Air conditioning system and method with chiller and water

Abstract

Air conditioning systems and methods for cooling a space that include a chiller, a cooling coil, a heat sink, various water conduits, and a pump. Different modes of operation are used under different conditions and the water is routed differently in different modes. In a first mode, the chiller rejects heat to water returning from the cooling coil, and in a second mode, there are separate loops of chilled and heated water with separate pumps. In a third (economizer) mode of operation, the chiller is off and water from the heat sink is delivered to the cooling coil. Control valves, check valves, or both, are used to direct the flow of water, which are strategically placed in various water conduits.

What is claimed is: 
     
         1 . An air conditioning system for cooling a space, the air conditioning system comprising:
 at least one chiller comprising an evaporator, a condenser, an evaporator inlet, an evaporator outlet, a condenser inlet, and a condenser outlet;   at least one cooling coil that cools air delivered to the space;   at least one heat sink that rejects heat to an environment outside the space;   a first water conduit that connects the evaporator outlet to the cooling coil;   a second water conduit that connects the cooling coil to the condenser inlet;   a third water conduit that connects the condenser outlet to the at least one heat sink;   a fourth water conduit that connects the at least one heat sink to the evaporator inlet;   at least one water pump that circulates water through the evaporator, the first water conduit, the cooling coil, the second water conduit, the condenser, the third water conduit, the at least one heat sink, and the fourth water conduit;   a further water conduit that connects the second water conduit to the fourth water conduit; and   an even further water conduit that connects the fourth water conduit to the second water conduit;   wherein the even further water conduit that connects the fourth water conduit to the second water conduit connects to the second water conduit between the further water conduit that connects the second water conduit to the fourth water conduit and the condenser inlet.   
     
     
         2 . The air conditioning system of  claim 1  further comprising:
 a fifth water conduit that connects the first water conduit to the second water conduit bypassing the cooling coil; 
 a first water valve that controls how much of the water passes through the fifth water conduit and that controls how much of the water passes through the cooling coil; 
 a sixth water conduit that connects the third water conduit to the fourth water conduit bypassing the at least one heat sink; and 
 a second water valve that controls how much of the water passes through the sixth water conduit and that controls how much of the water passes through the at least one heat sink. 
 
     
     
         3 . The air conditioning system of  claim 1  further comprising a water valve that controls whether the water passes through the further water conduit that connects the second water conduit to the fourth water conduit. 
     
     
         4 . The air conditioning system of  claim 1  further comprising a first check valve located in the further water conduit that connects the second water conduit to the fourth water conduit. 
     
     
         5 . The air conditioning system of  claim 1  further comprising a water valve that controls whether the water passes through the even further water conduit that connects the fourth water conduit to the second water conduit. 
     
     
         6 . The air conditioning system of  claim 1  further comprising a check valve located in the even further water conduit that connects the fourth water conduit to the second water conduit. 
     
     
         7 . The air conditioning system of  claim 1  wherein the further water conduit that connects the second water conduit to the fourth water conduit connects to the second water conduit between the cooling coil and the even further water conduit that connects the fourth water conduit to the second water conduit. 
     
     
         8 . The air conditioning system of  claim 7  wherein the further water conduit that connects the second water conduit to the fourth water conduit connects to the fourth water conduit between the even further water conduit that connects the fourth water conduit to the second water conduit and the evaporator inlet. 
     
     
         9 . The air conditioning system of  claim 8  wherein: the even further water conduit that connects the fourth water conduit to the second water conduit connects to the fourth water conduit between the at least one heat sink and the further water conduit that connects the second water conduit to the fourth water conduit. 
     
     
         10 . The air conditioning system of  claim 1  wherein the at least one water pump comprises a first water pump located in the third water conduit; and a second water pump located in the first water conduit. 
     
     
         11 . The air conditioning system of  claim 1  wherein:
 the at least one water pump comprises a first water pump and a second water pump; 
 the first water pump is a first variable-speed pump; 
 the second water pump is a second variable-speed pump; and 
 the system controls speed of the first water pump and the second water pump to control water flow through the at least one cooling coil and through the at least one heat sink. 
 
