Waste Heat Recovery Expander Compressor Mechanical Coupling

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Solution Overview

Problem

Existing vehicle internal combustion engine waste heat recovery systems are inefficient in utilizing recovered energy, often requiring complex and costly systems to reduce exhaust back pressure, which negatively impacts engine efficiency.

Innovation Solution

A waste heat recovery system that uses a working fluid loop to convert thermal energy from exhaust gases into mechanical energy, which is directly transferred to a compressor in the exhaust line, reducing back pressure without the need for intermediate energy forms or complex connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the expander is connected to the driveline to use recovered mechanical energy, then energy utilization is improved, but system complexity increases and requires additional space and weight

Engineering Contradiction:

Improveenergy utilizationVSAvoidsystem complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The invention merges the expander output directly with the compressor input, combining two functions (energy recovery and exhaust compression) into a single integrated system. This eliminates the need for separate driveline connections and intermediate energy conversion systems, reducing overall system complexity while maintaining effective energy utilization.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The compressor acts as an intermediary device that receives mechanical energy from the expander and uses it to perform the useful function of reducing exhaust back pressure. This direct mechanical coupling through the compressor avoids complex intermediate systems while effectively transferring and utilizing the recovered energy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If multiple devices are arranged in the exhaust line for energy recovery, then energy recovery capability is improved, but exhaust back pressure increases and harms engine efficiency

Engineering Contradiction:

Improveenergy recovery capabilityVSAvoidexhaust back pressure

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The compressor serves multiple functions: it recovers energy from the exhaust stream, reduces exhaust back pressure to improve engine efficiency, and prepares the exhaust gases for further treatment devices. By combining these functions in a single device, the system achieves energy recovery without proportionally increasing back pressure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system converts the harmful effect of exhaust back pressure into a beneficial force by using the pressure differential across the compressor to drive the expander-compressor assembly. The exhaust pressure that would normally be harmful is instead utilized to power the compression process, reducing net back pressure on the engine.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Use of energy by moving object

If a waste heat recovery system is implemented, then thermal energy recovery is improved, but system cost and complexity increase

Engineering Contradiction:

Improvethermal energy recoveryVSAvoidsystem complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The invention combines the waste heat recovery expander with the exhaust compression system into a single integrated assembly. This merging of functions reduces the number of separate components and connections required, thereby reducing system complexity and cost while maintaining effective thermal energy recovery capability.

Inventive Principle:

Principle #5Merging (Combining)

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 approach enhances engine efficiency by effectively utilizing waste heat to reduce exhaust back pressure with a simpler and less costly implementation, improving overall engine performance.

Implementation Method 1

heated in a heat exchanger by means of the exhaust gases

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

the thermal energy of at least one engine fluid, such as the engine exhaust gases, is converted by the waste heat recovery system into mechanical energy by the expander

Methodology Applied

Scientific EffectThermal energy to mechanical energy conversion: Heat Engine

Implementation Method 3

compress the exhaust gases, or more particularly to benefit from the suction effect at the input of the compressor

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS9874130B2Vehicle internal combustion engine arrangement comprising a waste heat recovery system for compressing exhaust gases

Publication Date: 2018.01.23 VOLVO TRUCK CORP

AI summary

A vehicle internal combustion engine arrangement includes an internal combustion reciprocating piston engine, and an exhaust line capable of collecting exhaust gases from the engine, a waste heat recovery system carrying a working fluid in a loop, in which the working fluid is successively compressed, heated in a heat exchanger by at least one engine fluid, and expanded in a first expander, a first compressor located in the exhaust line and mechanically connected to the first expander of the waste heat recovery system.