Patent Application
20150195949
Not Applicable
Not Applicable
The disclosed embodiments generally relate to air conditioning units used in telecommunication shelters and, more particularly, to DX cooling units used in telecommunication shelters.
A telecommunications shelter is a small compact space designed to house telecommunications equipment. Controlling the temperature inside these shelters ensures that the housed electronic equipment is maintained in proper working condition. Generally, the shelters must be maintained at an indoor temperature of between 50° F. and 80° F. year round. Small DX units are often used to air-condition telecommunications shelters. Sometimes, two identical units are even installed in the same shelter. Due to the small size of telecommunications shelters and the influence of weather conditions on the load, these air-conditioning units generally vary in weight from a fraction of a ton to up to 5 tons.
Exhaust fans, vortex coolers, Peltier coolers, and passive cooling systems have all been used in the prior art to air condition telecommunications shelters. Various measures have also been taken in the prior art to improve the energy performance of shelter cooling systems. Improvements suggested include such measures as adding an economizer to the cooling unit, installing additions to the refrigeration pump, and introducing natural ventilation. Variable frequency drive technologies have also been attached to unit fan motors in the prior art for the purpose of attaining greater energy savings.
Even with these improvements, however, the compressors of DX-cooling units in the prior art are still configured to run at a constant speed. When at a constant speed, the compressor creates excessive cycling and consumes excess power under lower load conditions. In order to save energy, extend the life of the compressor, and lower costs, it would thus be desirable to operate the compressors of the DX-cooling units at a variable speed.
A novel control system is described in this application that can be integrated with an existing controller to improve the operating performance of a DX cooling unit. Since a variable frequency drive is installed only on the unit compressor, the system refrigeration capacity can be adjusted to a range that is relatively wider than in the prior art. The control system is able to not only simplify room temperature control, but also greatly reduce compressor cycling.
Accordingly, it is one aspect of an embodiment to reduce the amount of energy consumed, improve the system efficiency, and significantly reduce operational and maintenance costs compared with the prior art.
It is another aspect of an embodiment to reduce the on and off cycling of the compressor so as to extend the compressors lifetime.
It is yet a further aspect of an embodiment to implement modulating control to create a smoother room temperature profile.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to an embodiment of the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
In one embodiment, a method of controlling the air temperature in a telecommunications shelter using at least one air conditioning unit including at least one terminal board, at least one fan, at least one compressor, at least one supply air temperature sensor, and a room air temperature sensor associated with the telecommunications center is proposed. The method involves determining a supply air temperature using said supply air temperature sensor and determining a room air temperature using said room air temperature sensor. It also involves providing a speed modulation device configured in communication with and operable to control a speed of said at least one compressor and providing a controller in communication with and operable to control the speed modulation device and the at least one terminal board. The method further entails receiving, by the controller, a fault signal from the speed modulation device. The method further entails inputting into said controller a plurality of temperature control bands and inputting into said controller a temperature set point. The method further entails selecting an initial operating mode. It further entails controlling the speed modulation device and the at least one fan and compressor based on a control logic of the initial operating mode, and determining a relationship between the room air temperature, the temperature set point, and at least one of the plurality of temperature control band parameters. The method further comprises selecting at least one additional operating mode based on the stated relationship and controlling the speed modulation device and the at least one fan and compressor based on the control logic of the stated additional operating mode.
In another embodiment, a system for controlling the temperature of a telecommunications shelter housing at least one air-conditioning unit in communication with a terminal board and including at least one fan, at least one compressor, a supply air temperature sensor operable to determine a supply air temperature, and a room air temperature sensor operable to determine a room air temperature of the shelter is proposed. The control system comprises a speed modulation device configured in communication with and operable to modulate a speed of said at least one compressor and a controller configured in communication with and operable to control the speed modulation device and the terminal board of the at least one air-conditioning unit that activates and deactivates the associated at least one fan and compressor.
