DSM ENABLING OF ELECTRO MECHANICALLY CONTROLLED REFRIGERATION SYSTEMS
An energy saving defrost control system for reducing power consumption of an electromechanically controlled refrigerator is provided. The system includes a defrost timer adapted to control a compressor according to an established run time, a defrost heater control operatively connected to the defrost timer and configured to activate a defrost heater in response to a timeout by the defrost timer, a DSM module responsive to demand state signals from an associated utility indicative of at least a peak demand and off peak demand state, and a time delay latching relay having a timer and configured to switch to one of a low position and a high position based on the demand state signal.
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This disclosure relates to energy management, and more particularly to energy management of household refrigeration appliances. The disclosure finds particular application to adapting electromechanically controlled refrigerators for operation in home energy management systems.
Many utilities are currently experiencing a shortage of electric generating capacity due to increasing consumer demand for electricity. Currently utilities charge a flat rate, but with increasing cost of fuel prices and high energy usage at certain parts of the day, utilities have to buy more energy to supply customers during peak demand, which causes prices to rise during these times. If peak demand can be lowered, then a potential huge cost savings can be achieved and the peak load that the utility has to accommodate is lessened. In order to reduce high peak power demand, many utilities have instituted time of use (TOU) metering and rates which include higher rates for energy usage during on-peak times and lower rates for energy usage during off-peak times. As a result, consumers are provided with an incentive to use electricity at off-peak times rather than on-peak times and to reduce overall energy consumption of devices at all times.
To take advantage of the lower cost of electricity during off-peak times, systems have been provided that can automatically operate power consuming devices during off-peak hours in order to reduce consumer's electric bills and also to reduce the load on generating plants during on-peak hours. Active and real time communication of energy costs of devices to the consumer enables informed choices of operating the power consuming functions of the devices. Although these systems are capable of being run automatically according to demand period, a user may choose to override the system and run a device normally, or delay the operation of the system for a particular period of time.
One method for providing low-cost reduction of peak and average power is to implement a simple demand side management “DSM” control device, also known as a smart appliance module “SAM”, in an existing electromechanical appliance that will adjust, or disable power consuming elements to reduce maximum power consumption. However, such a DSM/SAM add-on device will generally cut off the power to an entire appliance. Therefore, there exists a need for reducing peak power consumption without extinguishing all power to the appliance.
Electronically controlled refrigerators generally include a microcomputer that has control over various functions of the appliance, such as temperature set point for example, to which can be programmed to provide an appropriate DSM/SAM response. For example, when a utility transmits a signal corresponding to a peak demand period, the microcomputer may block access to, or temporarily shuts off, particular features, such as the quick chill, quick thaw, or quick cool features that have associated fans that require additional energy. In addition, or alternatively, the microcomputer may adjust the temperature set point of the freezer, allowing the freezer compartment temperature to increase slightly until the peak demand period is over. At the conclusion of the high rate period, the microcontroller resets the set point to the original set point temperature. The microcontroller may additionally delay a scheduled defrost if the defrost is set to occur during a peak demand period.
While electronically controlled refrigerators can adjust energy usage in response to a “high demand”, many refrigerators include less technically sophisticated controls that do not use a microprocessor.
The subject application provides a system that enables refrigerators that are not equipped with electronic controls to effectively adjust energy usage in response to “high demand” conditions.
SUMMARY OF THE DISCLOSUREAccording to one aspect of the present disclosure, an energy saving defrost control system for reducing power consumption of an electromechanically controlled refrigerator is provided. The system includes a defrost timer adapted to control a compressor according to an established run time, a defrost heater control operatively connected to the defrost timer and configured to activate a defrost heater in response to a timeout by the defrost timer, a DSM module responsive to demand state signals from an associated utility indicative of at least a peak demand and off peak demand state, and a time delay latching relay having a timer and configured to switch to one of a low position and a high position based on the demand state signal.
According to another aspect of the present disclosure, a method for reducing power consumption of an electronically controlled refrigeration system by disabling a defrost cycle during periods of peak demand. The method comprises controlling a compressor according to the established run time of a defrost timer, activating a defrost heater in response to a timeout by the defrost timer, wherein the activation initiates a defrost cycle, operatively associating a DSM module with the defrost timer, wherein the DSM module is responsive to demand state signals from an associated utility indicative of at least a peak demand and off-peak demand state, providing said DSM module with a time delay latching relay with first and second contacts, and switching the time delay latching relay into one of a high and low position based on the signal indicative of a peak demand period.
