Patent Application
20170284720
This disclosure generally involves approaches for determining an operating environment of a condenser unit, and to systems and methods related to such approaches.
Heat pumps are devices that transfer heat energy from one thermal bath (typically a thermally insulated chamber) to another, accomplishing this task by drawing power from an external source. Typically, a device containing a heat pump strives to maintain a nearly constant temperature in one of the thermal baths by using a feedback control system. In the example of an air condition system, the heat pump (typically in the form of a vapor compression system) transfers heat from the interior of a building to the exterior, while maintaining the interior at a nearly fixed cold temperature. The external power source is typically the mains power supply, and the control mechanism is based on a thermostat with bang-bang control of the vapor compression pump. This disclosure describes the inference of characteristic of the environment of heat pump device components in general (with air conditioner condensers as a particular instance) based on power consumption of such devices.
The local operating environment of a refrigerant condenser unit affects its power consumption. The local operating environment has traditionally been determined by a manual in-person audit of an air conditioning system or analysis using aerial or satellite photography.
Some embodiments described herein are directed to a system configured to remotely determine characteristics of the local operating environment of a refrigerant condenser unit. The system includes a detector configured to sample power consumption of a refrigerant condenser unit to obtain a sampled power consumption time series. An analyzer receives the sampled time series of the detector and determines characteristics of a local operating environment of the condenser unit from the power consumption time series. The analyzer generates an output that includes information about the local operating environment.
According to some implementations, the detector samples power consumption of the condenser unit at a resolution sufficient to determine durations of time in which it is active (“on”) and durations of time in which it is inactive (“off”). A period when a component is on immediately followed by or preceded by a period when the component is off will be referred to as a power cycle of the component. The duty cycle of a power cycle is defined as the ratio of the time duration in which the component is on divided by the time duration from when the component turns on until the next time the component is on (or the time duration between successive off times).
The analyzer extracts the power cycles from the sampled power consumption time series and determines the characteristics of the local operating environment of the condenser unit from the power cycles. For example, the detector may sample the power consumption at a frequency of about one sample per minute or a higher frequency.
According to some implementations, the characteristics of the local operating environment include one or more of shading, temperature, humidity, air flow, and exposure of the condenser unit to weather conditions.
According to some implementations, the condenser unit is a component of an air conditioner for a facility that includes other appliances and the detector samples power consumption of the facility. The analyzer is configured to disaggregate the power cycles of the condenser unit from power cycles of the other appliances. According to other implementations, the condenser unit is a component of an air conditioner for a facility that includes other appliances and the detector samples power consumption of the condenser unit separately from the other appliances. According to some implementations, the detector samples power consumption of appliances and devices of a facility, and the power consumption and performance of these appliances and devices is affected by their operating environment.
In some implementations, the analyzer is configured to receive weather data and to use the weather data in conjunction with the sampled power consumption time series to determine the characteristics of the local operating environment. For example, the weather data may include one or more of temperature, humidity, solar irradiance, cloud cover, and wind speed.
In some implementations of the system the analyzer extracts power cycles of the condenser unit from the power consumption time series by comparing the sampled power consumption time series to a threshold. The analyzer may dynamically determine a threshold, e.g., an optimal threshold, to use for extracting the power cycles.
In determining characteristics of the local operating environment, the analyzer may determine temperature of the local operating environment based on the power consumption of the condenser unit. The analyzer may determine air flow around the condenser unit based on wind speed used in conjunction with variation in the temperature of the local operating environment of the condenser unit. Alternatively or additionally, the analyzer may determine shading of the condenser unit based on transitory decreases in the power consumption of the condenser unit as related to position of the sun and cloud cover. Alternatively or additionally, the analyzer may determine relative humidity of the local operating environment of the condenser unit based on a difference between power consumption during relatively less shaded conditions and power consumption during relatively more shaded conditions of the condenser unit.
The analyzer may be further configured to flag one or more facilities for interactions, targeted communications, maintenance, or outreach from a party that has an interest in the facility, the appliance, or the energy consumption of the facility.
Some embodiments are directed to a method of determining a local operating environment of a refrigerant condenser unit. The method involves sampling power consumption of a refrigerant condenser unit and determining characteristics of a local operating environment of the condenser unit from the power consumption. An output is generated that includes information about the characteristics of the local operating environment.
According to some implementations, the characteristics of the local operating environment include one or more of shading of the condenser unit, temperature of the condenser unit, relative humidity of the environment around the condenser unit, and air flow around the condenser unit.
