Micro Gas Turbine Exhaust Heat Recovery via Piston Engine
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Solution Overview
Problem
Micro gas turbines with regenerators face inefficiencies in energy recovery due to low temperature and small volume of exhaust gas, limiting the effectiveness of existing energy recycling methods.
Innovation Solution
A combined circulating system incorporating a micro gas turbine, a heat exchange unit, a circulating water tank, and a piston engine, where the exhaust gas from the regenerator is used to generate high-pressure steam that drives a piston engine connected to a power generating apparatus, effectively recycling energy through a steam engine mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a rotating machine such as a turbine is adopted to recycle energy of tail gas discharged by the regenerator, then energy recovery is attempted, but the recovery effectiveness is insufficient due to relatively low temperature and small amount of tail gas
Solution Approach 1:
The patent changes the operating parameters by using a piston engine instead of a turbine, allowing effective utilization of low-temperature, small-volume exhaust gas. The piston engine can operate efficiently at lower temperatures and pressures where turbines would be ineffective, thereby converting the previously unusable exhaust gas into useful work.
Solution Approach 2:
The patent replaces the rotating machine (turbine) with a reciprocating piston engine. This mechanical substitution allows the system to effectively harness energy from small amounts of low-temperature exhaust gas, as the piston engine's compression-ignition mechanism is more suitable for low-flow conditions compared to continuous-flow turbines.
2Productivity
If a piston engine is used to drive the power generating apparatus, then the efficiency of the whole micro gas turbine is improved, but the device complexity increases
Solution Approach 1:
The patent merges the micro gas turbine with a piston engine to form a hybrid system. The exhaust gas from the gas turbine directly feeds into the piston engine, creating a combined cycle where waste heat from one component becomes the energy source for another, thereby improving overall efficiency while sharing common infrastructure.
Solution Approach 2:
The piston engine serves multiple functions: it acts as a power generator, a heat exchanger, and a compressor for the circulating water system. This multi-functionality reduces the need for separate dedicated components, thereby managing system complexity while achieving high overall efficiency.
3Loss of energy
If circulating water is used to recover heat from exhaust gas, then energy recovery is enhanced, but the device complexity increases due to additional heat exchange units and water circulation systems
Solution Approach 1:
The circulating water system serves the piston engine's cooling needs while simultaneously functioning as the heat transfer medium for recovering energy from exhaust gas. This self-service approach means the cooling water performs dual functions: cooling the engine and absorbing waste heat for power generation, thereby reducing the need for separate dedicated heat exchange systems.
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 system enhances the overall efficiency of the micro gas turbine by effectively utilizing the heat in exhaust gas, improving energy recovery rates and simplifying the structural design with diverse piston engine configurations and the use of vacuum pumps for enhanced performance.
Implementation Method 1
an exhaust port of the regenerator is connected with an air inlet of the heat exchange unit to provide a heat source to the heat exchange unit
Implementation Method 2
a steam outlet of the heat exchange unit is connected with the piston engine to enable high pressure steam to enter the piston engine to push the piston engine to act
Data Source
AI summary
A combined circulating system of a micro gas turbine, a transportation means, and a charging system are provided. The circulating system includes the micro gas turbine, a heat exchange unit, a circulating water tank, a piston engine, and a power generating apparatus, wherein the micro gas turbine is provided with a regenerator; an exhaust port of the regenerator is connected with an air inlet of the heat exchange unit to provide a heat source to the heat exchange unit; the exhaust port of the heat exchange unit is led to atmosphere, a water inlet of the heat exchange unit is connected with a water outlet of the circulating water tank, and a steam outlet of the heat exchange unit is connected with the piston engine to enable high pressure steam to enter the piston engine to push the piston engine to produce work.