According to yet another aspect of the present disclosure, a DSM enabled defrost control system capable of reducing peak power consumption in an electromechanically controlled refrigeration system is provided. The defrost control system comprises a defrost timer operatively associated with a compressor configured to operate the defrost timer according to an established run time, a defrost heater control configured to activate and deactivate a defrost heater based on the compressor run time, a DSM module associated with the defrost timer and responsive to demand state signals from an associated utility indicative of at least a peak demand and off peak demand state, and a time delay latching relay having first and second contacts. The DSM module is configured to switch said time delay latching relay to one of a high and low position based on the demand state.
Still other features and benefits of the present disclosure will become apparent from reading and understanding the following detailed description.
An exemplary embodiment of an energy management system for household appliances 100 is illustrated in
For example, under normal conditions, it is desirable to maintain the temperature of the freezer in a domestic refrigeration appliance at 0° F., plus or minus a few degrees. Therefore, the cold control for the freezer would be calibrated such that the center setpoint position of the selector would provide a freezer compartment at 0 degrees F. If the user selects the 0 degree F. set point, the cold control would cycle the compressor to maintain the temperature in the freezer at approximately 0 degrees F. The bourdon tube located in an area of the freezer senses the temperature in its vicinity and if the temperature rises 1° or 1.5°, the pressure in the bourdon tube also rises, which causes the bourdon tube to expand and overcome the counter spring located on the other side of the diaphragm seal. By overcoming the counter spring, a contact is tripped to activate the compressor. The compressor will remain activated until the temperature in the freezer returns to the selected set point of 0° F., or other set point as the user may select. In accordance with the decreasing compartment temperature, the pressure in the bourdon tube also decreases and causes the counter spring to overcome the bourdon tube pressure acting on the diaphragm and open the contacts to deactivate the refrigeration system.
The cold control 120 includes an input selector, typically a rotatable shaft with a knob, for manually selecting the temperature set point. Adjusting the angular position of the shaft in one direction or the other alters the spring loading on the diaphragm seal, which follows to alter the selected setpoint temperature. Typically, the control is calibrated such that when the knob is at its center point, the set point temperature is the temperature at the midpoint of the selectable setpoint range, which for a freezer cold control is approximately 0° F. As the knob is rotated, the selected setpoint temperature is shifted up or down relative to the calibration point within established limits.
The system described herein adapts the above-described cold control for use with a DSM control module of an energy management system. With reference to
The bourdon tubes 122(a) (b) are attached to cold controls cc1 and cc2 such that they run parallel to each other with each tube located in the same compartment and are sensing the same temperature. The first cold control cc1 is calibrated to provide a first specific calibration temperature set point, as the midpoint setting for the control shaft. The second cold control cc2 is calibrated to provide a second calibration temperature set point different from the first at the midpoint setting for its control shaft. In the illustrative embodiment, the first calibration set point temperature is set at 0° F., and the second calibration setpoint temperature is set to a higher temperature of 6° F. As illustrated schematically in
When the DSM module indicates a period of peak demand, the binary output of the DSM module will drive the DSM controlled switching device R1 to open, causing the system to enter energy savings mode and allowing only cc1 to control. Since cc1 has mid set point of 6° F., the refrigerator will now cycle around the 6° F. set point +/− hysteresis. At the conclusion of the peak demand period, R1 is driven to close and the system returns to normal mode, wherein the cc2 commands control, returning the refrigerator set point to 0° F. +/− hysteresis. There will be a limit on how warm a user can calibrate cc1, and there will be a max temperature the user is allowed to dial in. Therefore, the warmest possible setting of the cold control available to the user will need to coincide with this maximum allowable setpoint for food preservation criterion. This ensures that a compartment does not get too warm during a peak demand period and ruin any contents therein.
