Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B49/00—Arrangement or mounting of control or safety devices
  • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
  • F25B49/022—Compressor control arrangements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F11/00—Control or safety arrangements
  • F24F11/70—Control systems characterised by their outputs; Constructional details thereof
  • F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
  • F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
  • F24F11/85—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using variable-flow pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2600/00—Control issues
  • F25B2600/02—Compressor control
  • F25B2600/025—Compressor control by controlling speed
  • F25B2600/0251—Compressor control by controlling speed with on-off operation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2600/00—Control issues
  • F25B2600/23—Time delays

Definitions

• the invention relates in general to devices that consume electrical energy in the process of generating a cooling medium used for the purposes of reducing the temperatures within an area requiring reduced temperatures .
• This invention is particularly suited to reducing power consumption in refrigeration and air conditioning units.
• Air Conditioning/Cooling/Refrigeration systems which utilize compressors, are least efficient when starting up. Prior to reaching optimum running conditions, the average net BTU output of the refrigeration system is below its rated capacity. The optimum run conditions of a refrigeration system are not obtained until all of the component parts of the system have obtained their design operational temperatures . This can take considerable time after the compressor starts because the thermal inertia of each device, which was just off and is relatively hotter than when running, must be overcome.
• Coolant-media usually refrigerant gas
• heat-exchangers the evaporator (the heat- exchanger used to absorb heat from the area to be cooled and transfer that heat to the coolant-media) ; and the Condenser, the heat-exchanger used to release heat from the coolant-media to the external ambient environment .
• Coolant-media piping the Coolant-media piping.
• the invention increases the net BTU output of the refrigeration system by cycle control of the compressor. By intelligently increasing the delay between compressor run cycles, (the amount of which has been experimentally proven and to be within reasonable limits) longer more efficient (higher net BTU) output cycles are generated.
• the cooling system is over-sized. This "over-sizing" condition exists, within a typical properly designed system, about 85% of the time and causes the cooling system to cycle the compressor in an inefficient and energy consuming fashion.
• the present invention seeks to:
• the invention through the use of computer technology, is able to determine the thermodynamic loading imposed upon the compressor, without the need of any additional sensors, and to alter the compressor cycling pattern in such a fashion as to cause the cooling capacity of the system to more closely match the demand of the system.
• This more efficient ratio of capacity vs . demand causes a more efficient use of each compressor cycle and thereby a reduction of electric consumption.
• Short-cycling causes undo stress on the compressor as well as much greater than normal electrical demands due to locked-rotor conditions which can occur as a result of non-pressure-equalization within the compressor. This condition is caused by an insufficient time-lapse between when the compressor is stopped and then restarted.
• Another factor of short-cycling is the excess heat buildup in the motor windings which can be caused by repeated rapid starting of the compressor.
• the invention incorporates an anti- short-cycling algorithm as part of its program.
• the invention is therefore desirable for the invention to be an energy saving device capable of being used in cooling energy value sensor (such as a thermostat or pressuretrol) demand type control systems. It is not limited to such applications, but would also be suited for use with energy management systems. This invention would be suitable for new, retrofit and original equipment manufacturer (OEM) installations. It is also the invention's intent to be simple to install and not require any programming or adjustments.
• cooling energy value sensor such as a thermostat or pressuretrol
• OEM original equipment manufacturer
• Figure 1A is a diagrammatic representation of a typical refrigeration systems, using Thermostat control.
• Figure IB is a diagrammatic representation of a typical refrigeration systems, using pressure control.
• Figure 2 is a typical installation wiring diagram.
• Figure 3 is an electronic schematic.
• Figure 3A is another embodiment of the schematic of Figure 3.
• Figure 4 is a chart graphing system vs . load characteristics with and without the invention.
