Process of Control of the Storage of Thermal Energy in the Ground and Associated System

Abstract

A process of control of a thermal energy storage unit in the ground includes heat exchangers buried in the ground, each of the exchangers allowing a calorific energy exchange between a heat-conveying fluid traversing it and the ground, the energy storage unit being at the interface between a source and consumer of calorific energy to store thermal energy. One measures the temperature in various points of the ground using buried temperature gauges, the temperatures and flow of a heat-conveying fluid in input and output of the source to determine the thermal power provided by the source, and temperatures and flow of a heat-conveying fluid in input and output of the consumer to determine the thermal power to provide the consumer. One optimizes the storage of thermal energy in the storage unit by selecting active exchangers among the plurality of exchangers according to temperature measurements, flow measurements and thermal power measurements.

1 . Process of control of a unit of thermal energy storage in the ground comprising a plurality of exchangers of heat buried in the ground, each one of the aforesaid exchangers allowing a calorific energy exchange between a heat-conveying fluid traversing it and the ground, the aforementioned energy storage unit being laid out at the interface between a source and a calorific consumer of energy to store thermal energy, characterized in that one measures the temperature in various points of the ground by means of buried temperature gauges, the temperatures and flow of a heat-conveying fluid in input and output of the source to determine the thermal power provided by the source, and temperatures and flow of a heat-conveying fluid in input and output of the consumer to determine the thermal power to provide to the consumer, and in that one optimizes the storage of thermal energy in the aforementioned storage unit by selecting active exchangers among the aforementioned plurality of exchangers according to temperature measurements, flow measurements and thermal power measurements. 
   
   
       2 . Process according to  claim 1 , characterized in that it comprises the stages consisting in:
 determining beforehand an optimal map of the temperatures in the ground;   determining an instantaneous map of the temperatures in the ground by the means of the aforesaid temperature measurements taken in various points of the ground;   selecting active exchangers among the aforementioned set of exchangers in function of the local variations of temperature between the aforementioned instantaneous map and the aforementioned optimal map, of the temperatures and flow of the heat-conveying fluid in input and output of the source, and the temperatures and flow of the heat-conveying fluid in input and output of the consumer, in order to drive the transition of the storage unit from the current state corresponding to the instantaneous map towards the state corresponding to the optimum map, the transition taking an path which is either arbitrary or imposed by a set of constraints.   
   
   
       3 . Process according to  claim 1 , characterized in that one moves of heat inside the storage unit by circulation of the heat-conveying fluid between a loop comprising at least one exchanger activated in extraction and a loop comprising at least one exchanger activated in injection. 
   
   
       4 . Process according to  claim 1 , characterized in that it comprises an additional stage consisting in:
 When the thermal power provided by the source is adapted to the thermal power used by the consumer, not activating any the exchangers and making circulate the heat-conveying fluid between a loop comprising the source and a loop comprising the consumer;   When the thermal power provided by the source is not usable by the consumer, making circulate the heat-conveying fluid between a loop comprising the source and a loop comprising some exchangers activated in injection, and making circulate simultaneously the heat-conveying fluid between a loop comprising the consumer and a loop comprising some exchangers activated in extraction;   When the thermal power provided by the source is higher than the thermal power used by the consumer, making circulate the heat-conveying fluid on the one hand in a loop comprising the source and on the other hand in a loop comprising the consumer and a loop comprising some exchangers activated in injection;   When the thermal power used by the consumer is null, totally injecting the thermal power provided by the source in the storage unit;   When the thermal power provided by the source is lower than the thermal power used by the consumer, making circulate the heat-conveying fluid on the one hand in a loop comprising the consumer and on the other hand in a loop comprising the source and a loop comprising some exchangers activated in extraction;   When the thermal power provided by the source is null, completely extracting the thermal power used by the consumer from the storage unit.   
   
   
       5 . Hydronic system of control of a unit of thermal energy storage in the ground comprising a plurality of exchangers of heat buried in the ground, each one of the aforesaid exchangers allowing a calorific energy exchange between a heat-conveying fluid traversing it and the ground, the aforementioned hydronic system being intended to be laid out between a calorific energy source, a consumer of calorific energy and the aforementioned storage unit, characterized in that it comprises:
 a plurality of temperature gauges buried in the ground;   flow and temperature gauges to measure a thermal power provided by the source and a thermal power used by the consumer;   means of regrouping to group the aforementioned exchangers in a plurality of elementary exchange units, an exchange unit comprising at least one exchanger; and,   means of activation to activate the aforementioned elementary exchange units selectively.   
   
   
       6 . System according to  claim 5 , characterized in that, an exchanger comprising a hot end and a cold end, the means of regrouping allow to form groups of exchangers, known as exchange unit, the various hot ends of the aforesaid exchangers of the same group being connected to a hot manifold and the cold ends of these same exchangers being connected to a cold manifold, various exchangers of the said group being in parallel from each other. 
   
