JP2008500509A - Two-phase or supercooled reheat system - Google Patents

Abstract

A method of removing moisture from the air comprising providing an air conditioning system comprising a continuous circuit where the refrigerant flows from the compressor, through the condenser, through the heat exchanger, through the evaporator, and back to the compressor; Providing a bypass valve through which a part of the refrigerant bypasses the heat exchanger and a bypass circuit through which a part of the refrigerant passes from the upstream point of the condenser to be mixed with the refrigerant at the downstream point of the condenser Providing a discharge gas valve for controlling a part of the refrigerant flowing through the bypass circuit, measuring an outdoor temperature and relative humidity, determining a cooling stage, outdoor temperature, relative Operating a bypass valve and a discharge gas valve to remove a portion of the humidity from the air based on the humidity and cooling phase.

Description

  The present invention relates to a method for increasing the flexibility of an air conditioning system that utilizes dehumidification.

  This application is a continuation-in-part of US patent application Ser. No. 10 / 769,198, filed Jan. 30, 2004.

  A conventional air conditioning system comprises three basic components that function to cooperate and provide cooling. These three system components include a compressor, a condenser, and an evaporator. Referring to FIG. 1, an air conditioning system 10 known in the art is illustrated. The air conditioning system 10 moves the working fluid, i.e., refrigerant, through these operating components in a continuous operating cycle by means of a continuous closed circuit 23. Refrigerants typically contain chlorofluorocarbons, but any alcohol capable of accepting and releasing thermal energy, such as alcohol, when its temperature rises and falls and when its state changes between gas and liquid It can consist of a fluid.

  The refrigerant flows into the compressor 11 as a low-pressure and low-temperature gas and is compressed. After compression, the refrigerant flows out of the compressor 11 as high-temperature and high-pressure gas.

  The refrigerant moves to the condenser 13 in a gas state. In the condenser 13, the refrigerant gas received is reduced in energy at a constant pressure and is completely supercooled when it flows out of the condenser. Thereafter, the liquid refrigerant proceeds to the evaporator 17.

  In the evaporator 17, the refrigerant pressure is lowered by the expansion device 16. In the evaporator, energy is taken from the air stream and the refrigerant flows out in a gaseous state. In the evaporator 17, the air to be cooled is initially about 80 ° F., for example. Such air is moved through the evaporator 17 by a fan and cooled to about 50 ° F. to 55 ° F. or less.

  Often, when the air requires greater dehumidification, a heat exchanger 15 is provided to further subcool the refrigerant. The air across the evaporator 17 exhibits greater latent heat and sensible cooling when the heat exchanger is activated. However, the energy removed from the refrigerant by the heat exchanger 15 is returned to the air flow when the air flows out of the evaporator 17. Therefore, in the state in which the heat exchanger 15 is operated, the outflowing air is at a higher dry bulb temperature (relatively lower sensible heat capacity) and the humidity than in the state in which the heat exchanger 15 is not operated. Is low (relatively high latent heat capacity).

  Accordingly, it is an object of the present invention to provide a method for increasing the flexibility of an air conditioning system that utilizes dehumidification.

  In accordance with the present invention, a method for removing moisture from air includes an air conditioning system comprising a continuous circuit in which refrigerant flows from a compressor, through a condenser, through a heat exchanger, through an evaporator, and back to the compressor. A step of providing a bypass valve through which a part of the refrigerant bypasses the heat exchanger, and a part of the refrigerant is mixed with the refrigerant from the upstream point of the condenser to the downstream point of the condenser. A step of providing a bypass circuit, a step of providing a discharge gas valve for controlling a part of the refrigerant flowing through the bypass circuit, a step of measuring outdoor temperature and relative humidity, and a step of determining a cooling stage And operating a bypass valve and a discharge gas valve to remove a portion of the moisture from the air based on outdoor temperature, relative humidity, and cooling phase.

