Air-conditioning apparatus with primary and secondary heat exchange cycles

Patent metadata

Field	Value
Publication number	US-9366452-B2
Application number	US-200913266247-A
Country	US
Kind code	B2
Filing date	Jul 10, 2009
Priority date	May 12, 2009
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

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.

First claim

The invention claimed is:

1. An air-conditioning apparatus comprising:
a primary-side cycle including a compressor, a heat source side heat exchanger, a first expansion device, a second expansion device, a third expansion device, a fourth expansion device, a first intermediate heat exchanger, a second intermediate heat exchanger, a first flow switching valve and a second flow switching valve, all of which are connected in a closed loop allowing a primary-side heat transfer medium to circulate; and
a secondary-side cycle including a variable capacity pump configured to vary a flow rate of a secondary-side heat transfer medium continuously, a plurality of use side heat exchangers, the first intermediate heat exchanger and the second intermediate heat exchanger, all of which are connected in a closed loop allowing the secondary-side heat transfer medium to circulate, wherein the secondary-side heat transfer medium is different from the primary-side heat transfer medium, and contains at least either one of brine and water,
the first and the second intermediate heat exchangers exchanging heat between the primary-side heat transfer medium and the secondary-side heat transfer medium,
wherein the 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, respectively,
a control valve controlling the flow rate of the secondary-side heat transfer medium supplied to the first and second intermediate heat exchangers and the plurality of indoor units is provided in a relay unit, the relay unit being a separate enclosure from the indoor units and the outdoor unit,
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,
wherein the secondary-side cycle further comprises a first temperature detector and a second temperature detector of the secondary-side heat transfer medium provided before and after each of the first and second intermediate heat exchangers, respectively,
wherein a passage of the primary-side heat transfer medium provided to the relay unit includes a first branch portion branching the primary-side heat transfer medium at high pressure, a second branch portion branching the primary-side heat transfer medium at low pressure and a third branch portion branching the primary-side heat transfer medium at intermediate pressure, the intermediate pressure being lower than the high pressure,
wherein the third expansion device connects the first branch portion and the third branch portion, and the fourth expansion device connects the third branch portion and the second branch portion,
wherein a first end of the first intermediate heat exchanger is connected to the first flow switching valve and a second end of the first intermediate heat exchanger is connected to the first expansion device, the first flow switching valve selectively connects the first end of the first intermediate heat exchanger to the first branch portion and to the second branch portion,
wherein a first end of the second intermediate heat exchanger is connected to the second flow switching valve and a second end of the second intermediate heat exchanger is connected to the second expansion device, the second flow switching valve selectively connects the first end of the second intermediate heat exchanger to the first branch portion and to the second branch portion,
wherein during a cooling mode, the primary-side heat transfer medium flows in an order of the first branch portion, the third expansion device and the third branch portion, then is divided into a first stream and a second stream, the first stream flows in an order of the first expansion device, the first intermediate heat exchanger, and the first flow switching valve, the second stream flows, in parallel with the first stream, in an order of the second expansion device, the second intermediate heat exchanger, and the second flow switching valve, and then the first stream and the second stream merge and flow out from the relay unit via the second branch portion,
wherein during a heating mode, the primary-side heat transfer medium flows into the first branch portion, then is divided into a third stream and a fourth stream, the third stream flows in an order of the first flow switching valve, the first intermediate heat exchanger, and the first expansion device, and the fourth stream flows, in parallel with the third stream, in an order of the second flow switching valve, the second intermediate heat exchanger, the second expansion device, and then the third stream and the fourth stream merge at the third branch portion, flow through the fourth expansion device and flow out from the relay unit via the second branch portion,
the air-conditioning apparatus further comprises a controller for 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 first and second intermediate heat exchangers based on whether the operation mode is the heating mode or the cooling mode, and for controlling the flow rate of the secondary-side heat transfer medium flowing in the first and second intermediate heat exchangers such that the difference between the temperatures of the secondary-side heat transfer medium at the position before and at the position after the first and second intermediate heat exchangers detected by the first temperature detector and the second temperature detector will correspond to the target values in both the heating and cooling operations, by adjusting the capacity of the pump,
wherein the controller
sets 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 first and second intermediate heat exchangers during a rated operation in the heating operation so as to have a larger magnitude than 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 first and second intermediate heat exchangers during a rated operation in the cooling operation.

2. The air-conditioning apparatus of claim 1 , wherein in the heating operation, a target value of a degree of supercooling of the primary-side heat transfer medium at an outlet of the first and second intermediate heat exchangers is set to be equal to or lower than the difference in magnitude between the inlet and outlet temperatures of the secondary-side heat transfer medium at the position before and at the position after the first and second intermediate heat exchangers,
and the expansion devices are controlled based on a degree of supercooling of the primary-side heat transfer medium at an outlet of the first and second intermediate heat exchangers and the target value of the degree of supercooling.

3. The air-conditioning apparatus of claim 1 , wherein the target value of the difference in magnitude between the temperatures of the secondary-side heat transfer medium at the position before and at the position after the first and second intermediate heat exchangers 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 in magnitude between the temperatures of the secondary-side heat transfer medium in a case where a load on the use side heat exchanger is equal to or lower than a predetermined l

Assignees

• Takenaka Naofumi
• Wakamoto Shinichi
• Yamashita Koji
• Morimoto Hiroyuki
• Shimazu yusuke
• Mitsubishi Electric Corp

Inventors

• Takenaka Naofumi
• Wakamoto Shinichi
• Yamashita Koji
• Morimoto Hiroyuki
• Shimazu yusuke

Classifications

• F24F2110/10

  Temperature · CPC title

• F25B2600/021

  Inverters therefor · CPC title

• F25B2313/0272

  using bridge circuits of one-way valves · CPC title

• F25B2600/13

  Pump speed control · CPC title

• F25B2313/0233

  in parallel arrangements · CPC title