Compressor hierarchical control architecture for hot gas reheating system

Abstract

A method for controlling a heating, ventilation, and air conditioning (HVAC) system is provided. The method includes measuring a temperature and controlling a compressor of the HVAC system. The temperature is measured by a temperature sensor located between a metering device of the HVAC system and an evaporator coil of the HVAC system. The temperature represents a refrigerant temperature. The refrigerant temperature is a temperature of refrigerant fluid flowing from the metering device to the evaporator coil. The HVAC system further includes a reheating coil and a condenser coil. The compressor, the metering device, the evaporator coil, the reheating coil, and the condenser coil are in fluid communication with each other relative to a refrigerant fluid. The compressor is controlled by control circuitry configured to perform the control in a dehumidification mode based at least in part on a value of an air humidity parameter of airflow through the evaporator coil and the reheating coil, where the value is determined using the temperature.

Description

Technical Field

[0001] The present disclosure relates generally to heating, ventilation, and air conditioning (HVAC) engineering and, in particular, to one or more of the design, construction, operation, or use of HVAC systems. Background Art

[0002] The field of heating, ventilation, and air conditioning (HVAC) engineering generally involves the design, installation, and service of HVAC systems having equipment such as air handling units, variable air volume (VAV) units, compressors, air movers, chillers, furnaces, and ventilators. HVAC systems are generally configured to control environmental conditions at a facility such as an industrial facility, an institutional facility, a commercial facility, a residential facility, and the like. The facility may also include a building automation system (BAS) or other control system to provide some degree of computerized central control of the HVAC system and potentially other environmental control systems at the facility.

[0003] It is desirable to operate an HVAC system so that the conditioned air provided to one or more enclosed spaces maintains the relative comfort of the occupants in those enclosed spaces. As will be appreciated, factors that affect the comfort of the occupants include the temperature and humidity maintained in those enclosed spaces. In some cases, the temperature and humidity of the conditioned air may be controlled by using so-called hot gas reheating techniques to achieve a desired temperature and humidity. It will also be appreciated that, therefore, it is desirable to appropriately control the control of an HVAC system that employs hot gas reheating techniques so as to maintain such desired temperature and humidity levels. Summary of the invention

[0004] Example implementations of the present disclosure relate to the design, construction, operation, or use of an HVAC system. For purposes of the present disclosure, an HVAC system employing hot gas reheating technology may benefit from techniques such as those described herein, which may provide compressor staged control for an HVAC system employing such hot gas reheating technology.

[0005] Some example implementations provide a method for controlling a heating, ventilation, and air conditioning (HVAC) system. The method includes measuring a temperature and controlling a compressor of the HVAC system. The temperature is measured by a temperature sensor located between a metering device of the HVAC system and an evaporator coil of the HVAC system. The temperature represents a refrigerant temperature. The refrigerant temperature is the temperature of a refrigerant fluid flowing from the metering device to the evaporator coil. The HVAC system further includes a reheat coil and a condenser coil. The compressor, the metering device, the evaporator coil, the reheat coil, and the condenser coil are in fluid communication with each other relative to the refrigerant fluid. The compressor is controlled by a control circuit system, which is configured to perform control in a dehumidification mode based at least in part on a value of an air humidity parameter of an air flow through the evaporator coil and the reheat coil, wherein the value is determined using the temperature.

[0006] Some example implementations provide a non-transitory computer-readable storage medium including program instructions for controlling a heating, ventilation, and air conditioning (HVAC) system, which, when executed by one or more processors, performs a method including measuring a temperature and controlling a compressor of the HVAC system. The temperature is measured by a temperature sensor located between a metering device of the HVAC system and an evaporator coil of the HVAC system. The temperature represents a refrigerant temperature. The refrigerant temperature is the temperature of a refrigerant fluid flowing from the metering device to the evaporator coil. The HVAC system further includes a reheat coil and a condenser coil. The compressor, the metering device, the evaporator coil, the reheat coil, and the condenser coil are in fluid communication with each other relative to the refrigerant fluid. The compressor is controlled by a control circuit system, which is configured to perform control in a dehumidification mode based at least in part on a value of an air humidity parameter of an air flow through the evaporator coil and the reheat coil, wherein the value is determined using the temperature.

[0007] Some example implementations provide an apparatus for controlling an HVAC system, the apparatus comprising a hot gas reheat dehumidification circuit, a sensor, and a system control unit. The hot gas reheat dehumidification circuit may include an evaporator coil, a compressor, a reheat coil, and a metering device that are in fluid communication with each other relative to a refrigerant fluid. The metering device is in fluid communication with the evaporator coil via a refrigerant fluid line. The sensor is positioned between the metering device and the evaporator coil so that the sensor is positioned to measure a parameter representing a refrigerant fluid parameter of a portion of the refrigerant fluid flowing through the refrigerant fluid line. The system control unit is configured to measure the parameter and control the compressor in a dehumidification mode based at least in part on the value of an air humidity parameter of an air flow through the evaporator coil and the reheat coil. The parameter is measured by the sensor, and the value is determined using the parameter.

[0008] By reading the following specific implementation together with the attached drawings briefly described below, these and other features, aspects and advantages of the present disclosure will be apparent. The present disclosure includes any combination of two, three, four or more features or elements set forth in the present disclosure, regardless of whether such features or elements are explicitly combined or otherwise referenced in the specific example implementation described herein. The present disclosure is intended to be read as a whole so that any separable features or elements of the present disclosure should be considered combinable in any one of its aspects and example implementations, unless the context of the present disclosure clearly states otherwise.

[0009] Therefore, it will be appreciated that the present disclosure is provided only for the purpose of outlining some example implementations in order to provide a basic understanding of some aspects of the present disclosure. Therefore, it will be appreciated that the example implementations described above are merely examples and should not be construed as limiting the scope or spirit of the present disclosure in any way. Other example implementations, aspects, and advantages will become apparent from the following detailed description made in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of some of the described example implementations. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Having thus generally described example implementations of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0011] Figure 1 A system for establishing heating, ventilation, and air conditioning (HVAC) according to some example implementations of the present disclosure is shown.

[0012] Figure 2 Some example implementations according to the present disclosure are shown. Figure 1 Certain aspects of the HVAC system depicted in .

[0013] Figure 3 is a flow chart illustrating various example operations of a method for controlling an HVAC system, according to some example implementations of the present disclosure.

[0014] Figure 4 is a flow chart illustrating various example operations of a multi-level control process according to some example implementations of the present disclosure.

[0015] Figure 5 is a diagram showing the operational results of an example of a multi-level control process embodiment according to some example implementations of the present disclosure.

