Thermal energy unit for quasi-autonomous climate control

Abstract

A system includes: a housing; a hot water tank arranged within the housing and configured to store a first volume of water; a cold water tank arranged within the housing and configured to store a second volume of water; an exterior heat exchanger arranged on the housing and defining a set of fluid channels extending vertically along an exterior wall of the housing; and an interior heat exchanger thermally coupled to an interior volume of a building. The system also includes a set of valves configured to: during daytime, route the first volume between the hot water tank and the exterior heat exchanger and route the second volume between the cold water tank and the interior heat exchanger; and, during nighttime, route the first volume between the hot water tank and the interior heat exchanger and route the second volume between the cold water tank and the exterior heat exchanger.

I claim: 
     
         1 . A thermal energy unit comprising:
 a housing;   a hot water tank:
 arranged within the housing; and 
 configured to store a first volume of water; 
   a cold water tank:
 arranged within the housing; and 
 configured to store a second volume of water; 
   an exterior heat exchanger:
 arranged on the housing; and 
 defining a set of fluid channels extending vertically along an exterior wall of the housing; 
   an interior heat exchanger:
 thermally coupled to an interior volume of a building; and 
   a set of valves:
 configured to selectively:
 during a daytime period:
 route the first volume of water between the hot water tank and the exterior heat exchanger; and 
 route the second volume of water between the cold water tank and the interior heat exchanger; and 
 
 during a nighttime period:
 route the first volume of water between the hot water tank and the interior heat exchanger; and 
 route the second volume of water between the cold water tank and the exterior heat exchanger. 
 
 
   
     
     
         2 . The thermal energy unit of  claim 1 , wherein the set of valves comprises:
 a first valve:
 arranged proximal a first top of the hot water tank; and 
 operable in:
 a first state to route the first volume of water from the first top of the hot water tank to the interior heat exchanger; and 
 a second state to route the first volume of water from the exterior heat exchanger to the first top of the hot water tank; 
 
   second valve:
 arranged proximal a first bottom of the hot water tank; and 
 operable in:
 a third state to route the first volume of water from the first bottom of the hot water tank to the exterior heat exchanger; and 
 a fourth state route the first volume of water from the interior heat exchanger to the first bottom of the hot water tank; 
 
   third valve:
 arranged proximal a second top of the cold water tank; and 
 operable in:
 a fifth state to route the second volume of water from the second top of the cold water tank to the exterior heat exchanger; and 
 a sixth state to route the second volume of water from the interior heat exchanger to the second top of the cold water tank; and 
 
   a fourth valve:
 arranged proximal a second bottom of the cold water tank; and 
 operable in:
 a seventh state to route the second volume of water from the second bottom of the cold water tank to the interior heat exchanger; and 
 an eighth state to route the second volume of water from the exterior heat exchanger to the second bottom of the cold water tank. 
 
   
     
     
         3 . The thermal energy unit of  claim 1 , further comprising:
 a first temperature sensor configured to output:
 a first signal representing a first cold tank temperature of the second volume of water within the cold water tank at a first time; and 
 a second signal representing a second cold tank temperature of the second volume of water within the cold water tank at a second time; 
   a second temperature sensor configured to output:
 a third signal representing a first indoor temperature of the interior volume of building at the first time; and 
 a fourth signal representing a second indoor temperature of the interior volume of building at the second time; and 
   a controller configured to:
 at the first time during the daytime period:
 access the first cold tank temperature from the first temperature sensor; 
 access the first indoor temperature from the second temperature sensor; 
 access a target indoor temperature; and 
 in response to the target indoor temperature exceeding the first indoor temperature and in response to the first indoor temperature exceeding the first cold tank temperature, trigger the set of valves route the second volume of water between the cold water tank and the interior heat exchanger; and 
 
 at the second time during the daytime period:
 access the second cold tank temperature from the first temperature sensor; 
 access the second indoor temperature from the second temperature sensor; and 
 in response to the second cold tank temperature exceeding the second indoor temperature, trigger the set of valves to disable flow of the second volume of water between the cold water tank and the interior heat exchanger. 
 
