Loop Heat Pipe Exhaust Heat Recovery with Self-Pressure Valve
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Solution Overview
Problem
Existing exhaust heat recovery devices using loop heat pipes face issues with excessive heating and pressure buildup during high exhaust gas discharge, leading to unnecessary load on the system and potential failure, as well as inefficient heat transfer when the engine block is already at a high temperature.
Innovation Solution
An exhaust heat recovery device comprising a first heat exchanger, a second heat exchanger, a gas passage, a liquid passage, and a self-pressure valve forms a loop heat pipe that evaporates and condenses a heat medium using capillary phenomena, allowing for adjustable flow of exhaust gas and heat transfer without pumps or electric power, thereby managing pressure and heat efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the evaporation portion of the loop heat pipe is installed in the exhaust gas passage to recover heat, then heat recovery efficiency is improved, but the exhaust gas discharge is interrupted and unnecessary load is applied to the exhaust system
Solution Approach 1:
The patent applies a variable opening degree valve that dynamically adjusts the exhaust gas flow rate into the evaporation portion based on operating conditions. When the engine operates at high rotation speeds with large exhaust gas volumes, the valve reduces the flow rate to prevent excessive heating and pressure buildup, while maintaining sufficient flow during normal operating conditions for effective heat recovery. This dynamic adjustment resolves the contradiction by optimizing both heat recovery efficiency and exhaust gas discharge flow根据不同工况
Solution Approach 2:
The patent changes the operating parameters of the loop heat pipe system by controlling the exhaust gas flow rate into the evaporation portion. By adjusting the flow rate parameter based on engine operating conditions (rotation speed, load), the system maintains optimal heat recovery efficiency while preventing excessive pressure and temperature that would interrupt exhaust gas discharge. This parameter control resolves the contradiction between heat recovery and exhaust flow
2Loss of energy
If the evaporation portion continuously receives heat from exhaust gas to ensure heat recovery, then heat recovery function is maintained, but the evaporation portion may be excessively heated causing excessive evaporation and pressure buildup
Solution Approach 1:
The patent implements a feedback control mechanism where the valve opening degree is adjusted based on the actual exhaust gas flow rate and system pressure conditions. When pressure or temperature in the loop heat pipe system reaches critical levels, the valve automatically reduces exhaust gas flow into the evaporation portion, preventing excessive heating and pressure buildup. This feedback control maintains heat recovery function while ensuring system reliability by preventing excessive evaporation
Solution Approach 2:
The patent employs periodic adjustment of the exhaust gas flow rate into the evaporation portion rather than continuous maximum flow. By periodically modulating the valve opening degree according to system conditions, the system maintains effective heat recovery while allowing the loop heat pipe to dissipate excess heat and pressure, preventing continuous excessive heating and improving system reliability
3Device complexity
If the condensation portion is installed in the engine block to utilize existing temperature, then system structure is simplified, but heat transfer efficiency deteriorates when the engine block is already at high temperature
Solution Approach 1:
The patent applies dynamic control to the heat transfer process by using a variable opening degree valve to adjust the exhaust gas flow rate to the evaporation portion. When the engine block is already at high temperature, the valve reduces exhaust gas flow, thereby reducing the heat load on the condensation portion and maintaining effective heat transfer efficiency. This dynamic adjustment resolves the contradiction between simplified structure and heat transfer efficiency
Solution Approach 2:
The patent changes the operating parameters of the heat transfer system by controlling the exhaust gas flow rate based on engine operating conditions. When the engine block temperature is high, the system adjusts the exhaust gas flow parameter to prevent excessive heat transfer demand, maintaining efficient heat recovery while accounting for the simplified structure of using the engine block as the condensation portion
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively recovers heat from exhaust gas, reduces load on the engine's exhaust system, suppresses excessive evaporation and pressure, and simplifies the structure and control by eliminating the need for high-pressure resistance and electric actuators, enhancing fuel efficiency and energy conservation.
Implementation Method 1
a loop heat pipe is formed by the first heat exchanger (21), the second heat exchanger (22), the gas passage (23), and the liquid passage (25). The loop heat pipe is a device formed to circulate the fluid by using a capillary phenomenon
Implementation Method 2
The first heat exchanger (21) is formed to evaporate a heat medium by performing heat exchange between exhaust gas discharged from an internal combustion engine and the heat medium
Implementation Method 3
performing heat exchange between exhaust gas discharged from an internal combustion engine and the heat medium
Implementation Method 4
The second heat exchanger (22) is formed to heat a heated target and liquefies the heat medium by performing heat exchange between the heated target and the heat medium evaporated in the first heat exchanger
Implementation Method 5
The self-pressure valve (27) is formed to open and close such that an opening degree of the self-pressure valve (27) is changed by pressure of the exhaust gas
Data Source
AI summary
An exhaust heat recovery device includes a first heat exchanger, a second heat exchanger, a gas passage, a liquid passage, and a self-pressure valve. The first heat exchanger performs heat exchange between exhaust gas and a heat medium so as to evaporate the heat medium. The second heat exchanger performs heat exchange between a heated target and the heat medium evaporated in the first heat exchanger, the heated target being defined as at least one of cooling water and oil so as to heat the heated target and to liquefy the heat medium. A loop heat pipe is formed by the first heat exchanger, the second heat exchanger, the gas passage, and the liquid passage.