Thermal energy recovery system for an ice making plant of an ice rink

Abstract

A thermal energy recovery system for an ice making plant of an ice rink includes a refrigeration unit for generating temperatures suitable for maintaining an ice surface that generates low grade heat as a by-product. A storage tank for storing a heat transfer fluid is provided. A refrigeration loop conveys heat transfer fluid containing low grade heat from the refrigeration unit to the storage tank. A thermal energy utilization loop provides fluid communication from the storage tank to a building HVAC system. There is at least one heat pump on the thermal energy utilization output conduit adapted to take heat transfer fluid containing low grade heat and convert the low grade heat into one of high grade heat or comfort cooling for use in the building HVAC system.

1 . A thermal energy recovery system for an ice making plant of an ice rink, comprising:
 a refrigeration unit for generating temperatures suitable for maintaining an ice surface and generating low grade heat as a by-product, the refrigeration unit having a fluid input and a fluid output;   a storage tank for storing a heat transfer fluid;   a refrigeration loop having a refrigeration output conduit connecting the fluid output of the refrigeration unit to the storage tank such that heat transfer fluid containing low grade heat from the refrigeration unit is conveyed to the storage tank, and a refrigeration input conduit connecting the fluid input of the refrigeration unit to the storage tank;   at least one circulation pump on the refrigeration loop adapted to circulate heat transfer fluid from the storage tank through the refrigeration unit;   a thermal energy utilization loop having a thermal energy utilization output conduit providing fluid communication from the storage tank to a building HVAC system, and a thermal energy utilization return conduit providing fluid communication from the building HVAC system back to the storage tank;   at least one circulation pump on the thermal energy utilization loop adapted to circulate heat transfer fluid containing low grade heat from the storage tank through the building HVAC system; and   at least one heat pump on the thermal energy utilization output conduit adapted to take heat transfer fluid containing low grade heat and convert the low grade heat into one of high grade heat or comfort cooling for use in the building HVAC system.   
   
   
       2 . The thermal energy recovery system of  claim 1 , further comprising at least one temperature sensor on the thermal energy utilization loop adapted to monitor a temperature of heat transfer fluid in the thermal energy utilization loop. 
   
   
       3 . The thermal energy recovery system of  claim 2 , further comprising an auxiliary heat source connected to the thermal energy utilization loop, and a controller in communication with the temperature sensor and the auxiliary heat source, the controller providing supplementary heat from the auxiliary heat source when the temperature in the thermal energy utilization output conduit, as indicated by the temperature sensor, falls below a predetermined temperature threshold. 
   
   
       4 . The thermal energy recovery system as defined in  claim 3 , further comprising an auxiliary cooling source connected to the thermal utilization loop, the auxiliary cooling source being in communication with the controller, the controller providing supplementary cooling from the auxiliary cooling source when the temperature indicated by the temperature sensor rises above a predetermined temperature threshold. 
   
   
       5 . The thermal energy recovery system as defined in  claim 3 , wherein the auxiliary heat source is connected to the thermal energy utilization output conduit and the thermal energy utilization return conduit, such that, when the auxiliary heat source is activated, the heat transfer fluid bypasses the storage tank. 
   
   
       6 . The thermal energy recovery system as defined in  claim 4 , wherein the auxiliary cooling source is connected to the thermal energy utilization return conduit and the refrigeration input conduit, such that, when the auxiliary cooling source is activated, the heat transfer fluid bypasses the storage tank. 
   
   
       7 . The thermal energy recovery system as defined in  claim 1 , wherein the at least one temperature sensor comprises a temperature sensor for determining the temperature at an input to the at least one heat pump, and at least one temperature sensor for determining the temperature in the storage tank. 
   
   
       8 . The thermal energy recovery system of  claim 1 , wherein at least one of a dehumidifier, an underfloor heater, and a snow melt pit is connected on the thermal energy utilization loop to the at least one heat pump. 
   