[0016] Figure 6A computing system suitable for use in certain embodiments of methods and systems, such as those disclosed herein, is shown according to some example implementations of the present disclosure. DETAILED DESCRIPTION

[0017] Some implementations of the present disclosure are described more fully below with reference to the accompanying drawings, in which some, but not all, implementations of the present disclosure are shown. In fact, various implementations of the present disclosure can be embodied in many different forms and should not be construed as being limited to the implementations described herein; on the contrary, these example implementations are provided so that the present disclosure will be comprehensive and complete, and these example implementations will fully convey the scope of the present disclosure to those skilled in the art. Throughout the text, similar reference numerals refer to similar elements.

[0018] Unless otherwise specified or clear from the context, references to first, second, etc. should not be construed as implying a particular order. A feature described as being above another feature (unless otherwise specified or clear from the context) may alternatively be below the other feature, and a feature described as being below another feature (unless otherwise specified or clear from the context) may alternatively be above the other feature; and similarly, a feature described as being to the left of another feature may alternatively be to the right of the other feature, and a feature described as being to the right of another feature may alternatively be to the left of the other feature. Furthermore, although reference may be made herein to quantitative measurements, values, geometric relationships, etc., unless otherwise specified, any one or more (if not all) of these references may be absolute or approximate to account for acceptable variations that may occur, such as variations due to engineering tolerances, etc.

[0019] As used herein, unless otherwise specified or clear from the context, an "or" in a set of operands is an "inclusive or," and thus the set of operands is true if and only if one or more of the operands is true, in contrast to an "exclusive or," in which the set of operands is false when all of the operands are true. Thus, for example, "[A] or [B]" is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. Further, the articles "a" and "an" mean "one or more," unless otherwise specified or clear from the context to refer to the singular. In addition, it should be understood that, unless otherwise specified, the terms "data," "content," "digital content," "information," and similar terms may sometimes be used interchangeably.

[0020] As noted above, example implementations of the present disclosure relate generally to heating, ventilation, and air conditioning (HVAC) engineering, and specifically, to one or more designs, constructions, operations, or uses of HVAC systems. In this regard, Figure 1 A system 100 for establishing an HVAC system project according to some example implementations is shown. As shown, the system includes a facility 102, such as an industrial facility, an institutional facility, a commercial facility, a residential facility, etc. In some examples, the facility includes one or more buildings, such as an industrial building, an institutional building, a commercial building, a residential building, etc. Further, examples of suitable commercial buildings include office buildings, warehouses, retail buildings, etc.

[0021] The facility 102 is generally any facility having one or more environmental control systems configured to control the environmental conditions of the facility. For example, the environmental control system may include an HVAC system 104 having equipment 106 (such as air handling units, variable air volume (VAV) units, compressors, air movers, chillers, furnaces, and ventilators). Other examples of suitable environmental control systems include lighting control systems, shading control systems, security systems, etc. The facility may also include an industrial control system (ICS) (such as a supervisory control and data acquisition (SCADA) system, a distributed control system (DCS), etc.). A more specific example of a suitable DCS is a building automation system (BAS) 108. The ICS is configured to provide some degree of computerized central control of at least some of the environmental control systems (including the HVAC system).

[0022] In the context of some example implementations of the present disclosure, an HVAC system 104 and possibly also a BAS 108 may be installed at a facility and then placed in service at the facility. While in service and operated by a customer 112 (such as an owner of a facility), the HVAC system and / or BAS may be operated by the customer, the owner of the facility, or another party providing services related to the operation and maintenance of such HVAC systems.

[0023] It should also be appreciated that computers are often used throughout the installation and service of the HVAC system 104; and in this regard, a "computer" is generally a machine that is programmable or programmed to perform a function or operation. As shown, the installation and service of the HVAC system 104 at the facility 102 utilizes multiple example computers. These computers may include communication devices 116, 118, and 120 such as are used by technicians 110, customers 112, and service organizations 114 to communicate with each other during the operation of the HVAC system 104. Although the computer may be the same as the computer 120 used for communication, the service organization may also use a computer 122 for monitoring the operation of the HVAC system 104. And in some examples, the service organization includes a large number of units (e.g., offices) responsible for managing such systems.

[0024] A number of computers 116-122 that may be used may be co-located or directly coupled to one another, or in some examples, individual ones of the computers may communicate with one another across one or more networks. Further, while shown as part of system 100, it should be understood that any one or more of the computers may function or operate separately from the system without regard to any other of the other computers. It should also be understood that the system may include other than Figure 1 One or more additional or alternative computers than those shown.

[0025] Therefore, example implementations of the present disclosure are directed to improving the control of humidity in HVAC systems that employ hot gas reheat technology.

[0026] According to some example implementations, compressor staged control (e.g., a combination of parallel compressors, specific variable compressor speeds, and / or other such alternatives) may be employed to good effect. For example, in such HVAC systems, compressor staged control employing hot gas reheat techniques may be desirable with the dew point of the exhaust air as one of its inputs. It will be appreciated in light of this disclosure that while the dew point of the exhaust air is preferred because it directly represents the point at which humidity in the air condenses, a measurement of relative humidity may also be used to good effect.

[0027] However, it is generally not feasible to directly measure exhaust air humidity, at least in some HVAC systems, and using the dry bulb temperature leaving the evaporator (of the air between the evaporator and the reheat coil) as a proxy for dew point is difficult to implement in the design of such HVAC systems. To meet this need, control structures and logic have been developed that utilize parameters of the refrigerant fluid entering the evaporator (e.g., a temperature representative of the refrigerant fluid temperature, the refrigerant fluid temperature itself, or a proxy thereof) as input in order to implement a proxy for dew point measurement, wherein the term "refrigerant fluid" as used herein reflects the fact that the relevant refrigerant is in a liquid, gaseous, or a combination thereof (including transitions between the two). It is noted at this juncture that the parameter values ​​just noted (e.g., temperature values) are referred to as "representative" because the temperature measured at the outer surface of the refrigerant fluid line (or elsewhere sufficiently close) may differ from the temperature of the refrigerant fluid itself due to any number of factors (e.g., including the wall thickness of the refrigerant fluid line, the material(s) of construction of the refrigerant fluid line, the distance of the sensor from the refrigerant fluid line, and / or other such considerations). It will be appreciated that direct measurement of refrigerant fluid temperature is possible as are other types of parameters, for example, pressure of the refrigerant fluid (such as may be used to determine the saturated suction temperature of the refrigerant exiting the evaporator coil) and are intended to be understood by the present disclosure.