     
     
         12 . An air conditioning system for cooling a space, the air conditioning system comprising:
 at least one chiller comprising an evaporator, a condenser, an evaporator inlet, an evaporator outlet, a condenser inlet, and a condenser outlet;   at least one cooling coil that cools air delivered to the space;   at least one heat sink that rejects heat to an environment outside the space;   a first water conduit that connects the evaporator outlet to the cooling coil;   a second water conduit that connects the cooling coil to the condenser inlet;   a third water conduit that connects the condenser outlet to the at least one heat sink;   a fourth water conduit that connects the at least one heat sink to the evaporator inlet;   at least one water pump that circulates water through the evaporator, the first water conduit, the cooling coil, the second water conduit, the condenser, the third water conduit, the at least one heat sink, and the fourth water conduit;   a further water conduit that connects the second water conduit to the fourth water conduit; and   an even further water conduit that connects the fourth water conduit to the second water conduit;   wherein the even further water conduit that connects the fourth water conduit to the second water conduit connects to the fourth water conduit between the at least one heat sink and the further water conduit that connects the second water conduit to the fourth water conduit.   
     
     
         13 . The air conditioning system of  claim 12  further comprising:
 a fifth water conduit that connects the first water conduit to the second water conduit bypassing the cooling coil; 
 a first water valve that controls how much of the water passes through the fifth water conduit and that controls how much of the water passes through the cooling coil; 
 a sixth water conduit that connects the third water conduit to the fourth water conduit bypassing the at least one heat sink; and 
 a second water valve that controls how much of the water passes through the sixth water conduit and that controls how much of the water passes through the at least one heat sink. 
 
     
     
         14 . The air conditioning system of  claim 12  wherein the further water conduit that connects the second water conduit to the fourth water conduit connects to the second water conduit between the cooling coil and the even further water conduit that connects the fourth water conduit to the second water conduit. 
     
     
         15 . A method of cooling a space, the method comprising at least the acts of:
 in a first mode of operation:
 cooling chilled water in at least one chiller; 
 delivering at least a first portion of the chilled water from the at least one chiller to at least one cooling coil; 
 cooling supply air at the at least one cooling coil by transferring heat from the supply air to the at least the first portion of the chilled water with the at least one cooling coil; 
 delivering the supply air from the at least one cooling coil to the space; 
 delivering the at least the first portion of the chilled water from the at least one cooling coil to the at least one chiller; 
 rejecting heat from the at least one chiller to the chilled water from the at least one cooling coil to form heated water; 
 delivering the heated water from the at least one chiller to at least one heat sink; 
 rejecting heat from the heated water at the at least one heat sink to form the chilled water that is cooled in the at least one chiller; and 
 delivering the chilled water from the at least one heat sink to the at least one chiller; and 
   in a second mode of operation:
 cooling the chilled water in at least one chiller; 
 delivering the chilled water from the at least one chiller to the at least one cooling coil; 
 cooling the supply air at the at least one cooling coil by transferring heat from the supply air to the chilled water with the at least one cooling coil; 
 delivering the supply air from the at least one cooling coil to the space; and 
 delivering the chilled water from the at least one cooling coil to the at least one chiller; 
 wherein, in the second mode of operation, the cooling the chilled water in at least one chiller comprises cooling the chilled water delivered from the at least one cooling coil to the at least one chiller; and 
   transitioning from the first mode of operation to the second mode of operation or transitioning from the second mode of operation to the first mode of operation by: passing water through at least one check valve.   
     
     
         16 . The method of  claim 15  further comprising, in the second mode of operation:
 rejecting heat from the at least one chiller to heated water; 
 delivering the heated water from the at least one chiller to at least one heat sink; 
 rejecting heat from the heated water at the at least one heat sink; and 
 delivering the heated water from the at least one heat sink to the at least one chiller; 
 wherein, in the second mode of operation, the rejecting of the heat from the at least one chiller to the heated water comprises heating the heated water delivered from the at least one heat sink to the at least one chiller. 
 
     
     
         17 . The method of  claim 16  further comprising: operating a first water pump to circulate the chilled water; and operating a second water pump to circulate the heated water. 
     
     
         18 . The method of  claim 15  further comprising transitioning from the first mode of operation to the second mode of operation by operating at least one water control valve. 
     
     
         19 . The method of  claim 15  further comprising selecting between the first mode of operation and the second mode of operation based on outdoor ambient temperature. 
     
     
         20 . The method of  claim 15  further comprising, in a third mode of operation, without operating the at least one chiller:
 cooling the chilled water in the at least one heat sink; 
 delivering the chilled water from the at least one heat sink to the at least one cooling coil; 
 cooling the supply air at the at least one cooling coil by transferring heat from the supply air to the chilled water with the at least one cooling coil; 
 delivering the supply air from the at least one cooling coil to the space; and 
 delivering the chilled water from the at least one cooling coil to the at least one heat sink; 
 wherein, in the third mode of operation, the cooling the chilled water in the at least one heat sink comprises cooling the chilled water delivered from the at least one cooling coil to the at least one heat sink.