According to some implementations, the method includes receiving weather data for a location in the vicinity of the operating environment from an external source and using the weather data in conjunction with the power consumption of the condenser unit to determine the characteristics of the local operating environment. For example, the weather data can include one or more of temperature, humidity (relative an/or absolute), cloud cover, solar irradiance, and wind speed.
According to some implementations, customers are sent information relating to incentives, e.g., to increase efficiency and/or lower power consumption based on the generated output.
The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.
The local operating environment of a refrigerant condenser unit, such as a condenser unit of an air conditioner system, affects its power consumption. Characteristics of the local operating environment have traditionally been determined by manual inspection, such as an in-person audit of the condenser unit or inspection using aerial or satellite photography. Manual inspection is time consuming, costly, and potentially disruptive to the consumer, while aerial or satellite photography may be unavailable, out-of-date, inaccurate, and/or intrusive.
Embodiments described herein are directed to systems and methods for determining characteristics of the local operating environment of a outdoor condenser unit based on the power consumption of the condenser unit. The local operating environment is the environment within an area that affects operation of the condenser unit, e.g., within about 10 ft. of the condenser unit. The characteristics of the local operating environment may include one or more of shading of the condenser unit, local operating temperature, insolation, local humidity, airflow/ventilation of the condenser unit and/or amount of protection of the condenser unit from weather conditions. The weather conditions may include for example, the temperature, humidity, irradiance, wind speed, and/or any other conditions that are globally present near the condenser unit. For example, the weather conditions may be those available from weather data, wherein the weather data can be obtained locally from sensors or obtained from an external server. After one or more characteristics of the local operating conditions are determined, a consumer may be notified of the local operating conditions of the condenser unit and may be offered incentives to alter the local environment of the condenser unit in a way that would increase efficiency of the condenser unit and/or lower power consumption of the condenser unit.
The system 100 includes an analyzer 130 configured to analyze the power consumption time series data provided by the detector 121, 122 to extract power cycles of the condenser unit 110. In implementations wherein the sampled power consumption time series includes aggregated power consumption of the condenser unit 110 and other appliances 105 of the facility 101, the analyzer 130 is configured to disaggregate the sampled power consumption time series of the condenser unit 110 from that of the other appliances 105. The analyzer 130 is configured to use the power cycles to determine the local operating environment of the condenser unit, e.g., shading, local temperature, local humidity (relative or absolute), ventilation/airflow around the condenser unit and/or exposure/protection of the condenser unit to weather conditions. In some embodiments the analyzer may be coupled through a wired or wireless communication channel to a external source, e.g., remote server 140, that provides weather data to the analyzer 130. For example, the weather data received from the server can be time stamped data that includes temperature, relative and/or absolute humidity, cloud cover, wind speed, irradiance data, etc. at a location that includes the local operating environment. Note that the weather data, e.g., temperature, humidity, in the surrounding area of the condenser unit may or may not accurately reflect the local operating environment of the condenser unit. For example, weather data does not take into account factors of the condenser unit environment, such as the placement of the condenser unit with respect to a building, shading of the condenser unit by plants and/or other structures, and/or exposure of the condenser unit to wind, sun, moisture, and/or other local operating conditions. The analyzer may optionally use the weather data in conjunction with the sampled power consumption time series to determine characteristics of the local operating environment of the condenser unit.
If the power consumption of the facility is sampled, the power consumption, e.g., power cycles, of the condenser unit are disaggregated from the power consumption of other appliances of the facility. The analyzer may extract 220 the power cycles of the condenser unit from the sampled data. The analyzer determines 230 characteristics of the local operating environment of the condenser unit based on the power consumption of the condenser unit.
The analyzer generates 250 an output that includes information about the local operating environment of the condenser unit. Optionally, in some embodiments the analyzer may receive 240 weather data, e.g., from a remote external source, and use the weather data in conjunction with the sampled power consumption time series of the condenser unit to determine the local operating environment of the condenser unit.
In some embodiments, the analyzer may receive information from multiple facilities and identify facilities that have a condenser unit with a local operating environment that causes the efficiency and/or power consumption of the condenser unit to be sub optimal. These facilities may be targeted for communications, maintenance, or outreach to encourage consumers responsible for the facilities to alter the local operating environment of the condenser unit so that the condenser unit uses less power and/or provides more efficient power consumption. Alteration of the local operating environment of the condenser unit can involve actions such as moving the condenser unit, building an enclosure around the condenser unit, building a sun shade over the condenser unit, planting shade bushes/trees and/or other landscaping near the condenser unit, etc.
