In general, the refrigeration cycle device such as an air conditioner, a heat pump type hot-water heater and so forth includes a refrigerant circuit that a compressor, a throttle device such as a motor operated valve and so forth, a condenser and an evaporator are connected together by means of piping. In a refrigeration cycle of the refrigeration cycle device, the refrigerant which circulates through within the refrigerant circuit repetitively absorbs or radiates heat from air, water and so forth which would be objects to be heat-exchanged in a heat exchanger (the condenser and the evaporator).
For example, the heat exchanger of an indoor unit or an outdoor unit of the air conditioner efficiently performs heat transfer between the refrigerant in a refrigerant pipe and air by joining the plurality of refrigerant pipes to fins which configure an air-side heat transfer surface of the heat exchanger. In this structure, it is necessary to distribute the refrigerant to each of the plurality of refrigerant pipes which are arranged in parallel in the heat exchanger of the indoor unit or the outdoor unit. In the refrigerant which flows in the piping of the heat exchanger in the form of a gas-liquid two-phase flow, a difference in density amounts to several score times between the liquid refrigerant and the gas refrigerant and flow velocities of the gas refrigerant and the liquid refrigerant in the gas-liquid two-phase flow are made greatly different from each other. Therefore, in the refrigerant which flows in the form of the gas-liquid two-phase flow, a gas-liquid interface is disordered and flow of the refrigerant becomes complicated and unstable. Therefore, it becomes necessary to stably distribute the refrigerant configured by the two phases of gas and liquid to each of the refrigerant pipes of the heat exchanger of the indoor unit or the outdoor unit at a predetermined distribution ratio such that the refrigerant efficiently acts in the heat exchanger of the indoor unit or the outdoor unit.
In addition, since there are cases where the liquid refrigerant is diverted in the piping due to the action of gravity exerted onto the flowing liquid refrigerant, it is necessary to stably distribute the refrigerant configured by the two phases of gas and liquid to each of the refrigerant pipes of the heat exchanger at the predetermined distribution ratio, taking the influence of the gravity acting on the refrigerant into consideration.
In addition, when a flow rate of the refrigerant attained when operating at a rotational frequency which is less than a rated rotational frequency becomes lower than that attained in a rated operation, the flow velocity of the refrigerant is made different from that attained in the rated operation and the flowing form is changed. Therefore, it is necessary to appropriately distribute the refrigerant configured by the two phases of gas and liquid to each refrigerant pipe in accordance with a fluctuation in rotational frequency, by taking the above-mentioned matters into consideration.
A refrigerant distributor described in Patent Literature 1 (Japanese Patent Application Laid-Open No. 2013-002688) is of the type that a header pipe which is installed in a vertical direction is provided as a distribution unit and a plurality of pieces of piping (flat tubes) are installed horizontally relative to the header pipe. A concentric or spiral rib is provided in the header pipe as a refrigerant guiding structure, and thereby mixing of the gas refrigerant with the liquid refrigerant is promoted and uniform distribution of the refrigerant is attained.
Patent Literature 1: Japanese Patent Application Laid-Open No. 2013-002688
In the refrigerant distributor described in the above-mentioned Patent Literature 1, when the flow rate of the liquid refrigerant is low, the liquid refrigerant is liable to flow along a wall surface of the refrigerant guiding structure due to a reduction in flow velocity of the liquid refrigerant. For this reason, mixing of the gas refrigerant with the liquid refrigerant is not promoted and almost no effect of uniformly distributing the refrigerant to each of the plurality of pieces of piping (the refrigerant pipes) on the downstream side is obtained. Accordingly, such a disadvantage arises that the performance of the refrigerant distributor at the low flow rate is considerably reduced. In addition, the structure in the header pipe is considerably complicated and the production cost is increased.
The present invention has been made in view of the above-mentioned circumstance and aims to provide a refrigerant distributor making it possible to stably distribute the refrigerant to each of the refrigerant pipes while suppressing an increase in cost under flow rate conditions ranging from a rated operation condition to a low rotational frequency operation condition and a refrigerant cycle device using the above-mentioned refrigerant distributor.