EGR Cooler Precooling Flow Structure for Fatigue Life
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Solution Overview
Problem
Exhaust gas recirculation systems in motor vehicles face high thermal stress and strain due to high-temperature exhaust gases, leading to premature failure of the EGR cooler due to thermo-mechanical fatigue, which reduces the cooling effect and impacts engine power density.
Innovation Solution
A heat exchanger with a precooling flow structure that includes precooling tubes to cool exhaust gases before they enter the heat exchanger core, reducing thermal stress and strain by exchanging heat with a coolant before the gases reach the core, thereby extending the life of the heat exchanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If exhaust gases are cooled in the heat exchanger core, then the cooling effect on combustion is improved, but the thermal stress and strain in the inlet region cause excessive thermo-mechanical fatigue
Solution Approach 1:
The patent applies preliminary action by pre-cooling the exhaust gases in the precooling flow structure before they enter the heat exchanger core. This preliminary cooling action reduces the temperature of exhaust gases from approximately 950°C to a lower temperature before they reach the core, thereby reducing thermal stress and strain on the inlet region components and extending thermo-mechanical fatigue life while still achieving the required cooling effect.
2Object-generated harmful factors
If high temperature exhaust gases are mixed with fresh air, then nitrogen oxide emissions are reduced, but the cooling effect is reduced and engine power density is impacted
Solution Approach 1:
The precooling flow structure performs preliminary cooling of exhaust gases before they are mixed with fresh air and enter the engine. By cooling the exhaust gases in advance, the mixture temperature is reduced, improving cylinder filling and maintaining engine power density while still achieving the nitrogen oxide reduction benefit of exhaust gas recirculation.
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
The precooling of exhaust gases reduces thermal stress and strain on the heat exchanger, enhancing its lifespan and improving heat exchange efficiency, while maintaining engine performance by reducing nitrogen oxide emissions and fuel consumption.
Implementation Method 1
Each of the at least one precooling tubes is configured to convey the second fluid therethrough in order to precool the first fluid before the first fluid enters the inlet end of the heat exchanger core
Implementation Method 2
exchanging heat with a coolant before the gases reach the core
Implementation Method 3
a heat exchanger core configured for exchanging heat between a first fluid and a second fluid
Data Source
AI summary
A heat exchanger includes a housing having a heat exchanger core and a precooling flow structure disposed therein. The heat exchanger core is configured for exchanging heat between a first fluid and a second fluid. The precooling flow structure is coupled to each of the housing and an inlet end of the heat exchanger core with respect to a flow of the first fluid. An interior of the precooling flow structure is configured to convey the first fluid therethrough, The precooling flow structure includes at least one precooling tube extending through the interior of the precooling flow structure with each of the at least one precooling tubes configured to convey the second fluid therethrough in order to precool the first fluid before the first fluid enters the inlet end of the heat exchanger core.