COMFORT CONTROL SYSTEM AND METHOD

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/627,421 filed Jan. 31, 2024, the entirety of which is hereby incorporated by reference.

FIELD

The disclosure generally relates to heating systems and, more particularly, to electric heat pump systems.

INTRODUCTION

This section provides background information related to the present disclosure which is not necessarily prior art.

The U.S. Department of Energy reports that heat pumps are increasingly popular in the United States, with over 17 million units installed in housing units as of 2020. This trend can be attributed to the fact that heat pumps are highly efficient, environmentally friendly, and can save up to 50% on heating bills when compared to traditional systems. Air-source heat pumps (ASHP) are the most commonly used type of heat pump, as they can deliver three times more heat energy than the electrical energy they consume at normal ambient temperatures. However, ASHPs have historically been unsuitable for colder climates due to issues such as cold drafts. While recent technological advancements have made ASHPs a viable option for colder climates, the issue of cold drafts remains a challenge. This discomfort is caused by inadequate control strategies and improper adjustments in supply air temperature and flow rates, leading to suboptimal thermal comfort for users.

ASHPs tend to supply air at higher flow rates and lower temperatures than conventional residential forced-air heating systems. On a cold day, for example, a natural gas furnace might meet a 40,000 BTU/h load by supplying 725 cfm of 120° F. air. An ASHP might meet the same load by supplying 1,450 cfm of 95° F. air. These higher flow rates of lower-temperature air can give rise to the ‘cold blow’ problem: Some occupants find it uncomfortable to feel significant movement of lukewarm air. Cold blow can cause discomfort even if an ASHP maintains the room air temperature at its user-specified setpoint. Even when a cold blow does not cause discomfort, supplying air at high flow rates can stress existing duct systems, which are often designed for lower airflow rates.

Known solutions include providing an auxiliary heat source in conjunction with the heat pump. The auxiliary heat might bring the supply air temperature in the above example up to 110° F. and the flow rate down to 905 cfm. These parameters are much closer to those of a conventional furnace and, presumably, less likely to evoke perceptions of thermal discomfort among users. Increasing discharge air temperatures could also help in pull-up operations after cold starts. Unfortunately, auxiliary resistance heat significantly increases electricity use. In the above example, an ASHP operating alone with a COP of 2.5 would use 4.7 kW (16037 BTU/h). The combined ASHP and auxiliary heat system would use 7.3 kW (24908.6 BTU/h), a 55% increase: 2.9 kW (9895.2 BTU/h) from the ASHP (assuming the same 95° F. downstream of the ASHP coil), plus 4.4 KW (15013.4 BTU/h) of electric resistance. In addition to increasing energy costs, auxiliary heat can increase peak power demand, potentially stressing electrical infrastructure within the building or on the grid.

Additionally, smart control systems and user-centric control strategies, such as thermal sensation-based control using wristbands and Human Machine Interface technologies, are being considered to improve overall thermal comfort. However, these smart methodologies may also lead to inefficiencies and increased initial costs. For example, a user would need to remember to remove the wristband before stepping outside or into a garage, otherwise, the wristband sensor would read a very low temperature and inaccurately demand additional heat.

Accordingly, there is a continuing need for a heat pump that may balance indoor airflow and supply temperatures to militate against cold blows while maintaining efficiency. Desirably, the system may include a control system that uses as little auxiliary heat as possible while maintaining thermal comfort.

SUMMARY

In concordance with the instant disclosure, a comfort control system that may balance indoor airflow and supply temperatures to militate against cold blows while maintaining efficiency, has surprisingly been discovered. Desirably, the comfort control system may include a control system that uses as little auxiliary heat as possible while maintaining thermal comfort.

