Abstract: An exhaust heat recovery system (18) includes first and second loop heat pipes (20 and 30). The first loop heat pipe (20) recovers exhaust heat downstream of a catalyst (5) in an exhaust passage (4) of an internal combustion engine (1) to exchange heat with the catalyst (5). The second loop heat pipe (30) recovers heat of the catalyst (5) to exchange heat with coolant that is once delivered from the internal combustion engine (1).

Abstract: An exhaust gas heat recovery unit includes a plurality of heat pipes (23) each of which includes a heater-side heat pipe portion (23a) positioned on the side of a heater (21) which heats pure water using heat of exhaust gas discharged from an engine and an evaporator-side heat pipe portion (23b) positioned on the side of an evaporator (22) which evaporates the pure water, heated at the heater-side heat pipe portion (23a), using the heat of the exhaust gas. The pitch of heater-side corrugated fins (28a) on the outer periphery of the heater-side heat pipe portion (23a) is set to substantially half the pitch of evaporator-side corrugated fins (28b) on the outer periphery of the evaporator-side heat pipe portion (23b).

Abstract: A heat pipe 23 has seven heating unit side heat pipe portions 23a on the side of a heating unit 21 for heating pure water using heat of exhaust gas discharged from an engine, six evaporation unit side heat pipe portions 23b on the side of an evaporation unit 22 for evaporating the pure water heated by each heating unit side heat pipe portion 23a using heat of exhaust gas, and flow rate retardation means 4 for retarding the flow rate of the pure water flowing in the evaporation unit side heat pipe portions. The flow rate retardation means 4 is provided with a merging portion 23c that merges the pure water heated by each heating unit side heat pipe portion, on the evaporation unit side, and whose a flow path cross-sectional area is set to be larger than that of each heating unit side heat pipe portion 23a.