The power cycles of the condenser unit can be extracted from the power consumption time series by thresholding the power level of the power consumption samples against a predetermined threshold value. In some cases, the threshold value can be dynamically determined, for example by selecting a level that is half the maximum recorded power level in the recent recording history. In either case, the times the condenser is on can be determined, as well as its average power level during the cycle. The characteristics of the local operating environment typically fluctuate, and the analysis must account for the relevant time scales of these variations. In the preferred embodiment, the characteristics of the local operating environment are assumed to change on a time scale that is much longer than the duration of the power cycles so that power cycle averages are meaningful. In instances when the characteristics of the local operating environment vary rapidly with respect to the duration of power cycles, the inferred characteristics of the environment represent time-averaged parameters.
In some embodiments, the characteristics of the local operating environment of the condenser unit include local temperature in the area of the condenser unit and the analyzer is configured to determine local temperature.
In some embodiments, the characteristics of the local operating environment of the condenser unit include local relative humidity in the area of the condenser unit and the analyzer is configured to determine local relative humidity. The power consumption of the condenser unit may be correlated to local relative humidity. In the case of an air conditioning system, higher humidity leads to an increase in the heat capacity of the air in the local operating environment, which in turn increases the latent capacity of the system. This may cause an increase in the duty cycle if the volume being cooled also experiences higher humidity. Thus, based on the correlation between local relative humidity and power consumption, if the local temperature is known, e.g., from a thermometer, approximate changes in the local relative humidity can be inferred from the power consumption variations.
In some embodiments, the characteristics of the local operating environment of the condenser unit include shading of the condenser unit and the analyzer is configured to determine the presence and/or amount of shading. The analyzer may determine a degree of shading based on the magnitude of condenser power consumption variation throughout the day. A fully insolated condenser in a vapor compression system will have a greater degree of power variation than one that is not insolated due to the direct heating of the device and ambient air under sunlight. This in turn affects the pressure of the refrigerant within the vapor compression circuit and the power consumption as described previously. Furthermore, if the amount of shading varies throughout the day, the effect of shading can be observed as a disproportionate change in the condenser power draw with respect to the ambient temperature. In some embodiments, the presence of shading can be determined by transitory decreases in the power consumption envelope of the power cycles of the condenser unit.
According to some embodiments, the characteristics of the local operating environment of the condenser unit include airflow around the condenser unit and the analyzer is configured to determine the airflow. For example, all else being equal, if the power variation does not differ significantly between times of high and low wind, the analyzer may determine that the condenser environment is not well ventilated or is shielded from the wind. Alternatively, if the power variation does not differ significantly between times of high and low relative humidity or other confounding weather parameters, the analyzer may determine that the condenser is likely in an environment with regulated or buffered humidity.
According to some embodiments, the characteristics of the local operating environment of the condenser unit include exposure of the condenser unit to weather conditions such as sun and wind, etc. and the analyzer is configured to determine whether the condenser unit is exposed to the weather conditions and/or an amount of protection of the condenser unit from the weather conditions. Exposure to weather conditions may include exposure to wind, cloud cover, irradiance, temperature, humidity, and/or other weather conditions, for example. The analyzer can correlate weather conditions to observed parameters of the power consumption envelope of the condenser unit. For example, persistent clouds and high winds will generally produce cooler condenser units during the daytime, so the power consumption envelope is not likely to vary as much in amplitude over a day when these weather conditions are present relative to days in which temperature, cloud cover, and solar irradiance vary throughout the day. The analyzer may be configured to correlate the power consumption envelope amplitude with quantitative measures of wind speed and cloud cover to determine the degree of exposure of the condenser unit to environmental elements which provides a measure of how protected the condenser environment is, e.g., how “outdoors” the condenser environment is. For example, if there is high correlation between weather conditions (e.g., including wind and/or irradiance) and power consumption of the condenser unit, the analyzer may determine that the condenser unit is in an exposed location. If there is little correlation between the weather conditions and power consumption of the condenser unit, the analyzer may determine that the condenser unit is protected, e.g., because it is housed in an enclosure.
