Combined heating and cooling systems

Abstract

We describe a combined heating and cooling system, the system comprising: a working fluid circuit comprising a compressor, a gas cooler and an evaporator; a heating circuit, thermally coupled to said working fluid circuit via said gas cooler; and a cooling circuit, thermally coupled to said working fluid circuit via said evaporator; wherein said heating circuit further comprises a thermal storage tank, in particular a stratified thermal storage tank, controllably coupled to said heating circuit to controllably store heat for said heating circuit.

I claim: 
     
         1 . A combined heating and cooling system, the system comprising:
 a working fluid circuit comprising a compressor, a gas cooler and an evaporator;   a heating circuit, thermally coupled to said working fluid circuit via said gas cooler; and   a cooling circuit, thermally coupled to said working fluid circuit via said evaporator;   wherein said heating circuit further comprises a thermal storage tank, in particular a stratified thermal storage tank, controllably coupled to said heating circuit to controllably store heat for said heating circuit.   
     
     
         2 . A combined heating and cooling system as claimed in  claim 1  wherein said heating circuit further comprises a thermal dump controllably coupled to said heating circuit to controllably dump heat from said heating circuit. 
     
     
         3 . A combined heating and cooling system as claimed in  claim 1  wherein said stratified thermal storage tank comprises a set of heat storage temperature sensors at different stratified levels within the tank, the combined heating and cooling system further comprising a heating side control system responsive to said storage temperature sensors to control storage of heat in said thermal storage tank and dumping of heat from said heating circuit. 
     
     
         4 . A combined heating and cooling system as claimed in  claim 3  wherein said heating side control system is configured to control said compressor to maintain thermal energy stored in said stratified thermal storage tank within a target range. 
     
     
         5 . A combined heating and cooling system as claimed in  claim 4  further comprising at least one coolth storage temperature sensor, and wherein said heating side control system is configured to control said compressor responsive to said at least one coolth storage temperature sensor to maintain coolth stored in said cooling circuit within a range. 
     
     
         6 . A combined heating and cooling system as claimed in  claim 1  wherein said cooling circuit further comprises a controllable coolth dump to controllably dump coolth from said cooling circuit. 
     
     
         7 . A combined heating and cooling system as claimed in  claim 6  further comprising a cooling side control system to control said controllable coolth dump responsive to a sensed temperature of coolant within said cooling circuit to control a heat input to said evaporator provided by said coolant. 
     
     
         8 . A combined heating and cooling system as claimed in  claim 6  wherein said cooling circuit has a coolth output and is controllably reconfigurable between a parallel mode in which said controllable coolth dump is coupled in parallel with said coolth output and a series mode in which said controllable coolth dump is coupled in series with said coolth output. 
     
     
         9 . A combined heating and cooling system as claimed in  claim 8  further comprising a cooling side control system to control said controllable coolth dump responsive to a sensed temperature of coolant within said cooling circuit to control a heat input to said evaporator provided by said coolant, and wherein said cooling side control system is configured to control said cooling circuit between said series mode and said parallel mode dependent upon an ambient temperature of said controllable coolth dump. 
     
     
         10 . A combined heating and cooling system as claimed in  claim 1  further comprising a solar thermal energy capture system coupled to said stratified thermal storage tank; and/or wherein said working fluid comprises carbon dioxide. 
     
     
         11 . A method of controlling a combined heating and cooling system as claimed in  claim 1 , the method comprising:
 determining one or both of a stored heat in said heating circuit and a stored coolth in said cooling circuit; and   controlling one or both of said compressor and said coupling of said stratified thermal storage tank to said heating circuit responsive to said determination of stored heat/coolth to maintain one or both of said stored heat and said stored coolth in a steady state, more particularly within a respective target range.   
     
     
         12 . A method of controlling a combined heating and cooling system as claimed in  claim 1 , the method comprising:
 determining a temperature of coolant circulating in said cooling circuit; and   controlling dumping of coolth from said cooling circuit responsive to said coolant temperature to control a heat input to said evaporator provided by said coolant.   
     
     
         13 . A carbon dioxide-based combined heating and cooling system, the system comprising:
 a working fluid circuit comprising a compressor, a gas cooler and an evaporator;   a heating circuit, thermally coupled to said working fluid circuit via said gas cooler and having heat output; and   a cooling circuit, thermally coupled to said working fluid circuit via said evaporator and having a coolth output; and   a first control system to control said working fluid circuit responsive to one or both of heat stored in said heating circuit and coolth stored in said cooling circuit to partly satisfy heat and coolth demands from respective said heat and coolth outputs with stored heat and/or coolth.   
     
