High efficiency tankless water heater
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Solution Overview
Problem
Existing water heaters, whether tankless or storage types, face inefficiencies in heating water on demand while maintaining thermal efficiency and compactness, as they either waste energy or require complex configurations to achieve high efficiency.
Innovation Solution
A tankless water heater design incorporating a primary heat exchanger and a secondary brazed plate heat exchanger, where hot flue gases flow through the primary heat exchanger and then the secondary heat exchanger, with water flowing in a spiral path through the secondary heat exchanger to maximize heat transfer and efficiency, and featuring a compact modular structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a tankless water heater design is used to heat water on demand, then energy efficiency is improved and space requirements are reduced, but thermal efficiency and heating performance may be compromised
Solution Approach 1:
The heat exchanger is divided into multiple sections with different configurations - a first section with a first configuration and a second section with a second configuration. This segmentation allows each section to optimize for different thermal conditions, with the first section handling initial heat transfer and the second section maximizing thermal efficiency through enhanced surface area and optimized flow patterns.
Solution Approach 2:
Different sections of the heat exchanger are designed with locally optimized properties - the first section has characteristics optimized for its specific thermal load while the second section has different characteristics optimized for its thermal conditions. This local quality variation ensures maximum thermal efficiency at each stage of the heating process.
2Use of energy by moving object
If a complex heat exchanger configuration is used to maximize heat transfer, then thermal efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The complex heat exchanger is segmented into distinct first and second sections, each with its own configuration optimized for specific thermal conditions. This segmentation simplifies manufacturing by allowing each section to be produced and tested independently before assembly, while still achieving overall high heat transfer efficiency.
3Volume of moving object
If a compact modular structure is used to reduce space requirements, then space efficiency is improved, but heat exchange surface area may be limited
Solution Approach 1:
The heat exchanger sections are arranged in a nested or compact modular configuration where the first and second sections are integrated within a confined space. This nesting allows maximum heat exchange surface area to be packed into minimum volume, achieving both compactness and high heat transfer capacity.
Solution Approach 2:
The heat exchanger utilizes three-dimensional spatial arrangement with sections positioned at different locations and orientations. This dimensional optimization allows efficient heat transfer surfaces to be arranged vertically and horizontally within a compact footprint, maximizing heat exchange capacity while minimizing space requirements.
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 design achieves high thermal efficiency, with water heaters operating at 95% efficiency or greater, and allows for modular, self-contained units that efficiently heat water on demand while minimizing energy waste and space requirements.
Implementation Method 1
heating the water in the tube as the flue gases flow through the primary heat exchanger
Implementation Method 2
heating the water flowing along the first set of passages as the flue gases flow along the second set of passages
Implementation Method 3
water to be heated flows through the first set of passages then through the tube
Implementation Method 4
a plurality of plates coupled together by brazing to form a brazed plate heat exchanger
Implementation Method 5
the secondary heat exchanger includes a spiral flow path, and wherein the water is configured to be directed along the spiral flow path
Data Source
AI summary
A water heater includes an outer casing defining a longitudinal axis, an axial direction being defined as extending along the longitudinal axis. The water heater further includes a combustor for production of hot flue gases, a primary heat exchanger including a tube positioned within the outer casing, and a secondary heat exchanger including a plurality of plates coupled together by brazing to form a brazed plate heat exchanger. The secondary heat exchanger includes a first set of passages defined between the plates, and a second set of passages defined between the plates and alternating with the first set of passages in the axial direction. The primary and secondary heat exchangers are in fluid communication such that the flue gases flow through the second set of passages before being exhausted, and water to be heated flows through the first set of passages to a delivery point for use upon demand.