Heat storage apparatus, air conditioning apparatus, and heat storage method

Abstract

A disclosure describes a heat storage apparatus to store heat generated by a heat generator via a medium includes: a first circuit closed to circulate the medium therethrough in a direction; a heat exchanger to exchange the heat; a heat storage tank including a phase change material to exchange heat with the medium; a first measurement unit to measure a temperature of the medium; a cooling unit to cool the medium when the temperature of the medium is higher than a predetermined target temperature and to set the temperature of the medium to be approximately equal to the target temperature; a count unit to count an elapsed time from when the phase change material exchanges heat with the medium and starts a phase change; and a determination unit to determine whether the phase change material is allowed to be supercooled or not based on the elapsed time.

What is claimed is: 
     
         1 . A heat storage apparatus, configured to store heat generated by a heat generator via a medium, comprising:
 a first circuit closed to circulate the medium therethrough in a direction;   a heat exchanger that is provided at a part of the first circuit and is configured to exchange the heat generated by the heat generator with the medium;   a heat storage tank that is provided downstream of the direction in which the medium circulates, with respect to the heat exchanger of the first circuit, and includes a phase change material to exchange heat with the medium storing the heat generated by the heat generator;   a first measurement unit configured to measure a temperature of the medium that passes from the heat exchanger to the heat storage tank;   a cooling unit, that is configured to cool the medium when the measured temperature of the medium is higher than a predetermined target temperature, and to set the temperature of the medium that passes from the heat exchanger to the heat storage tank to be approximately equal to the target temperature;   a count unit configured to count an elapsed time from when the phase change material exchanges heat with the medium and starts a phase change from a solid phase to a liquid phase; and   a determination unit configured to determine whether the phase change material is allowed to be supercooled or not based on the elapsed time.   
     
     
         2 . The heat storage apparatus according to  claim 1 , further comprising
 a storage unit configured to store a first time from a start of the phase change of the phase change material to an end of the phase change in a case where the phase change material exchanges heat with the medium having the target temperature, wherein   the determination unit is configured to compare the first time and the elapsed time with each other and to determine whether the phase change material is allowed to be supercooled or not.   
     
     
         3 . The heat storage apparatus according to  claim 1 , further comprising:
 a storage unit configured to store a first heat storage quantity of heat that can be stored from a start of the phase change of the phase change material to an end of the phase change in a case where the phase change material exchanges heat with the medium having the target temperature; and   an estimation unit configured to estimate an estimation value of a heat storage quantity of the heat stored from the start of the phase change of the phase change material, using the temperature of the medium measured by the first measurement unit and the elapsed time, wherein   the determination unit is configured to compare the first heat storage quantity and the estimation value of the heat storage quantity with each other and to determine whether the phase change material is allowed to be supercooled or not.   
     
     
         4 . The heat storage apparatus according to  claim 1 , further comprising
 a second measurement unit configured to measure a second temperature of the medium after the medium passes through the heat storage tank, wherein   the count unit is configured to count an elapsed time starting from a time point from which the second temperature stays constant.   
     
     
         5 . The heat storage apparatus according to  claim 1 , further comprising
 a heating unit configured to apply heat to the phase change material, wherein   the heating unit is configured to heat, when the determination unit determines that the phase change material is not allowed to be supercooled, one of the phase change material and the medium.   
     
     
         6 . The heat storage apparatus according to  claim 1 , wherein
 the cooling unit includes
 a radiator that is connected to the first circuit, and 
 a fan that is opposed to the radiator, and 
   the heat storage apparatus further comprises a first control unit configured to control a rotating speed of the fan.   
     
     
         7 . The heat storage apparatus according to  claim 1 , wherein
 the cooling unit includes
 a first bypass circuit that is connected to the first circuit at a first branch point and is configured to bypass the radiator, and 
 a first control valve configured to switch a flow path of the medium to one of the first circuit and the first bypass circuit at the first branch point, and 
   the heat storage apparatus further comprises a first control unit configured to control switching of the first control valve.   
     
     
         8 . The heat storage apparatus according to  claim 1 , wherein
 the heat generator includes at least one of a motor, an inverter, and a battery.   
     
