Double-Pipe Heat Exchanger Layout to Prevent Compressor Liquid-Back
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Solution Overview
Problem
The double-pipe heat exchanger in air conditioners faces challenges in compact configuration and liquid-back phenomenon, where unevaporated liquid refrigerant flows into the compressor, and the inverted U shape configuration complicates refrigerant pipe connections.
Innovation Solution
The double-pipe heat exchanger is configured with both ends of the inner pipe at the upper end of vertical pipes, allowing for compact arrangement and preventing liquid refrigerant from flowing into the compressor, while enabling easy pipe connections without inversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the double-pipe heat exchanger is configured in an inverted U shape to achieve compact arrangement, then the arrangement space requirement is improved, but the liquid-back phenomenon occurs where unevaporated liquid refrigerant flows into the compressor
Solution Approach 1:
The patent inverts the conventional U-shaped configuration by placing the outlet at the upper end rather than the lower end. This inversion prevents liquid refrigerant from flowing back into the compressor by utilizing gravity to keep liquid at the lower portion while gas exits from the upper outlet, thus resolving the liquid-back phenomenon while maintaining compact arrangement.
Solution Approach 2:
The patent applies different quality requirements to different parts of the heat exchanger: the lower end is designed to accommodate liquid refrigerant accumulation, while the upper end is designed for gas outlet. This local differentiation of function prevents liquid carryover to the compressor while maintaining the compact inverted U-shape configuration.
2Productivity
If the double-pipe heat exchanger is configured in a vertical pipe shape to improve refrigerant flow, then the evaporation efficiency is improved, but the pipe connection task becomes troublesome requiring inversion of the heat exchanger
Solution Approach 1:
The patent inverts the conventional vertical arrangement by placing both inlet and outlet at the upper end, eliminating the need to invert the heat exchanger during installation. This maintains the vertical flow path for efficient evaporation while allowing straightforward pipe connections at the upper ends without requiring the unit to be flipped upside down.
3Ease of manufacture
If the outlet of the inner pipe is placed at the lower end to facilitate liquid drainage, then the liquid removal is improved, but the liquid-back phenomenon occurs when gas-liquid two-phase refrigerant flows upward and then downward through curved portions
Solution Approach 1:
The patent inverts the conventional lower-outlet configuration by placing the outlet at the upper end. This prevents the liquid-back phenomenon by ensuring that liquid refrigerant, being heavier, remains at the lower portion of the inverted U-shape while gas exits from the upper outlet, thus eliminating the problem of liquid carryover to the compressor.
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 prevents the liquid-back phenomenon and simplifies refrigerant pipe connections, achieving a stable and compact heat exchanger with reduced pressure loss.
Implementation Method 1
the gas-liquid two-phase refrigerant flowing in from the inlet side end of the inner pipe performs heat exchange with the high pressure liquid refrigerant flowing through the outer pipe
Implementation Method 2
is evaporated to become a gas refrigerant
Implementation Method 3
this liquid component does not easily go up in the inner pipe of the one vertical pipe
Data Source
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AI summary
A double-pipe heat exchanger capable of achieving a compact configuration and suppressing a liquid refrigerant contained in a gas-liquid two-phase refrigerant from flowing out from an inner pipe so as to prevent generation of a liquid-back phenomenon is provided. A double-pipe heat exchanger (31) includes an outer pipe (32) through which a high pressure liquid refrigerant flows, and an inner pipe (33) having an inlet side end (33A) into which a low pressure gas-liquid two-phase refrigerant obtained by reducing pressure of the high pressure liquid refrigerant flows, and an outlet side end (33B) connected to a suction side part of a compressor. The double-pipe heat exchanger (31) includes a plurality of vertical pipes (34A, 34B) arranged in the up and down direction, and a curve pipe (35) connecting ends of the plurality of vertical pipes (34A, 34B), the outlet side end (33B) of the inner pipe (33) is provided in an upper end of one vertical pipe (34B), and the inlet side end (33A) of the inner pipe (33) is provided in an upper end of the other vertical pipe (34A).