HVAC Hydronic System with Split Buffer Tank for Zero-Mixing System Operation

Abstract

The present invention relates to HVAC-systems operating under new ZERO-MIXING (ZM) water flow condition as innovative way to promote consistent highly energy efficient performance on SOURCE-heating/cooling thermal production and BUILDING's system distribution (FIG. 1 ). ZM technology is applicable; but not limited, to large-residential, commercial, institutional, and industrial facilities. Current state on HVAC technology, for system hydronics loop-flow, do not provide flows temperature segregation mechanisms between heating/chiller-plants hot/cold water supply and warmer water system returns. The result, a system that continuously operates at WATER MIXING conditions that impair equipment efficiency and output, and therefore, overall system energy performance.

1 . A hydronic HVAC system comprising:
 a heating/cooling source (B 1 -B 2 /CH) for heating or cooling a working fluid;   a buffer for holding a thermal mass warmed or cooled by said heating/cooling source;   a primary fluid loop and a primary pumping system (P 1 , P 2 ) installed therein in a manner operable to pump a working fluid through the heating/cooling source from a return outlet of the buffer to a supply inlet of the buffer;   a secondary fluid loop and a secondary pumping system (P 3 ) installed therein in a manner operable to pump the working fluid from a supply outlet of the buffer to at least one heating/cooling unit (FC 1 , FC 2 , FC 3 , HP, MUA, DHW) that uses the working fluid for heating/cooling purposes, said secondary fluid loop comprising at least one return line through which the working fluid is returnable from at least one heat/cooling unit to a return inlet of the buffer;   at least one control valve (CV 1 , CV 2 , CV 3 ) installed in said at least one return line, said at least one control valve being settable into a plurality of different operating states, including at least a recirculation state operable to recirculate said working fluid back through said secondary fluid loop, and a bypass state operable to return said working fluid to the return inlet of the buffer; and   a control system configured to perform monitoring of temperature conditions of the working fluid and controlled operation of the at least one control valve between the recirculation state and the bypass state depending on said temperature conditions of the working fluid.   
     
     
         2 . The system of  claim 1  wherein said monitoring of the temperature conditions and controlled operation of the at least one control valve comprises:
 (a) monitoring a fluid return temperature (T sWR ) of the working fluid in said at least one return line; 
 (b) determiningwhether the fluid return temperature (T SWR ) fulfills a targeted minimum temperature differential (ΔT) relative to an output temperature setpoint (T sp ) of the heating/cooling source to achieve operating efficiency thereof in an optimal range; 
 (c) when the return temperature of the working fluid fulfills said targeted minimum temperature differential, set or maintain said at least one control valve in the bypass state; and 
 (d) when the return temperature of the working fluid does not fulfill said targeted minimum temperature differential, set or maintain said at least one control valve in the recirculation state. 
 
     
     
         3 . The system of  claim 2  wherein said heat/cooling source is a heating source (B 1 -B 2 ), step (b) comprises determining whether the fluid return temperature fulfills the targeted temperature differential by checking whether the fluid return temperature is less than a control valve setpoint value, step (c) comprises setting or maintaining said at least one control valve in the bypass state when the fluid return temperature is less than the control valve setpoint value, and step (d) comprises setting or maintaining said at least one control valve in the recirculation state when the fluid return temperature is greater than the control valve setpoint value. 
     
     
         4 . The system of  claim 2  wherein said heat/cooling source is a cooling source (CH), step (b) comprises determining whether the fluid return temperature fulfills the targeted temperature differential by checking whether the fluid return temperature is greater than a control valve setpoint value, step (c) comprises setting or maintaining said at least one control valve in the bypass state when the fluid return temperature is greater than the control valve setpoint value, and step (d) comprises setting or maintaining said at least one control valve in the recirculation state when the fluid return temperature is less than the control valve setpoint value. 
     
     
         5 . The system of any  claim 2  wherein the control system is configured to variably adjust the targeted minimum temperature differential. 
     
     
         6 . The system of  claim 5  wherein the control system is configured to variably adjust the targeted minimum temperature differential based at least partly on an outdoor temperature. 
     
     
         7 . The system of  claim 3  wherein the control system is configured to variably adjust the control valve setpoint value. 
     
     
         8 . The system of  claim 7  wherein the control system is configured to variably adjust the control valve setpoint value based at least partly on an outdoor temperature. 
     