  According to the present invention, the air conditioner includes a continuous circuit in which the refrigerant flows from the compressor, through the condenser, through the heat exchanger, through the evaporator, and returns to the compressor, and a part of the refrigerant exchanges heat. A bypass valve that bypasses the condenser, a bypass circuit through which a part of the refrigerant passes from the upstream point of the condenser to mix with the refrigerant at the downstream point of the condenser, and a refrigerant that flows through the bypass circuit. A discharge gas valve for controlling a part and a control module for receiving the outdoor temperature, relative humidity, and return air temperature and controlling the operation of the compressor, the discharge gas valve, and the bypass valve.

  The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

  Like reference numerals and symbols in the various drawings indicate like elements.

  Accordingly, the teachings of the present invention provide a method for utilizing heat previously discarded in an air conditioning system and a system utilizing such a method to counteract the undesirable effects of sensible cooling. It is.

  It is sometimes desirable to simply dehumidify without sensible cooling. In such cases, as illustrated with reference to FIG. 2, additional heat is added to the air by actuating a valve 19 that diverts a portion of the flow so that it does not pass through the condenser 13. . In doing so, the heat exchanger 15 becomes the condenser of the two-phase mixture flowing into the heat exchanger 15 and its subcooler before the refrigerant flows out of the heat exchanger 15.

  Thus, various levels of dehumidification and sensible heat cooling are available in this scheme.

  Referring to FIG. 2, the air conditioning system of the present invention is illustrated. The most remarkable thing is to include a circuit for bypassing a part of the discharge gas so as not to flow into the condenser and a discharge gas valve 19 provided along the circuit. . When the discharge gas valve 19 is opened, it allows some of the hot gas flowing out of the compressor to bypass the condenser 13, which can provide high flexibility when dehumidification is required. Dehumidification is often necessary when the relative humidity in the space exceeds the desired value. In a preferred embodiment, the gas valve 19 is a solenoid valve.

  As pointed out above, prior art embodiments utilizing a heat exchanger 15 configured to also incorporate a subcooling unit or coil bypass the subcooler coil during normal operation without the need for dehumidification. Use the bypass valve. When the need for dehumidification arises, the bypass valve 21, which is normally open, preferably a solenoid valve, is closed and the supercooling coil in the heat exchanger 15 is activated to increase the latent heat capacity and increase the sensible heat capacity. Decrease.

  Referring to FIG. 3, a graph of refrigerant enthalpy versus pressure for a prior art system as the refrigerant passes through the closed circuit of the air conditioning system 10 is illustrated. Point 4 indicates the inflow to the compressor 11. As the refrigerant moves from point 4 to point 1, the pressure and energy increase. When the refrigerant moves from point 1 to point 2, it passes through the condenser 13 and the enthalpy decreases while maintaining a substantially constant pressure. The refrigerant pressure then decreases until it flows into the evaporator, where the enthalpy increases while maintaining a substantially constant pressure until it returns to the compressor at point 4.

  When the solenoid 21 is closed, the refrigerant is further cooled from point 2 to point 3 and flows into the evaporator with a lower enthalpy. The evaporator then absorbs more energy from the air. However, this energy is returned to the air as it traverses the heat exchanger 15, thus providing a greater latent heat capacity and a smaller sensible heat capacity. As pointed out above, the present invention includes a discharge gas valve 19 that allows a portion of the hot gas exiting the compressor to bypass the condenser 13 when opened. The bypass gas is mixed with the liquid refrigerant flowing out of the condenser. The resulting mixture (now in two phases) flows into heat exchanger 15 where it is condensed and subcooled.

  Referring to FIG. 4, there is illustrated a graph of refrigerant enthalpy versus pressure as the refrigerant moves through the circuit of the present invention when the discharge gas valve 19 is open. Refrigerant flows into and out of the compressor at point 5 and travels to point 1, where a portion of the refrigerant travels through the condenser while the remaining portion of the refrigerant bypasses the condenser and is discharged. Go past the gas valve 19. Such detour gas moves from point 1 to point 3. The refrigerant passing through the condenser at point 1 flows out of the condenser at point 2 and mixes with the detour gas to proceed to point 3. At this point, the refrigerant is condensed and supercooled, and the air is reheated. The It then flows into and out of the evaporator and returns to the condenser.