The controller of the control system is configured with a plurality of control modes comprising but not limited to an input mode, an off mode, a start-up mode, and a cooling mode. The input mode is configured to input parameters for the controller to read including the room air temperature and the supply air temperature, a fault signal from the speed modulation device, a user selected temperature set point for the at least one air conditioning unit, and a plurality of control band parameters indicative of an accepted temperature variation. In the embodiment, the off module is configured to deactivate the at least one compressor and speed modulation device and to operate the at least one fan at a full speed. The off module is configured to deactivate the fan when a difference between the room air temperature and the supply air temperature is less than a first band of the plurality of control band parameters. When the room temperature is higher than a summation of the room temperature setpoint and a second control band and the air conditioning system is deactivated for a predetermined period of time, the controller switches to the start-up mode. When the room temperature is higher than the summation of the room temperature setpoint and a third control band, the controller switches to the cooling mode. The start-up mode is configured to activate the at least one fan and operate the speed of speed modulation device at a start-up speed. When the start-up time of the controller is less than a predetermined period of time and the room air temperature of the shelter is less than the difference of the room temperature set point and the second control band, the controller switches to the off mode. When the start-up time is greater than a predetermined period of time, the controller switches to the cooling mode. The cooling mode is configured to activate the at least one fan and compressor and to modulate the speed of the modulation device based on the room temperature. When the room temperature is less than the difference between the room temperature set point and the second control band, the controller switches to the off mode.
The above-described features and advantages of the present disclosure thus improve upon aspects of those systems and methods in the prior art designed to calculate for
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the following figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Advantages, features and characteristics of the present disclosure, as well as methods, operation and functions of related elements of structure, and the combination of parts and economies of manufacture, will become apparent upon consideration of the following description and claims with reference to the accompanying drawings, all of which form a part of the specification, wherein like reference numerals designate corresponding parts in the various figures, and wherein:
When implemented, controller 116 is configured in signal communication with terminal boards 118 and 120, speed modulation device 114, and air temperature sensors 110 and 112. Power source 122 is configured in connection with speed modulation device 114. In some embodiments, power source 122 provides single-phase power, while in other embodiments it provides three-phase power. One of the primary purposes of power source 122 is to power fans 106 and 108 and compressors 102 and 104.
In the illustration, communications shelter 124 is a communications shelter air conditioned by either a single air-conditioning unit or two identical air-conditioning units. However, in other embodiments it can be served by additional or fewer units. In the figure, compressors 102 and 104 and fan motors 106 and 108 are existing compressors and fan motors for each unit. Shelter 124 also houses supply air temperature sensor 110 and room temperature sensor 112. The sensors are configured to measure the supply air temperature and room temperature, respectively, in shelter 124. Unit 1 and unit 2 existing terminal boards 118 and 120 are configured to command the start/stop function of fan motors 106 and 108 as well as that of unit compressors 102 and 104. Fan motors 106 and 108 are kept at a constant speed.
Speed modulation device 114 and controller 116 are configured in connection with the units serving shelter 124 and their (the units) terminal boards 118 and 120. In order to air-condition shelter 124, the supply air temperature of the existing air-conditioning unit as obtained from supply air temperature sensor 110, the room air temperature of shelter 124 collected by room air temperature sensor 112, and the fault signal obtained from speed modulation device 114 are input into controller 116. Based on this input data, controller 116 sends control commands to speed modulation device 114 and unit 1 and 2 terminal boards 118 and 120. Terminal boards 118 and 120 use the commands from controller 116 to start and/or stop the fans and compressors of the units. (In the figure, therefore, unit 1 terminal board 118 commands unit 1 compressor 102 and unit 1 fan motor 106. Likewise, unit 2 terminal board 120 commands unit 2 compressor 104 and unit 2 fan motor 108.)
Speed modulation device 114 is connected to controller 116 and compressors 102 and 104. Device 114 modulates the speed of compressors 102 and 104 to maintain the room temperature. If speed modulation device 114 has faults it sends fault signals to controller 116. Periodically, controller 116 will clear these faults and reset device 114.
Flow charts describing the control logic of controller 116 are illustrated in
The above-described features and advantages of the present disclosure thus improve upon aspects of those systems and methods in the prior art designed for air conditioning telecommunication shelters.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/924,931 filed on Jan. 8, 2014.
| Number | Date | Country | |
|---|---|---|---|
| 61924931 | Jan 2014 | US |