     
         14 . A carbon dioxide-based combined heating and cooling system as claimed in  claim 13  further comprising a second control system to control said cooling side circuit to control temperature of coolant in said cooling side circuit flowing into said evaporator to control an efficiency of said working fluid circuit. 
     
     
         15 . A carbon dioxide-based combined heating and cooling system as claimed in  claim 14  wherein said second control system is configured to control said coolant temperature up towards a target temperature. 
     
     
         16 . A carbon dioxide-based combined heating and cooling system as claimed in  claim 15  wherein said second control system is further configured to control said coolant temperature down towards said target temperature to achieve a target cooling effect. 
     
     
         17 . A carbon dioxide-based combined heating and cooling system as claimed in  claim 15  wherein said second control system is further configured to control a controllable coolth dump in said cooling circuit to control said coolant temperature. 
     
     
         18 . A carbon dioxide-based combined heating and cooling system as claimed in  claim 17  wherein said second control system is further configured to control said cooling circuit to selectively couple said coolth dump in series and in parallel with said coolth output responsive to a sensed ambient temperature. 
     
     
         19 . A carbon dioxide-based combined heating and cooling system in as claimed  claim 13  further comprising one or both of a stored heat gauge and a stored coolth gauge, wherein said stored heat gauge and a stored coolth gauge are configured to determine stored heat and stored coolth dependent upon one or more sensed temperatures in said heating circuit and said cooling circuit respectively, and where said first control system is responsive to said stored heat gauge and/or said stored coolth gauge to satisfy said heat and coolth demands. 
     
     
         20 . A carbon dioxide-based combined heating and cooling system as claimed in  claim 13  wherein said heating circuit further comprises a controllable heat dump and wherein said second control system is configured to control said heat dump to control said stored heat to within a target range, to control a combined heating and cooling effectiveness of said heating and cooling system. 
     
     
         21 . A method of controlling a carbon dioxide-based combined heating and cooling system, the combined heating and cooling system comprising a heating circuit and a cooling circuit each coupled to a shared carbon dioxide-based working fluid circuit, the combined heating and cooling system further comprising first and second heat exchangers to dump, respectively, heat and coolth from the working fluid of the system, the method comprising controlling the system in accordance with the following table: 
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                   Greater work 
                   Dump heat from the 
                   Dump coolth from 
                 
                     
                   heating or cooling 
                   working fluid 
                   the working fluid 
                 
                     
                     
                 
                     
                   Heating 
                   No 
                   Yes 
                 
                     
                   Cooling 
                   Yes 
                   No 
                 
                     
                     
                 
             
                
                
                
                
               
               
                
                
                
               
            
           
         
       
     
     
         22 . A method as claimed in  claim 21  further comprising controlling said coolth dumping responsive to a sensed temperature of said working fluid circuit. 
     
     
         23 . A method as claimed in  claim 21  further comprising controlling a rate of said coolth dumping by controlling a rate of operation of said second heat exchanger. 
     
     
         24 . A method as claimed in  claim 21  wherein said working fluid circuit comprises a compressor, a gas cooler and an evaporator, the method further comprising controlling said compressor responsive to one or both of a measure of stored heat and a measure of stored coolth in said system. 
     
     
         25 . A method as claimed in  claim 21  further comprising controlling dumping of heat from the working fluid of the system responsive to one or both of a measure of stored heat and a measure of stored coolth in said system 
     
     
         26 . A method as claimed in  claim 21  further comprising selectively coupling said first heat exchanger into said cooling circuit in parallel or in series dependent upon an ambient temperature of said first heat exchanger. 
     
     
         27 . A method as claimed in  claim 21 , used for providing combined heating and cooling for commercial premises, the method comprising:
 providing a combined heating and cooling system comprising a heating circuit and a cooling circuit each coupled to a shared carbon dioxide-based working fluid circuit, the combined heating and cooling system further comprising first and second heat exchangers to dump, respectively, heat and coolth from the working fluid of the system;   using said heating circuit to heat the commercial premises;   
       using said cooling circuit to cool a merchandising refrigerator in the commercial premises; and
 controlling said carbon dioxide-based combined heating and cooling system using the method of  claim 21 .