[0028] Additionally, such techniques may further take into account the humidity dynamics of the conditioned space. That is, it is understood that directly measuring the humidity of the exhaust air may present disadvantages in achieving such control. These issues may include the slower response speed of humidity sensors in the indoor airflow (e.g., space humidity sensors that sense humidity at the output of the evaporator coil; e.g., 30 minutes), the potential difficulty in installing such sensors, and the costs associated with such sensors and their installation. Therefore, when controlling an HVAC system that employs hot gas reheat technology, it is desirable to find a measurable refrigeration system property (parameter) that serves as a sufficiently accurate proxy for dew point. For example, sensing an adjusted temperature value is more accurate and sensitive than the information provided by a humidity sensor, and is also more accurate than a temperature reading on the evaporator coil.

[0029] Embodiments such as those described herein address such problems by using a parameter sensor configured to measure a refrigerant fluid parameter to sense a parameter value representing at least a portion of a refrigerant fluid parameter flowing through an HVAC system. In one such embodiment, the parameter value is a temperature value measured by a temperature sensor. In addition, certain such embodiments may use a single temperature sensor to perform such measurements to measure a temperature value representing the temperature of the refrigerant fluid. Such information may be combined with a properly configured control system (e.g., analog control circuitry, control logic, computer program instructions (e.g., firmware or software), etc.) to generate an approximate value of the discharge air dew point for controlling the compressor speed / stepping of the HVAC system. It can be further understood from this disclosure that, with respect to compressor stepping / speed control (and the various examples discussed herein in terms of temperature at the same time), another possibility for monitoring / estimating discharge humidity or dew point is to use evaporator pressure as a proxy for the desired dew point information (e.g., determination of the saturated suction temperature of the refrigerant fluid). Other alternatives, although less ideal due to factors such as cost, design difficulties, etc., use direct measurements of the dry bulb temperature of the discharge evaporator (i.e., the dry bulb temperature of the air between the back of the evaporator and before the reheat coil) and the humidity of the supply air.

[0030] Figure 2 Some example implementations according to the present disclosure are shown. Figure 1 Therefore, Figure 2 An HVAC system 200 is depicted showing various example components of an HVAC system, such as HVAC system 104. HVAC system 200 includes a compressor 205, a condenser coil 210, an evaporator coil 215, and a reheat coil 220. It will be appreciated that condenser coil 210, evaporator coil 215, and reheat coil 220 are essentially heat exchangers and are so named due to their respective locations in the refrigerant fluid circuit of HVAC system 200.

[0031] like Figure 2 205 . As shown and annotated, arrows depicted therein indicate the direction in which refrigerant fluid flows in certain refrigerant circuits, which refrigerant circuits include various annotated components, which include various refrigerant fluid lines, valves, and other hardware. To this end, the HVAC system 200 includes a plurality of such refrigerant circuits. For example, multiple refrigerant circuits can be traced in the HVAC system 200 starting with the compressor 205. It should be noted here that although the compressor 205 is depicted as a single compressor unit, other embodiments are intended to fall within the scope of the present disclosure, as noted earlier herein. For example, compression 205 can be achieved using multiple compressors in series, rather than a single compressor unit.

[0032] In one such refrigerant circuit, refrigerant fluid flows from the compressor 205 through the distribution valve 230, with a portion of it flowing to the condenser coil 210. An example of a distribution valve (such as the distribution valve 230) is a regulating valve (e.g., a proportional regulating valve). For example, such a proportional valve can provide a given percentage of the received refrigerant fluid flow to the condenser coil 210 and the remaining percentage of the received refrigerant fluid flow to the reheat coil 220 (wherein these percentages can be any combination that sums to 100%). In certain embodiments, the distribution valve 230 can support other refrigerant pipelines / circuits and provide refrigerant fluid in a manner suitable for these other embodiments. In addition, in certain embodiments, the compressor 205 can provide multiple refrigerant output pipelines to support such functionality.

[0033] This portion of the refrigerant fluid flows from the condenser coil 210 to the metering device 240, then flows through the evaporator coil 215, and back to the compressor 205. An example of a metering device such as the metering device 240 is a thermostatic expansion valve (TXV), which is a metering device designed to regulate the rate at which the refrigerant fluid ultimately flows into the evaporator coil 215. The metering device 240 can meter the refrigerant fluid based on parameters (e.g., temperature and pressure) detected by, for example, a metering device temperature sensor 242 and a sense line 244.

[0034] Similar to the description of the above refrigerant circuit, another such refrigerant circuit can also be traced starting from the compressor 205, which compresses the received refrigerant fluid and provides it to the distribution valve 230, as previously described. Another portion of the refrigerant fluid flows from the distribution valve 230 to the reheat coil 220, which receives this portion of the refrigerant fluid and, after heat transfer in its operation, provides the metering device 240 with outflowing refrigerant fluid via the check valve 237. As described above, the refrigerant fluid passes through the metering device 240 and the evaporator coil 215, and then returns to the compressor 205.

[0035] In both of the above examples, the metered refrigerant fluid (that portion that has flowed through the metering device 240 and is metered by the metering device 240) flows from the metering device 240 through another refrigerant fluid pipeline ( Figure 2 246), reaches a refrigerant fluid distribution block 248, and then continues to a refrigerant fluid distribution line 249, which distributes a metered amount of refrigerant fluid through the evaporator coil 215. In this manner, a metered amount of refrigerant fluid is transported through the evaporator coil 215 and then returned to the compressor 205 via yet another refrigerant fluid line.

[0036] exist Figure 2In the depicted configuration, the evaporator coil 215 and the reheat coil 220 along with various refrigerant fluid lines, valves, and other hardware form a hot gas reheat dehumidification circuit 250. Figure 2 As shown, in operation of the hot gas reheat dehumidification circuit 250, the air of the airflow 255 first flows through the evaporator coil 215 and then flows through the reheat coil 220. In doing so, the evaporator coil 215 can be operated so that the air of the airflow 255 flowing therethrough is cooled enough to cause the humidity in the air of the airflow 255 to condense (e.g., because the evaporator coil 215 cools the air of the airflow 255 to a temperature below the dew point of the air). This reduces the humidity in the air of the airflow 255 to a certain level, thereby causing the air humidity in the conditioned space to reach a desired level, providing a comfortable atmosphere for the occupants therein. However, such cooling may cause the air temperature of the air of the airflow 255 to potentially be lower than the desired temperature. The reheat coil 220 reheats the air of the airflow 255 flowing out of the evaporator coil 215 to a temperature that causes the desired air temperature in the conditioned space.

