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
  • F25B13/00—Compression machines, plants or systems, with reversible cycle
• • 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
  • F25B41/00—Fluid-circulation arrangements
  • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
  • F25B41/22—Disposition of valves, e.g. of on-off valves or flow control valves between evaporator and compressor
• • 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
  • F25B1/00—Compression machines, plants or systems with non-reversible cycle
  • F25B1/04—Compression machines, plants or systems with non-reversible cycle with compressor of rotary type
• • 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
  • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
  • F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
  • F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
• • 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
  • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
  • F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
  • F25B2313/02742—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using two four-way valves
• • 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
  • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
  • F25B2400/13—Economisers
• • 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
  • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
  • F25B2400/23—Separators
• • 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
  • F25B2600/026—Compressor control by controlling unloaders
  • F25B2600/0261—Compressor control by controlling unloaders external to the compressor
• • 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
  • F25B2600/25—Control of valves
  • F25B2600/2521—On-off valves controlled by pulse signals

Definitions

• This invention relates to a heat pump that is operable in both a cooling and a heating mode, and wherein at least one component is controlled by pulse width modulation techniques to vary the capacity of the heat pump.
• Refrigerant systems are utilized to control the temperature and humidity of air in various indoor environments to be conditioned.
• a refrigerant is compressed in a compressor and delivered to a condenser (or an outdoor heat exchanger in this case).
• heat is exchanged between outside ambient air and the refrigerant.
• the refrigerant passes to an expansion device, at which the refrigerant is expanded to a lower pressure and temperature, and then to an evaporator (or an indoor heat exchanger).
• the evaporator heat is exchanged between the refrigerant and the indoor air, to condition the indoor air.
• the evaporator cools the air that is being supplied to the indoor environment.
• the above description is of a refrigerant system being utilized in the cooling mode of operation.
• the refrigerant flow through the system is essentially reversed.
• the indoor heat exchanger becomes the condenser and releases heat into the environment to be conditioned (heated in this case) and the outdoor heat exchanger serves the purpose of the evaporator and exchanges heat with a relatively cold outdoor air.
• Heat pumps are known as the systems that can reverse the refrigerant flow through the refrigerant cycle, in order to operate in both heating and cooling modes. This is usually achieved by incorporating a four-way reversing valve (or an equivalent device) into the system design, with the valve located downstream of the compressor discharge port.
• the four-way reversing valve selectively directs the refrigerant flow through the indoor or outdoor heat exchanger when the system is in the heating or cooling mode of operation, respectively. Furthermore, if the expansion device cannot handle the reversed flow, than, for example, a pair of expansion devices, each along with a check valve, can be employed instead.
• the operation and control of refrigerant systems faces many challenges. One challenge is that the capacity for either cooling or heating demanded by an environment to be conditioned can vary. It would be desirable to only provide the required capacity, as the energy efficiency and comfort are then improved as the amount of unit cycling is reduced or eliminated. However, heat pumps have typically not been provided with the features assuring sufficient variability as may be desirable, in order to continuously match the required capacity to the capacity delivered by the unit without frequent cycling.
• a technique known as a pulse width modulation control has been provided.
• various components are provided with a pulse width modulation control that rapidly cycles the component "on” and “off to change the capacity.
• a suction pulse width modulation valve may be rapidly opened and closed to restrict the amount of refrigerant delivered to a compressor. While such pulse width modulation controls provide sufficient performance variability for air conditioning systems, they have not been incorporated into heat pumps to date.
• a four-way reversing valve selectively controls the flow of refrigerant from a compressor discharge to either an outdoor heat exchanger in a cooling mode, or to an indoor heat exchanger in a heating mode.
• the refrigerant flows through a complete cycle under either mode, and returns to the compressor.
• at least one component within the heat pump system is equipped with a pulse width modulation control.
• this component may be a suction pulse width modulation valve controlling the amount of refrigerant flowing through a suction line to the compressor.
• the component which is provided with a pulse width modulation control may be a compressor pump unit.
