This application is directed, in general, to climate control, and, more specifically, to climate control systems and methods of operating such systems.
Climate control systems may take different forms depending on the application. In a residential or commercial building, for example, typically a heating, ventilating and air conditioning (HVAC) system is used to heat and/or cool the air within the building. In automobiles, cooling may be provided by an engine-driven compressor, and heating may be provided by a heat exchanger that warms the passenger cabin with engine-warmed coolant. In either case, climate control may be provided by a controller that modulates the duty cycle of the cool air source and/or the warm air source. In some cases, the controller may also control the humidity in the conditioned space. The comfort perceived by an occupant of the conditioned space is typically a function of both an absolute temperature (e.g. a dry-bulb temperature) and the relative humidity.
One aspect provides a climate control system that includes a cooling source and/or a heating source, and a controller. The cooling and/or heating sources are configured to respectively cool and heat an enclosed space. The controller is configured to receive an apparent temperature set point. The controller is further configured to operate the cooling and/or heating sources to maintain an absolute air temperature within the enclosed space that is different from the apparent temperature set point.
Another aspect provides a method of manufacturing an HVAC system. The method includes in one step configuring a cooling source and/or a heating source to respectively cool and heat an enclosed space. In another step a controller is configured to receive an apparent temperature set point and to operate the cooling and/or heating sources to maintain an absolute air temperature within the enclosed space that is different from the apparent temperature set point.
Yet another aspect provides a climate control system. The system includes a cooling source and/or a heating source, and a controller. The cooling and/or heating sources are configured to respectively heat and cool an enclosed space. The controller is configured to display in lieu of a numerical value a non-alphanumeric icon representative of an apparent temperature set point. The controller is further configured to operate the cooling and/or heating sources to maintain air within the enclosed space at the apparent temperature set point.
Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
In the following discussion and in the claims, the following terms have following associated meanings:
Relative humidity (RH): the ratio of the partial pressure of water vapor in the air to the saturation vapor pressure of water vapor at the pressure and temperature of the air.
Absolute temperature (Ta): a measure of the temperature of air without regard to the relative humidity thereof. As an example, a dry-bulb thermometer provides a measure of absolute temperature.
Apparent temperature (AT): a value that describes human physiological perception of comfort in a conditioned (heated and/or cooled) space, the value taking into account both Ta and RH.
Depending on the RH, heat loss can cause a person to feel warmer or colder than the absolute temperature alone would suggest. Thus, apparent temperature is sometimes referred to as a “feels like” temperature, may be equivalently referred to herein without loss of generality. However, some operators of a climate control system, e.g. homeowners, may not have an interest or the ability to easily determine a combination of RH and absolute temperature to provide a desired level of personal comfort.
The inventors provide herein a new paradigm for controlling a climate control system to maintain a desired personal comfort level. Rather than require the individual to maintain personal comfort by independently adjusting multiple environmental parameters, e.g. absolute temperature and humidity, the climate control system controls such parameters to maintain a selected apparent temperature. The system determines a suitable combination of absolute temperature and/or RH and controls system components as necessary to achieve the desired combination. This control may be transparent to the user, who as mentioned previously may be uninterested in the particular combination of absolute temperature and humidity that results in the desired comfort level.
The system 100 includes a controller 110, an outdoor unit (OU) 120 and an indoor unit (IU) 130. The controller 110 may be referred to synonymously herein as a user interface (UI) 110. The controller 110 is configured to control the OU 120 and the IU 130, and may be configured to appear similar to a conventional wall-mounted thermostat. See, e.g. U.S. Patent Application No. 2010/0101854, incorporated herein by reference in its entirety. The controller 110 communicates via a bidirectional communication bus 140 with the OU 120, IU 130, and other components as described further below.
The communication bus 140 may be any suitable wired or wireless network. In some embodiments, the network is an RSBus network as described in U.S. Patent Application No. 2010/0106320 (the '320 application), incorporated herein by reference in its entirety. Such a system provides a protocol for addressed communication between networked devices. In other embodiments the bus 140 is a 4-wire system such as an RYWG 24-volt control system. In embodiments using a heat pump system, the bus 140 may be, e.g. a 7-wire control system.