[0037] The operation of the compressor 205 is controlled by a system control unit 260. The system control unit 260 may receive one or more signals from various sensors, such as may be included within the HVAC system 200, within a building or other structure / conditioned space providing conditioned air, outside the relevant structure, or elsewhere. An example of such a sensor is a sensor 270. In certain embodiments, the sensor 270 is a temperature sensor located on or near the surface of the refrigerant fluid line 246 and may be implemented using, for example, a thermistor. The sensor 270 provides a signal or other information (depending on the analog and / or digital nature of the sensor 270) to the system control unit 260, which in turn uses this input (and other such inputs) to determine appropriate control of the compressor 205.

[0038] like Figure 2 As shown, sensor 270 can be implemented using a single sensor. This implementation is advantageous in its simplicity and economy, but other implementations are also possible. Figure 2In the depicted structure, the sensor 270 is depicted as being centrally located along the refrigerant fluid line 246 for the sake of clarity. In practice, the sensor 270 is preferably located along the refrigerant fluid line 246 near the distribution block 248 to provide improved accuracy in parameter value measurement (e.g., in the case of temperature measurement). It should be noted that it is understood that multiple sensors can be used. For example, in these implementations, a sensor can be placed on one or more (or each) refrigerant fluid distribution line 249. Although such an embodiment is more complex and costly, at least due to the increase in the number of sensors, in certain embodiments, the positioning of such sensors can provide improved accuracy in the determination of the relevant temperature value.

[0039] Additionally, as described above, in some embodiments, the sensor 270 is a temperature sensor (thermistor), although other types of temperature sensors may be used to the same good effect. In fact, other sensor types (e.g., pressure, suction, and other such sensor types) may also be used, as the parameters measured by such sensors may be used as a proxy for a temperature value representing the temperature of the refrigerant fluid.

[0040] Additionally, it should be appreciated that for refrigerant fluid distribution lines 249 (e.g., microchannels), location may also be a consideration, as such structures may cause pressure drops large enough to affect the effectiveness of a parameter (temperature) used as a proxy / representative of a refrigerant fluid parameter (refrigerant fluid temperature) for the portion of the refrigerant fluid flowing through a given refrigerant fluid line. In certain implementations, if the refrigerant fluid distribution lines cause excessive pressure drops, thereby affecting the saturated suction temperature (as a surrogate for the discharge air dew point), this may need to be accounted for in the calculation of the adjusted temperature value. That is, such systems may in fact manage this situation using a variable parameter offset (e.g., a temperature offset), where the risk of oscillation, the pressure drop encountered, and other factors may be considered.

[0041] In the manner described above, embodiments such as those described herein are capable of providing partial load refrigeration system capacity during a hot gas reheat mode of an HVAC system such as those described herein. A system control unit (such as system control unit 260) determines an appropriate compressor stage (e.g., which may be understood as compressor speed and / or fan speed) for the HVAC system by calculating a discharge air dew point target value based on the dynamics of the humidity in the conditioned space. In order to make such a determination, the system control unit requires an input signal for generating a sufficiently accurate proxy for the actual discharge air dew point. This is particularly important in situations where direct measurements of humidity are not reasonably available (e.g., without excessive expense, complexity, and / or other such considerations). Using techniques such as those described herein, a single refrigerant temperature input may be used to determine a proxy for the dew point. The system control unit may also be designed to provide appropriate compressor stage commands for HVAC system conditions where the dew point proxy deviates from the true dew point value. For examples of such deviations and approaches to handling such situations, reference may be made to the description of the system control unit 260. Figure 5 Description.

[0042] In systems where a compressor (e.g., compressor 205) supports a plurality of operating stages (e.g., a multi-stage compressor), embodiments of the control logic may provide features including: When switching from cooling mode to reheating mode, the compressor will initially increase by one stage. For example, if cooling mode is at stage 1 when reheating is initiated, the compressor load will start at stage 2. In some embodiments, the lowest stage (eg, stage 1) of the compressor is not used during reheat mode. This may be due to compressor oil management concerns, for example. During the reheat mode, in some embodiments, the controller detects the refrigerant fluid temperature by monitoring a temperature value representative of the refrigerant fluid temperature, thereby using a normalized value of the input (e.g., a preliminary temperature offset of the refrigerant fluid temperature (e.g., based on (T refrigerant +T offset )) can be used as a proxy for the actual exhaust air dew point. Although the T of 0° offset is ideal, but in reality, a T of 1.5° offset can be used as a preliminary temperature offset as described above, and depending on conditions, HVAC system design, and other such considerations, a T in the range of 2°-5° may be used. offset value to achieve good results. For example, the system control unit may be configured to Figure 4The described logic "stages up" the compressor (increases the speed / stage of the compressor). Generally, under most operating conditions, a proportional / integral (PI) based control technique can be utilized to stage the compressor based on comparing the dew point proxy to the target dew point. • In certain embodiments, the compressor is not derated when reheat is required. • Compressor stage control performed by the system control unit can be independent of other features of the controller (such as the modulating valve control of the unit's discharge air temperature (DAT)).

[0043] Will combine Figure 3 and Figure 4 Functionality such as described above is discussed.

[0044] Figure 3 is a flow chart illustrating various example operations of a method for controlling an HVAC system, according to some example implementations of the present disclosure. Figure 3 Thus depicted is the HVAC control process 300. As will be appreciated, the operations depicted in the HVAC control process 300 are merely examples of operations relevant to the discussion herein, and as noted, other sensor inputs will be received by a system control unit such as the system control unit 260, which will then perform operations related to those sensor inputs and control the various components within the HVAC system 200 appropriately.

[0045] The HVAC control process 300 begins with the measurement of a parameter value, such as a temperature value (e.g., by sensing such a temperature value at or near a surface of a refrigerant fluid line), which represents a Figure 2 The temperature of the refrigerant fluid at the point depicted by the location of the sensor 270 (between the metering device 240 and the distribution block 248) in (310). In this implementation, the temperature value is provided to the system control unit, which may be as simple as the sensor sending a signal to the system control unit, or may also involve digitizing this information and transmitting it to the system control unit (e.g., via a wireless network device, etc.). Having provided the temperature value, the system control unit then executes the multi-stage control process (320). Subsequently, Figure 4 An example of such a multi-stage control process will be described in more detail. The HVAC control process 300 then proceeds to determine whether the control process should continue (330). In the event that the HVAC control process 300 continues to operate, the process loops to the measurement of the temperature value (310). Alternatively, the HVAC control process 300 ends.

[0046] Figure 44 is a process diagram illustrating various example operations of a multi-level control process according to some example implementations of the present disclosure. A multi-level control process 400 is thus depicted and begins with a system control unit receiving a measurement made by a sensor (410). For example, such a measurement may be a signal or other information representing the temperature value described above. The multi-level control process 400 then proceeds to determine whether a given parameter value satisfies a minimum parameter threshold (420). An example of such a minimum parameter threshold is an adjusted temperature value of 30°, and a temperature that satisfies such a threshold is greater than the adjusted temperature value.