  As a result, from the addition of mixing the hot gaseous refrigerant with the refrigerant flowing out of the condenser 13, the distance from point 3 to point 3 in FIG. The distance to point 4 is increased. The addition of heat to the refrigerant in the present invention counteracts sensible heat cooling. The amount of refrigerant flowing through the discharge gas valve 19 is controlled so that the sensible heat capacity is zero, that is, the dry bulb temperature flowing into the evaporator is equal to the dry bulb temperature flowing out of the evaporator. Is preferred.

  The opening, that is, the operation of the discharge gas valve 19 depends mainly on the necessity of dehumidification in the space to be cooled, the outside air temperature, and the ability to perform subcooling in the heat exchanger 15. When dehumidification is desired without the need for cooling, the air conditioning system 10 operates with the discharge gas valve 19 open and the bypass valve 21 closed to provide a bypass. If dehumidification and cooling is desired and the outside air temperature is low, it must be checked whether an economizer mode is available in which the damper is opened to draw cool outside air. If an economizer is available, the economizer is activated with the discharge gas valve 19 open and the bypass valve 21 closed to provide a bypass. If dehumidification and cooling are desired and the outside air is hot, the discharge gas valve 19 is closed, the economizer is shut off, and the heat exchanger 15 operates in the supercooling mode. When dehumidification is not required and cooling is required, the discharge gas valve 19 is closed and the bypass valve 21 is opened. “Low temperature” and “high temperature” mean whether the outside air is below or above the desired temperature or enthalpy of the air to be cooled by the air conditioning system 10, respectively.

  In another embodiment of the present invention, a method is provided for determining when to operate the compressor 11 and when to open and close the discharge gas valve 19 and bypass valve 21 to achieve the desired performance. In this method, the following table defines in what case the discharge gas valve 19 and the bypass valve 21 should be opened and closed.

[Table 1]
Cooling stage Outdoor temperature Relative humidity Economizer Compressor None Low Low Minimum outdoor air Off
High Minimum outdoor air Reheating

High Low Minimum outdoor air Off
High Minimum outdoor air Reheating

1st Low Low Maximum outdoor air Off
High Maximum outdoor air Reheating

High Low Minimum outdoor air Standard
High Minimum outdoor air Supercooling mode

2nd Low Low Minimum outdoor air Standard
High Minimum outdoor air Supercooling mode

High Low Minimum outdoor air Standard
High Minimum outdoor air Supercooling mode.

  The above table defines the compressor mode in which the air conditioning system 10 of the present invention operates over a range of variables. These variables include cooling stage, outdoor temperature, relative humidity in the space to be cooled, and outdoor air requirements. The cooling stage is classified into three cases. In the first cooling phase (referred to as “none”), there is no need for cooling because the return air temperature of the system is below the cooling setpoint. The cooling setpoint can be set to any desired temperature, but is typically between 70 ° F and 80 ° F, preferably about 75 ° F. The second cooling stage (referred to as “first”) corresponds to the situation where the return air temperature exceeds the aforementioned cooling set value but falls below the cooling set value plus the deviation. This deviation may be selected to achieve the desired range in which the first cooling stage operates, but a typical deviation is about plus or minus 3 ° F. Finally, in the cooling stage called “second”, the return air temperature exceeds the cooling set value with the aforementioned deviation added.