   
       7 . System according to  claim 6 , characterized in that the aforementioned means of regrouping allow to form series of exchangers as an exchange unit, a series of exchangers (S) comprising a number (nS) of groups of exchangers (Gi), the cold collector of one of the aforesaid groups (Gi) of a series being connected to the hot manifold of the following group (Gi+1) of the aforesaid series, so that the aforementioned groups of the same series of exchangers are laid out in series between an initial group (G 1 ) and a final group (Gn). 
   
   
       8 . System according to  claim 7 , characterized in that the aforementioned means of regrouping comprise first and second switches, each switch having a principal canalization and secondary canalization, the hot manifold of a group of exchangers being connected to the said first switch via one of its secondary canalizations equipped with a gate valve, and the cold manifold of the said group being connected to the said second switch via one of its secondary canalizations equipped with a gate valve, so that the means of regrouping make it possible to select arbitrarily, at a given time and according to the position of the valves of the first and second switches, a first group of exchangers (Gp) and the last group of exchanger (Gq), to form between the latter a sub-series of exchangers (S′) used as an exchange unit. 
   
   
       9 . System according to  claim 5 , characterized in that the means of activation comprise means of activation in injection suited to form a hydraulic loop of injection comprising at least one exchange unit for the injection of energy, and of the means of activation in extraction suited to form a hydraulic loop of extraction comprising at least one exchange unit for the extraction of energy; in what the aforementioned means of activation in injection comprise an input branch of injection and an output branch of injection, each exchange unit being connected by its hot end to the said input branch of injection and by its cold end to the said output branch of injection to form a connection of injection between the input and output branches of injection, the various exchange units being then in parallel from each other between the aforementioned input and output branches of injection, each connection of injection thus defined being equipped with means of regulation of flow in injection, so that the flow circulating in the aforementioned connection of injection can be arbitrarily fixed during an injection, and in what the aforementioned means of activation in extraction comprise an input branch of extraction and an output branch of extraction, the aforementioned exchange units being respectively connected by their cold end to the said input branch of extraction and by their hot end to the said output branch of extraction, to form a connection of extraction between the input and output branches of extraction, various exchange units being then in parallel from each other between the aforementioned input and output branches of extraction, each connection of extraction thus defined being equipped with means of regulation of flow in extraction, so that the flow circulating in the aforementioned connection of extraction can be arbitrarily fixed during an extraction. 
   
   
       10 . System according to  claim 9 , characterized in that a differential pressure sensor is connected between the aforementioned input and output branches, in that a canalization supplying the input branch comprises a pump controlled in differential pressure according to the measure taken by the aforementioned sensor, so that the flow in any of the connections in parallel between the input and output branches can be controlled individually. 
   
   
       11 . System according to  claim 5 , characterized in that it is provided with means of pumping comprising the pumps suited to make circulate the heat-conveying fluid in a loop of injection comprising at least one exchange unit functioning in injection of energy and a loop of extraction comprising at least one exchange unit functioning in extraction of energy, and with means of connection allowing at least one connection among:
 the connection of a loop of circulation in the source with the loop of injection;   the connection of the loop of circulation in the consumer with the loop of extraction;   the connection of the loop of circulation in the source with the loop of injection, and simultaneously, the connection of the loop of circulation in the consumer with the loop of extraction;   the connection of the loop of extraction with the loop of injection;   the connection of the loop of circulation in the source with the loop of circulation in the consumer;   the connection of the loop of extraction with the loop of injection, and simultaneously, the connection of the loop of circulation in the source with the loop of circulation in the consumer.   
   
   
       12 . System according to  claim 11 , characterized in that the aforementioned means of connection allow moreover:
 the connection of a loop of circulation in the consumer with a loop of extraction and the loop of circulation in the source; and,   the connection of a loop of circulation in the source with a loop of injection and the loop of circulation in the consumer.   
   
   
       13 . System according to  claim 11 , characterized in that the aforementioned means of connection comprise:
 a first hydraulic separator, connected to an expansion tank forming the neutral point of the said hydraulic system, the aforementioned first hydraulic separator being connected to the aforementioned loop of extraction on the one hand and the aforementioned loop of circulation in the consumer on the other hand;   a first pair of gate valves whose state allows to connect the aforementioned loop of circulation in the source to the aforementioned first hydraulic separator;   a second pair of gate valves whose state allows to connect the loop of injection to the aforementioned first hydraulic separator.   
   
   
       14 . System according to  claim 13 , characterized in that the aforementioned means of connection comprise moreover:
 a second hydraulic separator connected to the said expansion tank forming the neutral point of the said hydraulic system;   a third pair of gate valves whose state allows, in relation with the state of the aforesaid the first pair of valves, to connect the aforementioned loop of circulation in the source to the aforementioned second hydraulic separator, the loop in extraction being connected to the aforementioned first hydraulic separator;   a fourth pair of gate valves whose state allows, in relation with the state of the second pair of valves, to connect the aforementioned loop of injection to the aforementioned second hydraulic separator, the loop of circulation in the consumer being connected to the aforementioned first hydraulic separator.   
   
