Condensing Boiler Flue with Internal Condensate Separation
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Solution Overview
Problem
Condensing gas boilers experience reduced efficiency due to heat loss and undesirable pluming caused by condensation of moisture in the flue gas, which is visually unattractive and poses public health concerns, especially in densely populated areas.
Innovation Solution
A modified flue system with an elongate liquid collector and gas flow director within the flue pipe to collect and redirect condensation away from the flue gas stream, utilizing a cooled flue pipe, PTFE coating to prevent wetting, and baffle plates to guide condensate towards a collector, reducing re-evaporation and pluming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the flue gas temperature is reduced to maintain boiler efficiency in condensing mode, then heat loss is minimized and boiler efficiency is improved, but moisture condensation increases causing visible pluming and public health issues
Solution Approach 1:
The flue pipe is divided into multiple functional zones: a cooling section with internal fins for condensation, a separation section with a liquid collector to remove condensate, and a discharge section. This segmentation allows the system to condense moisture for heat recovery while separating and removing the condensed liquid before discharge, preventing pluming.
Solution Approach 2:
A liquid collector (baffle plate) is introduced as an intermediary component between the condensation zone and the discharge zone. This baffle plate collects and redirects condensate droplets away from the flue gas stream, preventing re-evaporation and pluming while allowing the flue gas to maintain lower temperatures for efficiency.
2Object-generated harmful factors
If the flue pipe is cooled to enhance condensation and moisture removal, then pluming is reduced, but the complexity of the flue system increases
Solution Approach 1:
The cooling fins are integrated directly into the flue pipe wall structure, merging the heat exchange function with the structural component. The liquid collector is formed as an integral feature of the flue pipe geometry. This merging approach reduces the number of separate components and simplifies manufacturing while achieving the cooling and condensation functions.
Solution Approach 2:
The flue pipe design uses the temperature difference between the hot flue gas and the external environment to drive the condensation process automatically. The internal fins passively cool the gas flow, and gravity causes condensate to drain along the pipe walls to the collection point, eliminating the need for active cooling systems or pumps.
3Object-generated harmful factors
If gas flow director means are added to urge flue gas adjacent to the flue pipe wall for enhanced condensation, then moisture removal is improved, but the device complexity increases
Solution Approach 1:
The flue pipe incorporates a helical or curved internal surface that guides the flue gas flow in a rotating pattern along the pipe wall. This curvature creates centrifugal forces that press the gas against the cooled surface, enhancing condensation without requiring additional mechanical flow directors or complex control 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
Significantly reduces moisture content in the flue gas exit, minimizing pluming and maintaining boiler efficiency by effectively collecting and removing condensate from the flue gas stream.
Implementation Method 1
the moisture within the flue gas formed as a by-product of the combustion process is far more likely to condense in the vicinity of the flue outlet
Implementation Method 2
the interior surface of the flue is coated with a material that does not wet. A suitable material is PTFE
Implementation Method 3
a liquid guide disposed within the flue pipe for directing droplets of moisture to flow towards the liquid collector
Implementation Method 4
an elongate liquid collector within the flue pipe and adapted to collect condensation from the interior of the flue pipe and to shield it from the flue gas
Data Source
AI summary
A flue offering reduced pluming is provided, the flue comprising a flue pipe for carrying flue gas and a liquid collector adapted to collect condensation from the interior of the flue pipe and to shield it from the flue gas.