Single pass high-efficiency condensing water heater
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Solution Overview
Problem
Commercial water heaters face challenges in achieving high-efficiency heat exchange from combustion gases to water, leading to inefficiencies and increased condensation formation.
Innovation Solution
A single-pass condensing water heating appliance with a heat exchanger structure featuring airflow obstructions that generate turbulence, a medial section with heat exchange fins, and a condensing section to enhance heat transfer and condensation collection, utilizing a flue tube, heat exchange structure, and condensing tubes to maximize heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional heat exchange structures are used in commercial water heaters, then the device complexity is reduced, but the thermal efficiency is insufficient to achieve high-efficiency heat exchange from combustion gases to water
Solution Approach 1:
The heat exchange structure is divided into multiple sections including a flue tube section, a heat exchange structure section with airflow obstructions, and a condensing section. This segmentation allows each section to perform specific functions (sensible heat exchange, turbulence generation, latent heat exchange) thereby achieving high thermal efficiency through optimized heat transfer in each zone.
Solution Approach 2:
The airflow path is configured to extend outward and generally perpendicular to the flue tube axis within the heat exchange structure. This dimensional change creates a radial airflow pattern that increases the surface area for heat exchange and enhances thermal efficiency by exposing combustion gases to heat exchange surfaces from multiple directions.
2Use of energy by moving object
If high-efficiency heat exchange is achieved through multiple passes and complex structures, then thermal efficiency improves, but the pressure drop increases
Solution Approach 1:
The heat exchange structure is designed as a single continuous pass where combustion gases flow sequentially through the flue tube section, heat exchange structure section, and condensing section. This continuous single-pass design maintains relatively low pressure drop while achieving high thermal efficiency through optimized heat transfer surfaces and turbulence generation in each section.
Solution Approach 2:
The design changes the flow parameters by generating controlled turbulence in the heat exchange structure section, which enhances heat transfer coefficients without requiring multiple passes. This turbulence, combined with the radial airflow configuration, achieves high thermal efficiency while maintaining acceptable pressure drop characteristics.
3Loss of energy
If conventional heat exchange designs are used, then the device simplicity is maintained, but condensation formation increases leading to efficiency losses
Solution Approach 1:
The condensing section is specifically designed to capture and utilize the condensation that occurs as combustion gases cool. By providing dedicated condensing surfaces and collection mechanisms, the design converts the harmful condensation loss into useful latent heat recovery, thereby reducing energy loss while managing the complexity of condensation handling.
Solution Approach 2:
The heat exchange structure is designed to facilitate the phase transition of water vapor to liquid condensate in the condensing section. This controlled phase change allows for latent heat recovery from the combustion gases, converting what would be energy loss into useful heat transfer to the water being heated.
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
The system achieves thermal efficiencies of at least 95% with reduced pressure drop, effectively transferring heat from combustion gases to water while minimizing condensate formation and ensuring thorough water heating.
Implementation Method 1
a heat exchange structure disposed downstream of the flue and defining a medial section of the airflow path... a heat exchange portion having airflow obstructions that generate a turbulence and transfer heat from the heated process air to a media surrounding an outer surface of the heat exchange structure
Implementation Method 2
transfer heat from the heated process air to a media surrounding an outer surface of the heat exchange structure
Implementation Method 3
a condensing section that defines a downstream section of the airflow path... effectively transferring heat from combustion gases to water while minimizing condensate formation
Implementation Method 4
airflow obstructions that generate a turbulence and transfer heat from the heated process air... increases a residency of the heated process air within the heat exchange structure
Data Source
AI summary
A heating system for a water heating appliance includes a heater for generating heated process air, a blower for delivering the heated process air through an airflow path, a flue that defines an upstream section of the airflow path, a heat exchange structure disposed downstream of the flue and defining a medial section of the airflow path, and a condensing section that defines a downstream section of the airflow path and is disposed downstream of the heat exchange structure. The heat exchange structure includes a heat exchange portion having airflow obstructions that generate a turbulence and transfer heat from the heated process air to a media surrounding an outer surface of the heat exchange structure. The airflow path within the heat exchange portion extends outward and generally perpendicular to a direction of the airflow path within the flue.