HVAC unit with hot gas reheat

• US 10,072,854 B2
• Filed: 04/01/2016
• Issued: 09/11/2018
• Est. Priority Date: 02/11/2011
• Status: Active Grant

• Current Assignee: Johnson Controls Tyco IP Holdings LLP (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Blanton, Norman J., Wilson, Stephen C., Pickle, Stephen B.
• Primary Examiner(s): Vazquez, Ana
• Application Number:
  US15/089,122
• Publication Number:
  US 20160216025A1
• Time in Patent Office: 893 Days
• CPC Class Codes: F24F 1/00075 receiving air from a central station
• CPC Class Codes: F24F 1/00077 receiving heat exchange fluid entering and leaving the unit as a liquid
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/61 using timers
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 11/65 for selecting an operating mode
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 11/84 using valves
• CPC Class Codes: F24F 11/86 by controlling compressors within refrigeration or heat pump circuits
• CPC Class Codes: F24F 11/871 by controlling outdoor fans
• CPC Class Codes: F24F 13/20 Casings or covers
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F24F 2140/12 Heat-exchange fluid pressure
• CPC Class Codes: F24F 2221/183 combined with a hot-water boiler
• CPC Class Codes: F24F 2221/54 Heating and cooling, simultaneously or alternatively
• CPC Class Codes: F24F 3/044 Systems in which all treatment is given in the central station, i.e. all-air systems
• CPC Class Codes: F24F 3/153 with subsequent heating, i.e. with the air, given the required humidity in the central station, passing a heating element to achieve the required temperature
• CPC Class Codes: F25B 2600/0271 the discharge pressure
• CPC Class Codes: F25B 2600/111 : of condenser fans
• CPC Class Codes: F25B 41/20 : Disposition of valves, e.g. of on-off valves or flow control valves expansion valves F25B41/31
• CPC Class Codes: F25B 47/022 : hot gas defrosting
• CPC Class Codes: F25B 5/02 : arranged in parallel
• CPC Class Codes: F25B 7/00 : Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit F25B9/00 takes precedence
• CPC Class Codes: F25D 17/06 : by forced circulation
• CPC Class Codes: Y02B 30/70 : Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

The present disclosure is directed to a single compressor HVAC system with hot gas reheat. The system includes a single compressor, a pair of condensers, a reheat heat exchanger, an evaporator, and an expansion device. Within the system, the refrigerant exiting the compressor is separated into two portions. In the cooling mode, the first and second portions of the refrigerant are directed from the compressor through the two condensers in parallel. In the reheat mode, the first portion of the refrigerant is directed through the first condenser, while the second portion of the refrigerant is directed through the reheat heat exchanger. The system also may include a head pressure control device that is designed to maintain the compressor discharge pressure within a desired range by adjusting the condenser fan speed.

Claims

1. A system, comprising:

a compressor configured to circulate a refrigerant through a refrigeration circuit;

a first condenser disposed along the refrigeration circuit, wherein the system is configured to direct a first portion of the refrigerant to the first condenser in a first operating mode of the system and in a second operating mode of the system, and wherein the first condenser is configured to transfer heat from the first portion of the refrigerant to ambient;

a second condenser disposed along the refrigeration circuit, wherein the system is configured to direct a second portion of the refrigerant to the second condenser in the first operating mode, wherein the system is configured to direct the second portion of the refrigerant to bypass the second condenser in the second operating mode, and wherein the second condenser is configured to transfer heat from the second portion of the refrigerant to ambient;

a reheat heat exchanger disposed along the refrigeration circuit, wherein the system is configured to direct the second portion of the refrigerant to the reheat heat exchanger in the second operating mode, wherein the system is configured to direct the second portion of the refrigerant to bypass the reheat heat exchanger in the first operating mode, and wherein the reheat heat exchanger is configured to transfer heat from the second portion of the refrigerant to a cooling fluid; and

a pressure control system disposed on a high pressure side of the compressor, wherein the pressure control system is configured to measure a discharge pressure of the refrigerant exiting the compressor and adjust a fan speed of the first condenser based on the discharge pressure when the system is in the second operating mode.

2. The system of claim 1, wherein the first condenser comprises one or more fans configured to direct ambient air over coils of the first condenser such that heat transfers from the first portion of the refrigerant to the ambient air.

3. The system of claim 2, wherein the pressure control system is configured to adjust the fan speed of the first condenser by adjusting a speed of one or more motors configured to supply power to the one or more fans.

4. The system of claim 1, wherein the pressure control system comprises a controller and a pressure sensor.

5. The system of claim 4, wherein the pressure control system comprises a variable speed device, a variable frequency device, or both, configured to adjust a speed of a motor configured to supply power to one or more fans of the first condenser.

6. The system of claim 1, wherein the pressure control system is configured to maintain the discharge pressure of the compressor within a predetermined range by adjusting the fan speed of the first condenser.