     
         9 . An air conditioning apparatus, comprising:
 a heat storage apparatus configured to store heat generated by a heat generator via a medium, the heat storage apparatus including
 a first circuit closed to circulate the medium therethrough in a direction, 
 a heat exchanger that is provided at a part of the first circuit and is configured to exchange the heat generated by the heat generator with the medium, 
 a heat storage tank that is provided downstream of the direction in which the medium circulates, with respect to the heat exchanger of the first circuit, and includes a phase change material to exchange heat with the medium storing the heat generated by the heat generator, 
 a first measurement unit configured to measure a temperature of the medium that passes from the heat exchanger to the heat storage tank, 
 a cooling unit that is configured to cool the medium when the measured temperature of the medium is higher than a predetermined target temperature, and to set the temperature of the medium that passes from the heat exchanger to the heat storage tank to be approximately equal to the target temperature, 
 a count unit configured to count an elapsed time from when the phase change material exchanges heat with the medium and starts a phase change from a solid phase to a liquid phase, and 
 a determination unit configured to determine whether the phase change material is allowed to be supercooled, or not based on the elapsed time; 
   a nucleating device configured to nucleate the phase change material;   a second bypass circuit that is connected to the first circuit at a second branch point and is configured to bypass the heat storage tank;   a second control valve configured to switch a flow path of the medium to one of the first circuit and the second bypass circuit at the second branch point; and   a second control unit configured to control, when the determination unit determines that the phase change material is allowed to be supercooled, switching of the second control valve to switch the flow path of the medium to the second bypass circuit.   
     
     
         10 . A heat storage method for one of a heat storage apparatus and an air conditioning apparatus including
 a medium,   a first circuit closed to circulate the medium therethrough in a direction,
 a heat exchanger that is provided at a part of the first circuit and is configured to exchange heat generated by a heat generator with the medium, 
 a heat storage tank that is provided downstream of the direction in which the medium circulates, with respect to the heat exchanger of the first circuit, and includes a phase change material to exchange heat with the medium storing the heat generated by the heat generator, the heat storage method comprising: 
   circulating the medium;   measuring a temperature of the medium that passes from the heat exchanger to the heat storage tank;   cooling the medium when the measured temperature of the medium is higher than a predetermined target temperature, and setting the temperature of the medium that passes from the heat exchanger to the heat storage tank to be approximately equal to the target temperature;   counting an elapsed time from when the phase change material exchanges heat with the medium and starting a phase change from a solid phase to a liquid phase; and   determining, by a determination unit, whether the phase change material is allowed to be supercooled or not based on the elapsed time.   
     
     
         11 . The heat storage method according to  claim 10 , further comprising:
 storing a first time from a start of the phase change of the phase change material to an end of the phase change in a case where the phase change material exchanges heat with the medium having the target temperature; and   comparing the first time and the elapsed time with each other and determining whether the phase change material is allowed to be supercooled or not.   
     
     
         12 . The heat storage method according to  claim 10 , further comprising:
 storing a first heat storage quantity of heat that can be stored from a start of the phase change of the phase change material to an end of the phase change in a case where the phase change material exchanges heat with the medium having the target temperature;   estimating an estimation value of a heat storage quantity of the heat stored from the start of the phase change of the phase change material, using the measured temperature of the medium and the elapsed time; and   comparing the first heat storage quantity and the estimation value of the heat storage quantity with each other and determining whether the phase change material is allowed to be supercooled or not.   
     
     
         13 . The heat storage method according to  claim 10 , further comprising:
 measuring a second temperature of the medium after the medium passes through the heat storage tank; and   counting an elapsed time from a time point from which the second temperature stays constant.   
     
     
         14 . The heat storage method according to  claim 10 , further comprising
 heating one of the phase change material and the medium by a heating unit configured to apply heat to the phase change material, when it is determined that the phase change material is not allowed to be supercooled.   
     
     
         15 . The heat storage method according to  claim 10 , further comprising
 controlling a rotating speed of a fan that is opposed to a radiator connected to the first circuit.   
     
     
         16 . The heat storage method according to  claim 10 , further comprising
 control switching of a first control valve that is configured to switch a flow path of the medium to one of the first circuit and a first bypass circuit at a first branch point, the first bypass circuit being connected to the first circuit at the first branch point and being configured to bypass a radiator.