   
       15 . System according to  claim 5 , characterized in that, the aforementioned means of activation, connection, and pumping being actionable automatically, the system comprises a calculating unit able to receive the signals of measure emitted by the various sensors and to emit a control signal towards the aforementioned means of activation, connection, and pumping, the aforementioned calculating unit executing the instructions of a program stored in means of memorizing of the aforesaid calculating unit to implement a process comprising steps of:
 measuring temperature in various points of the ground by means of buried temperature gauges, the temperatures and flow of a heat-conveying fluid in input and output of the source to determine the thermal power provided by the source, and temperatures and flow of a heat-conveying fluid in input and output of the consumer to determine the thermal power to provide to the consumer; and   optimizing the storage of thermal energy in the storage unit by selecting active exchangers among the plurality of exchangers according to temperature measurements, flow measurements and thermal power measurements.   
   
   
       16 . Storage system of calorific energy in the ground, characterized in that it comprises a hydronic system according to  claim 5  and one storage unit of energy comprising at least ten exchangers. 
   
   
       17 . Process according to  claim 2 , characterized in that one moves of heat inside the storage unit by circulation of the heat-conveying fluid between a loop comprising at least one exchanger activated in extraction and a loop comprising at least one exchanger activated in injection. 
   
   
       18 . Process according to  claim 2 , characterized in that it comprises an additional stage consisting in:
 When the thermal power provided by the source is adapted to the thermal power used by the consumer, not activating any the exchangers and making circulate the heat-conveying fluid between a loop comprising the source and a loop comprising the consumer;   When the thermal power provided by the source is not usable by the consumer, making circulate the heat-conveying fluid between a loop comprising the source and a loop comprising some exchangers activated in injection, and making circulate simultaneously the heat-conveying fluid between a loop comprising the consumer and a loop comprising some exchangers activated in extraction;   When the thermal power provided by the source is higher than the thermal power used by the consumer, making circulate the heat-conveying fluid on the one hand in a loop comprising the source and on the other hand in a loop comprising the consumer and a loop comprising some exchangers activated in injection;   When the thermal power used by the consumer is null, totally injecting the thermal power provided by the source in the storage unit;   When the thermal power provided by the source is lower than the thermal power used by the consumer, making circulate the heat-conveying fluid on the one hand in a loop comprising the consumer and on the other hand in a loop comprising the source and a loop comprising some exchangers activated in extraction;   When the thermal power provided by the source is null, completely extracting the thermal power used by the consumer from the storage unit.   
   
   
       19 . Process according to  claim 3 , characterized in that it comprises an additional stage consisting in:
 When the thermal power provided by the source is adapted to the thermal power used by the consumer, not activating any the exchangers and making circulate the heat-conveying fluid between a loop comprising the source and a loop comprising the consumer;   When the thermal power provided by the source is not usable by the consumer, making circulate the heat-conveying fluid between a loop comprising the source and a loop comprising some exchangers activated in injection, and making circulate simultaneously the heat-conveying fluid between a loop comprising the consumer and a loop comprising some exchangers activated in extraction;   When the thermal power provided by the source is higher than the thermal power used by the consumer, making circulate the heat-conveying fluid on the one hand in a loop comprising the source and on the other hand in a loop comprising the consumer and a loop comprising some exchangers activated in injection;   When the thermal power used by the consumer is null, totally injecting the thermal power provided by the source in the storage unit;   When the thermal power provided by the source is lower than the thermal power used by the consumer, making circulate the heat-conveying fluid on the one hand in a loop comprising the consumer and on the other hand in a loop comprising the source and a loop comprising some exchangers activated in extraction;   When the thermal power provided by the source is null, completely extracting the thermal power used by the consumer from the storage unit.   
   
   
       20 . System according to  claim 8 , characterized in that the means of activation comprise means of activation in injection suited to form a hydraulic loop of injection comprising at least one exchange unit for the injection of energy, and of the means of activation in extraction suited to form a hydraulic loop of extraction comprising at least one exchange unit for the extraction of energy; in what the aforementioned means of activation in injection comprise an input branch of injection and an output branch of injection, each exchange unit being connected by its hot end to the said input branch of injection and by its cold end to the said output branch of injection to form a connection of injection between the input and output branches of injection, the various exchange units being then in parallel from each other between the aforementioned input and output branches of injection, each connection of injection thus defined being equipped with means of regulation of flow in injection, so that the flow circulating in the aforementioned connection of injection can be arbitrarily fixed during an injection, and in what the aforementioned means of activation in extraction comprise an input branch of extraction and an output branch of extraction, the aforementioned exchange units being respectively connected by their cold end to the said input branch of extraction and by their hot end to the said output branch of extraction, to form a connection of extraction between the input and output branches of extraction, various exchange units being then in parallel from each other between the aforementioned input and output branches of extraction, each connection of extraction thus defined being equipped with means of regulation of flow in extraction, so that the flow circulating in the aforementioned connection of extraction can be arbitrarily fixed during an extraction.