• a pair of scroll members is selectively held into contact, or allowed to move away from each other in a pulse width modulated manner, thus controlling the amount of refrigerant compressed by the compressor and delivered to other system components.
• the present invention is able to tailor the delivered capacity to meet desired capacity requirements for the refrigerant heat pump system.
• heat pumps are provided that are better able to match the delivered system capacity and the conditioned environment demanded capacity (and its latent and sensible components) either in the heating or cooling mode of operation.
• an economizer cycle is incorporated into the heat pump schematic to provide additional capacity control.
• the economizer cycle essentially taps a portion of the refrigerant flow through an auxiliary expansion device. That portion of the refrigerant flow is passed through an economizer heat exchanger along with the main refrigerant flow. Heat is exchanged between the two refrigerant flows, with the tapped refrigerant cooling the main refrigerant. The tapped refrigerant exits the economizer heat exchanger typically in a vapor state. This vapor is returned to the compressor at some intermediate point in the compression process.
• the main refrigerant flow passes to a main expansion device and then to a downstream heat exchanger (evaporator), having a greater cooling potential due to additional cooling obtained by passing through the economizer heat exchanger.
• a downstream heat exchanger evaporator
• an unloader function allows for at least a portion of the partially compressed refrigerant to be diverted to the compressor suction to reduce capacity.
• the several embodiments disclosed in this application thus allow the use of full capacity with pulse width modulation.
• the control also has access to the unloader function and the economizer function in combination with a modulation of one of the components to further control system capacity.
• Figure IA is a schematic of a first view.
• Figure IB shows an alternative method.
• Figure 2 shows an alternative schematic
• Figure 3 shows an alternative schematic
• Figure 4 shows an alternative schematic
• Figure 5 shows an alternative for a standard economizer heat exchanger.
• Figure IA shows a heat pump refrigerant system 20 incorporating a compressor 22 having a discharge line 23 supplying a compressed refrigerant to a four-way reversing valve 26.
• the four-way reversing valve 26 selectively communicates the refrigerant from the discharge line 23 either to an outdoor heat exchanger 24, when the system is operating in a cooling mode, or to an indoor heat exchanger 30, when the system is operating in a heating mode. In either case, the refrigerant passes from the heat exchanger it first encounters after leaving the compressor to a main expansion device 28. From the main expansion device 28, the refrigerant passes through to the second heat exchanger, and back to the four-way reversing valve 26.
• the four-way reversing valve 26 routes the refrigerant into a suction line 31 leading back to the compressor 22.
• a pulse width modulation valve 40 is positioned on the suction line 31.
• the pulse width modulation suction valve 40 can be rapidly cycled to control the amount of refrigerant flowing through the compressor. In this manner, the capacity of the refrigerant system can be controlled.
• such controls are known for use in the air conditioning systems, but have not been utilized in the heat pumps.
• FIG. 1B shows an embodiment 301, schematically. It is known that the orbiting scroll member 302 and the non-orbiting scroll member 304 of a scroll compressor may be biased together by means of gas pressure in a chamber 306. Opening and closing the valve 310 can control pressure in the chamber 306. As shown, the valve 310 communicates via a refrigerant line 308 with another pressure source that is at different pressure than pressure in the chamber 306, when the valve 310 is closed.
• valve 310 can be controlled by a pulse width modulation control 312.
• the two scroll members 302 and 304 can be allowed to periodically move away from, and come into contact with, each other.
• the scroll 302 can be allowed to move axially while the scroll 304 remains essentially stationary in the axial direction.
• the valve 312 can be located internal or external to the compressor.
• the control 42 (or 312) is operated to provide variation in the amount of refrigerant delivered by the compressor based upon any number of factors. As the capacity demand on the system 20 changes, then the pulse width modulation control can change the amount of refrigerant flowing through the compressor. Moreover, it may well be that less refrigerant would be desirably passed through the compressor in one of the cooling or heating operating modes. Again, the inventive control easily allows such a modification.
• FIG. 2 shows another embodiment system 100 wherein a second routing valve 102 is positioned to selectively route refrigerant from the heat exchangers 24 and 30 either into a main liquid line 103.
• Refrigerant flows through the routing valve 102 from either of the heat exchangers 24 or 30 into the liquid line 103.
• the refrigerant passes from the heat exchanger 30 or the heat exchanger 24 to the liquid line 103 initially, through an economizer heat exchanger 104 and then through the main expansion device 28. This refrigerant then flows back through the routing valve 102 downstream to the heat exchanger 24 or the heat exchanger 30 accordingly.
• a tap line 106 selectively taps a portion of the refrigerant from the liquid line 103 and passes that tapped refrigerant to an economizer expansion device 108.