A comfort control system of the present disclosure may be configured to selectively increase the temperature of the air being supplied by a heat pump. The comfort control system may include an auxiliary heat source, a temperature sensor, and a controller. In a specific example, the comfort control system may also be provided with the heat pump. The heat pump may be integrated with the auxiliary heat source. The auxiliary heat source may be downstream from the heat pump within a duct or may be directly coupled to the heat pump for seamless integration. The temperature sensor and/or the controller may be communicatively coupled to the auxiliary heat source and/or the heat pump. In certain circumstances, while the heat pump is operating, the controller may engage the auxiliary heat source to provide supplemental heat to selectively increase the air temperature output from the heat pump system. The controller may include a pulse-width modulation (PWM) controller and a solid-state relay. The solid-state relay may efficiently engage and disengage the auxiliary heat source. The PWM may regulate the auxiliary heat source by precisely adjusting the electrical pulse duration of the solid-state relay. Advantageously, the use of the PWM with the solid-state relay may operate more efficiently than known methods to use as little auxiliary heat as possible while maintaining thermal comfort. For instance, the controller may provide instructions to engage the auxiliary heat source only until the sensor detects a desired temperature setting is achieved. Conversely, known methods engage the auxiliary heat source for a predetermined duration of time. Desirably, the PWM and the solid-state relay of the present disclosure may also lower the peak power demand compared to known methods.

The comfort control system may be designed, configured, and utilized in various ways. One approach may involve employing the comfort control system that may be used according to a method to selectively increase the temperature of the air being supplied by a heat pump. The method may include a step of providing the comfort control system which may include an auxiliary heat source, a temperature sensor, and a controller. In a specific example, the comfort control system may also include a heat pump. The temperature sensor may monitor indoor and/or supply air temperatures. The controller may determine the air temperature that is beyond a threshold setting. The controller may engage the heat pump. The controller may also engage the auxiliary heat source. Air provided from the heat pump may pass through and/or may pass substantially adjacent to the auxiliary heat source, thus supplementally heating the air further.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations and are not intended to limit the scope of the present disclosure.

FIG. 1 is a box diagram of the components of a comfort control system, according to one embodiment of the present disclosure;

FIG. 2 is a schematic diagram of the comfort control system integrated into a building, according to one embodiment of the present disclosure;

FIG. 3 is a schematic diagram of the comfort control system having an auxiliary heat source disposed downstream from a coil of a heat pump within a duct, according to one embodiment of the present disclosure;

FIG. 4 is schematic diagram of the comfort control system, further depicting the temperature sensor having a first sensor and a second sensor for monitoring an indoor air temperature and a supply air temperature, according to one embodiment of the present disclosure; and

FIG. 5 is a flowchart of a method for using the heat pump system, according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

The following description of technology is merely exemplary in nature of the subject matter, manufacture, and use of one or more inventions, and is not intended to limit the scope, application, or uses of any specific invention claimed in this application or in such other applications as may be filed claiming priority to this application, or patents issuing therefrom. Regarding methods disclosed, the order of the steps presented is exemplary in nature, and thus, the order of the steps can be different in various embodiments, including where certain steps can be simultaneously performed. “A” and “an” as used herein indicate “at least one” of the item is present; a plurality of such items may be present, when possible. Except where otherwise expressly indicated, all numerical quantities in this description are to be understood as modified by the word “about” and all geometric and spatial descriptors are to be understood as modified by the word “substantially” in describing the broadest scope of the technology. “About” when applied to numerical values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by “about” and/or “substantially” is not otherwise understood in the art with this ordinary meaning, then “about” and/or “substantially” as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters.

Although the open-ended term “comprising,” as a synonym of non-restrictive terms such as including, containing, or having, is used herein to describe and claim embodiments of the present technology, embodiments may alternatively be described using more limiting terms such as “consisting of” or “consisting essentially of.” Thus, for any given embodiment reciting materials, components, or process steps, the present technology also specifically includes embodiments consisting of, or consisting essentially of, such materials, components, or process steps excluding additional materials, components or processes (for consisting of) and excluding additional materials, components or processes affecting the significant properties of the embodiment (for consisting essentially of), even though such additional materials, components or processes are not explicitly recited in this application. For example, recitation of a composition or process reciting elements A, B and C specifically envisions embodiments consisting of, and consisting essentially of, A, B and C, excluding an element D that may be recited in the art, even though element D is not explicitly described as being excluded herein.