[0047] If the relevant parameter value does not meet the minimum parameter threshold, the system control unit sends a signal to the compressor to shut down (430). In this case, the compressor shuts down as a failsafe—the HVAC system is unable to provide the humidity level required to maintain the desired humidity, and in order to protect the system (e.g., the compressor), the multi-level control process 400 continues to have the system control unit send a shutdown signal to the compressor. Figure 5 As described above, this situation is caused by a given parameter value (e.g., the adjusted temperature value discussed elsewhere herein) deviating too far from the minimum threshold (reflecting that the HVAC system is unable to provide the desired humidity reduction level). The multi-stage control process 400 then ends and returns to Figure 3 The HVAC control process 300.

[0048] Alternatively, if the parameter value satisfies the minimum parameter threshold, the multi-stage control process 400 continues to determine whether the parameter value satisfies the maximum parameter threshold (440). An example of such a maximum parameter threshold is an adjusted temperature value of 42°, and the temperature that satisfies such a threshold is greater than the adjusted temperature value.

[0049] In the event that the parameter value does not meet the maximum parameter threshold, the system control unit sends a signal to the compressor to increase its speed by stepping up (470). Typically, this means that the system control unit will signal the compressor to immediately (or quickly) go to full load. The same is true for high superheat conditions, where such superheat measurement is made by another sensor (such as a temperature sensor) that measures the superheat of the refrigerant fluid exiting the evaporator coil. Subsequently, in combination with Figure 5represents an example of such a superheat measurement. Such an increase in speed may be continuous in nature (e.g., in the case of a variable speed compressor, providing continuously regulated reheat, so that, from the system's perspective, the response to humidity changes is continuously variable), or incremental (e.g., in the case of a multi-stage compressor). In certain embodiments, the system control unit's upshift of the compressor may also result in an increase in fan speed, thereby increasing the airflow rate through the evaporator coil and the reheat coil. In the event of a deviation, in certain embodiments, the higher airflow may result in a more accurate reflection of the actual parameter value (e.g., improved agreement between the adjusted temperature value and the actual temperature (and agreement between the estimated dew point and the actual dew point)). In the event of undercapacity, the higher airflow may also result in an increase in capacity, thereby correcting such undercapacity (e.g., overheating of the refrigerant).

[0050] At this point, it should be noted that such a deviation may be the result of a target temperature (the dew point of the air used to represent the airflow (e.g., airflow 250)) being too low, in which case such an upgrade will restore the proxy parameter (e.g., the adjusted temperature value) to be sufficiently close to the actual temperature and the actual dew point. Alternatively, such a deviation may represent a condition in which the HVAC system is overloaded (at the current compressor staging level), which would also artificially cause the target temperature (and dew point) to be too low, a condition referred to as an "evaporator starvation" condition (equivalent to a saturated suction temperature that is too low). In such a case, an increase in fan speed (and airflow) would help increase capacity in order to address the conditions present within the HVAC system and again bring the proxy parameter (e.g., the adjusted temperature value) back to sufficiently close agreement, as described above. In such a case, embodiments such as those described herein may equally successfully address deviations due to inaccuracies and deviations due to low actual capacity. Again, once these actions are taken, the multi-stage control process 400 ends and returns to Figure 3 The HVAC control process 300.

[0051] In a further alternative approach, if the parameter value satisfies the maximum parameter threshold (e.g., using the previous example of a threshold of 42°, and the adjusted temperature value is less than or equal to 42°), the control system (e.g., which may employ proportional (PI), proportional / integral / derivative (PID), and / or similar techniques) may be configured to set a dew point target for the HVAC system based on the change in humidity of the conditioned space determined using the adjusted parameter value (460). In this case, the HVAC system is operating normally and the relevant parameter (e.g., the adjusted temperature value) is not experiencing unacceptable deviations, so the compressor of the HVAC system may be appropriately staged to account for any changes in humidity of the conditioned space.

[0052] In the case of a temperature measurement (or a proxy thereof), such an adjusted parameter value may be an adjusted temperature value. Thus, in embodiments where the parameter value is a temperature value (or a temperature value determined from a proxy thereof), the adjusted temperature value is determined by adjusting the temperature value by a temperature offset. As described above, such a temperature offset is used to determine the adjusted temperature value. For example, in certain embodiments as described above, the controller monitors the refrigerant fluid temperature by monitoring a temperature value representative of the temperature of the refrigerant fluid during the reheat mode. As described above, this may be accomplished by using a normalized value for the input (e.g., a preliminary temperature offset for the refrigerant fluid temperature (e.g., based on (T refrigerant +T offset )) is achieved, as described above, this normalized value can be used as a proxy for the actual exhaust air dew point. Although the T offset is ideal, but in reality, a T of 1.5° offset can be used as a preliminary temperature offset as described above, and depending on conditions, HVAC system design, and other such considerations, a T in the range of 2°-5° may be used. offset To achieve good results, use a T greater than 0°. offset The values ​​are related to the actual physical characteristics of such systems and it is desirable to avoid oscillations in the control process which can lead to increased cycling and other undesirable effects in the HVAC system. This is because the adjusted temperature value tends to result in an estimated dew point that reflects the dew point of the actual exhaust air as accurately as possible while still avoiding the effects mentioned above.

[0053] Figure 5 is an operational result diagram illustrating an example of a multi-level control process operation according to some example implementations of the present disclosure. Figure 5 Thus, an operating results graph 500 is depicted, with the x-axis reflecting temperature (in degrees Fahrenheit (°F) in the given example) and the y-axis reflecting a given operating cycle (eg, simply cooling / dehumidification cycles one after another).

[0054] The operating results graph 500 depicts data for conditioned air at various indoor and outdoor conditions in the enclosure. The attributes shown in the operating results graph 500 include a temperature value (representing the refrigerant fluid temperature), the dew point of the air exiting the reheat coil (e.g., airflow 250), and a superheat value of the evaporator coil (leading evaporator superheat). As can be seen from the operating results graph 500, the adjusted temperature value (e.g., representing the refrigerant fluid temperature as the refrigerant fluid flows through the metering device, adjusted by the temperature offset described above) is effective as a proxy for the dew point of the air under most of the conditions depicted. However, as Figure 5As shown by the bold arrow depicted in , the adjusted temperature value may deviate to a value lower than the indoor discharge dew point. In this case, advantageously, while the system control unit may interpret such deviation as a low dew point condition (even though such a part-load condition is due to insufficient capacity being supplied to meet the potential cooling requirement in such a situation), the system control unit reacts by signaling the compressor of the HVAC system to ramp it up to full load, which in certain embodiments may also include increasing fan speed (potentially to maximum belt speed). As described above, the deviation of the adjusted temperature value (trending lower) from the indoor air dew point in the conditioned space may be interpreted by the system control unit as a lower dew point, when in fact such a situation represents a part-load condition in which the HVAC system is not providing sufficient capacity to meet the potential cooling requirement.