Although the system described herein is discussed mainly in terms of controlling the temperature in a refrigerator freezer, the system may alternatively or simultaneously be implemented into the fresh food compartment of a refrigerator and other refrigerated devices controlled by electromechanical cold controls described herein, for example a wine chiller, with set point temperatures adjusted within the limits of the acceptable performance limits of the said device. In the refrigerator example, the fresh food and freezer systems may be independent from each other or interrelated, such that shifting the freezer temperature set point also shifts the temperature set point in the fresh food compartment by a comparable degree.
In an alternative embodiment, the same dual tier selectable temperature control concept is achieved, however with only one cold control device, rather than two separate cold control devices, as provided above. As best seen in
In one illustrative example, an insulated nickel chrome wire is coiled around a bourdon tube 122, which is connected to a single pole, single throw relay R1. The relay R1 is generally closed to enable the heater to deliver a very low calibrated wattage of heat to the bourdon tube 122. During a peak demand response, binary output from the DSM module 144 opens the DSM switching device R1 de-energizing the heating element 140. Without the heat from the heating element, the cold control 120 responds to the actual temperature in the compartment rather than a temperature that is offset by the heater, which has the effect of increasing the effective setpoint temperature by an amount determined by the wattage of the heater. In the illustrative embodiment, the wattage of the heater is selected to provide the desired effective increase of 6 degrees F., which is achieved with a minimal wattage heater. This wattage will be dependent on the design of the cold control, specifically the nature of the inert gas as well as the stiffness of the diaphragm spring. Therefore, the refrigerator's compressor and fans will be controlled to a setpoint temperature, which is 6 degrees higher than the user selected setpoint, until the peak demand period is over and the DSM module 144 closes the switching device and enables the heater once again, restoring the selected setpoint temperature as the effective setpoint temperature.
According to another aspect of the present disclosure, the heating means for the bourdon tube 122 is provided by a heat pipe 150 that extends from within the fresh food section (temperature of between approximately 37-44° F.) to add heat to the bourdon tube 122 that is exposed to freezer airflow, cycling at approximately 0° F. The heat pipe 150 acts as a conductive pipe that resides in the fresh food compartment. Since the fresh food compartment is typically at least about 37° F. and always significantly warmer than the Freezer, the pipe 150 will naturally conduct heat into the bourdon tube 122. If the heat pipe 150 is thermally connected to the bourdon tube 122 at all times, the offset is present continuously.
As best illustrated in
According to another embodiment of the present disclosure, a means of achieving a dual tier selectable set point may include equipping a cold control device 120 with multiple spring tension positions. Referring back to
As best illustrated in
In addition to adjusting the temperature set point of a refrigerator compartment, another circuit described herein and exemplarily illustrated in
The timer motor 182, which advances the timer, runs only when the refrigerator cold control 172 is energized and calling for cooling from the refrigerator compressor. The defrost cycle is terminated in this non-DSM refrigerator when the defrost timer advances beyond the design defrost time or the defrost termination thermostat 176 opens due to a specified temperature being reached in the evaporator.
In the case of the DSM enabled electromechanical refrigerator and with reference to
Without a time delay feature added to the relay, the DSM module would disable a defrost by way of contacts C1 and C2 for the entire length of time that the utility allotted for the demand response event. The defrost cycle would be disengaged until the utility pricing returned to a low cost state. While such suspension provides desirable energy reduction, suspension of defrost for a prolonged period may result in an undesirable build up of frost on the evaporator. To avoid such an occurrence, in the embodiment of the energy saving defrost control system of
The DSM module is configured to switch relay R2 to its second state on receipt of a signal indicating the beginning of a peak demand state or high rate period, and to return the relay to its first state on receipt of a signal signifying the return to an off peak state of the end of the high rate period. For example, when a DSM high price event occurs, the DSM module 144 drives the time delay latching relay R2 to open contacts C1 & C2. By so doing, the defrost timer motor 182 is halted such that a defrost cannot be initiated in the future until the DSM module returns the relay to its first state, which occurs either at the end of the DSM event or the time delay inherent to the time delay latching relay is satisfied. Also, if a defrost is already underway when the DSM event occurs, the opening of contact C2 will terminate the defrost until the event is over or until the time delay latching relay timer “times out” and returns the system back to normal, i.e., unlatches the relay.
The invention has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations.