   
     
     
         4 . The thermal energy unit of  claim 1 , further comprising:
 a first temperature sensor configured to output a first signal representing a first cold tank temperature of the second volume of water within the cold water tank; and   a controller configured to:
 at a first time during the daytime period:
 receive a first request to cool the interior volume of the building to a target indoor temperature; and 
 in response to receiving the first request:
 access the first cold tank temperature from the first temperature sensor; and 
 in response to the target indoor temperature exceeding the first cold tank temperature, trigger the set of valves route the second volume of water between the cold water tank and the interior heat exchanger; and 
 
 
 at a second time during the daytime period:
 access a second request to terminate cooling the interior volume of the building; and 
 in response to receiving the second request, triggering the set of valves to disable flow of the second volume of water between the cold water tank and the interior heat exchanger. 
 
   
     
     
         5 . The thermal energy unit of  claim 4 :
 wherein the first temperature sensor is further configured to output a second signal representing a second cold tank temperature of the second volume of water within the cold water tank; and   wherein the controller is further configured to:
 at a third time subsequent the first time and prior to the second time:
 access the second cold tank temperature from the first temperature sensor; and 
 in response to the second cold tank temperature exceeding the target indoor temperature, trigger the set of valves to disable flow of the second volume of water between the cold water tank and the interior heat exchanger. 
 
   
     
     
         6 . The thermal energy unit of  claim 1 , further comprising:
 a heat pump configured to transfer thermal energy from the cold water tank to the hot water tank; and   a photovoltaic solar panel:
 arranged on the housing; and 
 configured to supply electrical energy to the heat pump. 
   
     
     
         7 . The thermal energy unit of  claim 1 , wherein the interior heat exchanger comprises a radiator arranged in the building. 
     
     
         8 . The thermal energy unit of  claim 1 , wherein the interior heat exchanger is arranged within a forced air heating, ventilation, and air conditioning system within the building. 
     
     
         9 . The thermal energy unit of  claim 1 , wherein the exterior heat exchanger:
 is configured to:
 during the daytime period, accumulate thermal energy from sunlight; and 
 during the nighttime period, radiate thermal energy into an outdoor environment; and 
   comprises a set of channels:
 fluidly coupled to the hot water tank and the cold water tank; and 
 configured exchange thermal energy with the exterior heat exchanger. 
   
     
     
         10 . A method comprising:
 during a daytime period:
 at a first time:
 accessing a first hot tank temperature of a first volume of water occupying a hot water tank; 
 accessing a first heat exchanger temperature of an exterior heat exchanger; and 
 in response to the first heat exchanger temperature exceeding the first hot tank temperature, triggering a set of valves to route the first volume of water between the hot water tank and the exterior heat exchanger; and 
 
 at a second time:
 triggering the set of valves to route a second volume of water between a cold water tank and an interior heat exchanger thermally coupled to an interior volume of a building; and 
 
   during a nighttime period:
 at a third time:
 triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger; and 
 
 at a fourth time:
 accessing a second cold tank temperature of the second volume of water in the cold water tank; 
 accessing a second heat exchanger temperature of the exterior heat exchanger; and 
 in response to the second cold tank temperature exceeding the second heat exchanger temperature, triggering the set of valves to route the second volume of water between the cold water tank and the exterior heat exchanger. 
 
   
     
     
         11 . The method of  claim 10 :
 wherein triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger comprises:
 accessing a first cold tank temperature of the second volume of water occupying the cold water tank; 
 accessing a first indoor temperature and a target indoor temperature; and 
 in response to the first indoor temperature exceeding the target indoor temperature and in response to the first indoor temperature exceeding the first cold tank temperature, triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger; and 
   wherein triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger comprises:
 accessing a second hot tank temperature of the first volume of water in the hot water tank; 
 accessing a second indoor temperature; and 
 in response to the target indoor temperature exceeding the second indoor temperature and in response to the second hot tank temperature exceeding the second indoor temperature, triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger. 
   
