Peak demand response operation with improved sensible capacity
An HVAC system includes a variable-speed compressor which compresses refrigerant flowing through the HVAC system, a blower which provides a flow of air through the HVAC system at a controllable flow rate, and a controller communicatively coupled to the variable-speed compressor and the blower. The controller receives a demand request which includes a command to reduce power consumption by the HVAC system. In response to receiving the demand request, a speed of the variable-speed compressor is decreased and the controllable flow rate of the flow of air provided by the blower is adjusted. Accordingly, a ratio of the first flow rate to the decreased tonnage of cooling is increased to a predefined value, and a power consumption of the HVAC system is decreased by at least a predefined percentage associated with the demand request.
1. A heating, ventilation, and air conditioning (HVAC) system comprising:
a variable-speed compressor configured to compress refrigerant flowing through the HVAC system;
a blower configured to provide a flow of air through the HVAC system at a controllable flow rate; and
a controller communicatively coupled to the variable-speed compressor and the blower, the controller configured to:
receive a demand request, the demand request comprising a command to reduce power consumption by the HVAC system by a predefined percentage;
in response to receipt of the demand request:
decrease a speed of the variable-speed compressor by at least the predefined percentage of the command to reduce power consumption, thereby operating the HVAC system at a decreased tonnage of cooling corresponding to the decreased speed of the variable-speed compressor; and
adjust the controllable flow rate of the flow of air provided by the blower to a first flow rate, based on a predefined ratio of blower flow rate to tonnage of cooling;
wherein, following decreasing the speed of the variable-speed compressor and adjusting the controllable flow rate of the flow of air:
a ratio of the first flow rate to the decreased tonnage of cooling is increased to a predefined value, and
a power consumption of the HVAC system is decreased by at least the predefined percentage associated with the demand request.
2. The HVAC system of claim 1 , wherein the predefined value is greater than or equal to 500 cubic feet per minute per tonnage of cooling.
3. The HVAC system of claim 1 , wherein the controller is further configured to:
determine if a relative humidity of a space conditioned by the HVAC system is greater than a predefined maximum relative humidity value; and
in response to determining the relative humidity of the space is greater than the predefined maximum relative humidity value:
adjust one or both of the speed of the variable-speed compressor to a second speed and the controllable flow rate of the flow of air provided by the blower to a second flow rate, such that a ratio of the first flow rate to the tonnage of cooling is decreased to a second predefined value, wherein the second predefined value is less than the first predefined value.
4. The HVAC system of claim 1 , wherein:
the demand request comprises a start time associated with the command to reduce power consumption; and
the controller is further configured to, prior to decreasing the speed of the variable-speed compressor, cause a space conditioned by the HVAC system to be dehumidified before the start time is reached.
5. The HVAC system of claim 1 , wherein the demand request is received from a third party.
6. A method of operating a heating, ventilation, and air conditioning (HVAC) system, the method comprising:
compressing refrigerant flowing through the HVAC system;
providing a flow of air through the HVAC system at a controllable flow rate;
receiving a demand request, the demand request comprising a command to reduce power consumption of the HVAC system by a predefined percentage;
in response to receiving the demand request:
decreasing a speed of a variable-speed compressor of the HVAC system by at least the predefined percentage of the command to reduce power consumption, thereby operating the HVAC system at a decreased tonnage of cooling corresponding to the decreased speed of the variable-speed compressor; and
adjusting the controllable flow rate of the flow of air provided by a blower of the HVAC system to a first flow rate, based on a predefined ratio of blower flow rate to tonnage of cooling;
wherein, following decreasing the speed of the variable-speed compressor and adjusting the controllable flow rate of the flow of air:
a ratio of the first flow rate to the decreased tonnage of cooling is increased to a predefined value, and
a power consumption of the HVAC system is decreased by at least the predefined percentage associated with the demand request.
7. The method of claim 6 , wherein the predefined value is greater than or equal to 500 cubic feet per minute per tonnage of cooling.
8. The method of claim 6 , further comprising:
determining if a relative humidity of a space conditioned by the HVAC system is greater than a predefined maximum relative humidity value; and
in response to determining the relative humidity of the space is greater than the predefined maximum relative humidity value:
adjusting one or both of the speed of the variable-speed compressor to a second speed and the controllable flow rate of the flow of air provided by the blower to a second flow rate, such that a ratio of the first flow rate to the tonnage of cooling is decreased to a second predefined value, wherein the second predefined value is less than the first predefined value.
9. The method of claim 6 , wherein the demand request comprises a start time associated with the command to reduce power consumption, and the method further comprising, prior to decreasing the speed of the variable-speed compressor, causing a space conditioned by the HVAC system to be dehumidified before the start time is reached.
10. The method of claim 6 , wherein the demand request is received from a third party.