A refrigerant evaporator for heat exchange between fluid and refrigerant, the refrigerant evaporator comprising:
- a first evaporation unit configured to allow the fluid to flow therethrough in a flow direction;
- a second evaporation unit configured to allow the fluid to flow therethrough in the flow direction, the second evaporation unit arranged in series with the first evaporation unit in the flow direction;
- a first core included in the first evaporation unit and having a plurality of first tubes extending along a tube longitudinal direction perpendicular to the flow direction and stacked in a tube stacking direction perpendicular to both the flow direction and the tube longitudinal direction, the plurality of first tubes being configured to allow the refrigerant to flow therethrough;
- a second core included in the second evaporation unit and having a plurality of second tubes extending along the tube longitudinal direction and stacked in the tube stacking direction, the second tubes being configured to allow the refrigerant to flow therethrough;
- a first plate disposed on one side of the first and second cores in the tube longitudinal direction to be connected to one end portion of the first core and one end portion of the second core, the first plate housing one end portions of the first tubes and one end portions of the second tubes;
- and
- a second plate facing the first core and the second core across the first plate and joined to the first plate in the tube longitudinal direction, wherein
- the second plate includes a plurality of ribs protruding from the second plate along the tube longitudinal direction away from the first core and the second core and extending along the flow direction,
- the plurality of ribs define, together with the first plate, a plurality of intermediate passageways therein,
- each of the plurality of first tubes is arranged to overlap with a respective one of the plurality of second tubes when viewed along the flow direction to form a pair of tubes facing each other along the flow direction, wherein
- each of the plurality of intermediate passageways is configured to allow the refrigerant having flowed out of a corresponding one of the plurality of first tubes to flow into a corresponding one of the plurality of second tubes,
- each of the plurality of first tubes defines a refrigerant passageway therein,
- the refrigerant passageway is divided into a plurality of narrowed passageways,
- the plurality of narrowed passageways are arranged in the flow direction,
- the plurality of narrowed passageways are formed of a 1st narrowed passageway to an nth narrowed passageway that are arranged sequentially toward the plurality of second tubes, where n is a natural number,
- the nth narrowed passageway has a cross-sectional area denoted as Sn,
- each of the plurality of intermediate passageways includes a portion with a cross-sectional area denoted as Mn, through which refrigerant that has just flowed out of the nth narrowed passageway of a corresponding one of the plurality of first tubes flows, and
- each of the plurality of intermediate passageways is configured to satisfy an expression (1) below
- [
- Expression
-
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- 0.3
-
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- i
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- M
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- 3.0
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- where k is a natural number equal to or smaller than n.