As referred to herein, disclosures of ranges are, unless specified otherwise, inclusive of endpoints and include all distinct values and further divided ranges within the entire range. Thus, for example, a range of “from A to B” or “from about A to about B” is inclusive of A and of B. Disclosure of values and ranges of values for specific parameters (such as amounts, weight percentages, etc.) are not exclusive of other values and ranges of values useful herein. It is envisioned that two or more specific exemplified values for a given parameter may define endpoints for a range of values that may be claimed for the parameter. For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that Parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping, or distinct) subsume all possible combinations of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if Parameter X is exemplified herein to have values in the range of 1-10, or 2-9, or 3-8, it is also envisioned that Parameter X may have other ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, 3-9, and so on.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer, or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the FIG. is turned over, elements described as “below”, or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The comfort control system 100 is an efficient control sequence system designed to heat residential buildings in cold climates. As shown in FIG. 1, the comfort control system 100 includes an auxiliary heat source 102, a temperature sensor 104, and a controller 106, 108. In some non-limiting circumstances, the auxiliary heat source 102 may also be known as a resistor. The comfort control system 100 may be specifically tailored for single-speed or variable speed air-source centrally ducted unitary heat pump systems. The comfort control system 100 may be designed to militate against cold drafts, reduce demand peaks, and ensure overall thermal comfort for residents. The comfort control system 100 may militate against cold drafts by monitoring indoor and/or supply air temperatures and adjusting the current of the auxiliary heat source 102 accordingly. Thus, the core elements of the comfort control system 100 have been designed to minimize peak demand of electrical usage while maintaining thermal comfort, which may be achieved through the precise adjustment of the electrical current through the auxiliary heat source 102. The comfort control system 100 may also include a heat pump 112. In a specific example, the comfort control system 100 showcases a 41.4% reduction in peak electrical demand, a 57.7% decrease in cold drafts, a 40% improvement in thermal comfort, and a potential to decrease the size of the heat pump 112 and eliminate the need for a variable-speed heat pump, thereby leading to a notable reduction in initial costs. These results were obtained from a simulation of a real residential building during extremely cold weather conditions. The simulation used a high-fidelity numerical solver, which accurately captures the dynamics of various components in the system. The simulation was conducted with temperatures dropping as low as −23° C./−9.4° F. The simulation incorporated detailed comfort models.

A comfort control system 100 of the present disclosure may be configured to selectively increase the temperature of the air being supplied by the heat pump 112. As shown in FIGS. 2-3, the heat pump 112 and the auxiliary heat source 102 may be located in a duct 114. The auxiliary heat source 102 may be located downstream from the coil of the heat pump 112 within the duct 114. The auxiliary heat source 102 may be coupled to the heat pump 112. For instance, the auxiliary heat source 102 may be electrically coupled to the heat pump 112. The temperature sensor 104 and/or the controller 106, 108 may be communicatively coupled to the auxiliary heat source 102 and/or the heat pump 112. In certain circumstances, while the heat pump 112 is operating, the controller 106, 108 may engage the auxiliary heat source 102 to provide supplemental heat to selectively increase the air temperature outputted from the heat pump 112. The controller 106, 108 may include a pulse width modulation (PWM) controller 106 and a solid-state relay (SSR) 108. The SSR 108 may efficiently engage and disengage the auxiliary heat source 102. The PWM 106 may regulate the auxiliary heat source 102 by precisely adjusting the electrical pulse duration of the SSR 108. In some instances, the PWM 106 may also be described as a communication relay switch. Advantageously, the use of the PWM 106 with the SSR 108 may operate more efficiently than known methods to use as little auxiliary heat as possible while maintaining thermal comfort. For instance, the controller 106, 108 may provide instructions to engage the auxiliary heat source 102 only until the temperature sensor 104 detects a desired temperature setting is achieved. This may more efficiently and accurately provide desired thermal comfort conditions compared to only engaging the auxiliary heat source 102 for a predetermined duration of time. Desirably, the PWM 106 and the SSR 108 of the present disclosure may also lower the peak power demand compared to known methods.

