Evaporator and rankine cycle system

A Rankine cycle system comprising:

• a working fluid passage that forms a loop through which a working fluid flows;
• an expander disposed in the working fluid passage;
• a condenser disposed in the working fluid passage;
• a generator driven by the expander;
• and
• an evaporator disposed in the working fluid passage, wherein
• the evaporator includes:
• an introducing portion that introduces a heat source gas from a heat source gas pipe;
• a heat source gas passage through which the heat source gas introduced from the introducing portion flows;
• a heating portion that is disposed in the heat source gas passage and at which the working fluid is heated by the heat source gas;
• an increasing portion that is located between the introducing portion and the heating portion, that constitutes the heat source gas passage, and at which a cross-sectional area of the heat source gas passage gradually increases from an upstream side towards a downstream side in the heat source gas passage;
• and
• a flow regulating plate that is disposed on any portion between an end of the increasing portion and an inlet of the heating portion, inclusive, in the heat source gas passage and that has a plurality of holes which allow the heat source gas to pass through the plurality of holes,
• wherein the heating portion includes a heat transfer pipe constituting a part of the working fluid passage through which the working fluid flows.