     
     
         12 . The method of  claim 10 , further comprising:
 during the daytime period:
 at a fifth time succeeding the first time:
 accessing a third hot tank temperature of the first volume of water in the hot water tank; 
 accessing a third heat exchanger temperature of the exterior heat exchanger; and 
 in response to the third hot tank temperature exceeding the third heat exchanger temperature, triggering the set of valves to disable flow of the first volume of water between the hot water tank and the exterior heat exchanger; and 
 
 at a sixth time succeeding the second time:
 accessing a third cold tank temperature of the second volume of water in the cold water tank; 
 accessing a first indoor temperature and a target indoor temperature; and 
 in response to the first indoor temperature falling below the target indoor temperature or in response to the second cold tank temperature exceeding the target indoor temperature, triggering the set of valves disable flow of the second volume of water from the cold water tank to the interior heat exchanger; and 
 
   during the nighttime period:
 at a seventh time succeeding the third time:
 accessing a fourth hot tank temperature; 
 accessing a second indoor temperature; and 
 in response to the target indoor temperature exceeding the fourth hot tank temperature or in response to the second indoor temperature exceeding the target indoor temperature, triggering the set of valves disable flow of the second volume of water between the hot water tank and the interior heat exchanger; and 
 
 at an eighth time succeeding the fourth time:
 accessing a fourth cold tank temperature of the second volume of water in the cold water tank; 
 accessing a fourth heat exchanger temperature of the exterior heat exchanger; and 
 in response to the fourth heat exchanger temperature exceeding the fourth cold tank temperature, triggering the set of valves to disable flow of the second volume of water between the cold water tank and the exterior heat exchanger. 
 
   
     
     
         13 . The method of  claim 10 :
 wherein triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger comprises:
 accessing a first signal representing a first request to cool the interior volume of the building; and 
 in response to receiving the first request, triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger; and 
   wherein triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger comprises:
 accessing a second signal representing a second request to heat the interior volume of the building; and 
 in response to receiving the second request, triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger. 
   
     
     
         14 . The method of  claim 10 , further comprising:
 during the daytime period:
 at a sixth time succeeding the second time:
 accessing a third signal representing a request to disable cooling of the interior volume of the building; and 
 in response to receiving the third signal, triggering the set of valves disable flow of the second volume of water from the cold water tank to the interior heat exchanger; and 
 
   during the nighttime period:
 at a seventh time succeeding the third time:
 accessing a fourth signal representing the request to disable heating of the interior volume of the building; and 
 in response to receiving the fourth signal, triggering the set of valves disable flow of the second volume of water between the hot water tank and the interior heat exchanger. 
 
   
     
     
         15 . The method of  claim 10 :
 further comprising:
 at the first time:
 accessing a first solar irradiance level from a pyranometer arranged on the exterior heat exchanger; 
 accessing a first ambient humidity level from a humidity sensor arranged proximal the exterior heat exchanger; and 
 based on the first solar irradiance level, the first ambient humidity, and the first heat exchanger temperature, calculating a first maximum water temperature of the first volume of water; and 
 
 at a fifth time succeeding the first time:
 accessing a second hot tank temperature of the first volume of water occupying the hot water tank; 
 accessing a second solar irradiance level from the pyranometer; 
 accessing a second ambient humidity level from the humidity sensor; 
 based on the second solar irradiance level, the second ambient humidity, and the second heat exchanger temperature, calculating a second maximum water temperature of the first volume of water; and 
 in response to the second maximum water temperature falling below the second hot tank temperature, triggering the set of valves disable flow of the first volume of water between the hot water tank and the exterior heat exchanger; and 
 
   wherein routing the first volume of water between the hot water tank and the exterior heat exchanger comprises:
 in response to the first maximum water temperature exceeding the first hot tank temperature, routing the first volume of water between the hot water tank and the exterior heat exchanger. 
   