[0055] As can be seen in the operational results graph 500, the result of these actions is to restore the adjusted temperature value to a level consistent enough to allow the estimate of the dew point of the discharge air to be sufficiently accurate. It is also important to note that these actions also reduce the superheat, as reflected by the second sensor configured to detect the superheat of the refrigerant fluid exiting the evaporator coil, to a level below a critical superheat value (e.g., 24° F. in certain embodiments).

[0056] According to example implementations of the present disclosure, system 100 and its subsystems including computers 118-122 may be implemented by various computing architectures. The computing architecture for implementing the system and its subsystems may include separate hardware, or hardware under the instruction of one or more computer programs (e.g., project-related software applications 124) from a computer-readable storage medium. In some examples, one or more devices may be configured to act as the system and its subsystems shown and described herein or otherwise implement the system and its subsystems shown and described herein. In examples involving more than one device, the corresponding devices may be connected to each other in a variety of different ways (such as, directly, or indirectly via a wired or wireless network, etc.) or communicate with each other in a variety of other ways.

[0057] Figure 6 An apparatus 600 according to some example embodiments of the present disclosure is shown. In general, the apparatus of the exemplary implementations of the present disclosure may include, comprise or be embodied in one or more fixed or portable electronic devices. Examples of suitable electronic devices include smart phones, tablet computers, laptop computers, desktop computers, workstation computers, server computers, PLCs, circuit boards, etc. The apparatus may include one or more of each of a plurality of components, such as, for example, a processor 604 connected to a memory 602.

[0058] Processor 602 is generally any computer hardware capable of processing information (such as, for example, data, computer programs, and / or other suitable electronic information). A processor includes one or more electronic circuits, some of which may be packaged as an integrated circuit or multiple interconnected integrated circuits (integrated circuits are sometimes more commonly referred to as "chips"). Depending on the particular implementation, a processor may be multiple processors, a multi-core processor, or some other type of processor.

[0059] The processor 602 may be configured to execute a computer program, such as a computer readable program code 606, which may be stored onboard the processor or otherwise stored in the memory 604. In some examples, the processor may be embodied as or otherwise include one or more microprocessors, ASICs, FPGAs, etc. Thus, while the processor may be capable of executing a computer program to perform one or more functions, the processor of various examples may be capable of performing one or more functions without the assistance of a computer program.

[0060] The memory 604 is generally any computer hardware capable of temporarily and / or permanently storing information such as, for example, data, computer readable program code 606 or other computer programs, and / or other suitable information. The memory may include: volatile memory such as random access memory (RAM) and / or non-volatile memory such as a hard drive, flash memory, etc. In various instances, the memory may be referred to as a computer readable storage medium, which is a non-transient device capable of storing information. Then, in some examples, the computer readable storage medium is non-transient and has a computer readable program code stored therein, which in response to being executed by the processor 602 causes the device 600 to perform various operations as described herein.

[0061] In addition to the memory 604, the processor 602 may also be connected to one or more peripheral devices (such as a network adapter 608, one or more input / output (I / O) devices, etc.). A network adapter is a hardware component configured to connect the device 600 to one or more networks to enable the device to transmit and / or receive information via the one or more networks. This may include transmitting and / or receiving information via one or more networks over a wired or wireless connection using an appropriate wired or wireless communication protocol.

[0062] The I / O devices may include one or more input devices 600 capable of receiving data or instructions for the apparatus 610, and / or one or more output devices 612 capable of providing output from the apparatus. Examples of suitable input devices include keyboards, keypads, etc., and examples of suitable output devices include display devices (such as one or more light emitting diodes (LEDs), LED displays, liquid crystal displays (LCDs), etc.).

[0063] As explained above and reiterated below, the present disclosure includes, but is not limited to, the following example implementations.

[0064] Clause 1. A method for controlling a heating, ventilation, and air conditioning (HVAC) system, the method comprising: measuring a temperature (wherein the temperature is measured by a temperature sensor located between a metering device of the HVAC system and an evaporator coil of the HVAC system, the temperature represents a refrigerant temperature, and the refrigerant temperature is the temperature of a refrigerant fluid flowing from the metering device to the evaporator coil), and controlling a compressor of the HVAC system (wherein the HVAC system further includes a reheat coil and a condenser coil, the compressor, the metering device, the evaporator coil, the reheat coil, and the condenser coil are in fluid communication with each other relative to the refrigerant fluid, the compressor is controlled by a control circuit system, the control circuit system is configured to perform control in a dehumidification mode based at least in part on a value of an air humidity parameter of an air flow through the evaporator coil and the reheat coil, and the value is determined using the temperature).

[0065] Clause 2. The method of clause 1, wherein the humidity parameter is the dew point of the air.

[0066] Clause 3. The method of clause 1 or clause 2, wherein the metering device is a thermostatic expansion valve.

[0067] Clause 4. The method of any one of Clauses 1 to 3, wherein the temperature sensor is a thermistor.

[0068] Clause 5. The method of any one of clauses 1 to 4, wherein controlling comprises determining whether the temperature is sufficient to perform the staged operation by comparing the temperature to a first temperature threshold, and shutting down the compressor in response to determining that the temperature is insufficient to perform the staged operation.

[0069] Clause 6. The method of any of Clauses 1 to 5, wherein controlling further comprises: in response to determining that the temperature is sufficient to perform the staging operation, comparing the temperature to a second temperature threshold, and in response to determining that the temperature exceeds the second temperature threshold, performing the staging operation.

[0070] Clause 7. The method of any one of clauses 1 to 6, wherein the humidity parameter is the dew point of the air, the staged operation comprises: setting the dew point of the air by increasing the compressor load of the compressor using a proportional integral control process, and the input to the proportional integral control process is temperature.

[0071] Clause 8. The method of any one of clauses 1 to 7, wherein another input to the proportional-integral control process is a temperature offset.

[0072] Clause 9. The method of any one of clauses 1 to 8, wherein controlling further comprises: in response to determining that the temperature does not exceed the second temperature threshold, performing another staged operation, wherein the another staged operation causes the compressor to increase operation to full load.

