Distributed Climate-Control Systems and Methods with Distributed Protection against Refrigerant Loss

Abstract

Distributed Climate-Control Systems and Methods with Distributed Protection against Refrigerant Loss: the system includes a central condenser unit in combination with a distributed network of air handling units. Each air handler includes an evaporator, in which condensed refrigerant can undergo a phase change while absorbing heat of vaporization, plus a heat exchanger (e.g. a coil) which permits the heat absorption of the evaporator to be coupled to a forced airflow. Preferably the evaporator includes a metering device to provide variable refrigerant flow, and hence variable rates of heat transfer. The individual evaporators also include a sensor to detect ambient levels of the refrigerant, electrically operable cutoff valves which permit the evaporator to be isolated from both the liquid-phase and the gas-phase refrigerant flows. Local control logic is preferably connected to shut the cutoff valves whenever an ambient refrigerant concentration is found to exceed a tolerable level.

1 . A multi-location climate control system comprising:
 a condenser, which receives evaporated refrigerant from a refrigerant return connection, and condenses the evaporated refrigerant to a liquid flow of condensed refrigerant which is supplied to a refrigerant supply connection; and   multiple air handler units in multiple locations, individually including
 an evaporator which is connected, through respective cutoff valves, to be supplied with condensed refrigerant and to discharge evaporated refrigerant, and 
 a heat exchanger which thermally couples the heat absorption of the evaporator to a forced airflow path, and 
 a refrigerant leak sensor which detects escaped refrigerant in the ambient air, and which is local to that air handler unit; and wherein the cutoff valves are also local to the same air handler unit; and 
   control logic which, under at least some circumstances, automatically activates the cutoff valve to cut off flow of condensed refrigerant into the respective evaporator, in dependence on the output of the leak sensor.   
     
     
         2 . The system of  claim 1 , wherein each of the cutoff valves is integrated with a respective solenoid. 
     
     
         3 . The system of  claim 1 , wherein each of the cutoff valves is an EEV. 
     
     
         4 . The system of  claim 1 , wherein each of the cutoff valves is an LEV. 
     
     
         5 . The system of  claim 1 , wherein at least two respective cutoff valves are connected to each evaporator, and are local to the same air handler unit which contains that evaporator. 
     
     
         6 . The system of  claim 1 , wherein at least some ones of the evaporators are reversibly operable as heat recovery units, and wherein the condenser is also a reversible heat recovery unit. 
     
     
         7 . The system of  claim 1 , wherein the refrigerant is a halocarbon. 
     
     
         8 . The system of  claim 1 , wherein the refrigerant is flammable. 
     
     
         9 . The system of  claim 1 , wherein individual ones of the air handlers further comprise a respective metering device which regulates flow of refrigerant through the respective evaporator in that same air handler, and wherein the metering device is operable to cut off refrigerant flow on one side of the evaporator. 
     
     
         10 . The system of  claim 1 , wherein the metering device is not one of the two cutoff valves. 
     
     
         11 . The system of  claim 1 , wherein the minimum value for the ambient refrigerant concentration is zero, and the control logic automatically shuts the cutoff valves whenever a nonzero value of ambient refrigerant concentration is detected. 
     
     
         12 . The system of  claim 1 , wherein the heat exchanger is a coil. 
     
     
         13 . The system of  claim 1 , wherein the control logic is local to each location which contains a respective one of the evaporators. 
     
     
         14 - 26 . (canceled) 
     
     
         27 . An air handler module, comprising:
 an evaporator, having
 a metering device which regulates flow of refrigerant through the evaporator, 
 first and second refrigerant connections which connect the evaporator to receive a liquid flow of condensed refrigerant from a refrigerant supply connection and to supply evaporated refrigerant to a refrigerant return connection, 
 one or more cutoff valves within the air handler module which, when activated, cut off the flow of refrigerant through the evaporator, and 
 a heat exchanger which thermally couples the heat absorption of the evaporator to a forced airflow path; 
   a refrigerant leak sensor which detects escaped refrigerant in the ambient air; and   control logic which, when the refrigerant leak sensor detects an ambient refrigerant concentration above a minimum, automatically shuts the cutoff valves.   
     
     
         28 . The module of  claim 27 , wherein the minimum value for the ambient refrigerant concentration is zero, and the control logic automatically shuts the cutoff valves whenever a nonzero value of ambient refrigerant concentration is detected. 
     
     
         29 . The module of  claim 27 , wherein the heat exchanger is a coil. 
     
     
         30 . The module of  claim 27 , wherein the control logic is local to each location which contains a respective one of the evaporators. 
     
     
         31 . The module of  claim 27 , wherein each of the cutoff valves is integrated with a respective solenoid. 
     
     
         32 . The module of  claim 27 , wherein each of the cutoff valves is an EEV. 
     
     
         33 - 37 . (canceled) 
     
     
         38 . The module of  claim 27 , further comprising a respective metering device within the air handler module which regulates flow of refrigerant through that evaporator, and wherein the metering device is operable to cut off refrigerant flow on one side of the evaporator. 
     
     
         39 - 71 . (canceled)