Gas Engine Heat Pump Exhaust Recirculation for NOx Reduction
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Solution Overview
Problem
Existing gas engine heat pump systems face challenges in reducing nitrogen oxide production, as current nitrogen oxide reduction technologies like selective catalytic reduction require additional devices and are inefficient in the presence of oxygen, and involve the use of liquid urea which adds weight and volume.
Innovation Solution
A gas engine heat pump system that compresses and stores exhaust gases in a buffer tank, then recirculates them into the engine's intake manifold or directly into the cylinder, using an exhaust gas sensor to control the operation of valves and nozzles to lower combustion temperatures and reduce nitrogen oxide production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If selective catalytic reduction (SCR of NOx) is used to reduce nitrogen oxides, then nitrogen oxide reduction performance is improved, but additional devices (ammonia storage container, spray device) are required which increase weight and volume
Solution Approach 1:
The system uses the engine's own exhaust gas as the reductant source, eliminating the need for external ammonia storage containers and spray devices. The exhaust gas recirculation system repurposes waste exhaust gas to reduce NOx, making the system self-sufficient without additional heavy equipment.
Solution Approach 2:
The system converts harmful exhaust gas (which contains NOx and requires treatment) into a beneficial reductant for reducing NOx emissions. By recirculating exhaust gas back into the combustion chamber, the system transforms a waste product into a useful substance for emission control.
2Object-generated harmful factors
If liquid urea is sprayed onto exhaust pipe for nitrogen oxide reduction, then ammonia is produced as reductant, but additional devices are required which add weight and volume and require continuous filling
Solution Approach 1:
The system eliminates complex external urea delivery systems by using the engine's own exhaust gas as the reductant source. The exhaust gas recirculation system requires no external storage containers, spray devices, or continuous filling operations.
Solution Approach 2:
The system extracts the necessary reductant (exhaust gas containing hydrocarbons and CO) directly from the engine's own exhaust stream, eliminating the need for separate urea storage and delivery systems.
3Object-generated harmful factors
If exhaust gas is recirculated to reduce combustion temperature and nitrogen oxide production, then nitrogen oxide reduction is improved, but combustion efficiency may be affected
Solution Approach 1:
The system recirculates only a portion of the exhaust gas rather than all of it, allowing sufficient oxygen and fuel to remain for efficient combustion while still achieving adequate NOx reduction. The partial recirculation strategy balances emission control with combustion efficiency.
Solution Approach 2:
The system changes the composition parameters of the combustion charge by adding recirculated exhaust gas, which lowers the combustion temperature and consequently reduces NOx formation while maintaining acceptable combustion efficiency through controlled recirculation rates.
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 effectively reduces nitrogen oxide production by lowering combustion temperatures within the engine cylinder, thereby improving the efficiency of nitrogen oxide reduction without the need for additional devices or liquid urea storage.
Implementation Method 1
an exhaust gas compressor for compressing exhaust gases coming from the engine
Implementation Method 2
spraying the exhaust gases stored in the buffer tank into a cylinder of the engine... lowering combustion temperatures within the engine cylinder
Data Source
Figure 1
Figure 2~3
Figure 4A
AI summary
A gas engine heat pump and a method of operating the same are provided. According to an embodiment of the present disclosure, the gas engine heat pump includes: an engine for burning a mixture of air and fuel; an exhaust gas compressor for compressing exhaust gases coming from the engine; a buffer tank for storing the exhaust gases compressed by the exhaust gas compressor; an exhaust gas valve disposed between the buffer tank and an intake manifold of the engine; an exhaust gas spray nozzle for spraying the exhaust gases stored in the buffer tank into a cylinder of the engine; an exhaust gas sensor for acquiring information on the exhaust gases coming from the engine; and a controller, wherein the controller controls the operation of at least one of the exhaust gas valve and the exhaust gas spray nozzle, based on the information on the exhaust gases acquired by the exhaust gas sensor. Other various embodiments are possible.