[0073] Clause 10. The method of any one of clauses 1 to 9, wherein the HVAC system further comprises a fan that causes air to flow through the evaporator coil and the reheat coil, and another staged operation causes the fan to increase the rate at which air passes through the evaporator coil and the reheat coil.

[0074] Clause 11. A computer-readable storage medium for establishing control of a heating, ventilation, and air conditioning (HVAC) system, the computer-readable storage medium being non-transitory and having computer-readable program code stored therein, the computer-readable program code comprising a software application, the software application in response to being executed by a processor, causing the device to at least: measure temperature (wherein the temperature is measured by a temperature sensor located between a metering device of the HVAC system and an evaporator coil of the HVAC system, the temperature representing a refrigerant temperature, and the refrigerant temperature is the temperature of the refrigerant fluid flowing from the metering device to the evaporator coil), and control a compressor of the HVAC system (wherein the HVAC system further includes a reheat coil and a condenser coil, the compressor, the metering device, the evaporator coil, the reheat coil, and the condenser coil are in fluid communication with each other relative to the refrigerant fluid, the compressor is controlled by a control circuit system, the control circuit system is configured to perform control in a dehumidification mode based at least in part on a value of an air humidity parameter of the airflow through the evaporator coil and the reheat coil, and the value is determined using the temperature).

[0075] Clause 12. The computer-readable storage medium of clause 11, wherein the humidity parameter is a dew point of the air, the metering device is a thermostatic expansion valve, and the temperature sensor is a thermistor.

[0076] Clause 13. A non-transitory computer-readable storage medium as in clause 11 or clause 12, wherein the method further comprises: determining whether the temperature is sufficient to perform a staged operation by comparing the temperature to a first temperature threshold, and in response to determining that the temperature is insufficient to perform the staged operation, shutting down the compressor; and in response to determining that the temperature is sufficient to perform the staged operation, comparing the temperature to a second temperature threshold, and in response to determining that the temperature exceeds the second temperature threshold, performing the staged operation.

[0077] Clause 14. A non-transitory computer-readable storage medium as in any one of clauses 11 to 13, wherein the humidity parameter is the dew point of the air, and the staged operation includes: setting the dew point of the air by increasing the compressor load of the compressor using a proportional-integral control process, an input of the proportional-integral control process is temperature, and another input of the proportional-integral control process is a temperature offset.

[0078] Clause 15. A non-transitory computer-readable storage medium as in any one of clauses 11 to 14, wherein the method further comprises: in response to determining that the temperature does not exceed a second temperature threshold, performing another staged operation, wherein: the another staged operation causes the compressor to increase operation to full load, the HVAC further comprises a fan, the fan causes air to flow through the evaporator coil and the reheat coil, and the another staged operation causes the fan to increase the rate at which air passes through the evaporator coil and the reheat coil.

[0079] Clause 16. A heating, ventilation, and air conditioning (HVAC) system comprising: a hot gas reheat dehumidification circuit, a sensor, and a system control unit. The hot gas reheat dehumidification circuit may include an evaporator coil, a compressor, a reheat coil, and a metering device in fluid communication with each other relative to a refrigerant fluid. The metering device is in fluid communication with the evaporator coil via a refrigerant fluid line. The sensor is located between the metering device and the evaporator coil so that the sensor can measure a parameter representative of a refrigerant fluid parameter of a portion of the refrigerant fluid flowing through the refrigerant fluid line. The system control unit is configured to measure the parameter and control the compressor in a dehumidification mode based at least in part on a value of an air humidity parameter of an air flow through the evaporator coil and the reheat coil. The parameter is measured by the sensor, and the value is determined using the parameter.

[0080] Clause 17. The HVAC system of clause 16, wherein the humidity parameter is the dew point of the air, the metering device is a thermostatic expansion valve, and the sensor is a thermistor.

[0081] Clause 18. The HVAC system of clause 16 or clause 17, wherein the parameter is temperature, the measurement of the temperature provides a temperature value, the temperature value represents a refrigerant fluid temperature, and the refrigerant fluid temperature is a temperature of a portion of the refrigerant fluid line through which the refrigerant fluid flows.

[0082] Clause 19. An HVAC system as described in any one of Clauses 16 to 18, wherein the system control unit is further configured to: determine whether the temperature is sufficient to perform a staged operation by comparing the temperature with a first temperature threshold, turn off the compressor in response to determining that the temperature is insufficient to perform the staged operation, and in response to determining that the temperature is sufficient to perform the staged operation, compare the temperature with a second temperature threshold, and perform the staged operation in response to determining that the temperature exceeds the second temperature threshold.

[0083] Clause 20. An HVAC system as in any one of clauses 16 to 19, wherein the humidity parameter is the dew point of the air, and the staged operation includes: setting the dew point of the air by increasing the compressor load of the compressor using a proportional-integral control process, an input to the proportional-integral control process is temperature, and another input to the proportional-integral control process is a temperature offset.

[0084] Clause 21. An HVAC system as in any one of clauses 16 to 20, wherein the system control unit is further configured to: in response to determining that the temperature does not exceed a second temperature threshold, perform another staged operation, wherein: the other staged operation causes the compressor to increase operation to full load, the HVAC further includes a fan, the fan causes air to flow through the evaporator coil and the reheat coil, and the other staged operation causes the fan to increase the rate at which air passes through the evaporator coil and the reheat coil.

[0085] Thanks to the teachings presented in the foregoing description and the associated drawings, the technical personnel in the field to which the present disclosure relates will understand many modifications and other implementations of the present disclosure set forth herein. Therefore, it should be understood that the present disclosure is not limited to the specific implementation disclosed, and modifications and other implementations are intended to be included within the scope of the appended claims. In addition, although the foregoing description and the associated drawings describe example implementations in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions can be provided by alternative implementations without departing from the scope of the appended claims. In this regard, for example, combinations of elements and / or functions different from those combinations explicitly described above are also contemplated, as are some of the same as those set forth in the appended claims. Although specific terms are used herein, these terms are used only in a general sense and descriptive sense, and not for restrictive purposes.

Claims

1. A method for controlling a heating, ventilation and air conditioning (HVAC) system, comprising: Measuring temperature, characterized in that: The temperature is measured by a temperature sensor located between a metering device of the HVAC system and an evaporator coil of the HVAC system, The temperature represents the refrigerant temperature, and The refrigerant temperature is the temperature of the refrigerant fluid flowing from the metering device to the evaporator coil; and Controlling a compressor of the HVAC system, characterized in that: The HVAC system further includes a reheat coil and a condenser coil, the compressor, the metering device, the evaporator coil, the reheat coil, and the condenser coil being in fluid communication with each other with respect to the refrigerant fluid, The compressor is controlled by a control circuit system. The control circuitry is configured to perform the control in a dehumidification mode based at least in part on a value of an air humidity parameter of air flow through the evaporator coil and the reheat coil, and The value is determined using the temperature.