     
     
         16 . The method of  claim 10 , further comprising:
 during the daytime period, charging an electrical battery via a photovoltaic solar panel; and   at a fifth time during the daytime period:
 accessing a third hot tank temperature of the first volume of water; 
 accessing a third cold tank temperature of the second volume of water; 
 in response to a temperature difference between the third hot tank temperature and the third cold tank temperature falling below a threshold difference, supplying electrical energy from the electrical battery to a heat pump to transfer thermal energy from the cold water tank to the hot water tank; and 
 in response to receiving a signal representing a request to cool the interior volume of the building, triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger. 
   
     
     
         17 . The method of  claim 10 , further comprising:
 accessing a series of historical indoor temperatures;   accessing a target indoor temperature;   based on the series of historical indoor temperatures, predicting an indoor temperature exceeding the target indoor temperature by temperature difference at a sixth time during the daytime period;   in response to the temperature difference exceeding a threshold difference:
 accessing a series of historical electricity demand levels; and 
 based on the series of historical electricity demand levels, predicting a period of low electricity demand at a fifth time preceding the sixth time; 
   at the fifth time, supplying electrical energy from an electrical grid to a heat pump to decrease a third cold tank temperature of the second volume of water within the cold water tank; and   at the sixth time, triggering the set of valves to route the second volume of water from the cold water tank to the interior heat exchanger.   
     
     
         18 . A method comprising:
 during a nighttime period:
 at a first time:
 accessing a first cold tank temperature of a first volume of water in a cold water tank; 
 accessing a first heat exchanger temperature of an exterior heat exchanger; and 
 in response to the first cold tank temperature exceeding the first heat exchanger temperature, triggering a set of valves to route the first volume of water between the cold water tank and the exterior heat exchanger; and 
 
 at a second time succeeding the first time:
 accessing a second cold tank temperature of the first volume of water in the cold water tank; 
 accessing a second heat exchanger temperature of the exterior heat exchanger; and 
 in response to the second heat exchanger temperature exceeding the second cold tank temperature, triggering the set of valves to disable flow of the first volume of water between the cold water tank and the exterior heat exchanger; and 
 
   during a daytime period:
 at a third time:
 accessing a first signal representing a first request to cool an interior volume of a building; and 
 in response to receiving the first request, triggering the set of valves to route the first volume of water between the cold water tank and an interior heat exchanger thermally coupled to the interior volume of the building; and 
 
 at a fourth time succeeding the third time:
 accessing a second signal representing a second request to maintain current temperature of the interior volume on the building; and 
 in response to receiving the second request, triggering the set of valves disable flow of the first volume of water from the cold water tank to the interior heat exchanger. 
 
   
     
     
         19 . The method of  claim 18 , further comprising:
 at a fifth time during the nighttime period:
 accessing a third cold tank temperature of the first volume of water in the cold water tank; and 
 in response to the first cold tank temperature exceeding the third cold tank temperature by over a threshold difference, maintaining a current state of the set of valves to continue routing the first volume of water between the cold water tank and the exterior heat exchanger. 
   
     
     
         20 . The method of  claim 18 , further comprising:
 during the daytime period:
 charging an electrical battery via a photovoltaic solar panel; 
 accessing a set of weather data from a weather station; and 
 based on the set of weather data, predicting a cooling event for cooling the interior volume of the building at a fifth time during the daytime period; 
   at a sixth time preceding the fifth time during the daytime period, supplying electrical energy from the electrical battery to a heat pump to transfer thermal energy from the cold water tank to a hot water tank; and   at the fifth time during the daytime period, triggering the set of valves to route the first volume of water between the cold water tank and the interior heat exchanger.