The OU 120 and the IU 130 may be conventional. The OU 120 includes a compressor 120-1 and a condenser (not shown). The IU 130 includes an evaporator 130-1 and a furnace 130-2. The compressor 120-1 and the evaporator 130-1 are configured to cool air passing through the IU 130, thereby operating as a cooling source. The furnace 130-2 is configured to warm air passing through the IU 130, thereby operating as a heating source. The IU 130 may thereby heat and/or cool air enclosed within the associated building.
The controller 110 is configured to receive an apparent temperature set point and to operate the compressor 120-1 and the furnace 130-2 to maintain the set point. Maintaining the set point includes at least actively controlling an absolute temperature of the indoor space, and in some embodiments also includes actively controlling the RH of the indoor space.
The system 100 may include a humidifier 160 and/or a dehumidifier 170. The controller 110 may control the humidifier 160 and/or the dehumidifier 170 as described below to maintain a selected RH within the conditioned space. In other embodiments, the evaporator 130-1 may provide dehumidification, e.g. by undercooling. Such dehumidification may include, e.g. reducing airflow over the evaporator 130-1 to increase the residence time of the air in contact with the evaporator coils. In some embodiments the humidifier 160 may be omitted, such as when natural sources of humidity provide sufficient moisture to the enclosed space of the building. In such embodiments the controller 130 may select an absolute temperature that provides a desired apparent temperature with the naturally generated humidity level.
The controller 110 receives environmental data from a comfort sensor (CS) 150. The CS 150 includes a temperature sensor 150-1 and a relative humidity (RH) sensor 150-2. While shown as collocated in the figure, the sensors 150-1, 150-2 may be spatially separated, may be enclosed in separate enclosures, and may be independently addressed via the communication bus 140. The temperature sensor 150-1 senses the absolute temperature of the air in the enclosed space conditioned by the system 100. The RH sensor 150-2 senses the RH of the air. In some embodiments the sensors 150-1 and 150-2 report the temperature and RH to the controller 110 via the bus 140, e.g. upon receiving a request from the controller 110. In other embodiments the sensors 150-1, 150-2 are collocated with the controller 110 and bypass the bus 140 to communicate directly with the controller 110.
The comfort sensor 150 may also in some embodiments include an airspeed sensor 150-3 and a radiant energy sensor 150-4. These sensors may be used in some embodiments, described below, to enhance the capability of the comfort sensor 150 to report various environmental conditions that may affect the perceived comfort of an occupant.
The controller 110 is capable of executing various control and computational algorithms. The controller 110 in
Various sources may dynamically contribute to the moisture within the conditioned space. In a humid location, for instance, moisture from outside air may intrude into the conditioned space. Conversely, moisture from the conditioned space may be lost to the environment in an arid location. Also, the occupants of a building, appliances and activities such as cooking may contribute significantly to both the absolute temperature and humidity of the conditioned space. To effectively maintain a personal comfort level, the climate control system 100 accommodates such heat and moisture variations by actively adding or removing heat and/or moisture to the conditioned space as necessary to maintain desired absolute temperature and RH set points. Unlike a conventional system, which may for example control RH to a specific value, the system 100 may allow the absolute temperature and RH to change while maintaining the apparent temperature set point. This approach may reduce over-controlling the absolute temperature and RH, and reduce operating costs by avoiding, e.g. unnecessary dehumidification.
A touch screen 230 provides input to and receives output from the controller 210. An operator may, e.g. enter a desired apparent temperature set point to the controller 110 via the touch screen 230. The processor 210 may display on the touch screen 230 a current apparent temperature set point and/or a current apparent temperature as determined from the measured absolute temperature and the RH. In other embodiments, the display and input functions of the touch screen are respectively provided instead by a separate keypad and screen.
