AIR-CONDITIONING APPARATUS

• US 20120042674A1
• Filed: 07/10/2009
• Published: 02/23/2012
• Est. Priority Date: 05/12/2009
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Takenaka, Naofumi, Wakamoto, Shinichi, Yamashita, Koji, Morimoto, Hiroyuki, Shimazu, Yusuke
• Granted Patent: US 9,366,452 B2
• Time in Patent Office: Days
• US Class Current: 62/180
• CPC Class Codes: F24F 1/14 Heat exchangers specially adapted for separate outdoor units
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/83 by controlling the supply of heat-exchange fluids to heat-exchangers
• CPC Class Codes: F24F 11/84 using valves
• CPC Class Codes: F24F 11/85 using variable-flow pumps
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/12 of the outside air
• CPC Class Codes: F24F 2140/20 Heat-exchange fluid temperature
• CPC Class Codes: F24F 3/06 characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2309/061 with cycle highest pressure above the supercritical pressure
• CPC Class Codes: F25B 2313/0233 in parallel arrangements
• CPC Class Codes: F25B 2313/0272 using bridge circuits of one-way valves
• CPC Class Codes: F25B 2313/0314 Temperature sensors near the indoor heat exchanger
• CPC Class Codes: F25B 25/005 using primary and secondary systems
• CPC Class Codes: F25B 2500/222 Detecting refrigerant leaks
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: F25B 2600/13 Pump speed control
• CPC Class Codes: F25B 2600/25 Control of valves
• CPC Class Codes: F25B 2700/1931 : Discharge pressures
• CPC Class Codes: F25B 2700/1933 : Suction pressures
• CPC Class Codes: F25B 2700/2104 : of an indoor room or compartment
• CPC Class Codes: F25B 2700/2106 : of fresh outdoor air
• CPC Class Codes: F25B 49/02 : for compression type machines, plants or systems
• CPC Class Codes: F25B 9/008 : the refrigerant being carbon dioxide
• CPC Class Codes: Y02B 30/54 : Free-cooling systems
• CPC Class Codes: Y02B 30/70 : Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

An air-conditioning apparatus capable of achieving enhancement of the system COP while suppressing product cost. The air-conditioning apparatus controls the difference between the temperatures of brine at a position before and at a position after an indoor heat exchanger or at a position before and at a position after an intermediate heat exchanger to be a preset target value and to be larger at the time of a heating operation than at the time of a cooling operation.

Claims

1. An air-conditioning apparatus comprising:

a primary-side cycle including a compressor, a heat source side heat exchanger, an expansion device, and at least one intermediate heat exchanger, which are connected, and allowing a primary-side heat transfer medium to circulate; and

a secondary-side cycle including a pump, a use side heat exchanger, and the intermediate heat exchanger, which are connected, and allowing a secondary-side heat transfer medium to circulate,

the intermediate heat exchanger exchanging heat between the primary-side heat transfer medium and the secondary-side heat transfer medium,

wherein the air-conditioning apparatus further comprises control means setting a target value of the difference between the temperatures of the secondary-side heat transfer medium at a position before and at a position after the use side heat exchanger or at a position before and at a position after the intermediate heat exchanger so as to be larger at the time of a heating operation than at the time of a cooling operation, and for controlling the flow rate of the secondary-side heat transfer medium before entering and after leaving the use side heat exchanger or flowing in the intermediate heat exchanger.

2. The air-conditioning apparatus of claim 1, wherein a degree of supercooling of the primary-side heat transfer medium at an outlet of the intermediate heat exchanger is controlled to be equal to or lower than the difference between the inlet and outlet temperatures of the secondary-side heat transfer medium at a position before and at a position after the intermediate heat exchanger.

3. The air-conditioning apparatus of claim 1, wherein the target value of the difference between the temperatures of the secondary-side heat transfer medium at the position before and at the position after the use side heat exchanger or at the position before and at the position after the intermediate heat exchanger is set according to the magnitude of a load on the use side heat exchanger.

4. The air-conditioning apparatus of claim 3, wherein the target value of the difference between the temperatures of the secondary-side transfer medium in a case where a load on the use side heat exchanger is equal to or lower than a predetermined load is set so as to be equal to or lower than a target value of the difference between the temperatures of the secondary-side heat transfer medium in a case where the load on the use-side heat exchanger is larger than the predetermined load.

5. The air-conditioning apparatus of claim 1, wherein

a plurality of use side heat exchangers are connected to a single outdoor unit, an operation mode of each of the use side heat exchangers being freely selectable between cooling and heating,

the compressor and the heat source side heat exchanger are provided in the outdoor unit,

the plurality of use side heat exchangers are provided in a plurality of indoor units,

means controlling the flow rate of the secondary-side heat transfer medium supplied to the intermediate heat exchanger and the plurality of indoor units is provided in a relay unit,

installation of the outdoor unit, the indoor units, and the intermediate heat exchanger at places away from each other is possible, and

heat transport from the outdoor unit to the relay unit is performed using the primary-side heat transfer medium and heat transport from the relay unit to the indoor units is performed using the secondary-side heat transfer medium.

6. The air-conditioning apparatus of claim 1, further comprising:

an outdoor unit side control device that controls each device accommodated in the outdoor unit; and

a relay unit control device that controls respective devices accommodated in the relay unit and that is capable of communicating with the outdoor unit side control device, wherein

a control signal including data on load information of the indoor units and/or a target value of the difference between the temperatures of the secondary-side heat transfer medium and/or a target value of the degree of supercooling of the primary-side heat transfer medium at an outlet of the intermediate heat exchanger or an adjustment value of the control target value is transmitted from the relay unit control device to the outdoor unit side control device or from the outdoor unit side control device to the relay unit control device.

7. The air-conditioning apparatus of claim 1, wherein

a plurality of the intermediate heat exchangers are provided,

each of the intermediate heat exchangers is installed in series with respect to the flow of the primary-side heat transfer medium and in parallel with respect to the flow of the secondary-side heat transfer medium,

the differences between the inlet and outlet temperatures of the secondary-side heat transfer medium in the respective intermediate heat exchangers are controlled to be identical at the time of a cooling operation, and

the difference between the inlet and outlet temperatures of the secondary-side heat transfer medium in the intermediate heat exchanger on the upstream side with respect to the flow of the primary-side heat transfer medium is controlled to be equal to or larger than the difference between the inlet and outlet temperatures of the secondary-side heat transfer medium in the intermediate heat exchanger on the downstream side with respect to the flow of the primary-side heat transfer medium at the time of a heating operation.

8. The air conditioning apparatus of claim 1, wherein

the intermediate heat exchanger is used as a condenser of the primary-side heat transfer medium, and

the primary-side heat transfer medium and the secondary-side heat transfer medium flowing in the intermediate heat exchanger flow in a counter-flow manner.

9. The air-conditioning apparatus of claim 1, wherein a heat medium having a critical temperature of 50 degrees C. or lower is used as the primary-side heat transfer medium.

10. The air-conditioning apparatus of claim 1, wherein the target value of the difference between the temperatures of the secondary-side transfer medium in a case where a distance from the pump to the use-side heat exchanger is not longer than 10 m is set in a range of 7 through 9 degrees C. at the time of a cooling operation or 5 through 15 degrees C. at the time of a heating operation.

11. The air-conditioning apparatus of claim 1, wherein the target value of the difference between the temperatures of the secondary-side transfer medium in a case where a distance from the pump to the use-side heat exchanger is 40 m or longer is set in a range of 7 through 9 degrees C. at the time of a cooling operation or 5 through 15 degrees C. at the time of a heating operation.