Refrigerant Heat Exchanger Pass-Length Layout for Uniform Cooling
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Solution Overview
Problem
Existing heat exchangers in HVAC systems experience inhomogeneous refrigerant fluid temperatures across and within passes, leading to inefficient air cooling and reduced overall performance.
Innovation Solution
A heat exchanger design with specific pass length ratios and configurations, including two rows of passes with equalized lengths and communication means, ensuring homogeneous refrigerant fluid circulation and enhanced heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the heat exchanger uses multiple passes with tubes arranged between header boxes, then the heat exchange area is increased, but the temperature distribution of refrigerant fluid becomes inhomogeneous across and within passes
Solution Approach 1:
The patent applies local quality by making the inlet pass length greater than the outlet pass length. Specifically, the inlet pass is designed with a length of 1.2 to 1.5 times that of the outlet pass, creating non-uniform pass lengths tailored to the specific thermal requirements of different sections. This ensures that the refrigerant fluid has adequate time to absorb heat in the inlet section where temperature difference is larger, while preventing overheating in the outlet section.
2Power
If the refrigerant fluid circulates through multiple tubes in parallel rows, then the heat exchange capacity is improved, but the temperature homogeneity within the same pass deteriorates
Solution Approach 1:
The patent applies asymmetry by designing the inlet pass to be longer than the outlet pass, breaking the symmetric configuration of equal-length passes. The inlet pass length is specifically designed to be 1.2 to 1.5 times the outlet pass length, creating an asymmetric flow path that compensates for the temperature distribution imbalance caused by parallel tube arrangements.
3Ease of manufacture
If the heat exchanger uses equal-length passes for simplicity of manufacture, then the manufacturing cost is reduced, but the air cooling efficiency in certain areas deteriorates
Solution Approach 1:
The patent applies local quality by making the inlet pass length greater than the outlet pass length. Specifically, the inlet pass is designed with a length of 1.2 to 1.5 times that of the outlet pass, creating non-uniform pass lengths tailored to the specific thermal requirements of different sections. This ensures that the refrigerant fluid has adequate time to absorb heat in the inlet section where temperature difference is larger, while preventing overheating in the outlet section.
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 design achieves uniform refrigerant fluid temperature distribution, improving heat exchange efficiency and air cooling effectiveness.
Implementation Method 1
The heat exchanger allows a heat exchange between the refrigerant fluid and an air flow circulating inside the HVAC system
Implementation Method 2
The core comprises a plurality of tubes extending in a direction transversal to the longitudinal direction of the header boxes, with respect to which a heat exchange is allowed between the refrigerant fluid and the air flow
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a heat exchanger (1) comprising a core and at least one header box (3) that extends mainly in a longitudinal direction (A1), said core comprising at least four passes (25) distributed in two rows (11, 12), with two first inlet-passes (25) being part of a first row (11) of the heat exchanger (1) and two last outlet-passes (25) being part of a second row (12) of the heat exchanger (1). Each pass (25) has a respective length (L) measured along the longitudinal direction (A1), wherein the sum of the length (L) of the two first inlet-passes (L) is equal +/-10% to the sum of the length (L) of the two last outlet-passes (L), and the length (L) of the first inlet-pass (L) is bigger than the length (L) of the last outlet-pass (25).