  For each of the cooling phases noted above, the table above shows all possible combinations of low or high relative humidity and low or high outdoor temperatures in the space to be harmonized. The compressor setting is determined from a combination of cooling stage, outdoor temperature reading, and relative humidity reading. Possible compressor settings include off, reheat, normal, and supercooling modes. When the compressor “off” is appropriate based on the cooling phase, outdoor temperature, and relative humidity values, it does not matter whether the discharge gas valve 19 and solenoid 21 are opened or closed, and the compressor 11 is stopped. When it is determined that the compressor “reheat” mode is appropriate, the discharge gas valve 19 is opened and the solenoid 21 is closed. When the compressor “supercooling mode” is appropriate, the discharge gas valve 19 is closed in the same manner as the solenoid 21. Finally, when the compressor “standard” is appropriate, the discharge gas valve 19 is closed, while the solenoid 21 is opened. Except for the “off” mode, the compressor is operated in all other modes.

  Referring to FIG. 5, the air conditioning system of the present invention comprising a control module 51 is shown. The control module 51 receives input consisting of outdoor temperature, return air temperature, relative humidity, and cooling phase, and based on such input, compresses the system to selectively operate in the modes discussed above. The machine 11 is operated / stopped, and the discharge gas valve 19 and the solenoid 21 are opened and closed. The control module 51 may be any electronic, configured to receive input data and send control signals to the solenoid 21, the discharge gas valve 19, and the compressor 11, for example by suitable programming and / or software. Digital or analog device.

  As can be seen from the above table, in each cooling phase mode, the outdoor temperature can be “low” or “high”. Values corresponding to “low” and “high” may be defined in any manner to achieve the desired operation of the discharge gas valve 19 and solenoid 21, but a low outdoor temperature typically reduces the cooling setpoint by 3 On the other hand, a high outdoor temperature is defined as an outdoor temperature that similarly exceeds a cooling setpoint of less than 3 ° F. Furthermore, at each cooling stage, there are two possible relative humidity settings or variable values, specifically “low” and “high”, for a given outdoor temperature. The actual value of relative humidity below which the relative humidity is considered low and above which the relative humidity is considered high may be selected to provide the desired compressor setting. Typically, low relative humidity is considered to be relative humidity below 55% relative humidity, and conversely, high relative humidity is considered to be relative humidity above 55% relative humidity. It is sometimes possible to use outdoor air for cooling instead of the compressor when operating in the economizer mode. In such a mode, minimal or maximum outdoor air may be utilized depending on outdoor air requirements. Thereafter, a desired compressor mode of the air conditioning system 10 is determined based on measurements of the cooling phase, outdoor temperature, and relative humidity. Once the compressor mode is established, the operating positions of the discharge gas valve 19 and the bypass valve 21 are determined.

  One or more embodiments of the present invention have been described. However, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the claims.

1 shows an air conditioning system known in the art. FIG. It is a figure which shows the air conditioning system of this invention. 6 is a graph showing pressure versus enthalpy of refrigerant flow in the prior art. 3 is a graph showing pressure versus enthalpy of refrigerant flow of the present invention. FIG. 3 shows an embodiment of the invention in which a control module is shown.

Claims (23)