• Figure 5 is a chart graphing compressor cycling pattern for given load, with and without the invention, portraying cycle reduction with the invention.
• Figure 6 is a chart graphing compressor cycle pattern with and without the invention illustrating the maximum on-time effect of the invention on the compressor cycling when the compressor would not normally cycle.
• Figure 7 is a chart graphing compressor cycles with and without the invention, displaying the effect of the anti-short-cycling algorithm.
• FIG. 1A shows a refrigeration system, generally designated 2, which includes the present invention.
• the system comprises a compressor 4, which pumps high pressure gas through high pressure pipe 6 to condenser 8.
• Fan 10 is propelled by motor 12, and drives air 14 across condenser 8 to cool the condenser coils 9, and the gas therein, causing the gas to condense to liquid and give up its heat of condensation.
• cooling air 14 Through the length of the condenser 8, large amounts of heat are lost to cooling air 14, which brings down the temperature and heat content of the media leaving the condenser, bringing said media to a liquid state.
• the liquid media is driven by pressure and it flows from condenser 8 through liquid pipe 16.
• Liquid media flows along the liquid pipe 16, to evaporator 18, where fan 20, driven by motor 22, drives hot air 24 to be cooled by the evaporator 18.
• the liquid media from liquid pipe 16, in evaporator 18 absorbs heat from the air 24, and the media evaporates, absorbing the heat of evaporation, and exits along low pressure gas pipe 26, returning to compressor 4, which again drives it through its cycle via high pressure gas pipe 6.
• thermostat 28 controls fan motor 22, by closing a relay 29 between current source 30 and fan motor 22. Absent the invention, thermostat 28 would simultaneously close relay 31 between current 32 and compressor 4, so that current could flow across relay 31 and would actuate power compressor 4.
• control apparatus 34 of the present invention interrupts the connection 36, which provides voltage to relay 31, and thereby prevents the compressor 4 from turning on. This results in a delay, which is controlled according to the program outlined further below.
• control apparatus 34 is interposed in the wire 39 between the compressor 4 and energy value sensor, which is pressuretrol 40.
• Pressuretrol 40 is typically found as the temperature equivalent sensor on a refrigeration unit.
• a program also provides an appropriate delay to increase efficiency.
• FIG. 2 is a typical installation wiring diagram which shows a control unit 34 of the present invention, wired into the cooling circuit.
• Figure 2 shows control circuit power 42, which may be 230, 115 or 24 volts AC in the embodiment shown depending on which contact 44 a, b, or c it is attached to.
• Wires 44-46 supply control circuit power to control unit 34.
• Control wire 36 or 39 would provide control voltage to compressor contactor relay 31, but is broken so that yellow wire 48 and blue wire 49 insert control unit 34 into the circuit to prevent the compressor from operating until an appropriate delay has intervened.
• FIG. 3 is a more detailed circuit diagram of the control unit 34.
• AC power is supplied by wires white 44 and brown 46 to transformer 47, then to rectifier 50, comprising four ring diodes, which rectifies the AC to DC.
• Approximately 14 volt DC is output across smoothing capacitor 56 to voltage regulator 57 across bypass capacitor 58 to pin 1 of BS-1.
• BS-1 distributes 12 volts DC to control circuit 60 and its micro-controller chips 61 and memory 62 via voltage regulating chip 63 and power-on reset chip 64.
• Light Emitting Diode 101 (LED) indicates mode status .
• LED 102 indicates if an energy value sensor is calling for compressor.
• Optoisolator 104 provides a sensor call to the controller over a wide range of possible call voltages, making this unit well suited for a variety of cooling systems.
• Controller 34 operates according to the computer program at the end of this specification, entitled "COOLING ROUTINE”.
• the program incorporates a 180 second anti-short-cycling delay to always avoid starting the compressor within 180 seconds of compressor shut down. This is sufficient time to reduce undue stress on the compressor, as well as much greater than normal electrical demands, due to locked-rotor conditions, by allowing pressure-equalization within the compressor. A 180 second rest reduces excess heat buildup in the motor windings which heat can be caused by repeated rapid starting of the compressor.
• An anti-short-cycling algorithm tests off-time against the program constant MINOFFTIME, before allowing the compressor to start.
• the compressor off-time has been greater than 1 hour
• the compressor is started immediately upon a call for cooling, the counter is reset, and a new count begins. If off-time has not been greater than an hour, the delay is calculated as 10% of the last off time, and a countdown for that interval from the sensor call continues . Once the countdown ends, the compressor relay actuates the compressor, and a new timecount starts.