   
       9 . The thermal energy recovery system of  claim 1 , wherein the storage tank has a top and a bottom, the heat transfer fluid having a temperature gradient that decreases from the top of the tank to the bottom, the refrigeration output conduit and the thermal energy utilization output conduit being connected toward the top of the tank, and the refrigeration input conduit and the thermal energy utilization return conduit being connected toward the bottom of the tank. 
   
   
       10 . The thermal energy recovery system of  claim 1 , comprising one or more storage tanks. 
   
   
       11 . The thermal energy recovery system of  claim 1 , wherein the refrigeration unit comprises a chiller for removing heat from a refrigerant and a condenser for transferring the low grade heat to the heat transfer fluid. 
   
   
       12 . The thermal energy recovery system of  claim 11 , wherein the chiller receives warmed refrigerant from a cold floor to be cooled and returned to the cold floor. 
   
   
       13 . The thermal energy recovery system of  claim 1 , wherein the at least one heat pump has a heating mode and a cooling mode, such that in the heating mode the heat pump converts the low grade heat into high grade heat, and in the cooling mode the heat pump converts the low grade heat into comfort cooling. 
   
   
       14 . A thermal energy recovery system for an ice making plant of an ice rink, comprising:
 a refrigeration unit for generating temperatures suitable for maintaining an ice surface and generating low grade heat as a by-product, the refrigeration unit having a fluid input and a fluid output, the refrigeration unit comprising a chiller for removing heat from a secondary refrigerant and a condenser for transferring the low grade heat to a heat transfer fluid;   at least one storage tank for storing a heat transfer fluid;   a refrigeration loop having a refrigeration output conduit connecting the fluid output of the refrigeration unit to the storage tank such that heat transfer fluid containing low grade heat from the refrigeration unit is conveyed to the storage tank, and a refrigeration input conduit connecting the fluid input of the refrigeration unit to the storage tank;   at least one circulation pump on the refrigeration loop adapted to circulate heat transfer fluid from the storage tank through the refrigeration unit;   a thermal energy utilization loop having a thermal energy utilization output conduit providing fluid communication from the storage tank to a building HVAC system, and a thermal energy utilization return conduit providing fluid communication from the building HVAC system back to the storage tank;   at least one circulation pump on the thermal energy utilization loop adapted to circulate heat transfer fluid containing low grade heat from the storage tank through the building HVAC system;   at least one heat pump on the thermal energy utilization output conduit, the at least one heat pump having a heating mode and a cooling mode, in the heating mode the heat pump taking the heat transfer fluid and converting the low grade heat into high grade heat, and in the cooling mode the heat pump taking the heat transfer fluid and converting the low grade heat into comfort cooling;   at least one temperature sensor for determining the temperature of the heat transfer fluid at an input to the at least one heat pump, and at least one temperature sensor for determining the temperature of the heat transfer fluid in the storage tank;   an auxiliary heat source connected to the thermal energy utilization output conduit and the thermal energy utilization loop;   an auxiliary cooling source connected to the thermal energy utilization return conduit and the refrigeration loop; and   a controller in communication with the temperature sensors, the auxiliary heat source, and the auxiliary cooling source, the controller providing supplementary heat from the auxiliary heat source when the temperature in the thermal energy utilization output conduit, as indicated by the temperature sensors, falls below a predetermined temperature threshold, and the controller providing supplementary cooling from the auxiliary cooling source when the temperature indicated by the temperature sensors rises above a predetermined temperature threshold.   
   
   
       15 . A method of recovering thermal energy from an ice plant, the method comprising the steps of:
 circulating a heat transfer fluid through a refrigeration unit, the refrigeration unit transferring low grade heat to the heat transfer fluid;   conveying heat transfer fluid containing low grade heat from the refrigeration unit to the storage tank;   conveying heat transfer fluid containing low grade heat from the storage tank to a building HVAC system;   operating at least one heat pump to convert the low grade heat into one of high grade heat or comfort cooling for use in the building HVAC system; and   monitoring and controlling the temperature of the heat transfer fluid in the heat transfer utilization loop.   
   
   
       16 . The method of  claim 15 , further comprising the step of cooling the heat transfer fluid using an auxiliary cooling source when the temperature rises above a predetermined temperature.