A method for removing moisture from air,
Providing an air conditioning system comprising a continuous circuit in which refrigerant flows from the compressor, through the condenser, through the heat exchanger, through the evaporator, and back to the compressor;
Providing a bypass valve through which a part of the refrigerant bypasses the heat exchanger;
Providing a bypass circuit through which a part of the refrigerant passes from an upstream point of the condenser to be mixed with the refrigerant at a downstream point of the condenser;
Providing a discharge gas valve for controlling the part of the refrigerant flowing through the bypass circuit;
Measuring outdoor temperature and relative humidity;
Determining the cooling stage; and
Operating the bypass valve and the discharge gas valve to remove a portion of the moisture from the air based on the outdoor temperature, the relative humidity, and the cooling stage. The step of determining the cooling stage comprises:
Determining a no-cooling stage when the return air temperature is below the cooling set value;
Determining a first cooling stage when the return air temperature exceeds the cooling set value but falls below the cooling set value with a deviation;
2. The method of claim 1, further comprising: determining a second cooling stage when the return air temperature exceeds the cooling setpoint plus the deviation.   The method of claim 2, wherein the cooling setpoint is between 70 ° F. and 80 ° F. and the deviation is about 3 ° F.   The step of operating the bypass valve and the discharge gas valve includes opening the discharge gas valve when the outdoor temperature is low, the relative humidity is high, and a no cooling stage is determined, and the bypass valve is opened. The method of claim 2 including closing.   The step of operating the bypass valve and the discharge gas valve opens the discharge gas valve when the outdoor temperature is high, the relative humidity is high, and the no cooling stage is determined, and the bypass valve is opened. The method of claim 2 including closing.   The step of operating the bypass valve and the discharge gas valve opens the discharge gas valve when the outdoor temperature is low, the relative humidity is high, and the first cooling stage is determined, and The method of claim 2 including closing the bypass valve.   The step of operating the bypass valve and the discharge gas valve closes the discharge gas valve when the outdoor temperature is high, the relative humidity is low, and the first cooling stage is determined, and The method of claim 2 including opening a bypass valve.   The step of operating the bypass valve and the discharge gas valve closes the discharge gas valve when the outdoor temperature is low, the relative humidity is low, and the second cooling stage is determined, and The method of claim 2 including opening a bypass valve.   The step of operating the bypass valve and the discharge gas valve closes the discharge gas valve when the outdoor temperature is high, the relative humidity is low, and the second cooling stage is determined, and The method of claim 2 including opening a bypass valve.   The step of operating the bypass valve and the discharge gas valve closes the discharge gas valve when the outdoor temperature is high, the relative humidity is high, and the first cooling stage is determined, and The method of claim 2 including closing the bypass valve.   The step of operating the bypass valve and the discharge gas valve closes the discharge gas valve when the outdoor temperature is low, the relative humidity is high, and the second cooling stage is determined, and The method of claim 2 including closing the bypass valve.   The step of operating the bypass valve and the discharge gas valve closes the discharge gas valve when the outdoor temperature is high, the relative humidity is high, and the second cooling stage is determined, and The method of claim 2 including closing the bypass valve. A continuous circuit from which the refrigerant flows from the compressor, through the condenser, through the heat exchanger, through the evaporator, and back to the compressor;
A bypass valve through which a part of the refrigerant bypasses the heat exchanger;
A bypass circuit through which a part of the refrigerant passes from an upstream point of the condenser to be mixed with the refrigerant at a downstream point of the condenser;
A discharge gas valve for controlling the part of the refrigerant flowing through the bypass circuit;
An air conditioner comprising: a control module that receives an outdoor temperature, a relative humidity, and a return air temperature and controls operations of the compressor, the discharge gas valve, and the bypass valve.   The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a reheating mode when the no-cooling stage is determined, the outdoor temperature is low, and the relative humidity is high.   The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a reheating mode when the no-cooling stage is determined, the outdoor temperature is high, and the relative humidity is high.   The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a reheating mode when the first cooling stage is determined, the outdoor temperature is low, and the relative humidity is high.   14. The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a standard mode when a first cooling stage is determined, the outdoor temperature is high, and the relative humidity is low.   14. The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a standard mode when a second cooling stage is determined, the outdoor temperature is low, and the relative humidity is low.   14. The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a standard mode when a second cooling stage is determined, the outdoor temperature is high, and the relative humidity is low.   The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a supercooling mode when the first cooling stage is determined, the outdoor temperature is high, and the relative humidity is high.   The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a supercooling mode when a second cooling stage is determined, the outdoor temperature is low, and the relative humidity is high.   The air conditioning apparatus according to claim 13, wherein the control module operates the apparatus in a supercooling mode when a second cooling stage is determined, the outdoor temperature is high, and the relative humidity is high.   The control module includes an off mode in which the compressor is off, a reheating mode in which the discharge gas valve is opened and the bypass valve is closed, a supercooling mode in which the discharge gas valve and the bypass valve are closed, and 14. An air conditioner according to claim 13, provided to selectively operate the system in a standard mode in which a discharge gas valve is closed and the bypass valve is opened.

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