• the sensor call ends, which starts a new off-time count; or a substantial run time elapses, sufficient to bring the space to be cooled to equilibrium, such as an hour, at which time the compressor is given a short rest, but sufficient to allow compressor pressure equalization and compressor motor cooling, such as a 6 minute rest, before restarting.
• Figure 4 graphs the difference between: standard compressor on/off time cycles, and the compressor on/off time cycles with the present invention, under three different load conditions: loads A, B, and C.
• Tl, T6 and Til represent points on the temperature or pressure graphs that correspond to points when the compressor is started.
• T3 , T8 and T13 correspond to the temperature or pressure levels when the compressor is stopped.
• T2 correspond to the new temperature or pressure compressor start points.
• T4, T9 and T14 correspond to the respective longer intervals before the compressor stop points.
• T0-T1, T5-T6 and T10-T11 are the time intervals from the last compressor shut-down to a point when there is a need for cooling, hereinafter the off-call-time .
• T0-T2, T5-T7, and T10-T12 are the new off-intervals required due to the invention, including the invention's extended off-intervals of T1-T2, T6-T7 and T11-T12.
• Figure 5 graphs the effect of a load, over seven cycles of a conventional cooling system, without the present invention (top) . As can be seen on the bottom of figure 5, the same load is handled in only five on-cycles, with reduced on-time, with the present invention. Temperature excursions beyond the high point are insignificant and brief. The graph also illustrates the compressor response either to temperature or cooling media pressure, depending on whether the energy value sensor is a thermostat or a pressuretrol .
• Tl represents the compressor turn-on point along the temperature or pressure curves without the invention
• T2 represents the new turn-on point and includes the extended off- time T1-T2
• T3 corresponds to the turn-off point of the temperature or pressure curves without the invention
• T4 with the invention.
• Figure 6 graphs a saturation load. Without the invention, the compressor runs continuously. The invention gives the compressor a 6 minute rest (T3-T4; T5-T6; etc.) every 54 minutes (T2-T3, T5-T6, etc.), to cool down, to save energy in the brief off-time. Temperature (not graphed) is largely unaffected by this rest period.
• FIG. 7 graphs a short cycle restart without the invention.
• the T1-T2 interval is too short to equalize compressor pressure or to cool the motor coils.
• a severe and power consuming electrical load results, that might even burn out the motor.
• the short compressor off-time (T1-T2) is extended by T2-T3 to an adequate 3 minutes (T1-T3) , resulting in an easier starting load on the motor.
• SYMBOL FLAG_REG BO 'FLAG BYTE, CONTAINS BITS BO - B7
• SYMBOL DWNCNTFLAG BIT2 'set when counting down for delay
• SYMBOL PERCOUNTER W2 'temp reg for percent calculation
• SYMBOL MULTLIM W3 ' reg used for multiplier upper limit
• SYMBOL PERCENT_DELAY 10 'used for delay time mutiplyer factor
• SYMBOL OFFTIME 360 ' rev2 — 360 forced off cycle time
• DIRS %10000110 'SETS PINS 1,2 AND 7 FOR OUTPUT
• MAXCOUNTER 0 ' rev2 - set to known value
• MULTLIM 65535 / PERCENT_DELAY 'set multlim to value, used in off time calculation
• PAUSE 450 'loop time delay used for timing
• COUNT COUNT ⁇ 1 'generates seconds
• GOSUB COUNTUP counts up during comtressor off time
• COUNTER COUNTER + COUNT MAX 65534
• MINOFFFLAG TRUE GOTO COUNTUP: COUNTDWN:
• COUNTER COUNTER - COUNT
• COUNTER COUNTER MIN 0

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Air Conditioning Control Device (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)
• Control Of Positive-Displacement Pumps (AREA)
• Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
• Compressor (AREA)

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Citations (6)

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• 1998
  • 1998-01-26 DE DE69837347T patent/DE69837347T2/de not_active Expired - Lifetime
  • 1998-01-26 WO PCT/US1998/001550 patent/WO1999032838A1/fr active IP Right Grant
  • 1998-01-26 AU AU62514/98A patent/AU747039B2/en not_active Ceased
  • 1998-01-26 AT AT98904711T patent/ATE356963T1/de not_active IP Right Cessation
  • 1998-01-26 CN CN98813780A patent/CN1125297C/zh not_active Expired - Fee Related
  • 1998-01-26 EP EP98904711A patent/EP1040304B1/fr not_active Expired - Lifetime
  • 1998-01-26 ES ES98904711T patent/ES2285761T3/es not_active Expired - Lifetime
  • 1998-01-26 NZ NZ505835A patent/NZ505835A/en not_active IP Right Cessation
• 2001
  • 2001-04-04 HK HK01102439A patent/HK1033598A1/xx not_active IP Right Cessation

Patent Citations (6)

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