Heat pipe, exhaust heat recoverer provided therewith

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.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to a heat pipe used in a vehicle such as an automobile, an exhaust heat recoverer provided therewith.[0003]2. Description of the Related Art[0004]A conventional example of the related art uses the principle of a heat pipe to recover exhaust heat of exhaust gas discharged from an engine of a vehicle and use this exhaust heat to promote engine warming and the like.[0005]In addition, a loop heat pipe heat exchanger has been proposed that utilizes the principle of a heat pipe (see, for example, Japanese Patent Application Publication No. 4-45393 (JP-A-4-45393)). This heat exchanger has a closed circulation path that forms a closed loop, a working fluid charged into the circulation path enabling evaporation and condensation, an evaporation unit arranged in the circulation path that evaporates the working fluid by introducing heat from the outside, and a condensation unit arranged at a higher location th...

AI Technical Summary

Benefits of technology

[0008]The invention provides a heat pipe capable of enabling heat exchange with a target of promotion of warming, such as during cold starting, to be carried out efficiently by adequately reheating an evaporated, vapor phase working fluid using heat of exhaust gas, an exhaust heat recoverer provided therewith.

[0009]A first aspect of the invention relates to a heat pipe provided with a heating unit that is provided with a heating unit side heat pipe portion that heats a working fluid using heat of exhaust gas discharged from an engine, an evaporation unit that is provided with an evaporation unit side heat pipe portion through which the working fluid flows, and that evaporates the working fluid heated by the heating unit using the heat of the exhaust gas, and flow rate retardation means for retarding the flow rate of the working fluid flowing into the evaporation unit side heat pipe portion.

[0011]As a result of employing this configuration, the working fluid merged from each heating unit side heat pipe portion is retained in the merging portion resulting in retardation of the flow rate thereof. As a result, the heat of exhaust gas is able to easily act on the working fluid for which the flow rate thereof has been retarded in the merging portion on the side of the evaporation unit, thereby enabling vapor phase working fluid evaporated in the merging portion on the side of the evaporation unit to be adequately reheated by the heat of exhaust gas to ensure an adequate amount of heat. As a result, during cold starting and the like during which promotion of warming is particularly required, the direct loss of heat by the vapor phase working fluid caused by contact with the peripheral walls of the condensation unit and the like is avoided, thereby enabling heat exchange with a target of promotion of warming to be carried out efficiently.

[0015]Moreover, the heat pipe according to this first aspect may be provided near the center of the exhaust pipe. According to this configuration, the heat of exhaust gas near the center of the exhaust pipe where the temperature within the exhaust pipe is the highest acts on the working fluid inside the merging portion, and the heat of exhaust gas is efficiently imparted to the working fluid retained in the merging portion. As a result, the vapor phase working fluid evaporated in the merging portion on the side of the evaporation unit is efficiently heated by the heat of high-temperature exhaust gas near the center of the exhaust pipe to ensure an adequate amount of heat.

[0019]In summary of that described above, by retarding the flow rate of the working fluid with flow rate retardation means provided with a merging portion and the like that merges the working fluid heated in each heating unit side heat pipe portion of the heat pipe on the side of the evaporation unit, the heat of exhaust gas easily acts on the working fluid for which the flow rate thereof has been retarded in the merging portion on the side of the evaporation unit, thereby ensuring an adequate amount of heat for the vapor phase working fluid, and making it possible to efficiently carry out heat exchange with a target of promotion of warming by avoiding the heat of the vapor phase working fluid being lost directly due to contact with the cold peripheral walls and the like of the condensation unit, particularly during cold starting when promotion of warming is required.

[0021]A third aspect of the invention relates to an exhaust heat recoverer comprising a heat pipe including a heating unit for heating a working fluid using heat of exhaust gas discharged from an engine, and an evaporation unit that is provided with an evaporation unit side heat pipe portion through which the working fluid flows, and that evaporates the working fluid heated by the heating unit using the heat of the exhaust gas. In the exhaust heat recoverer, the heat pipe is provided with flow rate retardation means for retarding the flow rate of the working fluid flowing through the evaporation unit side heat pipe portion.

Problems solved by technology

As a result of employing this configuration, the working fluid merged from each heating unit side heat pipe portion is retained in the merging portion resulting in retardation of the flow rate thereof.

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