A network interface 240 provides an electrical interface between the processor 210 and the communication bus 140. The interface 240 may include any combination of analog, digital, discrete and/or integrated components to provide interfacing functions. Without limitation, one embodiment of the network interface is described in the '320 application.
A memory 250 may include tabular data associating a selected apparent temperature with one or more combinations of an absolute temperature and an RH level, as described further below. The memory 250 is not limited to any particular type, but may be, e.g. a PROM. While shown as a separate component, the memory 250 may be a portion of the memory space provided by the instruction memory 220, or may be embedded within the processor 210.
Either or both of the areas 310 and 320 may be represented in a format readable by the processor 210 in various embodiments described herein. For example, the area 310 may be described by the absolute temperature and RH at each corner of the quadrilateral corresponding to the area 310. Alternatively or in combination, ranges of comfortable absolute temperatures on each RH curve that intersects the area 310 may be determined and tabulated. If desired, a separate tabulation may be determined for each of the areas 310, 320. In some embodiments a tabulation associated with a lower clothing insulation value, e.g. the area 320, is used in summer months, while a tabulation associated with a higher clothing insulation value, e.g. the area 310, is used in winter months.
In some embodiments, an equation may be determined that predicts a perceived temperature, e.g. the apparent temperature Ta. For example, Equation 1 below, attributed to Steadman (1994), predicts the apparent temperature AT (in ° C.) perceived by an individual as a function of absolute temperature (in ° C.) and RH. (See, e.g. www.bom.gov.au/info/thermal_stress.)
AT=Ta+0.33·(RH/100·6.105*exp(17.27·Ta/(237.7−Ta)))−4.00 (1)
In some embodiments the parameters of Eq. 1 or a similar equation may be embedded in operating instructions of the processor 210, enabling the processor 210 to directly compute a value of the apparent temperature from the measured Ta and RH. In some embodiments Eq. 1 or a similar equation may be used to generate tabular data that are then stored in the memory 250. For example, Table I presents an illustrative and nonlimiting example of such tabular temperature data, determined from Eq. 1 for a range of absolute temperature consistent with expected operation of the system 100 in some embodiments.
The personal comfort model may also in some embodiments include other comfort characteristics. For example, as described above the comfort sensor 150 may include the airspeed sensor 150-3 and the radiant energy sensor 150-4. ASHRAE STD 55 describes inclusion of the radiant energy (RE) and airspeed (AS) in a model of apparent temperature. Such a model may be generally expressed as
AT=f(Ta,RH,RE,AS).
For example, radiant energy from, e.g. windows or appliances may not be perceived by the temperature sensor 150-1, but heat absorbed by an occupant's body may cause the occupant to perceive a higher temperature than would otherwise be the case. Moreover, moving air may cool the occupant, lowering the perceived temperature. The airspeed sensor 150-3 and the radiant energy sensor 150-4 provide a measure of these comfort characteristics to the user interface 110. In some embodiments the airspeed sensor 150-3 and/or the radiant energy sensor 150-4 are portable units that may be collocated with the occupant to accurately reflect the microenvironment the occupant experiences. In some embodiments the airspeed sensor 150-3 and/or the radiant energy sensor 150-4 are wirelessly connected to the user interface 110 via a wireless extension of the communication bus 140 to enable greater portability.
The method 500 begins with a step 501, such as a subroutine entry point called upon the activation of the down arrow 420. In a step 510 the processor 210 receives the apparent temperature set point entry from the touch screen 230. In a step 520 the controller 130 determines one or more combinations of actual temperature and RH that result in an apparent temperature about equal to the apparent temperature set point. The method 500 then advances to a decisional step 530.
