Fluid control for a variable flow fluid circuit in an hvacr system

Abstract

A method of controlling an HVACR unit in an HVACR system including an HVACR unit through which a process fluid is pumped to meet a temperature control demand includes monitoring, by a controller, a flowrate of the process fluid through the HVACR unit. When the flowrate of the process fluid is above a minimum flowrate threshold, the process fluid is provided to one or more terminals in the HVACR system according to the temperature control demand. A bypass flow of the process fluid through a bypass line is disabled by changing a state of a valve fluidly connected to the bypass line and one of the one or more terminals to a flow disabled state. When the flowrate of the process fluid is below the minimum flowrate threshold, the controller enables the bypass flow of the process fluid through the bypass line.

What is claimed is: 
     
         1 . A method of controlling an HVACR unit in a heating, ventilation, air conditioning, and refrigeration (HVACR) system that includes an HVACR unit through which a process fluid can be pumped to meet a temperature control demand, comprising:
 monitoring, by a controller, a flowrate of the process fluid through the HVACR unit;   in response to the monitoring:
 when the flowrate of the process fluid is greater than a minimum flowrate threshold, providing the process fluid to one or more terminals in the HVACR system via the HVACR unit according to the temperature control demand, and disabling a bypass flow of the process fluid through a bypass line by changing a state of a valve fluidly connected to the bypass line and one of the one or more terminals to a flow disabled state; 
 when the flowrate of the process fluid is below the minimum flowrate threshold, enabling, by the controller, the bypass flow of the process fluid through the bypass line by changing the state of the valve fluidly connected to the bypass line and the one of the one or more terminals to a flow enabled state. 
   
     
     
         2 . The method of  claim 1 , wherein monitoring the flowrate of the process fluid through the HVACR unit includes monitoring at least one of a flow sensor and a differential pressure sensor. 
     
     
         3 . The method of  claim 1 , wherein the HVACR system includes a second HVACR unit through which the process fluid can be pumped to meet the temperature control demand, the method further comprising, monitoring a second flowrate of the process fluid through the second HVACR unit. 
     
     
         4 . The method of  claim 3 , wherein monitoring the second flowrate of the process fluid includes monitoring at least one of a flow sensor and a plurality of differential pressure sensors, each of the plurality of differential pressure sensors corresponding to the first and second HVACR units. 
     
     
         5 . The method of  claim 3 , wherein the flowrate and the second flowrate are the same. 
     
     
         6 . The method of  claim 3 , wherein enabling, by the controller, the bypass flow of the process fluid through the bypass line by changing the state of the valve fluidly connected to the bypass line and the one of the one or more terminals to a flow enabled state is in response to the flowrate being below the minimum flowrate threshold or in response to the second flowrate being below the minimum flowrate threshold. 
     
     
         7 . The method of  claim 6 , wherein the minimum flowrate threshold includes a first minimum flowrate threshold for the HVACR unit and a second minimum flowrate threshold for the second HVACR unit that is different from the first minimum flowrate threshold, enabling, by the controller, the bypass flow of the process fluid through the bypass line by changing the state of the valve fluidly connected to the bypass line and the one of the one or more terminals to a flow enabled state is in response to the flowrate being lower than the first minimum flowrate threshold or the second minimum flowrate threshold, or enabling, by the controller, the bypass flow of the process fluid through the bypass line by changing the state of the valve fluidly connected to the bypass line and the one of the one or more terminals to a flow enabled state is in response to the second flowrate being lower than the first minimum flowrate threshold or the second minimum flowrate threshold. 
     
     
         8 . The method of  claim 1 , wherein the HVACR system includes a plurality of terminals, and enabling, by the controller, the bypass flow of the process fluid through the bypass line by changing the state of the valve fluidly connected to the bypass line and the one of the one or more terminals to a flow enabled state includes changing the state of a plurality of valves fluidly connected to the plurality of terminals and a plurality of bypass lines. 
     
     
         9 . The method of  claim 1 , wherein the valve is a three-way valve. 
     
     
         10 . A fluid circuit for a heating, ventilation, air conditioning, and refrigeration (HVACR) system, comprising:
 an HVACR unit;   a variable flowrate pump;   a plurality of terminals;   at least one of the plurality of terminals including a bypass line, wherein a portion of a fluid in the fluid circuit flowing through the bypass line bypasses the at least one of the plurality of terminals;   the at least one of the plurality of terminals including the bypass line having a valve fluidly connected to the at least one of the plurality of terminals and fluidly connected to the bypass line, wherein a flow control state of the fluid through the bypass line is selectively controlled to maintain a minimum flowrate of the process fluid through the HVACR unit; and   a controller configured to monitor a flowrate of the process fluid in the fluid circuit and to control the flow control state of the bypass line.   
     
     
         11 . The fluid circuit of  claim 10 , wherein a plurality of the plurality of terminals each include the bypass line, each bypass line having the valve fluidly connected to a respective terminal. 
     
     
         12 . The fluid circuit of  claim 10 , wherein the valve is a three-way valve including an inlet downstream of the terminal, an inlet from the bypass line, and an outlet, and a flow through the terminal is separately controllable from a flow through the bypass line. 
     
     
         13 . The fluid circuit of  claim 10 , wherein a flow through the bypass line is independently actuatable relative to a flow through the terminal. 
     
     
         14 . A fluid circuit for circulating a process fluid in a heating, ventilation, air conditioning, and refrigeration (HVACR) system, comprising:
 a plurality of HVACR units, including:
 a first HVACR unit having a first minimum flowrate threshold; and 
 a second HVACR unit having a second minimum flowrate threshold; 
   a first variable flowrate pump;   a second variable flowrate pump;   a plurality of terminals for providing temperature control to a conditioned space within the HVACR system,   at least one of the plurality of terminals including a bypass line, wherein a portion of the process fluid in the fluid circuit flowing through the bypass line bypasses the at least one of the plurality of terminals;   the at least one of the plurality of terminals including the bypass line having a valve fluidly connected to the at least one of the plurality of terminals and fluidly connected to the bypass line, wherein a flow control state of the fluid through the bypass line is selectively controlled to maintain a minimum flowrate of the process fluid through the first HVACR unit and the second HVACR unit; and   a controller configured to monitor a flowrate of the process fluid in the fluid circuit and to control the flow control state of the bypass line.   
     
     
         15 . The fluid circuit of  claim 14 , wherein a second of the plurality of terminals includes a second bypass line. 
     
     
         16 . The fluid circuit of  claim 14 , wherein the valve is defaulted into a state in which flow through the bypass line is disabled. 
     
     
         17 . The fluid circuit of  claim 14 , wherein the controller is configured to selectively enable flow through the bypass line by changing the valve to a flow enabled state in which flow through the bypass line is enabled in response to the flowrate as monitored being below a minimum flowrate threshold. 
     
     
         18 . The fluid circuit of  claim 17 , wherein the minimum flowrate threshold is a relatively lower of the first minimum flowrate threshold and the second minimum flowrate threshold.