Claims
1. A system for reducing the peak power consumption by a refrigeration system, comprising;
- a first electromechanical cold control calibrated to a first temperature setpoint;
- a second electromechanical cold control calibrated to a second temperature setpoint, said first and second cold controls each having a setpoint selector member, said setpoint selector members being operatively linked such that adjustment of one results in a corresponding adjustment of the other;
- a DSM module responsive to demand state signals from an associated utility indicative of at least a peak demand and an off peak demand state; and
- a DSM switching device responsive to said DSM module and operative to selectively render one or the other of said cold controls effectively operative to control the cooling system depending upon the demand state signal.
2. The system according to claim 1, wherein said first cold control is calibrated to a temperature set point of about 0° F.
3. The system according to claim 1, wherein said second cold control is calibrated to a temperature set point higher than the setpoint of the first cold control.
4. The system according to claim 3, wherein the DSM module causes the switching device to render said second cold control operative in response to a peak demand state signal, whereby the cooling system is controlled to a higher setpoint in response to a peak demand state signal.
5. The system according to claim 1, wherein the system controls the temperature in at least one of a freezer component and fresh food compartment of said refrigerator.
6. The system according to claim 1, wherein said DSM switching device is an electromechanical single pole, single throw relay device.
7. A method for reducing peak power consumption in an electromechanically controlled refrigerator having at least one compartment, said method comprising:
- mechanically linking a first cold control having a first adjustable switch to a second cold control having a second adjustable switch;
- calibrating the first cold control to a first temperature set point and the second cold control to a second temperature set point, wherein said second temperature set point is higher than said first temperature set point; and
- opening and closing a DSM switching device in response to a signal received from an associated DSM module indicative of at least a peak demand and an off peak demand state of an associated utility, wherein opening said DSM switching device shifts control from said first cold control to said second cold control, causing the temperature to be controlled to a higher setpoint temperature.
8. The method according to claim 7, further comprising opening said DSM switching device in response to receiving a signal indicative of a peak demand period.
9. The method according to claim 8, further comprising controlling the temperature by the second cold control when said DSM switching device is open.
10. The method according to claim 7, further comprising closing the DSM switching device during a non-peak demand period, whereby the temperature is controlled by the first cold control.
11. (canceled)
12. The method according to claim 7, further including calibrating said first cold control to about 0° F. and calibrating said second cold control to a temperature set point higher than the setpoint of the first cold control.
13. A system for reducing the power consumption in an electromechanically controlled refrigerator during periods of peak power demand, including at least a freezer compartment and a fresh food compartment, said system comprising;
- a cold control device being calibrated to a temperature set point;
- a bourdon tube having a first end operatively connected to said cold control, and a second end, opposite said first end, located in one of said freezer and said fresh food compartment;
- a heat source operative to supply a metered amount of heat to said bourdon tube; and
- a DSM switching device operatively controlled by an associated DSM module, wherein said DSM module is configured to receive a signal indicative of at least one of a peak or non-peak demand period of an associated utility.
14. The system according to claim 13, wherein said cold control device is calibrated to said temperature setpoint with the metered amount of heat being provided from said heating source.
15. The system according to claim 13, wherein said DSM module is capable of causing said DSM switching device to selectively enable and disable the heating of said bourdon tube by said heat source in response to a signal indicative of at least one of a non-peak and peak demand period respectively.
16. The system according to claim 15, wherein said DSM module causes said DSM switching device to disable the heating of said bourdon tube upon receiving a signal indicative of a peak demand period.
17. The system according to claim 13, wherein said heat source comprises an electric heating element.
18. The system according to claim 13, wherein said heating element comprises a wire heater coiled around said bourdon tube.
19. The system according to claim 13, wherein said heat source comprises a heat pipe housed in said fresh food compartment and projecting from said fresh food compartment into said freezer compartment for thermal engagement with said bourdon tube.
20. The system according to claim 19, further including a heat block, comprising a first portion attached to said bourdon tube and a moveable second portion in contact with said heat pipe.
21. The system according to claim 20, wherein said second portion is moveable into sufficient proximity to said first portion to enable heat flow from said heat pipe to said bourdon tube.
22. (canceled)
Type: Application
Filed: Nov 22, 2010
Publication Date: Mar 1, 2012
Applicant:
Inventor: John K. Besore (Prospect, KY)
Application Number: 12/951,451
International Classification: F25D 21/08 (20060101); F25D 21/06 (20060101);