2. The method according to claim 1, characterized in that: The humidity parameter is the dew point of the air.

3. The method according to claim 1, characterized in that: The metering device is a thermostatic expansion valve.

4. The method according to claim 1, characterized in that: The temperature sensor is a thermistor.

5. The method according to claim 1, characterized in that The control includes: determining whether the temperature is sufficient to perform a binning operation by comparing the temperature to a first temperature threshold; and In response to determining that the temperature is insufficient to perform the staging operation, the compressor is shut down.

6. The method according to claim 5, characterized in that The control further includes: In response to determining that the temperature is sufficient to perform a classification operation, comparing the temperature to a second temperature threshold, and In response to determining that the temperature exceeds the second temperature threshold, the classification operation is performed.

7. The method according to claim 6, characterized in that: The humidity parameter is the dew point of the air, The classification operation includes: setting the dew point of the air by increasing the compressor load of the compressor using a proportional-integral control process, and The input to the proportional-integral control process is the temperature.

8. The method according to claim 7, characterized in that: Another input to the proportional-integral control process is the temperature offset.

9. The method according to claim 6, characterized in that The control further includes: In response to determining that the temperature does not exceed the second temperature threshold, performing another classification operation characterized by: The further staged operation increases the operation of the compressor to full load.

10. The method according to claim 9, characterized in that: The HVAC further comprises a fan, The fan causes air to flow through the evaporator coil and the reheat coil, and The alternative staged operation causes the fan to increase the rate at which the air passes through the evaporator coil and the reheat coil.

11. A non-transitory computer readable storage medium comprising program instructions for controlling a heating, ventilation, and air conditioning (HVAC) system, which, when executed by one or more processors, perform a method comprising: Measuring temperature, characterized in that: The temperature is measured by a temperature sensor located between a metering device of the HVAC system and an evaporator coil of the HVAC system, The temperature represents the refrigerant temperature, and The refrigerant temperature is the temperature of the refrigerant fluid flowing from the metering device to the evaporator coil; as well as Controlling a compressor of the HVAC system, characterized in that: The HVAC system further includes a reheat coil and a condenser coil, the compressor, the metering device, the evaporator coil, the reheat coil, and the condenser coil being in fluid communication with each other with respect to the refrigerant fluid, The compressor is controlled by control circuitry including the one or more processors, The control circuitry is configured to perform the control in a dehumidification mode based at least in part on a value of an air humidity parameter of air flow through the evaporator coil and the reheat coil, and The value is determined using the temperature.

12. The non-transitory computer-readable storage medium of claim 11, wherein: The humidity parameter is the dew point of the air, The metering device is a thermostatic expansion valve, and The temperature sensor is a thermistor.

13. The non-transitory computer-readable storage medium of claim 11, wherein: The method further comprises: determining whether the temperature is sufficient to perform a binning operation by comparing the temperature to a first temperature threshold; In response to determining that the temperature is insufficient to perform the staging operation, shutting down the compressor; and In response to determining that the temperature is sufficient to perform a classification operation, comparing the temperature to a second temperature threshold, and In response to determining that the temperature exceeds the second temperature threshold, the classification operation is performed.

14. The non-transitory computer-readable storage medium of claim 13, wherein: The humidity parameter is the dew point of the air, The classification operation includes: setting the dew point of the air by increasing the compressor load of the compressor using a proportional-integral control process, The input to the proportional-integral control process is the temperature, and Another input to the proportional-integral control process is the temperature offset.

15. The non-transitory computer-readable storage medium of claim 13, wherein: The method further comprises: In response to determining that the temperature does not exceed the second temperature threshold, performing another classification operation characterized by: The further staged operation causes the compressor to increase operation to full load, The HVAC further comprises a fan, The fan causes air to flow through the evaporator coil and the reheat coil, The alternative staged operation causes the fan to increase the rate at which the air passes through the evaporator coil and the reheat coil.

16. A heating, ventilation and air conditioning (HVAC) system comprising: Hot gas reheating dehumidification circuit, characterized in that: The hot gas reheating and dehumidification circuit includes an evaporator coil, a compressor, a reheating coil and a metering device. the evaporator coil, the compressor, the reheat coil and the metering device are in fluid communication with each other with respect to the refrigerant fluid, and The metering device is in fluid communication with the evaporator coil via a refrigerant fluid line; The sensor is characterized by: the sensor being located between the metering device and the evaporator coil such that the sensor is capable of measuring a parameter representative of a refrigerant fluid parameter of a portion of the refrigerant fluid flowing through the refrigerant fluid line; and The system control unit is characterized by: The system control unit is configured as follows: Measuring said parameter, characterized in that: The parameter is measured by the sensor, and The compressor is controlled in a dehumidification mode based at least in part on a value of an air humidity parameter of the air flow through the evaporator coil and the reheat coil, characterized in that: The value is determined using the parameters.

17. The HVAC system of claim 16, wherein: The humidity parameter is the dew point of the air, The metering device is a thermostatic expansion valve, and The sensor is a thermistor.

18. The HVAC system of claim 16, wherein: The parameter is temperature, The measurement of the temperature provides a temperature value, The temperature value represents the refrigerant fluid temperature, and The refrigerant fluid temperature is the temperature of a portion of the refrigerant fluid flowing through the refrigerant fluid line.

19. The HVAC system of claim 18, wherein: The system control unit is further configured to: determining whether the temperature is sufficient to perform a binning operation by comparing the temperature to a first temperature threshold; In response to determining that the temperature is insufficient to perform the staging operation, shutting down the compressor; as well as In response to determining that the temperature is sufficient to perform a classification operation, comparing the temperature to a second temperature threshold, and In response to determining that the temperature exceeds the second temperature threshold, the classification operation is performed.

20. The HVAC system of claim 19, wherein: The humidity parameter is the dew point of the air, The classification operation includes: setting the dew point of the air by increasing the compressor load of the compressor using a proportional-integral control process, The input to the proportional-integral control process is the temperature, and Another input to the proportional-integral control process is the temperature offset.

21. The HVAC system of claim 19, wherein: The system control unit is further configured to: In response to determining that the temperature does not exceed the second temperature threshold, performing another classification operation characterized by: The further staged operation causes the compressor to increase operation to full load, The HVAC further comprises a fan, The fan causes air to flow through the evaporator coil and the reheat coil, and The alternative staged operation causes the fan to increase the rate at which the air passes through the evaporator coil and the reheat coil.

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