Adjustable Heater Head Annular Gap for Stirling Engine Self-Cleaning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The inefficiency in transferring combustion heat from solid fuels to the high-temperature area of a heat engine due to deposits of combustion particles, which reduces the system's efficiency and increases maintenance costs, particularly in Stirling engine systems.
Innovation Solution
An adjustment mechanism and control unit that allows the heater head to move relative to the inflow unit, changing the annular gap's cross-section to enhance flue gas flow and remove deposits, while optimizing operational performance by switching between cleaning and performance modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If cleaning nozzles with compressed air are used to remove deposits, then cleaning is simplified, but cleaning is incomplete requiring frequent cleaning and energy consumption increases
Solution Approach 1:
The heating device performs self-cleaning by utilizing its own flue gas flow. The adjustable annular gap creates a self-cleaning effect where flue gases automatically remove deposits from the heater head and inflow unit surfaces during normal operation, eliminating the need for external cleaning interventions and associated energy consumption.
Solution Approach 2:
The annular gap between the heater head and inflow unit is made dynamically adjustable rather than fixed. This dynamic adjustment allows the gap cross-section to be optimized for different operating conditions, enabling effective self-cleaning through controlled flue gas flow patterns while maintaining optimal thermal performance.
2Reliability
If induced draft fan speed is increased to compensate for deposits, then pressure conditions are maintained, but system efficiency deteriorates
Solution Approach 1:
The adjustable annular gap provides a dynamic solution to maintain optimal flue gas flow characteristics. By adjusting the gap cross-section, the system can compensate for deposit formation without increasing fan speed, thereby maintaining pressure conditions while avoiding the energy penalty of higher fan power consumption.
Solution Approach 2:
The cross-section of the annular gap is changed as a control parameter to optimize system performance. By varying this geometric parameter, the system maintains efficient heat transfer and appropriate pressure conditions even when deposits are present, avoiding the need to increase fan speed and preserve system efficiency.
3Productivity
If the annular gap cross-section is reduced to improve heat transfer, then combustion heat utilization improves, but deposits accumulate more rapidly
Solution Approach 1:
The adjustable annular gap allows the system to dynamically optimize the balance between heat transfer efficiency and deposit management. The gap can be adjusted to provide sufficient self-cleaning flow while maintaining effective heat transfer, preventing excessive deposit accumulation that would otherwise occur with a permanently reduced gap.
Solution Approach 2:
The system employs periodic adjustment of the annular gap cross-section to alternate between heat transfer optimization and self-cleaning modes. This periodic action allows the system to accumulate some deposits during high-efficiency heat transfer phases, then use increased flue gas flow through gap adjustment to remove them, preventing excessive buildup while maintaining overall efficiency.
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 solution effectively reduces deposits on heat transfer surfaces, improves combustion heat utilization, enhances system efficiency, and decreases maintenance efforts by adjusting the annular gap's cross-section to maintain optimal pressure conditions without increasing induced draft fan power.
Implementation Method 1
a heater head (3) thermally coupled to the high-temperature area of a heat engine (4)
Implementation Method 2
The working gas expands in the heated cylinder space and contracts again in the cold cylinder, resulting in usable mechanical work
Implementation Method 3
cleaning nozzles, which are aimed at the lateral surface of the heater head and/or the inner surface of the inflow unit surrounding the heater head and through which a cleaning fluid (e.g. compressed air) is introduced in order to remove particle deposits
Data Source
Figure 1
Figure 2
AI summary
Heating device with a combustion chamber for the combustion of solid fuel and a flame tube (1) whose inlet area faces the combustion chamber and whose outlet area faces a subsequent outlet area for the removal of flue gases, wherein a heater head (3) connected to a heat engine (4) is arranged in the outlet area, which has a shell surface that tapers towards the inlet area and is surrounded by an inlet unit (6) that delimits the outlet area, the clear cross-section of which widens towards the outlet area, and an annular gap (2) for the outflowing flue gases is formed between the shell surface of the heater head (3) and the inner surface of the inlet unit (6).It is proposed that an adjustment mechanism be provided which changes the relative positioning of the heater head (3) to the inflow unit (6), as well as a control and regulation unit for the adjustment mechanism, with which the clear cross-section of the annular gap (2) formed between the outer surface of the heater head (3) and the inner surface of the inflow unit (6) can be controlled and changed.