Refrigeration apparatus controlling opening degree of a second expansion mechanism based on air temperature at the evaporator or refergerant temperature at the outlet of a two stage compression element

摘要

A refrigerating apparatus, where refrigerant reaches a supercritical state in at least part of a refrigeration cycle, includes at least one expansion mechanism, an evaporator connected to the expansion mechanism, first and second sequential compression elements, a radiator connected to the discharge side of the second compression element, a first refrigerant pipe interconnecting the radiator and the expansion mechanism, a heat exchanger arranged to cause heat exchange between the first refrigerant pipe and another refrigerant pipe. Preferably, a heat exchanger switching mechanism is switchable so that refrigerant flows in the first refrigerant pipe through the first heat exchanger or in a heat exchange bypass pipe connected to the first refrigerant pipe. Alternatively, a heat exchanger switching mechanism increases refrigerant flowing through a second expansion mechanism when an air temperature at the evaporator and/or a compressed refrigerant temperature detected is higher and/or lower than predetermined values.

主权项

1. A refrigerating apparatus where a working refrigerant reaches a supercritical state in at least part of a refrigeration cycle, the refrigerating apparatus comprising:
a first expansion mechanism arranged and configured to reduce pressure of refrigerant; a second expansion mechanism arranged and configured to reduce pressure of refrigerant; an evaporator connected to the first expansion mechanism, the evaporator being arranged and configured to evaporate refrigerant; a first compression element arranged and configured to suck in, compress and discharge refrigerant; a second compression element arranged and configured to suck in, further compress and discharge refrigerant that has been discharged from the first compression element; a third refrigerant pipe arranged and configured to allow refrigerant that has been discharged from the first compression element to be sucked into the second compression element; a radiator connected to a discharge side of the second compression element; a first refrigerant pipe interconnecting the radiator and the first expansion mechanism; a fourth refrigerant pipe branching from the first refrigerant pipe and extending to the second expansion mechanism; a fifth refrigerant pipe extending from the second expansion mechanism to the third refrigerant pipe; a second heat exchanger arranged and configured to cause heat exchange to be performed between refrigerant flowing through the first refrigerant pipe and refrigerant flowing through the fifth refrigerant pipe; a temperature detector arranged and configured to detect a value of at least either one of
a temperature of air around the evaporator, anda temperature of refrigerant discharged from at least either one of the first compression element and the second compression element; a controller configured to control the second expansion mechanism to increase a quantity of the refrigerant passing therethrough
when the value detected by the temperature detector is temperature of air, and the air temperature is lower than a predetermined tow-temperature air temperature, orwhen the value detected by the temperature detector is temperature of refrigerant, and the refrigerant temperature is higher than a predetermined high-temperature refrigerant temperature; an external cooler arranged and configured to cool refrigerant passing through the third refrigerant pipe; an external temperature detector arranged and configured to detect a temperature of a fluid passing through the external cooler; and a third refrigerant temperature detector arranged and configured to detect a temperature of refrigerant passing through the third refrigerant pipe, the controller being further configured to control the second expansion mechanism to increase the quantity of the refrigerant passing therethrough when a difference between the temperature detected by the external temperature detector and the temperature detected by the third refrigerant temperature detector has become less than a predetermined value.