Drive Unit Cooling Circuit with Parallel Heat Recovery
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Solution Overview
Problem
The existing drive unit cooling system struggles to efficiently cool both the internal combustion engine and charge air while effectively utilizing exhaust gas heat for recovery, leading to incomplete evaporation of the working fluid and inadequate cooling of recirculated exhaust gas.
Innovation Solution
A drive unit with a special cooling circuit divided into two partial cooling circuits and a hydraulically decoupled heat recovery circuit, where the working medium is divided into parallel branches for evaporation in EGR and exhaust gas heat exchangers, allowing for efficient phase transition and mechanical energy generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat exchangers are arranged in series in the heat recovery circuit, then the working fluid is heated and converted into vaporous state, but the working fluid cannot be completely evaporated at high pressures and the recirculated exhaust gas cannot be cooled to the desired low temperature level
Solution Approach 1:
The patent divides the heat recovery circuit into two parallel heat exchangers (first heat exchanger for EGR cooling and second heat exchanger for exhaust gas heat recovery) instead of using a single series arrangement. This segmentation allows the working fluid to be distributed into two parallel streams, each receiving heat from different sources, thereby achieving complete evaporation at high pressures while also cooling the recirculated exhaust gas to the desired temperature level.
2Productivity
If a large amount of working fluid is pumped through the second cooling circuit, then both the charge air and engine cooling water can be cooled, but the working fluid cannot be completely evaporated even by heat from higher-quality heat sources
Solution Approach 1:
The patent segments the working fluid flow into two parallel branches, each passing through a separate heat exchanger. This allows the total heat input to be distributed across two heat transfer surfaces simultaneously, enabling complete evaporation of the working fluid without requiring an excessively large single-stream flow rate, thus maintaining adequate cooling capacity while achieving complete phase change.
Solution Approach 2:
The patent merges two heat recovery functions into a single parallel heat exchanger system: cooling the recirculated exhaust gas (EGR) and recovering heat from the exhaust gas to evaporate the working fluid. By combining these functions in parallel, the system achieves both cooling objectives simultaneously while ensuring complete working fluid evaporation through the combined heat input from both exchangers.
3Loss of energy
If the working fluid enters the EGR heat exchanger already preheated, then heat recovery efficiency is reduced, but the system complexity increases with separate parallel heat exchangers
Solution Approach 1:
The patent segments the heat recovery process into two independent parallel heat exchangers, allowing each to operate with fresh cold working fluid entering both simultaneously. This eliminates the preheating problem that occurs in series arrangements, maximizing heat recovery efficiency in both exchangers while the parallel configuration, though more complex, provides independent heat transfer paths that can be optimized separately.
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 achieves highly efficient cooling and heat recovery, ensuring complete evaporation of the working fluid and optimal conversion of exhaust gas heat into mechanical energy, enhancing engine performance and reducing fuel consumption.
Implementation Method 1
an increase in pressure and circulation of a working medium can be achieved within the heat recovery circuit by means of at least one pump
Implementation Method 2
a first heat exchanger that can be cooled by ambient air is arranged in the first partial cooling circuit and a further heat exchanger that can be cooled by ambient air is arranged in the second partial cooling circuit
Implementation Method 3
a phase transition of the same from liquid to vaporous aggregate state and back can be brought about in heat exchangers
Implementation Method 4
This vaporous working fluid is then fed to an expander and converted into useful mechanical energy by means of this with appropriate relaxation
Implementation Method 5
The working fluid is then converted back into its liquid state as it flows through a cooled condenser
Data Source
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AI summary
The invention relates to a drive unit whose two-stage turbocharged internal combustion engine is, according to the invention, assigned a special cooling circuit (10) and an independent heat recovery circuit (11) hydraulically decoupled from the latter. Within the cooling circuit (10), a coolant is circulated by means of at least one pump (12) into a first partial cooling circuit (10/1) and a second partial cooling circuit (10/2) which is hydraulically coupled or decoupled from the first partial cooling circuit. The first (10/1) is a high-temperature circuit and the second (10/2) is a low-temperature circuit. An air-cooled heat exchanger (13 or 16) is arranged in each of them. Furthermore, a main charge air cooler (9) and an intercooler (8) are arranged in the second partial cooling circuit (10/2).Within the heat recovery circuit (11), a pressure increase and circulation of a working fluid can be achieved by means of at least one pump (17), whereby this fluid can be converted from the liquid to the vaporous state and back again in heat exchangers (18, 19, 20). After the pump (17), the working fluid is divided into two parallel partial flows: in a first parallel branch (11a) into an EGR heat exchanger (18) through which recirculated exhaust gas flows, and in a second parallel branch (11b) through which exhaust gas flows downstream of the low-pressure turbine (2/1) in the exhaust gas stream (4, 4d), it is converted into a vaporous state. This vaporous state is then fed to an expander (21) and converted into usable mechanical energy by means of this expander. This working fluid is then passed through a cooled condenser (20), thereby being liquefied again, and subsequently fed back into the aforementioned circuit by means of the pump (17).