT unit connected to the first FT unit via the inlet and outlet port ports. 
     
     
         27 . The thermal storage system according to  claim 26 , further comprising a second thermal storage module comprising a second inlet port and a second outlet port, and a connecting element on the thermal storage module configured form at least part of a connection between the inlet port and the second inlet port. 
     
     
         28 . The thermal storage system according to  claim 26 , wherein the thermal storage system has an L-shape or a U-shape. 
     
     
         29 . A method for charging the first PCM of the thermal storage system according to  claim 1 , the method comprising the steps of:
 a) providing a heat transfer fluid system, such as a chiller or a boiler;   b) connecting the heat transfer fluid system to the inlet and outlet ports of the thermal storage system to form a closed circuit for the heat transfer fluid;   c) operating the heat transfer fluid system such that the heat transfer fluid is supplied to the passageway of the FT unit via the inlet port of the FT unit;   d) operating the heat transfer fluid system such that the heat transfer fluid supplied in step c) is released from the passageways of the FT unit via the outlet port of the FT unit;   e) charging of the first PCM for a time period during which the PCM at least partially changes phase; and   f) removing at least some of the heat transfer fluid from the passageway of the FT unit before, during or after disconnecting the thermal storage system from the heat transfer fluid system.   
     
     
         30 . The method for charging the first PCM according to  claim 29 , wherein the heat transfer fluid system comprises a hydraulic circuit configured to circulate the heat transfer fluid through the FT unit of the thermal storage system. 
     
     
         31 . The method for charging the first PCM according to  claim 30 , wherein the hydraulic circuit comprises a pump. 
     
     
         32 . A temperature controlled container unit comprising:
 a thermally insulated payload space arranged for receiving temperature sensitive products; and   at least one thermal storage system according to  claim 1 , positioned in the thermally insulated payload space.   
     
     
         33 . The temperature controlled container unit according to  claim 32 , wherein the temperature controlled container unit is mobile.