In certain circumstances, the comfort control system 100 may be incorporated into existing Air-source heat pumps (ASHPs). For instance, the controller 106, 108 may be communicatively coupled and/or physically coupled with a heat pump 112. In a specific example, the heat pump 112 may include a single-speed air source unitary comfort control system 100 that use ducts 114 for air distribution. A compressor of the heat pump 112 may run at a fixed speed, and all vital components. Then, at least one current auxiliary heater element in the ASHP may be disconnected and replaced with the SSR 108 of the controller 106, 108. This may allow independent control of at least one heating element separately from the others. Additionally, the temperature sensor 104 (thermocouple), may be utilized for the controller 106, 108 to monitor when the auxiliary heating element should be engaged via the SSR 108. In a specific example, the comfort control system 100 may include two or more sensors 104. For instance, a first sensor 1S may monitor the supply temperature, near the auxiliary heat source 102, while a second sensor 2S may measure indoor air temperature, commonly referred to as a thermometer. One skilled in the art may select other suitable ways for providing the auxiliary heat source 102, within the scope of the present disclosure.

In certain circumstances, the controller 106, 108 may more efficiently operate the auxiliary heat source 102 in comparison to known methodologies. In a specific example, a plurality of SSRs 108 and/or a plurality of PWMs 106 may be used. The SSRs 108 are electronic switching devices that control the on/off state of a load without using moving contacts. They may employ semiconductor switching elements, such as thyristors, triacs, diodes, and transistors, making them versatile and capable of switching both AC and DC loads. SSRs 108 offer advantages such as fast switching speed, zero voltage turn-on, zero current turn-off, and minimal wear. They may use photocouplers to isolate input and output signals and relay signals at high speed. SSRs 108 do not use switching contacts that physically wear out, making them more reliable than mechanical relays. The PWM 106 is utilized to control the SSR 108, regulating the auxiliary heat source 102 by precisely adjusting the electrical pulse duration; in this process, the PWM 106 signal determines when the SSR 108 allows current modulation. A skilled artisan may select other suitable ways for providing the controller 106, 108, within the scope of the present disclosure.

In certain circumstances, as illustrated in FIG. 4, the controller 106, 108 may also include software modifications to enhance the heat pump 112. For instance, in cool weather, when the heat pump 112 cannot provide comfortable supply air temperatures on its own, the comfort control system 100 may modulate the current through the auxiliary heat source 102 such that the supply air temperature (the air temperature at the resistor outlet) tracks a comfortable supply temperature setpoint. The comfort control system 100 may do this even when the heat pump 112 has sufficient capacity to maintain comfortable indoor temperatures. For example, even where the heat pump 112 alone would sufficiently maintain a comfortable indoor temperature, the comfort control system 100 may engage the auxiliary heat source 102 to provide a warmer air flow to militate against cold drafts and/or to satisfy the particular preferences of a user. In very cold weather, when the heat pump 112 cannot maintain comfortable indoor temperatures on its own, the controller 106, 108 may modulate the resistor 116 such that the indoor air temperature tracks the indoor air temperature setpoint. A logic system of the controller 106, 108 may track two crucial parameters: the air temperature exiting the resistor heater (supply temperature) and the indoor temperature. Provided as a non-limiting example, these measurements may then be compared to predefined values of 21° C. for indoor temperature and 40° C. for supply temperature. It is contemplated for other predefined values to be used. It is also contemplated for the values to be determined by a user and changed at any time. Based on the comparison of the measured temperatures with the predefined values, the controller 106, 108 may adjust the compressor's on/off state and utilizes PWM 106 to modulate the current supplied to an auxiliary heat source 102 via the SSR 108.

