Heat Exchanger Tube Layout for Low-Weight CO2 Pressure Balance
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Solution Overview
Problem
Conventional heat exchangers face challenges in achieving sufficient heat exchange capability while reducing dimensions and weight, particularly when using carbon dioxide as a refrigerant, as smaller tube diameters lead to increased pressure loss and reduced heat exchange efficiency.
Innovation Solution
Optimizing the dimensions of heat transfer tubes and fins, with outer diameters between 5 mm and 6 mm, thickness between 0.05D and 0.09D, and specific pitch ranges for vertical and longitudinal arrangements, along with a fin pitch that maximizes heat exchange per unit weight and area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the outer diameter of heat transfer tubes is reduced to decrease weight, then the weight of the heat exchanger is reduced, but the pressure loss of the refrigerant increases significantly
Solution Approach 1:
The patent applies parameter changes by precisely optimizing the outer diameter of heat transfer tubes to a specific range (5mm≤D≤6mm) and thickness ratio (0.05×D≤t≤0.09×D), along with optimizing pitch parameters (vertical pitch 3×D≤L1≤4.2×D, longitudinal pitch 2.6×D≤L2≤3.64×D). These parameter optimizations balance the competing requirements of reducing weight while maintaining acceptable pressure loss characteristics for carbon dioxide refrigerant flow.
2Productivity
If the number of heat transfer tubes is increased to ensure sufficient heat exchange capability, then the heat exchange capability is improved, but the weight of the heat transfer tubes increases
Solution Approach 1:
The patent resolves this contradiction through parameter changes by optimizing the outer diameter to 5-6mm and establishing specific pitch relationships (vertical pitch 3-4.2 times the diameter, longitudinal pitch 2.6-3.64 times the diameter). These optimized parameters enable sufficient heat exchange capability with a reduced number of tubes compared to conventional designs, thereby reducing overall weight while maintaining performance.
3Reliability
If the thickness of heat transfer tubes is increased to ensure durability against high pressure, then the reliability is improved, but the weight of the heat exchanger increases
Solution Approach 1:
The patent applies parameter changes by defining an optimized thickness range as 0.05×D≤t≤0.09×D (where D is the outer diameter). For the specified outer diameter range of 5-6mm, this results in optimal wall thickness that provides sufficient durability against high carbon dioxide refrigerant pressure while minimizing weight. This proportional thickness specification ensures adequate strength without excessive material usage.
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 heat exchange capability per unit weight, reduces dimensions and weight, and maintains performance by minimizing pressure loss and optimizing fin pitch, resulting in a higher coefficient of performance compared to conventional designs.
Implementation Method 1
Heat exchange is effected between the refrigerant that circulates through the heat transfer tubes and the outside air by means of the heat transfer fins
Implementation Method 2
Heat exchange is effected between the refrigerant that circulates through the heat transfer tubes and the outside air
Implementation Method 3
Heat exchange is effected between the refrigerant that circulates through the heat transfer tubes
Data Source
AI summary
Provided are a heat exchanger capable of providing sufficient heat exchange capability even with heat transfer tubes having a reduced outer diameter, and a heat pump device using the same. The heat transfer tubes has an outer diameter D in a range of 5 mm≦D≦6 mm, has a thickness t in a range of 0.05×D≦t≦0.09×D, are disposed at a vertical pitch L1 in a range of 3×D≦L1≦4.2×D, and are disposed at a longitudinal pitch L2 in a range of 2.6×D≦L2≦3.64×D. A sufficiently increased heat exchange rate per unit weight is obtainable with the heat exchanger.