Hot gas reheat modulation

Patent metadata

Field	Value
Publication number	US-9726387-B2
Application number	US-201414322427-A
Country	US
Kind code	B2
Filing date	Jul 2, 2014
Priority date	Jul 2, 2013
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A stepped approach to cooling capacity control and the HGRH status logic to achieve the requisite control of humidity and temperature provided to an interior area or building space receiving conditioned air. The system includes at least two independent circuits, each circuit having at least one compressor. At least one of the independent circuits includes hot gas reheat hardware thereby providing HGRH capability. The logic provides an efficient method for maintaining both humidity and temperature in the interior area comfortable for occupants within limits as determined by psychrometrics. The system and method match the sensible capacity and latent capacity of the system match to the sensible and latent loads of the conditioned space.

First claim

We claim:

1. An air conditioning system, comprising:
a multi-circuit system having a plurality of independent cooling circuits, each of the independent cooling circuits having at least one compressor;
a hot gas reheat circuit integral with a first independent cooling circuit of the plurality of independent cooling circuits;
a controller including a logic program that matches the latent heat capacity of the system to the latent load of an interior space being conditioned and also matches the sensible heat capacity of the system to the sensible load of the interior space being conditioned by activation of a second independent cooling circuit of the plurality of independent cooling circuits and selective activation of the first independent cooling circuit including the hot gas reheat circuit;
a return air temperature sensor in communication with the controller monitoring return air temperature;
a return air humidity sensor in communication with the controller monitoring return air humidity;
a supply air temperature sensor in communication with the controller monitoring supply air temperature;
a supply air dewpoint setpoint; and
a supply air temperature setpoint;
wherein the controller adjusts a supply air dewpoint setpoint in response to a signal from the return air humidity sensor;
wherein the controller adjusts a supply air temperature setpoint in response to a signal indicative of a temperature from at least one of the return air temperature sensor and the supply air temperature sensor; and
wherein the controller modulates operation of one of the plurality of independent cooling circuits and modulates operation of the hot gas reheat circuit integral with one of the plurality of independent cooling circuits in response to the supply air dewpoint setpoint and the supply air temperature setpoint.

2. The system of claim 1 wherein the logic program of the controller determines a number of independent cooling circuits to activate of the plurality of independent cooling circuits and the number of compressors in each of the activated independent cooling circuits to activate in response to at least one of the signal from the return air temperature sensor indicative of return air temperature, the signal from the return air humidity sensor indicative of return air humidity, the supply air dewpoint setpoint and the supply air temperature setpoint.

3. The system of claim 1 wherein the hot gas reheat circuit integral with the first independent cooling circuit of the plurality of independent cooling circuits further includes:
a reheat coil, the reheat coil being downstream of at least one evaporator of a plurality of evaporators in the multi-circuit system;
a first line placing the reheat coil in communication with a compressor discharge line of the first independent cooling circuit integral with the hot gas reheat circuit, the first line providing hot compressed refrigerant gas to the reheat coil; and
a second line placing the reheat coil in communication with a liquid line, the liquid line supplying liquid refrigerant to an evaporator of the first independent cooling circuit integral with the hot gas reheat circuit, the second line providing condensed refrigerant from the reheat coil to the liquid line.

4. The system of claim 3 wherein the hot gas reheat circuit further includes:
a valve in the first line selectively isolating the reheat coil from the compressor discharge line; and
a check valve in the second line, the check valve positioned preventing the back flow of liquid refrigerant into the reheat coil from the liquid line to the evaporator.

5. The system of claim 4 , further including a bleed valve in the second line between the check valve and the reheat coil, and a capillary tube between the bleed valve and a compressor suction line, the bleed valve metering a controlled amount of liquid refrigerant from the reheat coil into the compressor suction line without flooding a compressor, thereby preventing isolation of refrigerant liquid in the reheat coil when the valve in the first line selectively isolates the reheat coil from the compressor discharge line.

6. The system of claim 1 further including:
an economizer;
an outside temperature sensor in communication with the controller monitoring outside temperature;
an outside humidity sensor in communication with the controller monitoring return air humidity monitoring outside air humidity; and
wherein the logic of the controller determines selective operation of the economizer in adding fresh outside air to return air as a function of outside temperature and outside humidity.

7. An air conditioning system, comprising:
a multi-circuit system having a plurality of independent cooling circuits, each of the independent cooling circuits having at least one compressor;
a hot gas reheat circuit integral with a first independent cooling circuit of the plurality of independent cooling circuits, comprising:
a reheat coil, the reheat coil being downstream of at least one evaporator of a plurality of evaporators in the multi-circuit system;
a first line placing the reheat coil in communication with a compressor discharge line of the first independent cooling circuit of the plurality of independent cooling circuits, the first line providing hot compressed refrigerant gas to the reheat coil; and
a second line placing the reheat coil in communication with a liquid line, the liquid line supplying liquid refrigerant to an evaporator in the first independent cooling circuit integral with the hot gas reheat circuit, the second line providing condensed refrigerant from the reheat coil to the liquid line; and

a controller including a logic program that matches the latent heat capacity of the system to the latent load of an interior space being conditioned and also matches the sensible heat capacity of the system to the sensible load of the interior space being conditioned by activation of a second independent cooling circuit of the plurality of independent cooling circuits and selective activation of the first independent cooling circuit integral with the hot gas reheat circuit.

8. The air conditioning system of claim 7 , further comprising:
a return air temperature sensor in communication with the controller monitoring return air temperature;
a return air humidity sensor in communication with the controller monitoring return air humidity;
a supply air temperature sensor in communication with the controller monitoring supply air temperature;
a supply air dewpoint setpoint;
a supply air temperature setpoint;
wherein the controller adjusts a supply air dewpoint setpoint in response to a signal from the return air humidity sensor;
wherein the controller adjusts a supply air temperature setpoint in response to a signal indicative of a temperature from at least one of the return air temperature sensor and the supply air temperature sensor; and
wherein the controller modulates operation of one of the plurality of independent cooling circuits and modulates operation of the hot gas reheat circuit integral with the first independent cooling circuit in response to the supply air dewpoint setpoint and the supply air temperature setpoint.

9. The system of claim 8 , wherein the logic program of the controller determines a number of independent cooling circuits to activate of the plurality of independent cooling circuits and the number of compressors in each of the activated independent cooling circuits to activate in response to at least one of the signal from the return air temperature sensor indicative of return air temperature, the signal from the return air humidity sensor indicative of return air humidity, the supply air dewpoint setpoint, and the supply air temperature setpoint.

Assignees

• Johnson Controls Tech Co

Inventors

• Karkhanis Rajiv
• Caskey Curtis Wayne

Classifications

• F24F11/65

  for selecting an operating mode · CPC title

• F24F11/86

  by controlling compressors within refrigeration or heat pump circuits · CPC title

• F24F11/84

  using valves · CPC title

• F24F11/46

  Improving electric energy efficiency or saving · CPC title

• F25B2600/2501

  Bypass valves · CPC title