Condensation boiler with double return
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Solution Overview
Problem
Conventional boilers fail to optimally meet the energy efficiency needs of heating systems that combine high-temperature wall radiators and low-temperature underfloor heating, as they are not designed to handle water returned at different temperatures effectively, leading to suboptimal operation and energy loss.
Innovation Solution
A condensing boiler with a dual heat transfer fluid return system, featuring an additional return duct for the hotter fluid from wall radiators and a direct return duct for the colder underfloor heating fluid, optimized with separation walls and deflectors to maintain efficient heat transfer and prevent hot spots, allowing parallel treatment of fluids at different temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional boiler is used to heat both wall radiators and underfloor heating circuits, then the boiler can supply heat to both circuits, but it cannot optimally recover condensation energy because the mixed return water temperature is too high
Solution Approach 1:
The return water flow is segmented into two separate channels: a first return channel for underfloor heating circuit water and a second return channel for wall radiator circuit water. This segmentation allows each channel to maintain its specific temperature characteristics, enabling the underfloor heating water (lower temperature) to promote condensation while the wall radiator water (higher temperature) is handled separately, thus resolving the contradiction between energy recovery and circuit compatibility.
Solution Approach 2:
A mixing chamber acts as an intermediary element between the two return channels and the burner. The mixing chamber allows the colder underfloor heating return water to mix with the hotter wall radiator return water in a controlled manner, creating an optimal mixture temperature for condensation recovery while maintaining separate inlet paths that preserve the temperature advantages of each circuit type.
2Loss of energy
If the return water temperature is lowered to optimize condensation recovery, then condensation efficiency improves, but this creates incompatibility with wall radiator circuits that require higher return temperatures
Solution Approach 1:
The return water system is divided into temperature-zoned channels: the first return channel carries cooler water from underfloor heating (optimal for condensation), while the second return channel carries warmer water from wall radiators. This spatial segmentation of temperature zones allows each circuit to operate at its optimal temperature without compromising the other, with the cooler channel driving condensation recovery.
Solution Approach 2:
Different regions of the heat exchanger are assigned different thermal qualities: the first heat exchange zone interacts with cooler underfloor heating return water to maximize condensation and latent heat recovery, while the second heat exchange zone interacts with warmer wall radiator return water. This local differentiation of thermal conditions allows simultaneous optimization for both condensation efficiency and circuit compatibility.
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 configuration enhances the overall efficiency of the boiler by 2-6% by promoting condensation and maintaining effective heat transfer, optimizing energy recovery from both heating circuits.
Implementation Method 1
The thermal energy generated in the boiler, whatever its origin, is transferred via an exchanger to a heat transfer medium
Implementation Method 2
The thermal energy generated in the boiler, whatever its origin, is transferred via an exchanger to a heat transfer medium
Implementation Method 3
the passage of which from the gaseous state to the liquid state during cooling leads to a release of energy in the form of latent heat of condensation
Implementation Method 4
the passage of which from the gaseous state to the liquid state during cooling leads to a release of energy in the form of latent heat of condensation
Implementation Method 5
a burner supplied for example with domestic fuel oil, natural gas or LPG, the combustion reaction of which in the air is exothermic and generates fumes
Implementation Method 6
a burner supplied for example with domestic fuel oil, natural gas or LPG, the combustion reaction of which in the air is exothermic and generates fumes
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a condensing boiler (1) comprising a heating body (2) with a central combustion chamber (5) equipped with a burner (4) and surrounded by an exchanger (6) consisting of a volume peripheral housing a double row of pipes (11, 12) for evacuating the fumes constituting the primary of the exchanger (6), the pipes (11) of a first inner row communicating with the combustion chamber (5) and with the pipes (12) of a second outer row connected to an exhaust stack (7), at least one outgoing duct (10) and at least one return duct (8) for the coolant fluid opening out in the upper part and lower part of the peripheral volume and constituting the secondary of the exchanger (6). This boiler is characterized in that it comprises an additional duct (9) for the return of heat transfer fluid opening between the two rows of pipes (11, 12) and, in the height of the peripheral volume, between the duct(s) outlet (10) and the return duct(s) (8).