     
         9 . The system  claim 1  wherein the secondary fluid loop comprises a plurality of fluid circuits through which the working fluid is respectively delivered to a plurality of different heating/cooling equipment types (HP, MUA, DHW), the at least one return line comprises a plurality of respective return lines each belonging to a respective one of the fluid circuits, the at least one control valve comprises a plurality of respective control valves (CV 1 /CV 1 ′, CV 2 , CV 3 ) each installed in a respective one of said plurality of return lines, and the control system is configured to monitor a respective fluid return temperature in each of said return lines, and to control the respective control valve of each return line based on the respective fluid return temperature in said return line. 
     
     
         10 . The system of  claim 9  wherein each respective control valve (CV 1 , CV 2 , CV 3 ), in the recirculation state thereof, is operable to recirculate the working fluid back through a same one of the fluid circuits in which said respective control valve is installed. 
     
     
         11 . The system of  claim 9  wherein at least one of the respective control valves (CV 1 ′), in the recirculation state thereof, is operable to recirculate the working fluid through a different one of the fluid circuits that that in which said respective control valve is installed. 
     
     
         12 . The system of  claim 11  wherein the heating/cooling source is a heating source (B 1 -B 2 ), and said at least one of the respective control valves is a first control valve (CV 1 ′) installed in the respective return line of a first fluid circuit whose respective fluid return temperature is greater than a second fluid circuit into which the first control valve is operable, in the recirculation state thereof, to recirculate the working fluid. 
     
     
         13 . A method of controlling hydronic heating or cooling, said method comprising:
 having a hydronic HVAC system comprising:
 a heating/cooling source (B 1 -B 2 /CH) for heating or cooling a working fluid; 
 a buffer for holding a thermal mass warmed or cooled by said heating/cooling source; 
 a primary fluid loop in which the heating/cooling source is fluidly connected between a supply inlet and a return outlet of the buffer to receive said working fluid from the return outlet and heat/cool said working fluid, before loading thereof into the buffer through the supply inlet; 
 a secondary fluid loop in which at least one heating/cooling unit (FC 1 , FC 2 , FC 3 , HP, MUA, DHW) is fluidly connected between a supply outlet and return inlet of the buffer to receive said working fluid from the supply outlet and use said working fluid to address a heating/cooling load, before returning said working fluid to the buffer through the return inlet; and 
   perform monitoring of temperature conditions of the working fluid and controlled operation of the at least one control valve between the recirculation state and the bypass state depending on said temperature conditions of the working fluid.   
     
     
         14 . The method of  claim 13  wherein said monitoring of the temperature conditions and controlled operation of the at least one control valve comprises:
 (a) monitoring a fluid return temperature (T SWR ) of the working fluid in said at least one return line; 
 (b) determining whether the fluid return temperature (T SWR ) fulfills a targeted minimum temperature differential (ΔT) relative to an output temperature setpoint (T sp ) of the heating/cooling source to achieve operating efficiency thereof in an optimal range; 
 (c) when the return temperature of the working fluid fulfills said targeted minimum temperature differential, set or maintain said at least one control valve in the bypass state; and 
 (d) when the return temperature of the working fluid does not fulfill said targeted minimum temperature differential, set or maintain said at least one control valve in the recirculation state. 
 
     
     
         15 . The method of  claim 14  wherein said heat/cooling source is a heating source (B 1 -B 2 ), step (b) comprises determining whether the fluid return temperature fulfills the targeted temperature differential by checking whether the fluid return temperature is less than a control valve setpoint value, step (c) comprises returning the working fluid to the return chamber of the split buffer when the fluid return temperature is less than the control valve setpoint value, and step (d) comprises recirculating the working fluid back through the secondary loop when the fluid return temperature is greater than the control valve setpoint value. 
     
     
         16 . The method of  claim 14  wherein said heat/cooling source is a cooling source (CH), step (b) comprises determining whether the value of the fluid return temperature fulfills the targeted temperature differential by checking whether the fluid return temperature is greater than a control valve setpoint value, step (c) comprises returning the working fluid to the return chamber of the split buffer when the fluid return temperature is greater than the control valve setpoint value, and step (d) comprises recirculating the working fluid back through the secondary loop when the fluid return temperature is less than the control valve setpoint value. 
     
     
         17 . The method of  claim 14  wherein comprising, over time, variably adjusting the targeted minimum temperature differential. 
     
     
         18 . The method of  claim 14  comprising, over time, variably adjusting the targeted minimum temperature differential based at least partly on an outdoor temperature. 
     
     
         19 . The method of  claim 15  comprising, over time, variably adjusting the control valve setpoint value. 
     
     
         20 . The method of  claim 19  comprising, over time, variably adjusting the control valve setpoint value based at least partly on an outdoor temperature.