An outdoor system for an air conditioner may include at least one outdoor unit, the at least one outdoor unit including a compressor; an outdoor heat exchanger; a pair of two-stage compression lines that extends to outside of the outdoor system; a pair of connection lines that extends to the outside of the outdoor system and communicates with an indoor unit; and multiple valves that open/close the pair of two-stage compression lines and the pair of connection lines when the outdoor system is operated in a one-stage heating mode or a two-stage heating mode.

The present invention addresses a problem of providing a mixed refrigerant that combines three kinds of performances of having a refrigeration capacity (this may also be referred to as a cooling capacity) and of having a coefficient of performance (COP) equivalent to those of R410A, and of having a sufficiently small GWP. As a means for solving the problem, provided is a refrigerant-containing composition, wherein the refrigerant contains trans-1,2-difluoroethylene (HFO-1132 (E)), trifluoroethylene (HFO-1123) and 2,3,3,3-tetrafluoro-1-propene (R1234yf), and R32.

Excessive specifications of a shutoff valve leads to increase in production cost. An air conditioner configured to circulate a lower flammability refrigerant in a refrigerant circuit includes a first shutoff valve and a second shutoff valve configured to inhibit refrigerant leakage into a predetermined space. Each of the first shutoff valve and the second shutoff valve in a shutoff state has a shutoff leakage rate, as an air leakage rate in a case where fluid is air at 20° C. and a differential pressure between upstream and downstream of the valve is 1 MPa, more than 300 (cm.sup.3/min) and less than 300×R (cm.sup.3/min). R satisfies

[00001]$R=\left({\rho }_{\mathrm{md}}\times V_{\mathrm{md}}\times A_d\right)\text{/}\left(C_r\times {\left(2\times \Delta P_r\text{/}{\rho }_{1\mathrm{rl}}\right)}^{0.5}\times A_v\times {\rho }_{1\mathrm{rl}}+A_v\times {\left(2\text{/}\left(\lambda +1\right)\right)}^{\left(\left(\lambda +1\right)\text{/}2\left(\lambda -1\right)\right)}\times {\left(\lambda \times P_{1r}\times {\rho }_{1\mathrm{rg}}\right)}^{0.5}\right).$

The present disclosure provides a multi-air conditioner for heating/cooling operation including: at least one of indoor units for heating/cooling operation including an indoor heat exchanger respectively; and an outdoor unit for heating/cooling operation including a compressor, an outdoor heat exchanger, and a switching unit configured to be disposed in a discharge side of the compressor to switch a flow of refrigerant, wherein the outdoor unit for heating/cooling operation includes a receiver which selectively stores refrigerant or oil according to a cooling or heating operation mode and provides the stored refrigerant or oil to the compressor. Accordingly, in the accumulator of the multi-air conditioner for heating/cooling operation using the receiver, the receiver that is not used in the heating mode can be converted and used for oil storage, thereby preventing oil burnout without adding a structure.

The present disclosure provides a multi-air conditioner for heating/cooling operation, including: at least one indoor unit which is installed in a room, and comprises an indoor heat exchanger; an outdoor unit which is connected to the indoor unit through a refrigerant pipe, and comprises an outdoor heat exchanger, a compressor, an outdoor expansion valve, and a four-way valve; at least one leakage blocking valve which is formed on the refrigerant pipe, and blocks a refrigerant flow in the refrigerant pipe when a refrigerant leak occurs from the refrigerant pipe in the room; and a buffer unit which is installed on the refrigerant pipe between the indoor unit and the outdoor unit, and collects refrigerant leaking from the refrigerant pipe. Accordingly, when the refrigerant leaks into the room, it is possible to minimize the amount of the leaking refrigerant by collecting the refrigerant in the buffer tank.

An air-conditioning apparatus includes a main circuit in which a compressor, a load side heat exchanger, a first pressure reducing device, and a plurality of parallel heat exchangers connected in parallel with each other are connected by pipes, a bypass pipe diverting a portion of refrigerant discharged by the compressor, a flow switching unit connecting a parallel heat exchanger to be defrosted to the bypass pipe, a plurality of flow rate control devices controlling flow rates of refrigerant flowing through the plurality of parallel heat exchangers, and a controller which controls, in the heating-defrosting operation mode or in the heating operation mode after execution of the heating-defrosting operation mode, the flow rate control devices to control, in accordance with a frost state of a parallel heat exchanger functioning as an evaporator among the plurality of parallel heat exchangers, the flow rate of refrigerant flowing through the parallel heat exchanger.

An air conditioner includes a use-side unit, a heat source-side unit, refrigerant connection pipes, cutoff valve provided in the refrigerant connection pipes, a refrigerant leakage detector, and a controller control. When the refrigerant leakage detector detects a refrigerant leakage, the controller performs pressure reduction control to lower the pressure of the refrigerant in the use-side unit, and thereafter puts the cutoff valves into a cutoff state.

A multi-air conditioner for heating and cooling may include at least one indoor unit installed in an indoor space and comprising an indoor heat exchanger and an indoor expansion valve; an outdoor unit connected to the at least one indoor unit via a refrigerant pipeline and comprising an outdoor heat exchanger, a compressor, an outdoor expansion valve, and a four-way valve; and at least one leak shut-off valve provided on the refrigerant pipeline, that blocks a flow of refrigerant in the refrigerant pipeline when a refrigerant leak from the refrigerant pipeline occurs in the indoor space. The outdoor unit may decrease a pressure of the refrigerant pipeline when a refrigerant leak occurs from the refrigerant pipeline. Therefore, it is possible to minimize an amount of refrigerant leakage when there is a refrigerant leak in the indoor space.

A heat pump and a method for operating a heat pump are provided. The heat pump may include a compressor that compresses a refrigerant, at least one fluid-refrigerant heat exchanger that exchanges heat between the refrigerant and a fluid, such as water, a pump including a motor, the pump forcing the fluid to flow into the at least one fluid-refrigerant heat exchanger, and a controller. The controller may be configured to calculate power consumption of the pump, calculate a flow rate of fluid flowing due to the pump based on the power consumption of the pump, and control an operation of the pump to be stopped when the flow rate of the fluid is less than a predetermined reference flow rate.

A refrigeration cycle device includes: a refrigeration cycle circuit including: a compressor and an indoor heat exchanger; an indoor air-sending device including a fan and a motor to supply air to the indoor heat exchanger; and a controller to control the frequency of the compressor and the rotation speed of the motor. The controller controls the rotation speed of the motor by controlling a frequency of an alternating current output from an inverter to the motor. The inverter is disposed at a position exposed to air heat-exchanged in the indoor heat exchanger. The controller controls the frequency of the compressor to a frequency at which a temperature of the inverter becomes lower than a first prescribed temperature in a state where the rotation speed of the motor is lower than a prescribed rotation speed.