In the step 530 the controller 110 determines if there is at least one solution within a preferred RH range, e.g. between about 40% and about 60%. The controller 110 may be configured to allow the operator to input the preferred RH range via a setup screen, or this range may be programmed by the manufacturer. If the controller 110 determines there is at least one such solution within the preferred RH range the method 500 advances to a decisional step 540. In the step 540 the controller 110 determines if there are multiple solutions in the preferred RH range. It is apparent by inspection of Table I that in some cases multiple combinations of Ta and RH may produce a same apparent temperature. If there are multiple solutions the method 500 advances to a step 550. In the step 550 the controller 110 selects the solution that has an RH that is closest to the current RH as reported by the RH sensor 150-2. The method 500 then advances to a step 560 in which the controller 110 controls for the selected Ta and RH.
If in the step 530 the controller 110 determines that there is not at least one solution within the preferred RH range, the controller 110 selects the solution with an RH closest to the upper or lower limit of the preferred range, e.g. 60% or 40%. For example, if the RH prior to the new apparent temperature set point is less than 40%, the controller may select a combination of Ta and RH that results in the desired apparent temperature while providing an RH as close to 40% as possible. The method then advances to the step 560 and controls for the selected solution.
If in the step 540 the controller determines there are not multiple solutions in the preferred RH range, the method 500 advances to a step 580. In the step 580 the controller selects the unique solution within the preferred RH range. The method 500 advances to the step 560 and controls for the selected solution. The method ends with a return step 599 that returns, e.g. to a calling master control routine.
Returning to the example of the apparent temperature set point change in
In a first illustrated case, the Ta and RH are initially 73° F. (˜22.8° C.) and 35%, respectively prior to the change of apparent temperature. Referring to Table I, two possible combinations of Ta and RH that result in an apparent temperature of 71° F. are 72° F./40% and 74° F. (23.3° C.)/25%. Referring to the method 500 without limitation, the former combination is selected, because the RH is within the preferred range of 40%-60% RH.
In a second illustrative case, the RH at the initial absolute temperature set point of 72° F. is about 60%. Again referring to Table I, the absolute temperature that corresponds to an apparent temperature Ta of 72° F. at 60% RH is about 70° F. At the new apparent temperature set point of 71° F. (
In both of these illustrative cases, the controller 110 operates the system 100 to maintain an apparent temperature of the conditioned space at 71° F. after the set point is reduced. However, the absolute temperature may differ from the displayed apparent temperature set point. In the first case, the displayed apparent temperature set point is 71° F., while the absolute temperature is 72° F. This feature is contrary to known climate control methods and systems, for which the system controller operates the climate control system to maintain an absolute temperature that is equal to a displayed temperature set point.
As an example,
In some embodiments (not shown), the space conditioned by the system 100 is one of a plurality of zones in a conditioned building. For example, the controller 110 may be located in a first zone that includes bedrooms of a home. An occupant of a bedroom may select an apparent temperature that is subjectively more comfortable for sleeping via the controller 110 within that zone. The described capabilities of the system 100 allow the occupant to easily adjust the apparent temperature set point by numeric value or by symbolic icon for comfortable sleeping. An occupant of a second zone including, e.g. common areas of the home, may adjust the apparent temperature of the second zone independently of the first zone. Such control may be, e.g. via the controller 100 or a second controller.
Turning to
In a step 810 a cooling source and/or a heating source are configured to respectively cool and heat an enclosed space. In a step 820 a controller is configured to receive an apparent temperature set point. The controller is further configured to operate the cooling and/or heating sources to maintain an absolute air temperature with the enclosed space that is different from the apparent temperature set point.
In a step 830 the controller is further configured to maintain a relative humidity that, in combination with the absolute temperature, results in the apparent temperature. In a step 840 the controller is configured to maintain the relative humidity by undercooling the enclosed space. In a step 850 the controller is configured to maintain the relative humidity by operating a humidifier.
In a step 860 the controller is configured to display the apparent temperature set point. In a step 870 the controller is configured to display a non-alphanumeric icon representative of the apparent temperature set point.
In a step 880 the controller is configured to control the cooling and/or heating sources via a bidirectional communication bus.
In a step 890 the controller is configured to control both absolute temperature and relative humidity to maintain the apparent temperature.
Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.
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