The analysis may determine 765 a relative degree or amount of protection of the condenser unit based on the correlation between the weather conditions and the variation of the power consumption envelope. For example, the degree or amount of protection may be expressed as a parameter value between 1 and 10 such that if the parameter value is high, this is an indication of a relatively high amount of protection from the weather conditions and if the parameter value is low it indicates a relatively low amount of protection from the weather conditions. The analyzer may generate 780 a signal that includes information about whether the condenser unit is protected from certain weather conditions, (e.g., 1=exposed to sunlight, 0=shaded) and/or an amount of protection from the weather conditions, e.g., value from 1 to 10 that indicates an amount of protection). Alternatively, this analysis may evaluate multiple facilities only on a comparative basis without determining an absolute degree of protection from weather conditions for each facility. For example, based on a comparative analysis, the analyser may determine that one facility contains a condenser more protected from the weather than another facility.
Based on the analysis of the local operating environment of the condenser unit, a utility with data on multiple condenser units can select from these analyses a group of consumers or facility operators to receive incentives, instructions, suggestions, and more generally, communications, related to reducing energy consumption, e.g., air conditioning energy consumption, by adding shielding from the sun. For example, this may be in the form of planting trees or constructing awnings. After offering such incentives, the same analysis used to identify the targeted facilities could be used to evaluate the effectiveness of the energy efficiency programs.
The approaches discussed herein can be used to make a broad comparison of the local operating environments of condenser units without the time and expense of a manual inspection. Furthermore, the approaches allow for continuous long-term monitoring of such environments, allowing the recommendation of maintenance. The approaches disclosed herein provide the ability to compare different units. The relative values provided by this comparison can be of great value even in cases where quantitative accuracy is lower. The approaches discussed above may not be as accurate as going to the facility and surveying the environment, however, the cost/benefit ratio of the disclosed approaches is superior because of the information that is obtainable at reduced cost. The approaches discussed herein are not limited to external (outdoor) condenser units. Interior condenser units may also be analyzed in a similar fashion. For example the ambient temperature variations of a condenser enclosed in a room may be determined from the methods described previously. In these cases direct insolation and/or other external weather conditions are not expected to have a major effect on the power consumption of the condenser unit if it is completely enclosed in a room or other controlled environment.
Air conditioning and/or other vapor compression systems operating in controlled or extreme environments may be monitored this way to provide a simple non-intrusive measurement of such environments.
Characteristics of the local operating environment of a condenser unit, e.g., an air conditioner condenser, can be determined from power consumption data without requiring additional measurement apparatus or manual inspections. The characteristics of the local operating environment can include, for example, local temperature over time, local relative humidity over time, relative shading from insolation, airflow around the condenser unit, amount of exposure of the condenser unit to weather conditions. The analysis goes beyond the simple question of which air conditioners use more energy, and attempts to provide a reason for higher air conditioner energy usage due to the dependence of condenser power consumption on its ambient operating environment. Inferences about the local operating environment of a condenser unit can be used to targeting incentive programs that recommend modifications of the condenser environment to improve energy efficiency. More generally, these inferences allow for indirect measurement of local operating environment characteristics in situations in which it would be inconvenient or impossible to perform a direct measurement.
Approaches discussed herein involve methods and systems for remotely determining characteristics of air conditioner condenser local environments. The characteristics can be determined from high resolution power use data from either disaggregation from power consumption data obtained from facility power line or a dedicated power consumption monitor. High resolution means that the individual power cycles of the compressor can be clearly resolved (e.g., about 1 minute resolution). The characteristics of the local operating environment of the condenser unit may include local temperature, insolation, and wind speed or air flow, for example. These characteristics may be obtained continuously over time. According to some aspects, energy efficiency programs can be targeted to consumers based on these characteristics. The energy efficiency programs may include one or more of providing incentives to improve condenser shading (e.g. by constructing shades or planting trees, providing incentives to improve condenser ventilation, and/or other such targeted communications.
The analyzer may be implemented as a processor or circuit configured to implement the processes outlined by the flow diagrams discussed herein. The detector and/or analyzer described herein may be implemented in hardware or by any combination of hardware, software and/or firmware. For example, in some embodiments, all or part of the analyzer may be implemented in hardware. In some embodiments, the analyzer may be implemented by a microcontroller implementing software instructions stored in a computer readable medium.
The foregoing description of various embodiments has been presented for the purposes of illustration and description and not limitation. The embodiments disclosed are not intended to be exhaustive or to limit the possible implementations to the embodiments disclosed. Many modifications and variations are possible in light of the above teaching.
