Methods of controlling fan capacity and coil capacity in HVAC systems

Patent metadata

Field	Value
Publication number	US-10197300-B2
Application number	US-201715594893-A
Country	US
Kind code	B2
Filing date	May 15, 2017
Priority date	Nov 9, 2012
Publication date	Feb 5, 2019
Grant date	Feb 5, 2019

Abstract

A heating, ventilation, and air conditioning (HVAC) system includes a fan with a variable fan capacity; a coil with a variable discharge air temperature; and a controller configured to control the variable fan capacity of the fan and the variable discharge air temperature of the coil. The controller is configured to vary the variable capacity of the fan to maintain a space temperature at a space temperature setpoint while maintaining the variable discharge air temperature of the coil at a low discharge air temperature limit. The controller is configured to vary the variable discharge air temperature between a high discharge air temperature limit and the low discharge air temperature limit to maintain the space temperature at the space temperature setpoint while maintaining the variable capacity of the fan at a low fan capacity setting.

First claim

The invention claimed is:

1. A heating, ventilation, and air conditioning (HVAC) system, comprising:
a fan configured to provide a variable fan capacity between a high fan capacity setting and a low fan capacity setting;
a coil configured to provide a variable discharge air temperature between a high discharge air temperature limit and a low discharge air temperature limit; and
a controller configured to control the variable fan capacity of the fan and the variable discharge air temperature of the coil so as to maintain a space temperature at a space temperature setpoint;
wherein when the variable discharge air temperature reaches the high discharge air temperature limit, the controller is configured to vary the variable fan capacity of the fan to maintain the space temperature at the space temperature setpoint while maintaining the variable discharge air temperature of the coil at the high discharge air temperature limit;
when the variable discharge air temperature reaches the low discharge air temperature limit, the controller is configured to vary the variable capacity of the fan to maintain the space temperature at the space temperature setpoint while maintaining the variable discharge air temperature of the coil at the low discharge air temperature limit; and
when the variable discharge air temperature is between the high discharge air temperature limit and the low discharge air temperature limit, the controller is configured to vary the variable discharge air temperature between the high discharge air temperature limit and the low discharge air temperature limit to maintain the space temperature at the space temperature setpoint while maintaining the variable capacity of the fan at the low fan capacity setting.

2. The HVAC system of claim 1 ,
wherein when the coil discharge air temperature reaches the low discharge air temperature limit and the discharge fan capacity reaches the high fan capacity setting, varying the coil discharge air temperature toward a first boost discharge air temperature that is lower than the low discharge air temperature limit; or
when the coil discharge air temperature reaches the high discharge air temperature limit and the discharge fan capacity reaches the high fan capacity setting, varying the coil discharge air temperature toward a second boost discharge air temperature that is higher than the high discharge air temperature limit.

3. The HVAC system of claim 1 , wherein the fan is configured to provide an intermediate fan capacity setting.

4. The HVAC system of claim 1 , further comprising an airflow damper having a variable opening.

5. The HVAC system of claim 4 , wherein the airflow damper is configured to vary an airflow capacity between a minimum airflow setpoint and a maximum airflow setpoint.

6. The HVAC system of claim 1 , further comprising a variable speed compressor, and wherein the controller is configured to determine the low fan capacity setting based on an operation speed of the variable speed compressor.

7. The HVAC system of claim 1 , wherein the fan is a two-speed discharge fan having a low speed setting and a high speed setting.

8. The HVAC system of claim 1 , wherein the fan is a variable speed discharge fan having a variable speed between a low speed setting and a high speed setting.

9. The HVAC system of claim 1 , wherein the fan is a three-speed discharge fan with a high speed setting, an intermediate speed setting, and a low speed setting.

Assignees

• Trane Int Inc

Inventors

• Zhou John
• Clanin Thomas J

Classifications

• F24F11/30 Primary

  for purposes related to the operation of the system, e.g. for safety or monitoring · CPC title

• F24F2110/10

  Temperature · CPC title

• F28F27/00

  Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus (control arrangements in general G05) · CPC title

• F24F11/85

  using variable-flow pumps · CPC title

• F24F11/83

  by controlling the supply of heat-exchange fluids to heat-exchangers · CPC title