In a more specific example, the controller 106, 108 may utilize one or more algorithms to operate the heat pump 112. For instance, the one or more algorithms may include:

• • Initialize {dot over (W)} h(k)={dot over (W)} h(k−1), {dot over (W)} f(k)={dot over (W)} f(k−1), and {dot over (W)} r(k)={dot over (W)}r(k−1), and set the resistor mode with the previous resistor mode.
  • If the indoor temperature exceeds the setpoint by the threshold for the compressor being on (δ₁=0.5), then turn off the compressor, fan, and resistor, and switch to supply mode
    • If T(k)>T_set+δ₁, set {dot over (W)}_h(k)=0, {dot over (W)}_f(k)=0, {dot over (W)}_r(k)=0, and set the resistor mode to supply.
  • If the difference between the setpoint and the “compressor on” threshold is greater than the indoor temperature, activate the compressor and fan to operate at their maximum capacity.

If ⁢ T ⁡ ( k ) < T set - δ 1 , set ⁢ W . h ( k ) = W _ . h ( k ) ⁢ and ⁢ W . f ( k ) = W _ . f .

• • If the difference between the setpoint and the resistor turn-on threshold (δ₂=1.5° C.) is greater than the indoor temperature, set the resistor mode to indoor.
    • If T(k)<T_set−δ₂, set the resistor mode to indoor.
  • If the heat pump 112 is on ({dot over (W)} h(k)>0):
    • If the resistor mode is supply, modulate the current such that T_r(k) tracks T_set,supply.
    • If the resistor mode is indoor, modulate the current such that T(k) tracks T_set,indoor.

Where:

• • T(k): Indoor temperature
  • T_r(k): Supply temperature
  • T_set,supply: Supply setpoint temperature
  • T_set,indoor: Indoor setpoint temperature
  • {dot over (W)}_f: Maximum fan capacity (KW).
  • {dot over (W)}_f: Rate of input work to the fan.
  • {dot over (W)}_h: Rate of work input to the heat pump.
  • {dot over (W)}_r: Rate of work input to the resistor.

The PWM 106 generates pulses of different widths depending on the difference between the desired temperature (setpoint) and the temperature feedback from both indoor and supply temperature sensors 104. These pulses are used to control the heating element and are facilitated by the SSR 108 that acts as a responsive switch. The controller 106, 108 may adjust the duration of electrical pulses, turning the auxiliary heat source 102 on and off as needed to maintain precise temperature control. In a specific example, setpoints may be directly inputted or transmitted via Modbus communication, making it a flexible and user-friendly system.

The comfort control system 100 may be designed, configured, and/or utilized in various ways. For instance, the comfort control system 100 may be used according to a method that selectively increases the temperature of the air being supplied. As shown in FIG. 5, the method may include a step of providing the comfort control system 100 may include a heat pump 112, an auxiliary heat source 102, a sensor, and a controller 106, 108. The sensor may monitor an air temperature. The controller 106, 108 may determine the air temperature that is beyond a threshold setting. The controller 106, 108 may engage the heat pump 112. The controller 106, 108 may also engage the auxiliary heat source 102. Air provided from the heat pump 112 may pass through and/or may pass substantially adjacent to the auxiliary heat source 102, thus supplementally heating the air further.

Provided as a non-limiting example, the comfort control system 100 was tested during an extremely cold week when the temperature ranged between −5° C. to −23° C. (23° F. to −9.4° F.). The comfort control system 100 of the present disclosure achieved a remarkable 41.4% reduction in peak demand; however, the increase in average electricity consumption was 19%. The thermal comfort level was improved by approximately 40%, ensuring a consistent and comfortable indoor temperature. Cold drafts were reduced by an impressive 57.7%, creating a more pleasant and enjoyable environment for occupants. Advantageously, the comfort control system 100 of the present disclosure has the potential to decrease the size of the heat pump 112 and eliminate the need for a variable-speed heat pump, thereby leading to a notable reduction in initial costs.

Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Equivalent changes, modifications and variations of some embodiments, materials, compositions, and methods can be made within the scope of the present technology, with substantially similar results.