Systems and methods for air conditioning a building using an energy recovery wheel

Patent metadata

Field	Value
Publication number	US-9907214-B2
Application number	US-201414508925-A
Country	US
Kind code	B2
Filing date	Oct 7, 2014
Priority date	Oct 8, 2013
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

Systems and methods for air conditioning a building using an energy recovery wheel are provided. An exemplary system includes a rotatable energy recovery wheel configured to rotate successively through a recirculated air stream and a second air stream separate from the recirculated air stream, and a refrigeration circuit configured to circulate a refrigerant through a cooling coil arranged in the recirculated air stream and a condenser arranged in the second air stream. The refrigeration circuit includes a pressure sensor configured to measure a condensing head pressure. The system further includes one or more temperature sensors configured to measure a temperature of the recirculated air stream upstream of the energy recovery wheel and downstream of the energy recovery wheel, and a controller configured to operate the energy recovery wheel and the refrigeration circuit based on the condensing head pressure and the temperatures of the recirculated air stream.

First claim

What is claimed is:

1. A system for air conditioning a building, the system comprising:
a rotatable energy recovery wheel configured to rotate successively through a first air stream and a second air stream separate from the first air stream, wherein the energy recovery wheel is configured to transfer heat between the first air stream and the second air stream, wherein at least one of the first air stream and the second air stream is a recirculated air stream;
a refrigeration circuit configured to circulate a refrigerant through a cooling coil arranged in the first air stream and through a condenser arranged in the second air stream, wherein the refrigeration circuit includes a pressure sensor configured to measure a pressure of the refrigerant at the condenser;
a first temperature sensor configured to measure a first temperature of the recirculated air stream upstream of the energy recovery wheel and a second temperature sensor configured to measure a second temperature of the recirculated air stream downstream of the energy recovery wheel; and
a controller configured to receive measurements from the pressure sensor and the first and second temperature sensors, wherein the controller is configured to operate the energy recovery wheel and the refrigeration circuit based on the measured pressure of the refrigerant at the condenser and the measured temperatures of the recirculated air stream, wherein operating the energy recovery wheel and the refrigeration circuit comprises:
calculating a temperature differential of the recirculated air stream across the energy recovery wheel by subtracting the first temperature from the second temperature;
activating or deactivating the energy recovery wheel based on the calculated temperature differential of the recirculated air stream across the energy recovery wheel; and
activating or deactivating the refrigeration circuit based on the calculated temperature differential of the recirculated air stream across the energy recovery wheel.

2. The system of claim 1 , wherein the controller is configured to operate the energy recovery wheel and the refrigeration circuit without measuring an outdoor air temperature.

3. The system of claim 1 , wherein the recirculated air stream enters the system as a return air stream from the building and exits the system as a supply air stream to the building, the system further comprising:
a supply air temperature sensor configured to measure a temperature of the supply air stream,
wherein operating the energy recovery wheel and the refrigeration circuit comprises operating the energy recovery wheel and the refrigeration circuit to maintain the temperature of the supply air stream at a supply air temperature setpoint.

4. The system of claim 1 , wherein operating the energy recovery wheel and the refrigeration circuit comprises operating in a first stage cooling mode in which the energy recovery wheel is active and the refrigeration circuit is inactive,
wherein operating in the first stage cooling mode includes modulating a speed of rotation of the energy recovery wheel to maintain a temperature of a supply air stream at a supply air temperature setpoint.

5. The system of claim 1 , further comprising:
one or more devices for controlling a flow rate of the first air stream or the second air stream,
wherein the controller is configured to modulate the flow rate of the first air stream or the second air stream using the one or more devices to maintain a temperature of a supply air stream at a supply air temperature setpoint.

6. The system of claim 1 , wherein operating the energy recovery wheel and the refrigeration circuit comprises operating in a second stage cooling mode in which both the energy recovery wheel and the refrigeration circuit are active,
wherein operating in the second stage cooling mode includes operating the refrigeration circuit to maintain a temperature of a supply air stream at a supply air temperature setpoint.

7. The system of claim 6 , wherein the controller is configured to cause the energy recovery wheel to rotate at a constant rotational speed in the second stage cooling mode.

8. The system of claim 1 , wherein operating the energy recovery wheel and the refrigeration circuit comprises operating in a third stage cooling mode in which the energy recovery wheel is inactive and the refrigeration circuit is active,
wherein operating the system in the third stage cooling mode includes operating the refrigeration circuit to maintain a temperature of a supply air stream at a supply air temperature setpoint.

9. The system of claim 1 , wherein operating the energy recovery wheel and the refrigeration circuit comprises operating in a first stage cooling mode in which the energy recovery wheel is active and the refrigeration circuit is inactive and in a second stage cooling mode in which both the energy recovery wheel and the refrigeration circuit are active,
wherein the controller is configured to monitor a speed of rotation of the energy recovery wheel in the first stage cooling mode,
wherein the controller is configured to transition from the first stage cooling mode to the second stage cooling mode in response to at least one of:
the speed of rotation of the energy recovery wheel exceeding a threshold value, and
a temperature of a supply air stream exceeding a supply air temperature setpoint.

10. The system of claim 1 , wherein operating the energy recovery wheel and the refrigeration circuit comprises operating in a second stage cooling mode in which both the energy recovery wheel and the refrigeration circuit are active and in a third stage cooling mode in which the energy recovery wheel is inactive and the refrigeration circuit is active,
wherein the controller is configured to transition from the second stage cooling mode to the third stage cooling mode in response to the second temperature of the recirculated air stream downstream of the energy recovery wheel being greater than the first temperature of the recirculated air stream upstream of the energy recovery wheel.

11. The system of claim 1 , wherein operating the energy recovery wheel and the refrigeration circuit comprises operating in a second stage cooling mode in which both the energy recovery wheel and the refrigeration circuit are active and in a third stage cooling mode in which the energy recovery wheel is inactive and the refrigeration circuit is active,
wherein the controller is configured to use the pressure sensor to measure and record a transition pressure of the refrigerant at the condenser upon a transition from the second stage cooling mode to the third stage cooling mode,
wherein the controller is configured to transition from the third stage cooling mode to the second stage cooling mode in response to the pressure of the refrigerant at the condenser dropping below the measured and recorded transition pressure.

12. The system of claim 1 , wherein operating the energy recovery wheel and the refrigeration circuit comprises operating in a first stage cooling mode in which the energy recovery wheel is active and the refrigeration circuit is inactive and in a second stage cooling mode in which both the energy recovery wheel and the refrigeration circuit are active,
wherein the controller is configured to transition from the second stage cooling mode to the first stage cooling mode in response to at least one of:
the second temperature of the recirculated air stream downstream of the energy recovery wheel being less than the first temperature of the recirculated air stream upstream of the energy recovery wheel, and
the refrigeration circuit being not utilized for a predetermined period of time.

Assignees

• Johnson Controls Tech Co

Inventors

• Dagley James F
• West Jonathan D
• Polyzois Christos A
• Swank Kevin

Classifications

• Y02B30/52

  Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency · CPC title

• F24F2203/10

  Rotary wheel · CPC title

• H05K7/20836 Primary

  Thermal management, e.g. server temperature control · CPC title

• F24F12/006

  using an air-to-air heat exchanger (F24F12/002 takes precedence) · CPC title

• F25B2700/195

  of the condenser · CPC title