• This refrigerant flows through the economizer heat exchanger 104 and cools the main refrigerant flow.
• a vapor injection line 110 returns the tapped refrigerant back to an intermediate compression point in the compressor 22. While the flow of the tapped refrigerant and the main refrigerant flow through the economizer heat exchanger 104 are shown in the same direction, in practice, it is typically preferable that they be in counter-flow relationship. However, for simplicity of illustration, they are shown flowing in the same direction. Also, it has to be noted that the auxiliary expansion device 108 and the economizer flow diversion point can be located downstream of the economizer heat exchanger 104.
• an economizer function allows the provision of increased capacity (and efficiency) by additional cooling of the refrigerant in the main liquid line.
• the pulse width modulation valve 40 positioned on a suction line 31 may be controlled using pulse width modulation techniques to tailor the provided capacity with the demanded capacity.
• the economizer feature, along with the optional unloader feature, and the pulse width modulation control, allows the system to operate with minimal amount of cycling to meet particular cooling/heating capacity demands.
• Figure 3 shows another embodiment, wherein the economizer function is achieved somewhat differently. In the economized cooling mode, tapped refrigerant having passed through a cooling mode economizer expansion device 204 located on a tap line is returned through a vapor injection line 110 to the compressor 22.
• the refrigerant from the main liquid line passes through a cooling mode economizer heat exchanger 202, the main expansion device 28, and a heating mode economizer heat exchanger 206 to the indoor heat exchanger 30 and back to the compressor 22. Since the tapped refrigerant would not be flowing through the heating mode economizer expansion device 208 in this mode of operation, there is no heat exchanged in the heating mode economizer heat exchanger 206.
• the refrigerant flow direction throughout the system is essentially reversed, and the tapped refrigerant flows through the heating mode economizer heat exchanger 206 but not through the cooling mode economizer heat exchanger 202.
• a control controls the economizer expansion devices 204 and 208 such that they also provide a shutoff valve function.
• the expansion device 204 is open and the expansion device 208 is closed.
• the position of the valves is reversed.
• FIG. 4 shows another embodiment 220 wherein a single economizer heat exchanger 230 is provided. A pair of main expansion devices 224 is provided on each side of the economizer heat exchanger. A bypass line 202 and a check valve 226 are also provided around each main expansion device 224.
• the refrigerant will pass through one of the selective main expansion devices 224 depending on the mode of operation (cooling or heating) and the refrigerant flow direction, since the flow of the refrigerant around this expansion device will be blocked by the respective check valve 226. At the same time, the refrigerant flow will be allowed around another expansion device but not through it.
• An economizer expansion device 228 and heat exchanger 230 operate in a manner similar to the Figure 3 embodiment, with the only difference that the economizer flow is tapped either upstream or downstream of the economizer heat exchanger 230.
• FIG. 5 shows an embodiment 260 wherein the economizer heat exchanger is replaced with a flash tank 262.
• an inlet line 264 is the main liquid line. It passes into the flash tank 262, where a refrigerant liquid 266 is separated away from a vapor. The vapor is returned through the vapor injection line 268 back to the compressor intermediate port.
• a return liquid line 270 passes downstream to a heat exchanger or additional expansion device.
• the unloader function may also be incorporated as shown in the Figure 2 embodiment.
• the present invention thus provides the ability to not only control capacity with an unloader function, and the economizer function, as known.
• the present invention also provides the increased ability to control capacity by operating either the suction pulse width modulation valve 40, or modulating the scroll members by separating them from each other, to control the amount of refrigerant pumped by the compressor (see Figure IB) to further control the delivered capacity.
• a worker of ordinary skill in the art would recognize when such control over capacity would be desirable.
• the invention allows reduction in system "on” and “off cycling and thus enhance its performance and improve comfort in the conditioned space.
• the pulse width modulation duty of the refrigerant system component is rapid enough not to cause substantial temperature fluctuations in the conditioned environment.
• the pulse width modulation cycle is between 3 and 30 seconds.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
• Air Conditioning Control Device (AREA)

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Publications (1)

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Cited By (2)

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Citations (6)

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• 2005
  • 2005-12-16 US US12/088,879 patent/US20080209930A1/en not_active Abandoned
  • 2005-12-16 EP EP05854510A patent/EP1996875A4/de not_active Withdrawn
  • 2005-12-16 WO PCT/US2005/045810 patent/WO2007070060A1/en active Application Filing
  • 2005-12-16 CN CNA2005800523179A patent/CN101341367A/zh active Pending

Patent Citations (6)

Non-Patent Citations (1)

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