BINARY REFRIGERATION APPARATUS

• US 20150176866A1
• Filed: 08/05/2013
• Published: 06/25/2015
• Est. Priority Date: 08/06/2012
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Takayama, Keisuke, Ishikawa, Tomotaka, Sugimoto, Takeshi, Yamashita, Tetsuya, Ikeda, Takashi
• Granted Patent: US 10,077,924 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F25B 2309/061 with cycle highest pressure above the supercritical pressure
• CPC Class Codes: F25B 2400/0403 for the condenser
• CPC Class Codes: F25B 2400/0409 for the evaporator
• CPC Class Codes: F25B 2400/0415 for the receiver
• CPC Class Codes: F25B 2400/16 Receivers
• CPC Class Codes: F25B 2600/2501 Bypass valves
• CPC Class Codes: F25B 2700/1931 Discharge 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 2700/2108 of a receiver
• CPC Class Codes: F25B 47/022 hot gas defrosting
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: F25B 5/04 arranged in series
• CPC Class Codes: F25B 7/00 Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit F25B9/00 takes precedence
• CPC Class Codes: F25B 9/008 the refrigerant being carbon dioxide
• CPC Class Codes: F25D 21/002 Defroster control

Abstract

A two-stage refrigeration apparatus includes a high-stage refrigeration cycle including a high-stage-side refrigerant circuit including a high-stage-side compressor, high-stage-side condenser, high-stage-side expansion valve, and high-stage-side evaporator connected by pipes, a low-stage refrigeration cycle including a low-stage-side refrigerant circuit including a low-stage-side compressor, low-stage-side condenser, low-stage-side receiver, low-stage-side expansion valve, and low-stage-side evaporator connected by pipes, a cascade condenser including the high-stage-side evaporator and low-stage-side condenser, a receiver heat exchanging portion configured to cool the low-stage-side receiver, and a high-stage refrigeration cycle controller configured to perform controlling so as to activate the high-stage-side compressor when estimating a low-stage-side refrigerant will reach a supercritical state while the low-stage-side compressor his defrosted on the basis of the pressure of the low-stage-side refrigerant.

Claims

1. A two-stage refrigeration apparatus comprising:

a first refrigeration cycle device including a first refrigerant circuit in which a first compressor, a first condenser, a first expansion device, and a first evaporator are connected by pipes, the first refrigerant circuit circulating a first refrigerant;

a second refrigeration cycle device including a second refrigerant circuit in which a second compressor, a second condenser, a receiver, a second expansion device, and a second evaporator are connected by pipes, the second refrigerant circuit circulating a second refrigerant;

a cascade condenser including the first evaporator and the second condenser and configured to cause the first refrigerant flowing in the first evaporator and the second refrigerant flowing in the second condenser to exchange heat with each other;

a receiver heat exchanging portion configured to cool the receiver by heat exchange with a portion in which the first refrigerant being low-pressure flows in the first refrigerant circuit;

a heat-exchanging-portion bypass portion for bypassing the receiver heat exchanging portion in the first refrigerant circuit;

a heat-exchanging-portion opening and closing device configured to control passage of the refrigerant through the receiver heat exchanging portion;

a defrosting unit configured to defrost the second evaporator;

a controller configured to perform controlling so as to activate the first compressor and so as to open the receiver heat-exchanging-portion opening and closing device on the basis of the pressure of the second refrigerant while the second evaporator is being defrosted by the defrosting unit.

3. The two-stage refrigeration apparatus of claim 1, further comprising:

a pressure determining unit configured to determine a pressure of the second refrigerant in the second refrigerant circuit,

wherein the pressure determining means includes

a pressure detecting device disposed between a discharge side of the second compressor and a refrigerant inlet side of the second expansion device in the second refrigerant circuit and configured to detect the pressure of the second refrigerant on a high-pressure side of the second refrigerant circuit.

4. The two-stage refrigeration apparatus of claim 1, further comprising:

a pressure determining unit configured to determine a pressure of the second refrigerant in the second refrigerant circuit,

wherein the pressure determining unit includes

a liquid-refrigerant temperature detecting device configured to detect a temperature of the refrigerant in a liquid state on a high-pressure side of the second refrigerant circuit, and

a calculating unit configured to calculate the pressure of the second refrigerant on the basis of the temperature relating to the detection by the liquid-refrigerant temperature detecting device.

5. The two-stage refrigeration apparatus of claim 1, wherein the second refrigerant circuit further includes a bypass that connects a refrigerant pipe between the second compressor and the second condenser and a refrigerant pipe between the receiver and the second evaporator, and

the defrosting unit is hot gas being a low-stage-side refrigerant caused to pass through the bypass and flow into the second evaporator by driving of the second compressor.

6. The two-stage refrigeration apparatus of claim 1, wherein the defrosting unit is an electrical heater disposed on the second evaporator.

7. The two-stage refrigeration apparatus of claim 1, further comprising a heat-exchanging-portion bypass opening and closing device disposed on the heat-exchanging-portion bypass portion, and

the controller closes the heat-exchanging-portion bypass opening and closing device in cooling the second refrigerant in the receiver heat exchanging portion.

8. The two-stage refrigeration apparatus of claim 1, wherein the second refrigerant is carbon dioxide.

2. (canceled)